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Improving nitrogen fertilizer recommendations for arable crops in the Lower Fraser Valley Weinberg, Naomi Hélène 1987

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IMPROVING NITROGEN FERTILIZER RECOMMENDATIONS FOR ARABLE CROPS IN THE LOWER FRASER VALLEY by NAOMI HELENE WEINBERG B.Sc. ( H o n o u r s ) U n i v e r s i t y o f N e w c a s t l e Upon T y n e , 1983 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n FACULTY OF GRADUATE STUDIES (Dep a r t m e n t o f S o i l S c i e n c e ) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 1987 @ Naomi H e l e n e W e i n b e r g , 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6(3/81) ABSTRACT A two year f i e l d study located i n Delta M u n i c i p a l i t y , B r i t i s h Columbia, was conducted to inves t igate the poss ib le improvement of nitrogen (N) f e r t i l i z e r recommendations for arable crops i n the Lower Fraser Val ley (LFV). After reviewing current N f e r t i l i z e r recommendation systems i n other humid regions, the approach taken i n the study was to determine the a p p l i c a b i l i t y of a spr ing s o i l tes t and/or a N Index system for the LFV region. The project , which used sweet corn (Zea Mays saccharata) as the t r i a l crop, consisted of two interconnected part s : 1) A 'Repl icated F e r t i l i z e r Response T r i a l ' which aimed to; a) Monitor s o i l N0 3 -N and NH 4-N during spr ing to a depth of 80cm, using i n t e r v a l s of 0-20, 20-50, and 50-80cm. b) Invest igate y i e l d response and N uptake e f f i c i e n c y at four d i f f e r e n t rates of s idedress appl ied urea, 0, 50, 100 and 200 kg h a - 1 N. c) Compare the e f fect iveness of urea appl ied broadcast preplant , and appl ied by s idedress ing , when the crop was approximately 30cm t a l l . 2) A 'Mult i farm Survey' at 28 locat ions , comparing p lo t s s idedressed with 135 kg h a - 1 N, to contro l p lo ts containing only s t a r t e r N. The aim of t h i s survey vas to e s t a b l i s h the range of N supplying capac i t i e s i n some LFV s o i l s and r e l a t e these c a p a c i t i e s to other s o i l propert ies and s i t e h i s tory . Monitoring mineral N in the s o i l demonstrated that s o i l N0 3 -N increased during the spr ing , reaching a peak 5-6 weeks af ter i i p l a n t i n g . Maximum N0 3-N l e v e l s i n the 0-80cm p r o f i l e were 90 and 135 kg ha" 1 i n 1984 and 1985 r e s p e c t i v e l y . NH«-N l e v e l s tended t o be low compared to NOj-N. As a p r o p o r t i o n of t o t a l m i n e r a l N, NH*-N decreased from approximately 25% at the beginning of May, t o between 10 and 15% by mid June. Large amounts of s p a t i a l and temporal v a r i a b i l i t y i n both N0 3-N and NH«-N were observed on the two s i t e s s t u d i e d . The d i f f e r e n c e i n magnitude of m i n e r a l N between the years was due to a l a r g e number of s i t e and weather f a c t o r s which c o u l d not be separated. No s i g n i f i c a n t d i f f e r e n c e s i n corn y i e l d or crop N content were found between any of the f o u r f e r t i l i z e r treatments i n the R e p l i c a t e d Response T r i a l . S i m i l a r l y , no s i g n i f i c a n t d i f f e r e n c e s were found i n the comparison of urea N a p p l i e d by b r o a d c a s t i n g b e f o r e p l a n t i n g and urea N a p p l i e d by s i d e d r e s s i n g . Two reasons f o r t h i s l a c k of response were suggested, one, t h a t the s o i l p l u s s t a r t e r N p r o v i d e d s u f f i c i e n t N f o r the crop's needs, and two, t h a t the f e r t i l i z i n g t e chniques were i n e f f i c i e n t c o n s i d e r i n g the s o i l and weather c o n d i t i o n s . The M u l t i f a r m Survey p r o v i d e d the g r e a t e s t amount of i n f o r m a t i o n r e l e v a n t to the p r o j e c t ' s o b j e c t i v e s . I t showed t h a t the range of s o i l types and c r o p p i n g regimes on corn f i e l d s i n D e l t a M u n i c i p a l i t y was too narrow to have a d i r e c t i n f l u e n c e on N s u p p l i e d by the s o i l . S o i l N s u p p l y i n g c a p a c i t y was shown t o be weakly r e l a t e d t o o r g a n i c matter, the study r e s u l t s suggested t h a t a knowledge of s i t e h i s t o r y was necessary b e f o r e t h i s r e l a t i o n s h i p c o u l d be assumed to be p o s i t i v e . Such f i n d i n g s favoured the implementation of a s p r i n g s o i l t e s t r a t h e r than a N i i i Index system. V a r i o u s approaches t o e s t i m a t i n g N f e r t i l i z e r requirements u s i n g a s p r i n g s o i l sample were examined. In c o n c l u s i o n , the p r o j e c t showed t h a t s u b s t a n t i a l amounts of N vere made a v a i l a b l e by the s o i l and t h a t these should be taken i n t o c o n s i d e r a t i o n when f e r t i l i z e r recommendations are made. The study suggested t h a t i n a s m a l l a g r i c u l t u r a l r e g i o n such as D e l t a M u n i c i p a l i t y , s p r i n g s o i l N0 3-N appeared t o be s u f f i c i e n t l y w e l l c o r r e l a t e d with t o t a l s o i l p l u s crop n i t r o g e n t o warrant the f u r t h e r i n v e s t i g a t i o n of a s o i l t e s t f o r N. T h i s t e s t , f o r corn, should be as c l o s e as p o s s i b l e t o s i d e d r e s s time and the i d e a l sampling depth would be t o 80cm. Anomalous s i t e s with adverse s o i l c o n d i t i o n s , such as poor drainage, marine i n f l u e n c e s , low pH or compaction should not be i n c l u d e d i n the t e s t . i v TABLE OF CONTENTS PAGE ABSTRACT i i TABLE OF CONTENTS v LIST OF TABLES. v i i i LIST OF FIGURES x LIST OF APPENDICES x i ACKNOWLEDGEMENTS. x i i i 1. INTRODUCTION 1 1.1 Nitrogen f e r t i l i z e r and i t s use i n the Lower Fraser Valley 1 1.2 Objectives 5 2. LITERATURE REVIEW 6 2. 1 The Nitrogen Requirement Equation 6 2.1.1 The Nitrogen Requirement & 2. 1. 2 Nitrogen supplied by the s o i l 8 2.1.3 Nitrogen supplied by manure and f e r t i l i z e r 11 2.2 Nitrogen f e r t i l i z e r recommendations i n humid regions...14 2.2.1 Plant analysis 14 2. 2. 2 S o i l sampling 18 Mineral nitrogen measurements 21 Estimating mineralization 23 S o i l sampling methods used i n Western Europe 25 S o i l sampling methods proposed i n Eastern USA 28 2.2.3 S o i l Nitrogen Index Systems. 30 2. 2. 4 Computer modelling 34 2. 3 Approach used i n t h i s study 39 3. METHODS 42 3. 1 Project design 42 3. 2 F i e l d methods 44 3.2.1 Nitrogen Monitoring Study, F e r t i l i z e r Response T r i a l and Preplant versus Sidedress Urea Study...44 Plot layout 45 Methods of f e r t i l i z a t i o n 45 S o i l measurements 46 Crop harvest 47 3.2.2 Multifarm Survey of s o i l nitrogen supplying a b i l i t y 48 v 3. 3 Laboratory methods 49 3. 4 S t a t i s t i c a l a n a l y s i s 50 4. RESULTS AND DISCUSSION 52 4. 1 N i t r o g e n monitoring d u r i n g s p r i n g 53 4.1.1 S o i l m i n e r a l n i t r o g e n , magnitude and v a r i a b i l i t y 53 4.1.2 S o i l ammonium 56 4.1.3 S o i l n i t r a t e and s o i l temperature 57 4.1.4 V a r i a b i l i t y of bulk d e n s i t y measurements 57 4.2 F e r t i l i z e r N i t r o g e n Response T r i a l and P r e p l a n t v e r s u s S i d e d r e s s Urea Study 60 4. 2. 1 Crop response to f e r t i l i z e r 60 4. 3 M u l t i f a r m Survey 63 4. 3. 1 S o i l n i t r o g e n s u p p l y i n g c a p a c i t i e s 63 4.3.2 Bulk d e n s i t i e s o f the M u l t i f a r m T r i a l s i t e s 65 4. 3. 3 S o i l n i t r o g e n and p r e v i o u s c r o p p i n g 65 4.3.4 S p r i n g s o i l n i t r o g e n and s o i l p r o p e r t i e s 67 Organic matter and t o t a l n i t r o g e n 68 S o i l t e x t u r e 68 pH 70 Marine e f f e c t s 70 S o i l n i t r a t e measured by the Kelowna l a b o r a t o r y 71 4. 3. 5 S p r i n g s o i l n i t r o g e n and corn response 73 Numbers of t i l l e r s , cobs and s t a l k s 77 Y i e l d s of s t a l k s , cobs and the whole plant..77 R e l a t i v e y i e l d 79 S t a l k , cob and whole p l a n t n i t r o g e n 80 4. 3. 6 Corn response on problem s o i l s 81 5. NITROGEN FERTILIZER RECOMMENDATIONS IN THE LOWER FRASER  VALLEY - INTERPRETATION OF THE RESULTS 83 5. 1 Ni t r o g e n requirement f o r sweet corn 83 5. 2 N i t r o g e n s u p p l i e d by the s o i l 86 5.2.1 S o i l sampling versus a N i t r o g e n Index System 86 5. 2. 2 Implementing a s p r i n g s o i l t e s t 89 Depth of sampling 89 Time of sampling 90 5.2.3 E s t i m a t i n g s o i l a v a i l a b l e n i t r o g e n u s i n g h a r v e s t - t i m e measurements 90 5.2.4 P r e d i c t i n g s o i l a v a i l a b l e n i t r o g e n from n i t r a t e found at s i d e d r e s s time 94 5.3 E f f i c i e n c y of crop uptake of s o i l m i n e r a l n i t r o g e n 98 5.4 E f f i c i e n c y of crop uptake of f e r t i l i z e r n i t r o g e n 100 5.5 N i t r o g e n s u p p l i e d by f e r t i l i z e r and/or manure 101 5. 5. 1 E s t i m a t i n g f e r t i l i z e r requirements u s i n g the Nit r o g e n Requirement Equation 101 5.5.2 E s t i m a t i n g f e r t i l i z e r requirements u s i n g the r e l a t i o n s h i p s between crop response and s o i l n i t r a t e 102 v i E s t i m a t i n g f e r t i l i z e r requirements u s i n g the l i n e a r r e l a t i o n s h i p between crop response and s o i l n i t r a t e 103 E s t i m a t i n g f e r t i l i z e r requirements u s i n g the l o g a r i t h m i c r e l a t i o n s h i p between crop response and s o i l n i t r a t e 105 6. CONCLUSIONS 114 7. REFERENCES. 117 8. APPENDICES 126 v i i LIST OF TABLES PAGE Table 1. P r e c i p i t a t i o n and temperature summaries Oct. 1983 -Sept. 1985 3 Table 2.1 Approximate t o t a l N content and d i s t r i b u t i o n i n good y i e l d s of some major crops 7 Table 2.2 General summary of current s o i l nitrogen evaluation systems i n various regions of the United States 19 Table 2.3a Ess e n t i a l data of N. t„ method for crops grown on deep s o i l s 27 Table 2.3b Rapid nitrogen test before the usual date of top dressing for winter wheat 27 Table 2. 4 Nitrogen Index - based on l a s t crop grown 33 Table 2.5 Summary of processes considered i n the s i x models presented at the Nitrogen Cycle Simulation Model Workshop - Netherlands 1983 36 Table 4. 1 S o i l n i t r a t e during spring 1984 and 1985 55 Table 4. 2 S o i l ammonium during spring 1984 and 1985 55 Table 4.3 Replicated F e r t i l i z e r Response T r i a l : Means and c o e f f i c i e n t s of v a r i a t i o n for n i t r a t e and bulk density 59 Table 4.4 Replicated F e r t i l i z e r Response T r i a l , Urea Preplant versus Sidedress T r i a l 1984, 1985: Corn data, s i t e means and c o e f f i c i e n t s of v a r i a t i o n 61 Table 4.5 Replicated F e r t i l i z e r Response T r i a l 1984, 1985: S o i l n i t r a t e , means and c o e f f i c i e n t s of v a r i a t i o n before planting and at sidedress time 62 Table 4.6 Multifarm T r i a l : S o i l n i t r a t e and ammonium at sidedress time, mean and range over 27 s i t e s 64 Table 4.7 Multifarm T r i a l : Bulk density, range and averages...66 Table 4.8 Multifarm T r i a l : S o i l parameter ranges and s i g n i f i c a n t c o r r e l a t i o n s at three depths between s o i l c h a r a c t e r i s t i c s and ' F i e l d Moist' extracted s o i l n i t r a t e at sidedress time 69 v i i i Table 4.9 Multifarm T r i a l : S i g n i f i c a n t c o rrelations between s o i l / c r o p parameters and s o i l n i t r a t e (sidedress time) extracted by the'Kelowna' and 'F i e l d Moist' methods 72 Table 4.10a Multifarm T r i a l : S i g n i f i c a n t c o r r e l a t i o n s between s o i l n i t r a t e and ammonium extracted 'F i e l d Moist' and corn y i e l d parameters 74 Table 4.10b Multifarm T r i a l : S i g n i f i c a n t c o r r e l a t i o n s between s o i l n i t r a t e and ammonium extracted 'F i e l d Moist' and corn y i e l d parameters 75 Table 4.10c Multifarm T r i a l : S i g n i f i c a n t c o r r e l a t i o n s between s o i l n i t r a t e and ammonium extracted ' F i e l d Moist' and corn y i e l d parameters 76 Table 4.11 Multifarm T r i a l , Problem s o i l s : Selected c o r r e l a t i o n s between crop parameters and s o i l n i t r a t e , problem s i t e s excluded 62 Table 5.1 Multifarm T r i a l : Estimating nitrogen supplied by the s o i l . Linear regressions between crop nitrogen plus s o i l mineral nitrogen at harvest and s o i l mineral nitrogen at sidedress 95 Table 5.2 Nitrogen F e r t i l i z e r Recommendations: C r i t i c a l ranges of n i t r a t e d i v i d i n g responsive and unresponsive s i t e s using the Cate-Nelson method....112 ix LIST OF FIGURES PAGE Figure 1. Annual water balance of the Lower Fraser Valley 4 Figure 2. Measured and simulated course of nitrate-nitrogen i n the arable layer and i n the upper 60cm 37 Figure 3. Multifarm T r i a l : Plot locations, Delta Municipality, B r i t i s h Columbia 43 Figure 4.1 S o i l n i t r a t e to a depth of 80cm during spring 54 Figure 4.2 Relationship between s o i l n i t r a t e (0-20cm depth) and s o i l temperature 58 Figure 5.1 Relationship between t o t a l corn nitrogen and cob y i e l d , fresh 84 Figure 5.2 Relationship between mineralization as a proportion of organic matter and organic matter (0-50cm) 88 Figure 5.3 Relationship between mineralization and s o i l mineral nitrogen (0-50cm) at sidedress 93 Figure 5.4 Relationship between s o i l n i t r a t e (0-80cm) plus crop nitrogen at harvest and s o i l n i t r a t e (0-80cm) at sidedress 97 Figure 5.5 Relationship between crop nitrogen uptake and t o t a l crop plus s o i l nitrogen at harvest 99 Figure 5.6 Relationship between cob y i e l d , fresh and s o i l n i t r a t e (0-80cm) at sidedress..... 104 Figure 5.7 Relationship between stalk y i e l d , fresh and s o i l n i t r a t e (0-20cm) at sidedress showing population s p l i t using the Cate-Nelson method 107 Figure 5.8 Relationship between whole plant y i e l d , fresh and s o i l n i t r a t e (0-20cm) at sidedress showing population s p l i t using the Cate-Nelson method 108 Figure 5.9 Relationship between r e l a t i v e y i e l d , fresh and s o i l n i t r a t e <0-50cm) at sidedress showing population s p l i t using the Cate-Nelson method 109 x LIST OF APPENDICES PAGE Appendix 1. Daily p r e c i p i t a t i o n Apr. - Sept. 1984/1985 126 Appendix 2. S o i l c h a r a c t e r i s t i c s of Reynelda Farm s i t e s 127 Appendix 3. F i e l d plan example, Replicated F e r t i l i z e r Response T r i a l , S i t e A 128 Appendix 4. Questionnaire sent to farmers to obtain s i t e information 129 Appendix 5. Methods used for s o i l analysis by B. C. Feed and Tissue Testing Laboratory, Kelowna 130 Appendix 6. Multifarm T r i a l : Previous cropping, mineralization, crop plus s o i l nitrogen (0-80cm) and f e r t i l i z e r e f f i c i e n c y estimates 131 Appendix 7. Multifarm T r i a l : S o i l n i t r a t e and ammonium (kg h a - 1) at sidedress 132 Appendix 8a. Nitrogen monitoring study: 1) 25 A p r i l 1984 2) 9 May 1984 133 Appendix 8b. Nitrogen monitoring study: 1) 23 May 1984 2) 7 June 1984 134 Appendix 8c. Nitrogen monitoring study: 1) 20 June 1984 2) 4 July 1984 135 Appendix 8d. Nitrogen monitoring study: 1) 8 May 1985 2) 22 May 1985 136 Appendix 8e. Nitrogen monitoring study: 1) 5 June 1985 2) 19 June 1985 137 Appendix 8f. Nitrogen monitoring study: 1) 2 July 1985 2) 16 July 1985 138 Appendix 9a. Replicated f e r t i l i z e r response t r i a l : S o i l data, preplant 139 Appendix 9b. Replicated f e r t i l i z e r response t r i a l : S o i l data, sidedress 140 Appendix 9c. Replicated f e r t i l i z e r response t r i a l : S o i l data, harvest 141 Appendix 10. Replicated f e r t i l i z e r response t r i a l : Corn data.142 x i Appendix 11a. P r e p l a n t versus s i d e d r e s s urea t r i a l : S o i l data, p r e p l a n t 143 Appendix l i b . P r e p l a n t versus s i d e d r e s s urea t r i a l : S o i l data, s i d e d r e s s 144 Appendix 11c. P r e p l a n t versus s i d e d r e s s urea t r i a l : S o i l data, h a r v e s t 145 Appendix 12. P r e p l a n t versus s i d e d r e s s urea t r i a l : Corn data.146 Appendix 13a. M u l t i f a r m t r i a l : S i t e p r o p e r t i e s 147 Appendix 13b. M u l t i f a r m t r i a l : S i t e p r o p e r t i e s 148 Appendix 13c. M u l t i f a r m t r i a l : S i t e p r o p e r t i e s 149 Appendix 13d. M u l t i f a r m t r i a l : S i t e p r o p e r t i e s 150 Appendix 14a. M u l t i f a r m t r i a l : S o i l data from c o n t r o l p l o t s at s i d e d r e s s 151 Appendix 14b. M u l t i f a r m t r i a l : S o i l data from f e r t i l i z e d p l o t s at s i d e d r e s s 152 Appendix 14c. M u l t i f a r m t r i a l : S o i l data from c o n t r o l p l o t s at h a r v e s t 153 Appendix 14d. M u l t i f a r m t r i a l : S o i l data from f e r t i l i z e d p l o t s at h a r v e s t 154 Appendix 15. M u l t i f a r m t r i a l : Kelovna s o i l n i t r a t e v a l u e s . . . . 155 Appendix 16a. M u l t i f a r m t r i a l : Corn data 156 Appendix 16b. M u l t i f a r m t r i a l : Corn data 157 Appendix 16c. M u l t i f a r m t r i a l : Corn data. 158 Appendix 16d. M u l t i f a r m t r i a l : Corn data 159 x i i ACKNOWLEDGEMENTS I wish to thank my supervisor. Dr. Art Bomke, for his advice, support and patience regarding t h i s endeavour. I also thank him f o r his help during the f i e l d seasons and extend s i m i l a r thanks to Elizabeth Deom and Dave McKimm my hard-working summer assistants. I would also l i k e to 'thank the many people who assisted with harvesting and eating the sweet corn. I am indebted to Mr. Hugh Reynolds and Mr. John Malenstyn for allowing the experimental plots to be located on t h e i r f i e l d s . I am also e s p e c i a l l y g r a t e f u l to Mr. Irvine Schinkel of Royal City Foods, without his cooperation the Multifarm Survey could not have existed. The B.C.A.S.C.C. are also thanked for providing f i n a n c i a l support f o r the project. The laboratory analysis could i n no way have been completed without the assistance, patience and good humour of P a t t i Carbis and Eveline Wolterson, these two technicians cannot be thanked enough. The B.C. Feed and Tissue Testing Laboratory, Kelowna, i s also appreciated f o r providing gratuitously t h e i r services for analyzing the Multifarm Survey s o i l s . I am also g r a t e f u l for the assistance of Bruce McGillvray regarding the computer analyses. I f i n a l l y thank my f r i e n d Ian E l l i o t who p e r s i s t e n t l y encouraged me during the arduous parts of t h i s project and a l l those who read the thesis and provided constructive c r i t i c i s m notably my committee members Mr. Ron Bertrand, Dr.Lawrence Lowe and Dr. Les Lavkulich. x i i i 1 1. INTRODUCTION 1.1 NITROGEN FERTILIZER AND ITS USE IN THE LOWER FRASER VALLEY Over the past 30 years, world f e r t i l i z e r nitrogen (N) production has increased from approximately 5 m i l l i o n tonnes to almost 50 m i l l i o n tonnes (Hignett 1985). This large increase i n N f e r t i l i z e r demand i s just one i n d i c a t i o n of the current importance of N for a g r i c u l t u r a l crop production. N i s e s s e n t i a l i n a l l a g r i c u l t u r a l crops to form proteins and c h l o r o p h y l l ; N deficiency i s displayed by a d i s t i n c t chlorosis, usually s t a r t i n g i n the lower leaves, the upper leaves tending to remain green due to the high mobility of N i n the plant. Inadequate N, or an N imbalance r e l a t i v e to other s o i l nutrients, w i l l cause lowered protein concentrations i n grains and i n general, lowered yields. N i s the most commonly d e f i c i e n t plant nutrient. The vast amount of research l i t e r a t u r e regarding N use shows that crops i n most a g r i c u l t u r a l regions of the world respond favourably to i n t e l l i g e n t l y applied N; consequently, most countries f e r t i l i z e at l e a s t some proportion of t h e i r crops with N. In the Lower Fraser Valley (LFV) of B r i t i s h Columbia, the region of t h i s study, N addition i s a routine management practice f o r growing a l l the major crops, i . e . hay and fodder, vegetables, and corn. The problem however, i s that farmers i n the LFV know very l i t t l e about how much N should be applied. Present N f e r t i l i z e r recommendations i n the LFV consist of a single rate of N for an in d i v i d u a l crop, as outlined i n the publication, " F e r t i l i z e r Guide for the Lower Mainland" (B.C. Ministry of Agriculture 1977). These recommendations do not incorporate any form of s o i l t e s t for N, they take no account of previous cropping or s o i l type, and pay only l i p service to any manure applications, ('Manure' i n t h i s thesis r e f e r s to manure and s l u r r y ) . The r e s u l t of such crude recommendations i s that frequently excess f e r t i l i z e r i s applied, p o t e n t i a l l y causing s o i l a c i d i f i c a t i o n (Kowalenko 1986), environmental p o l l u t i o n (Kohut, Leibscher, personal communications with C.G.Kowalenko, Agriculture Canada:Agassiz 1986), and wasted money; less often, i n s u f f i c i e n t applications are made, these can cause a loss i n potenti a l crop y i e l d . Winter p r e c i p i t a t i o n (Oct.- Mar.) averages 815mm at Vancouver International Airport, the most Western point of the LFV (Table 1), and annual p r e c i p i t a t i o n across the region ranges from 1,000mm to 1,500mm, 75% of t h i s f a l l i n g over winter. Fig.1 shows the annual water balance of the LFV. As a consequence of the high winter r a i n f a l l i n the LFV i t was generally assumed that minimal carry-over of residual N occurred season to season, hence s o i l t e s t i n g for N, as used i n other parts of B.C., was considered inappropriate. Recent studies however, have shown appreciable quantities of mineral N i n LFV s o i l s at the s t a r t of the growing season (Guthrie and Bomke 1980; Khan 1986). For example, Khan (1986) found 99 kg ha" 1 i n the top 90cm of a previously unmanured LFV s o i l i n May 1983. At the same time, Table 1. Precipitation and temperature summaries Oct.1983 - Sept.1985. Vancouver International Airport. (Monthly Means) Month Precipitation (urn) Air Temperature (°C) 1983-84 1984-85 30Yr.Av. 1983-84 1984-85 30Yr.Av Oct 89.9 129.5 122.2 9.5 5.6 10.1 Nov 350.8 237.2 141.2 7.6 3.2 6.1 Dec 83.9 159.6 165.4 0.7 -2.2 3.8 Jan 223.9 28.2 147.3 4.4 I- 5 2.4 Feb 177.6 93.1 116.6 6.2 3.3 4.4 Mar 128.6 101.9 93.7 7.9 5.2 5.8 Apr 124.2 80.6 61.0 8.8 8.5 8.9 May 111.1 44.1 47.5 11.3 12.2 12.4 Jun 69.0 31.8 45.2 14.7 15.1 15.3 Jul 3.9 TR 29.7 17.2 19.3 17.4 Aug 15.7 31.5 37.1 17.6 17.0 17.1 Sep 41.6 59.1 61.2 13.9 13.1 14.2 F R A S E R V A L L E Y W A T E R B A L A N C E 160 8 0 mm -i month S T O R A G E J F M A M J J A S O N D drainage irrigation Ficjure 1. Annual water balance of tne Lower F r a s e r V a l l e y . (From Hare and Thomas 1974) 144 kg ha" 1 N was found i n a s i m i l a r depth of s o i l to which 120 t ha" 1 pig manure had been applied i n 1982. Such results, plus s i m i l a r findings by Meisinger (1982) i n Maryland, suggest that even i n humid regions s o i l mineral N should be included i n f e r t i l i z e r recommendations. In his recent evaluation of N use in B.C., Kowalenko (1986), concluded that N applications i n the LFV are currently close to, or exceeding, the maximum recommended, e s p e c i a l l y when manure i s included. Furthermore, he stressed that the research data on s o i l N i n t h i s region i s at present inadequate for improving N f e r t i l i z e r recommendations. 1.2 OBJECTIVES In order to improve the precision of current N f e r t i l i z e r recommendations i n the LFV, t h i s study was set up with the following objectives: 1. To monitor s o i l mineral N changes during the spring. 2. To i d e n t i f y the N requirement for corn on a s p e c i f i c s i t e and investigate y i e l d response and N uptake e f f i c i e n c y at four rates of applied N. 3. To compare preplant versus sidedress applied urea. 4. To determine the N supplying capacities of some LFV s o i l s and r e l a t e these to other s o i l properties, previous cropping and crop response. 2.LITERATURE REVIEW 2.1 THE NITROGEN REQUIREMENT EQUATION N Requirement = e t (N supplied by the s o i l ) + e e (N provided by f e r t i l i z e r and/or manure) (e = e f f i c i e n c y factor for N uptake) This equation represents the most extreme s i m p l i f i c a t i o n of the N requirement components for a non-leguminous crop. The following discussion w i l l expand on these components i n order to outline the factors involved i n the improvment of N recommendations i n the Fraser Valley. 2.1.1 THE NITROGEN REQUIREMENT The N requirement f o r a s p e c i f i c crop i s determined by the N demand of that crop and the y i e l d objective. The N demand varies greatly with species, s u b s t a n t i a l l y larger N contents are found i n forages than i n representative y i e l d s of cereal crops (Table 2.1). The y i e l d objective, or 'Target Yield', i s derived by one of many pathways, ranging from pure 'seat of the pants' guesswork or experience, to sophisticated computer modelling. The most recent trend for the determination of t h i s y i e l d objective i s the use of the 'Maximum economic y i e l d ' (MEY) philosophy, (Tisdale et a l . 1985). This i s simply the y i e l d 7 Tab le 2 .1 Approximate t o t a l N content and d i s t r i b u t i o n i n good y i e l d s o f some major c r o p s . From Olson and K u r t z (1982) and B e t t e r Crops (1979) . Crop P l a n t P a r t s %N Dry Y i e l d kg ha"' T o t a l N kg h a ' Corn ( S i l a g e ) G r a i n 1.5 10,000 150 S tove r 0 .9 9,000 80 Corn (Sweet) G r a i n 2 .2 4,100 90 S tover 1.2 5,500 65 Pota toes ( I r i s h ) Tubers 0 .3 56,000 170 V i n e s 2 .3 5,000 115 Wheat G r a i n 2 . 0 5,400 110 Straw 0 .8 6,000 45 Peas Whole pods 0 .9 1,100 100 V i n e s 1.1 6,800 80 A l f a l f a T o t a l forage 2 .8 18,000 510 Orchard g r a s s / T o t a l forage 2 .2 12,700 280 P e r e n n i a l ryeg ras s which gives the highest possible net return per hectare. It i s a s p e c i f i c point on the y i e l d curve which i s usually within 5 to 10% of the maximum, the production of such high y i e l d s i n e v i t a b l y involves high inputs, e s p e c i a l l y f e r t i l i z e r . The maximum economic y i e l d s are governed mainly by climate and s o i l conditions and by water a v a i l a b i l i t y . A t y p i c a l MEY for sweetcorn on a deep loess w i l l probably be higher than on a shallow sandy s o i l due to the d i f f e r e n t nutrient status, water holding capacities and rooting depths. The MEY i s also dictated by the farmer's l i m i t a t i o n s with respect to finances, manpower and expertise i n growing the crop. In order to reach the target y i e l d a s p e c i f i c amount of N i s required. This requirement i s f i l l e d by the other two components i n the N requirement equation, i e . the s o i l N and fertilizer\manure N. 2 . 1 . 2 NITROGEN SUPPLIED BY THE SOIL In comparison to target y i e l d s and the associated N required by a crop, the N supplied by the s o i l i s an extremely uncertain entity. Irrespective of whether the t o t a l s o i l N i s known, the amount of N a c t u a l l y available to the crop for uptake over the growing season, i s d i f f i c u l t to predict. The reason for t h i s i s that, i n contrast to other macronutrients, s o i l N i s more affected by b i o l o g i c a l processes than by physical and chemical reactions. S o i l N i s considered to be comprised of 2 main components: an inorganic component composed mainly of residual N0»-N, and an 9 organic component which i s mineralized throughout the growing season. 95% or more of the N i n surface s o i l s usually occurs i n the organic form (Stevenson 1982), and i n most temperate a g r i c u l t u r a l regions the t o t a l N concentration i n the top 20cm varies between 0.03 and 0.4*/. (Tisdale et a l . 1985). The organic N i s d i r e c t l y related to s o i l organic matter which i s approximately 5% N. In the LFV organic matter l e v e l s generally range from 0-10%, however there are a few areas of peaty s o i l s which can contain much higher l e v e l s . S o i l organic matter l e v e l s depend on the history of the s o i l , the previous management practices, and the climate of the region. Some researchers (Jansson and Persson 1984) consider the organic component to be comprised of four interconnected phases: a) The l i v i n g biomass, b) The fresh or recent organic debris, making up the so-c a l l e d 'Active phase' of s o i l organic N, c) A 'Passive phase', comprising very old material which i s r e s i s t a n t to microbial breakdown, and d) The phase which Paul and Juma (1981) define as 'S t a b i l i z e d N' which has a h a l f - l i f e somewhere between the active and passive f r a c t i o n s . Broadbent (1984) stated that many s o i l t e s t i n g procedures attempt to determine the s i z e of the active phase which i s then taken to represent p o t e n t i a l l y available N. The inorganic component of s o i l N derives either from mineralization of the organic portion or from residual f e r t i l i z e r remaining from the previous crop. The amount of r e s i d u a l N at the beginning of a f i e l d season can be r e a d i l y measured, i t depends upon the e f f i c i e n c y of uptake of the l a s t crop, the f e r t i l i z e r requirement of that crop, and the amount of leaching or d e n i t r i f i c a t i o n that has occurred between cropping seasons. The amount of organic N mineralized over the growing season i s a component of the N requirement which can only be estimated. Mineralization rate depends heavily on s o i l conditions, such as pH, 0 e, moisture, and temperature; thus mineralization i s l a r g e l y influenced by the spring and summer weather which in v a r i a b l y changes from year to year i n the LFV. The amount of organic N mineralized also depends on the nature of the active phase such as the type of residues l e f t by the previous crop; e.g. pea vines are more e a s i l y decomposed than wheat stubble, due to t h e i r lower C/N r a t i o . Once mineralized, the N i n i t s inorganic form, p a r t i c u l a r l y N03-N, i s extremely susceptible to loss, e s p e c i a l l y by leaching in the humid LFV region of B.C.. Other pote n t i a l sources of N loss are ammonia v o l a t i l i z a t i o n and d e n i t r i f i c a t i o n , the l a t t e r may occur i n the LFV because the s o i l i n spring i s often very wet and anaerobic. The amount of mineral N available f o r use by the plant i s not necessarily d i r e c t l y related to the amount i n the s o i l . The ' e i ' value i n the N Requirement equation re l a t e s the amount of N found i n the s o i l to the amount taken up by the crop. This value varies between crops and between s o i l s under d i f f e r e n t management conditions. For example, a crop such as sweet corn 11 has a lower N requirement than s i l a g e corn and consequently would 'suck up' les s N from the s o i l and hence possibly cause a lower e t value. S i m i l a r l y , a s o i l with a compacted layer may prevent normal root exploration and thus l i m i t crop uptake of s o i l N again lowering the e t value. 2.1.3 NITROGEN SUPPLIED BY MANURE AND FERTILIZER 'N Supplied by Manure and F e r t i l i z e r ' i s e s s e n t i a l l y the difference between the 'N Requirement' and the 'N supplied by the s o i l ' . However, t h i s component of the N Requirement Equation was also preceded by an e f f i c i e n c y factor, "ee", which i n t h i s case stands f o r an estimate of the proportion of 'added' N which i s act u a l l y a v a i l a b l e and taken up by the plant. The transfer from added N to plant incorporated N, l i k e mineralization, i s a function of several i n t e r a c t i n g N transformations, however i t i s also dependent on several management variables, such as N source, placement and timing. One of the main fact o r s a f f e c t i n g the e f f i c i e n c y value (e e) i s the type of N added. There are many d i f f e r e n t kinds of N f e r t i l i z e r and t h i s i s not the place to l i s t these, however the major difference i n t h e i r e f f i c i e n c y i s the form i n which the N i s present, i . e . farm produced or manufactured (e.g. manure or N f e r t i l i z e r ) , organic or inorganic, N03-N or NH4-N or both. Two of the differences a f f e c t i n g the e f f i c i e n c y of N applied as manure and N applied as f e r t i l i z e r are, 1) the dynamic state of N i n the manure before i t even reaches the f i e l d , and 2) the varying, and generally uncontrolled amounts of s o l i d matter and 12 water contained i n the manure. The method of application a f f e c t s the e 8 value for manure even more than for N f e r t i l i z e r . Since many of the N forms i n manure are rapidly converted to NHa a s i g n i f i c a n t portion of the N i n manure can be l o s t to the atmosphere depending on the spreading, handling and storage techniques. Vanderholm (1975) and Gilbertson et a l . (1979) reported NH4-N losses of 10-99% and 10-75% respectively, depending on types of manure management and treatment systems. Thus the farmer i s generally uncertain of the amount of N he obtains from his manure applications and often makes no allowances f o r t h i s input when c a l c u l a t i n g his N f e r t i l i z e r requirements. This uncertainty should soon diminish however with an increased adoption of the recently published 'Manure Management Guidelines'(Bertrand and Bulley 1985) based on the manure management simulation model developed by Bulley and Cappelaere (1978). When manure i s applied, about half the N i s usually present as NH4-N the remainder being i n organic forms (Khan 1986). Organic forms of N i n either manure or f e r t i l i z e r are not used d i r e c t l y by the plant (with the exception of f o l i a r applied urea), however when the organic forms are converted to NH4-N and NOj-N the N becomes rapidly available f o r uptake. Urea, C0(NH s >e , a synthetic organic f e r t i l i z e r which i s becoming the major source of applied N i n North America and Western Europe was the f e r t i l i z e r used i n t h i s study. On ap p l i c a t i o n to the s o i l , urea i s converted f i r s t to H e NC00NH4, then to 2NH3 + C0 a and f i n a l l y to N0a-N. The i n i t i a l transformation to NH4 i s catalyzed by the hydrolytic enzyme urease and proceeds rapidly under favourable conditions of temperature, moisture and pH. Plants can take up inorganic N as both NH*-N and N03-N although some crops prefer one form or the other. Thus i n theory, farmers should choose the N source which produces the highest e 8 value f o r t h e i r s o i l conditions. N03-N i s f a r more mobile i n the s o i l than NH*-N, hence i t i s les s suitable for use under wet, leaching conditions, however where the environment i s conducive to n i t r i f i c a t i o n , NH*-N i s rap i d l y transformed to N03-N. In practice, the choice of f e r t i l i z e r i s most frequently made on the basis of factors such as current price and a v a i l a b i l i t y . The reason f o r the increased popularity of urea i s i t s r e l a t i v e l y low cost and high N concentration, also the uniform p r i l l s are easy to transport and spread evenly on a f i e l d . In order to ensure a high e 8 value for urea good management practices must be applied. After a p p l i c a t i o n urea i s highly susceptible to v o l a t i l i z a t i o n and to leaching. Ideally, urea should be applied to a depth of 5 cm or washed to t h i s depth within 3-6 days a f t e r f e r t i l i z a t i o n (Tisdale et a l . 1985). It i s not possible to predict e« from f i r s t p r i n c i p l e s , the problem therefore has generally been approached empirically by estimating f e r t i l i z e r e f f i c i e n c i e s over a range of s o i l and cl i m a t i c conditions. Most l i t e r a t u r e values estimate e a f o r manufactured f e r t i l i z e r N to be between 50 and 70% (Stanford 1973; Hauck 1984; Boswell et a l . 1986). In s p i t e of knowing e s, the c r u c i a l question s t i l l remains, i e . "How much addit i o n a l N i s needed to f i l l the N Requirement under s p e c i f i e d f i e l d conditions?". There have been many approaches taken to t h i s question i n d i f f e r e n t parts of the world over the past century; the following section outlines a few of these which may be relevant to a humid region such as the LFV and also provides a background to the approach used i n the project. 2.2 NITROGEN FERTILIZER RECOMMENDATIONS IN HUMID REGIONS Many of the methods proposed f o r making N f e r t i l i z e r predictions have recently been discussed and c r i t i q u e d i n reviews by Jungk and Wehrmann (1978), Stanford (1982), Keeney (1982), and Meisinger (1984); the methods f a l l i nto four main categories: 1) Plant Analysis 2) S o i l Sampling 3) S o i l N Index Systems 4) Computer Modelling 2. 2. 1 PLANT ANALYSIS Plant analysis for N f e r t i l i z e r recommendations generally involves taking a sap, leaf, or whole plant sample from the crop once, or a number of times, during the growing season (FAO 1984) . The sample i s analysed f o r t o t a l N (Moller Nielsen 1985) , inorganic N (Scaife and Bray 1977; Wehrmann et a l . 1982) or N-associated pigments, such as chlorophyll and carotenoids 15 (O'Neill et a l . 1983). Another method of plant analysis i s the non-destructive use of standard l e a f colour charts being used i n Japan (Yazawa 1977). The charts are based on the Munsell Renotation System with the aid of a colour difference meter. Plant analysis cannot be used to determine basal N applications, i t s main use i s to reveal and confirm deficiency symptoms. If a N deficiency becomes v i s u a l , crop N applications w i l l probably be too l a t e to prevent at least some y i e l d loss. Thus regular plant sampling must be used to detect pot e n t i a l d e f i c i e n c i e s and also s u b c l i n i c a l d e f i c i e n c i e s which may be caused by a reduction i n mineral supply, eg. waterlogging, s o i l drying, leaching, low temperatures, or by a high N demand re s u l t i n g from p a r t i c u l a r l y good growing conditions. Scaife and Bray (1977) outlined the importance of frequent plant sampling and developed a 'Quick Sap Test' which could e a s i l y be used by farmers i f refined and manufactured. The test used 'Merckoquant' test s t r i p s introduced into the UK by BDH chemicals i n 1976. These are thin p l a s t i c s t r i p s , 75mm x 5mm, to which are attached two squares of white f i l t e r paper impregnated with an aromatic amine and N-(l napthyl)ethylene diamine. Both squares turn v i o l e t when wetted with a N0e-N solution, and one of them contains a reducing agent and hence turns v i o l e t with NO,-N. Colour standards representing 0,10,30,100,250 and 500 mg kg" 1 N03 < =0, 2, 7, 23, 56, 113, mg kg" 1 N) are printed on the tube containing the s t r i p s . Because the Merckoquant s t r i p s were not intended f o r plant sap analysis, Scaife and Bray (1977) found that the standard colours did not 16 extend as high as the optimum value In most young plants (about 1000 mg kg " 1 N0»-N). Nevertheless, when plants suffered N stress, t h e i r sap N03-N le v e l s , p a r t i c u l a r l y i n the lower leaves, soon f e l l to l e v e l s within the range covered by the s t r i p s . Other rapid methods for determining n i t r a t e i n plants are currently i n use i n C a l i f o r n i a , (Rauschkolb and Brown 1974) and West Germany, (Wehrmann et a l . 1982). The i n t e r p r e t a t i o n of plant analyses for N recommendations i s based on the concept that the N content i n the plant w i l l r e f l e c t N a v a i l a b i l i t y i n the s o i l . In p r i n c i p l e t h i s concept i s sound, because N present i n the plant must o r i g i n a l l y have been avail a b l e i n the s o i l (with the exception of f o l i a r N applications and N f i x e d by legumes). O'Neill et al.(1983) showed that analysis of spring barley, as early as three weeks aft e r emergence, was an e f f e c t i v e assessment of s o i l N status. However, the N content i n the plant not only depends on N a v a i l a b i l i t y i n the s o i l but also on factors such as growth rate, t o x i c i t y l e v e l s , and the concentrations of other nutrients i n the s o i l and plant. Consequently, two approaches have been used f o r i n t e r p r e t i n g plant analyses f o r N; 1) The ' C r i t i c a l Value' approach (Barber 1984). 2) The 'Diagnosis and Recommendation Integrated System' (DRIS) approach, proposed by Sumner (1977). The c r i t i c a l value approach has been widely used. Plants or plant parts are analyzed f o r N i n experiments where y i e l d varies due to N f e r t i l i z a t i o n . A plot i s made of the N concentration vs. y i e l d , and from t h i s a c r i t i c a l value i s obtained. The 17 c r i t i c a l value i s the plant N content above which y i e l d no longer increases s i g n i f i c a n t l y . Above the c r i t i c a l value there i s a range which indicates that the N l e v e l i s adequate. When nutrient concentration increases above a c e r t a i n l e v e l , y i e l d depression may occur i n some crops due to excess nutrients. One of the problems i n using t h i s method i s that when a nutrient other than N r e s t r i c t s y i e l d s , the N content i n the plant may be disproportionately high. In the DRIS approach, a l l factors that can be measured and that have an a f f e c t on y i e l d , are measured. The components of y i e l d are characterized i n terms of indices, allowing the y i e l d f actors to be c l a s s i f i e d i n order of l i m i t i n g importance. Thus the concept of 'Balance of Nutrients' i s incorporated into the system. The main l i m i t a t i o n to t h i s approach i s i n obtaining a r e l i a b l e index f o r each nutrient f o r high-yielding plants and i n measuring f a c t o r s other than nutrients that l i m i t y i e l d . Nevertheless, the DRIS approach i s an improvement over using c r i t i c a l values. The major drawback to plant analysis i s that t i s s u e t e s t i n g i s most r e l i a b l e when the crop i s well developed. At t h i s point, e. g. f o r corn at s i l k i n g , the s p e c i a l i z e d equipment required to apply N i s generally too costly to make the f e r t i l i z e r a p p l i c a t i o n worthwhile. However plant analysis i s currently being used f o r some perennial crops, such as cotton, and f o r most tree crops. The promising r e s u l t s of O'Neill et a l . (1983) with spring barley, and Moller Nielsen (1985) i n Denmark and Wehrmann et a l . (1982) i n West Germany with winter 18 wheat, suggest that plant analysis may be important i n improving N f e r t i l i z e r use e f f i c i e n c y , p a r t i c u l a r l y i n regions in t e n s i v e l y growing one major crop. 2.2.2 SOIL SAMPLING Although evaluating ava i l a b l e N through s o i l mineral N contents was considered to be of limi t e d value as recently as 1965 (Bremner 1965) i t i s now a common practice i n many parts of Western Europe and North America (Meisinger 1984). Residual inorganic N i n the root zone i s approximately equivalent i n a v a i l a b i l i t y to f e r t i l i z e r N (Keeney 1982), consequently s o i l sampling for residual NQ»-N i s a routine practice i n areas where winter leaching i s small, a f t e r summer fallow, and afte r heavy N applications. Table 2.2 shows that N0»-N evaluations are currently used f o r N f e r t i l i z e r recommendations i n most of the Western states of the U.S.A., they are also commonplace i n the P r a i r i e Provinces of Canada, the Peace Region of B. C. and many parts of Western Europe (Netherlands: Kolenbrander et a l . 1981; Neeteson 1982; Neeteson and Smilde 1983; Neeteson 1985; Ris et a l . 1981. Belgium: Boon 1981. Germany: Wehrmann and Scharpf 1979; Wehrmann et a l . 1982. Denmark: Ostergaard 1982). In semiarid areas, where extensive leaching and d e n i t r i f i c a t i o n do not occur before planting, s o i l sampling i s often performed i n the f a l l . Studies i n these areas have shown strong r e l a t i o n s h i p s between f a l l N03-N and crop requirements. In semihumid areas, s o i l sampling i s generally performed i n the spring and i s directed more towards estimating mineralized N 19 Table 2.2 General summary of current soil N evaluation systems in various regions of the Doited States. (Adapted from Meisinger 1984) - -- ••-Region-states included Soils data commonly solicited N factor for crop yield goal Soil N evaluation Average N credits Manure Legumes Crop Avg value Inorganic Mineralization Soybeans Alfalfa kg N t"' kg N t"' kg N ha -t Northeast Conn,NY,Pa Soil type, drainage Com 24.5 None Based on soil type 2.3 NA 150 (grain) in one state Mid-Atlantic Del,Ky,Md, Soil type, texture. Corn 24.9 None None 3.0 18 80 NJ,Va,WVa drainage (grain) Southeast Geographic area. Com 26.4 None None NA 30 55 Ga,NC,Miss,SC soil type (grain) Midwest Soil type,texture. Com 26.2 One state Based an total N and 2.4 32 100 111,Ind,Iowa, drainage. (grain) tests for soil texture in one Mich,Minn,Mo geographic area state West Com 29.8 Colo,Kan,Neb, Soil type, drainage. (grain) NOj-N Two states use total 2.4 36 90 ND,SD geographic area Wheat 40.5 N and fixed Mineralization rates Southwest Soil association. Wheat 41.4 N03-N None NA NA 90 Ariz,Okla,Tex topographic area. texture Northwest Soil type .drainage. Wheat 46.2 N0,-N A region within one NA NA NA Mont,Ore, geographic area state uses aerobic Wash,Idaho mineralization NA refers to inadequate data or infrequently used in area. than residual N, except where conditions favouring N retention p r e v a i l , eg. deep s o i l s or large previous N inputs. In the LFV, Bomke (Personal communication 1986) sampling s o i l s on Westham Island B. C. consistently found minimal amounts of N03-N i n the plough layer i n January. However Khan (1986), and Guthrie and Bomke (1980) a l l found some mineral N i n Hay mainly i n the 30-60cm depth. It i s possible that N03-N found i n the surface horizons i n spring i s due to mineralization, and N03-N found at depth i s residual N from the previous cropping season which has been washed down the p r o f i l e during winter. The objective of a l l s o i l sampling, whether i n spring or f a l l , i s to obtain an estimate of the s o i l N ava i l a b l e to the plant. There are two approaches to making t h i s estimate, the f i r s t where N f e r t i l i z e r recommendations are made s o l e l y on the basis of r e s i d u a l s o i l N03-N, and the second, where recommendations are made on the basis of two components; a) a measure of mineral N i n the s o i l p r o f i l e on a s p e c i f i c date and b) an estimate of N mineralized over the growing season. In most cases, e s p e c i a l l y i n semihumid areas, the two component approach i s considerably more accurate. In t h i s two component approach, the f i r s t component i s somewhat simpler to determine than the second. Mineral N measurements just require accurate and precise chemical analyses and the c o l l e c t i o n of a representative s o i l sample. In contrast, estimates of mineralization f o r f e r t i l i z e r recommendations must be able to give an accurate prediction of the amount of N becoming ava i l a b l e over the growing season and must also be simple, rapid 21 and reproducible, and not affected by sample pretreatment. MINERAL NITROGEN MEASUREMENTS Chemical analyses f o r mineral N present no major problems since t h i s component of availa b l e N i s generally measured i n the form of NO,-N or NH*-N which can be e a s i l y extracted with various s a l t solutions and i s rea d i l y analyzed with modern equipment (Bremner 1965; Jackson et al.1975). The major problem with mineral N determination i s the c o l l e c t i o n of a representative s o i l sample, t h i s i s due mainly to s o i l N03-N v a r i a b i l i t y but also to sample preparation and economic l i m i t a t i o n s on s o i l sampling. S o i l v a r i a b i l i t y i s multidimensional and involves s p a t i a l components i n the horizontal and v e r t i c a l d i r e c t i o n s as well as temporal components. The v a r i a b i l i t y stems from; a) the s o l u b i l i t y and mobility of N03-N, b) the nonuniform application of N, (e.g sidedressing, manure), c) the natural s p a t i a l heterogeneity of s o i l organic matter and s o i l water, and d) the s p a t i a l and temporal heterogeneity of s o i l N transformations such as leaching, d e n i t r i f i c a t i o n , and immobilization. The v a r i a b i l i t y of s o i l mineral N influences the time of sampling, the sampling depth and the number of samples that must be taken f o r a representative s o i l sample. Ward (1971) and Stanford (1982) i n t h e i r reviews of s o i l sampling methods recommend sampling as close to f e r t i l i z i n g time as possible, or a l t e r n a t i v e l y i n the l a t e autumn i n areas of low winter r a i n f a l l . Minimizing the time between sampling and f e r t i l i z i n g 22 w i l l minimize the e f f e c t s of weather on the s o i l N and thus increase the accuracy of recommendations. Sampling must be done each year f o r mineral N determinations. Recommended depth of sampling varies from 30cm (Nyborg et al.1976; Onken and Sunderman 1972; Magdoff et a l . 1984) to anything as deep as 180cm (Dahnke and Vasey 1973). MoBt recommendations are either 60cm or 100cm, normally depending on the rooting depth of the crop but sometimes modified by the presence of an impeding s o i l layer (Carter et a l . 1976), or other p r e v a i l i n g s o i l conditions such as moisture d i s t r i b u t i o n (Meisinger 1984) and surface s o i l a v ailable N status. Plough depth sampling i s i n most cases inadequate due to N0»-N mobility, however deeper samples add to the cost of sampling. A number of studies have shown that N03-N to depth can sometimes be estimated from shallower s o i l samples (Stanford 1982). Local experimentation over several years i s required to determine the minimum sampling depth for a given soil-crop-climate condition. Common s o i l sampling i n s t r u c t i o n s c a l l f o r a 10-20 core composite from an area that i s selected to r e f l e c t s i m i l a r past management, topography, s o i l type, etc. (Bole and Pittman 1976; Cameron et a l . 1971; Reuss et al.1977; Smith 1980). This sampling i n t e n s i t y estimates the mean N03-N l e v e l to approximately +_ 20'/. i n about 75% of the area sampled, or to +25% of the mean i n about 90% of the area (Meisinger 1984). Without an extensive s o i l sampling programme Meisinger (1984) believes i t quite u n l i k e l y that a f i e l d N03-N mean can be estimated to better than +_ 20% of the mean. As a consequence of t h i s s p a t i a l 23 v a r i a b i l i t y , both Meisinger (1984) and Kowalenko (1985) suggest that the problem can be lessened i f the s o i l N0a-N test i s used to c l a s s i f y areas into categories, such as, low, medium or high s o i l NOj-N, rather than t r y i n g to determine s p e c i f i c l e v e l s . ESTIMATING MINERALIZATION In s p i t e of the v a r i a b i l i t y problem and the uncertainty regarding the best time and depth at which to sample f o r a s p e c i f i c crop, measurements of mineral N i n the p r o f i l e are inv a r i a b l y more precise than estimates of mineralization. The amount of mineral N made available by mineralization i s very d i f f i c u l t to predict, e s p e c i a l l y i n humid regions, because mineralization i s greatly dependent on environmental factors such as temperature and moisture which fluctuate over the growing season. Consequently, estimates of mineralization tend to be imprecise because they ei t h e r ; a) try to simulate growing season weather conditions, or b) t r y to project growing season mineralization from either 'point values' of s o i l N or short term incubations. The many approaches used to determine mineralization have been reviewed on several occasions (Bremner 1965; Dahnke and Vasey 1973; Stanford 1982; Keeney 1982) thus i t i s not necessary to examine these i n d e t a i l here. Most reviews consider f i v e main approaches: i ) Vegetative procedures. These include both f i e l d and greenhouse procedures which r e l a t e t o t a l dry matter y i e l d , N concentration or preferably t o t a l N uptake, to s o i l N. i i ) Microbial procedures. These involve incubations of s o i l 24 samples under temperature and water conditions conducive to mineralization and measure the t o t a l mineral N produced aft e r a given time period. i i i ) Total analysis procedures. These usually estimate t o t a l N d i r e c t l y by a Kjeldahl analysis, or i n d i r e c t l y through a Walkley-Black organic matter determination. Mineral N i s determined using the assumption that a f i x e d percentage of t o t a l N i s mineralized. iv) Chemical extraction procedures. These separate a l l , or part of, the active N pool using extracting agents that can vary greatly i n i n t e n s i t y , ranging from strong acids or bases to neutral s a l t s or water. Different components of s o i l N are presumed to contribute more or less to mineralizable N. v) Indirect Procedures. These involve extrapolating from the N s o i l sample, using information obtained from f i e l d experiments and other sources. Many of the recommendation systems which use a s o i l sample, calc u l a t e mineralization by such an i n d i r e c t procedure. Most reviews of experiments using any of the f i r s t four approaches have shown that there i s poor c o r r e l a t i o n between laboratory or greenhouse indices of mineralized N and f i e l d r e s u l t s ; they are therefore undesirable f o r use i n N recommendations. The cause of these poor c o r r e l a t i o n s i s generally the strong influence of growing season climate on f i e l d mineralization and i n some cases, notably the b i o l o g i c a l methods, due to the e f f e c t of sample pretreatment (Meisinger 1984, Keeney 1982) or the presence of varying amounts of 25 re s i d u a l mineral N from previous f e r t i l i z a t i o n . Furthermore, the b i o l o g i c a l methods require a minimum of a week for re s u l t s and would thus be unsuitable for rapid recommendations, however i f they only had to be performed every few years they may have some pot e n t i a l . Indeed Carter et al.(1974,1976) and Stanford (1977) showed i n two studies that use of a mineralizable N index based on an incubation, i n conjunction with p r o f i l e N0 3-N, would improve the prediction of N f e r t i l i z e r needs above that made so l e l y on the basis of p r o f i l e N0 3-N. These two experiments however, used sugar beets i n a c a r e f u l l y managed crop environment and i n a climate where excess p r e c i p i t a t i o n did not occur, therefore i t i s unl i k e l y such r e s u l t s could be applied to the Fraser Valley. SOIL SAMPLING METHODS USED I N WESTERN EUROPE Most of the regions that use s o i l N0 3-N sampling i n t h e i r f e r t i l i z e r recommendations use some form of i n d i r e c t method to estimate mineralized N, either from the mineral N found on a s p e c i f i c date or from other s o i l factors such as organic matter, manure, previous cropping etc.. The methods which account for mineralized N from mineral N i n the p r o f i l e are most common i n Western Europe, notably the Netherlands, West Germany and Belgium (e.g. Bakker et a l . 1981; Boon 1981; Neeteson 1985; Neeteson et a l . 1984; Wehrmann and Scharpf 1979,1986; Wehrmann et al.,1982). The methods used i n these countries, generally termed *N«i„' methods, do not act u a l l y estimate mineralization, instead they determine the required f e r t i l i z e r rate 'N 0p', from a knowledge of the crop's f e r t i l i z e r N requirement at zero re s i d u a l N and the s o i l mineral N at f e r t i l i z i n g time. After years of large scale f i e l d experimentation, consisting of many s i t e s containing a range of applied N f e r t i l i z e r l e v e l s , r e l i a b l e recommendations have now been achieved f o r wheat, sugar beet, potatoes and a number of vegetable crops, (Wehrmann et a l . 1982). For example, i n the Netherlands, the N recommendation for sugar beet (Neeteson and Smilde, 1983) i s based on the regression l i n e r e l a t i n g s o i l mineral N (N« t f >) at the end of the winter period (March) to the optimum N f e r t i l i z e r rate ( N o p ) : N„p = 220 - 1.7 N. , „ N o p , N„i„ i n kg ha - 1 N, sampling depth for N.,„ i s 60 cm, and Nop i s based on the y i e l d value (in Df1) i r r e s p e c t i v e of N f e r t i l i z e r cost. Following green manures, 20-30 kg ha - 1 of f e r t i l i z e r are subtracted, and with bad s o i l structure add i t i o n a l N above the recommended dose i s suggested. For winter wheat i n West Germany, further refinements to the N o p technique have been made using plant sampling (Wehrmann et a l . 1982). I f a rapid n i t r a t e test, performed on wheat st a l k segments at the booting stage, or at ear emergence, indicates a deficiency, top dressing i s performed. Tables 2.3a and b summarize the N0 p recommendations f o r crops i n West Germany and the Netherlands. In Belgium the N,u method i s used, but the N« P value i s 27 Table 2.3a Essential data of Nmin method for crops grown in deep soils. (Adapted from Wehrmann and Scharpf 1982) Soil analysis Total N supply (soil N + N applic.) Time Soil including top dressing Crop plants depth cm Winter Wheat Feb/Mar 90 200 Notes Winter Barley n 90 160 Winter Rye n 90 140 Oats seed-time 90 100 Sugar Beet Mar or May 90 220 Potatoes May/June 60 300 * Without Cabbage Plant-time 90 350 Cauliflower n 90 250** * * 100 kg ha"' Spinach Seed-time 60 250* must be in Peas n 30 80 top 0 - 3 0 cm Beans n 60 140** Table 2.3b Rapid N test before the usual date of top dressing for Winter Wheat. Test value at booting stage or ear emergence resp. 0 - 1 1 - 2 2 - 3 N-application at booting stage (kg ha"' ) 50 - 40 40 - 20 20 - 0 N-application at ear emergence (kg ha"' ) 90 - 60 60 - 30 30 - 0 r e f i n e d by modifications f o r s o i l humus content, NH*-N, N content of previous crop and organic manure. Boon (1985) showed recommendations incorporating these modifications to be s i g n i f i c a n t l y improved over the simple N, t„ method. In the Netherlands, i n areas where s o i l s could not be analyzed f o r N i n spring, a general guideline was given. This recommendation was based on 45 f i e l d s with a range of preceding crops sampled several times during winter. Values were compared with previous years' figures, and recommendations made for each preceding crop taking account of the deviation from the f e r t i l i z e r N needed i n previous years. The high i n t e r e s t and confidence i n s o i l sampling i n the Netherlands causes 10,000 samples to be taken each year (Cooke 1980). SOIL SAMPLING METHODS PROPOSED IN EASTERN USA It i s u n l i k e l y that there w i l l ever be s u f f i c i e n t research information i n the LFV to develop such precise recommendations for a s p e c i f i c crop as those used i n Benelux and West Germany, however the general p r i n c i p l e s and some of the research performed i n Western Europe could be applicable to LFV conditions. An approach, possibly more suitable to the LFV, i s one being proposed i n some of the Eastern States of the USA. This region, i n a s i m i l a r fashion to the LFV, was previously thought to be unsuitable for s o i l sampling due to the heavy winter r a i n f a l l . However, i n 1982 Meisinger et a l . demonstrated the importance of accounting for spring s o i l N when making f e r t i l i z e r recommendations i n Maryland. Likewise, Fox and 29 Piekelek (1983) i n Pennsylvania, Magdoff et a l . (1984) i n Vermont, and Ruby and G r i f f i n (1985) i n Conneticut have a l l reported the v a l i d i t y of a spring s o i l test f o r N on humid region s o i l s . The recommendation system now being proposed i n Eastern USA, instead of being based on f i e l d t r i a l s with a range of applied f e r t i l i z e r l e v e l s , i s based on t r i a l s which involved paired comparisons between plots with no applied f e r t i l i z e r N (apart from s t a r t e r ) and those with just one rate of applied N (Dahnke et a l . 1977; Fox and Piekelek 1983; Magdoff et a l . 1984). By using the Cate-Nelson S t a t i s t i c a l Procedure (Cate and Nelson 1971; Nelson and Anderson 1977) applied to a graph of 'Relative Y i e l d ' (ie. y i e l d of control p l o t / y i e l d of f e r t i l i z e d plot) versus s o i l NQ3-N, the t r i a l s i t e s could be s p l i t into two categories; a)'Probable Response to F e r t i l i z e r ' and b)'Unlikely Response to F e r t i l i z e r ' depending on the l e v e l of s o i l N03-N found i n spring i n the 0-30cm depth. The Cate-Nelson procedure separates two populations by means of a ' C r i t i c a l Level'. The C r i t i c a l Level i s found by d i v i d i n g a Y-X scattergram into four quadrants, maximising the number of points i n the p o s i t i v e quadrants while minimizing them i n the negative quadrants. When t h i s i s done, the point at which the v e r t i c a l axis of the quadrant cuts the y-axis of the scattergram i s the C r i t i c a l Level. F e r t i l i z e r recommendations were made on the basis of a l i n e a r - l i n e a r model with the i n t e r s e c t i o n of the two l i n e s corresponding to the C r i t i c a l Level. Although the recommendations proved imprecise where s i t e s had a low 30 p r o b a b i l i t y of response, they were greatly improved over previous recommendations which did not include a s o i l test. In an e f f o r t to improve the precision of the system, e s p e c i a l l y on 'Unresponsive' s i t e s , Magdoff et a l . (1983) investigated the use of a N a v a i l a b i l i t y test based on NH*-N released by autoclaving i n comparison to the simple mineral N extracted with 2M KCl. Their r e s u l t s showed that although autoclaving provided a reasonable basis for estimating s o i l N a v a i l a b i l i t y , the method was time consuming and needed great care to assure reproducible r e s u l t s . The 'Probable/Possible Response' method of recommendation system i s not as precise as the 'N. l n ' system but i s more adaptable to a variety of crops and could possibly be developed for the LFV using l o c a l and foreign research r e s u l t s . In general, reviews of s o i l sampling systems suggest that advisory systems based on s o i l analysis are most e f f e c t i v e i n areas with uniform s o i l and a wide range i n mineral s o i l N; when such conditions do not p r e v a i l , 'N Index' or 'Budget' systems appear to be more r e l i a b l e . 2.2.3 SOIL NITROGEN INDEX SYSTEMS 'S o i l N Index Systems' r e f e r i n t h i s review to pr e d i c t i v e methods which do not involve s o i l sampling. In the U.K. and some states of the U.S.A. consistent c o r r e l a t i o n s between N03-N i n the s o i l and crop response have eithe r not been found or not yet been investigated. In these areas N recommendations are generally made on the basis of crop t r i a l s , they consist of 31 indices which are estimates of the N available from sources other than f e r t i l i z e r . In the U.K., the i n a b i l i t y to f i n d c o r r e l a t i o n s s i m i l a r to those found i n Benelux and West Germany, i s suggested by Needham (1984) to be due to the more variable s o i l conditions, rooting depths and growing season climate. The LFV, with respect to climate, i s more comparable to continental Europe than the U.K., although winter r a i n f a l l i n the LFV i s higher. However, the wide range of s o i l types, the variety of cropping systems and the lack of experimental data i n the LFV, would possibly make the region more amenable to methods used i n the U.K. than those used on the European continent. Table 2.2 (Sec.2.2.2) summarizes N recommendation methods used i n states across the U.S.A., v i r t u a l l y a l l the factors used for deriving N indices are shown i n t h i s table. The most common factors are s o i l properties or productivity, manure use and previous cropping to legumes. The r e l a t i v e contributions of each of these factors varies from state to state according to research c a r r i e d out i n the region. Table 2.2 also shows the average N c r e d i t s for manure and legumes i n various regions i n the U.S.A.. N indices sometimes take organic matter into consideration although there i s c o n f l i c t i n g evidence as to whether t h i s factor i s d i r e c t l y related to a v a i l a b l e N. Some researchers (Needham 1984, Greenwood 1982, Stanford 1982) suggest that there i s only a r e l a t i o n s h i p when the region of study contains a wide range of organic matter l e v e l s eg. 0-15%. The lack of r e l a t i o n s h i p i s generally attributed to varying mineralization rates due mainly 32 to the growing season climate, and the C/N r a t i o of the organic matter which i s i n part due to previous cropping. Carter et a l . (1975) did show that the amount of N supplied from mineralizable sources i n a f i e l d continuously planted to one crop, could be expected to remain constant from one year to the next. They suggested that once the mineralization capacity of the s o i l had been determined the test need only be repeated every few years unless unusual f e r t i l i z e r practices had been applied. Needham (19S4) concluded that i n the U.K., the only fac t o r s which consistently influenced the crop requirement for added N were s o i l type and previous cropping. From these two factors the ' S o i l N Index' (MAFF 1985-86) has been developed to give a simple but reasonably r e l i a b l e recommendation system f o r N f e r t i l i z e r applications. S o i l type i s based on texture and depth, the texture-depth r e l a t i o n s h i p being important i n the retention of r e s i d u a l N. The previous cropping regimes are s p l i t into three l e v e l s assigned the indices 0, 1 or 2, based on the amount of crop residues remaining and the f e r t i l i z e r applied. F i e l d s i n Index 0 have low N reserves and more N f e r t i l i z e r i s needed compared to f i e l d s i n Index 1. Index 2 s o i l s have the highest s o i l N reserves. Usually only the l a s t crop grown i s used, but a f t e r lucerne ( a l f a l f a ) , long leys, and permanent pasture, h i s t o r i e s longer than one year are considered. Table 2.4 shows the N Index system used i n the U.K.. Recommended values f o r s i l a g e corn are 60 kg h a - 1 , 40 kg ha - 1 and 40kg ha - 1 f o r indices 0, 1 and 2 respectively. Table 2.4 Nitrogen Index - based on last crop grown (MAFF F e r t i l i s e r recommendations 1985-86) Nitrogen Index 0 Nitrogen Index 1 Nitrogen Index 2 Cereals Forage crops removed Leys (1-2 year) cut Leys (1-2 year) grazed, low N(a) Beans Forage crops grazed Leys (1-2 year) grazed, high N(b) Long leys, low N(a) Any crop i n f i e l d receiving large frequent dressings of farmyard manure or slurry Long leys, high N(b) Maize Oilseed rape Lucerne Permanent pasture -poor quality, matted Peas Permanent pasture -average Sugar beet, tops removed Sugar beet, tops ploughed i n Permanent pasture -high N(b) Vegetables receiving less than 200 kg ha"1 N Vegetables receiving more than 200 kg ha"' N (a) Low N - less than 250 kg ha - 1 N per year and low clover content (b) High N - more than 250 kg ha"' N per year or high clover content 34 Adjustments are only made fo r manure i f greater than 50 m* ha" 1 of cow s l u r r y i s applied shortly before sowing; i f t h i s i s the case no additional N i s recommended, (MAFF 1985-86). Host of the states i n the U. S. A. which use N indices use some form of 'Balance Sheet' or 'Budget System' (Hauck, 1984) as used i n France (Remy and Viaux 1982), Switzerland (Neyroud et Vez 1981) and Sweden (Nommik 1979). These can be considered as refinements of the N Index System i n that y i e l d p o t e n t i a l i s taken into account, and usually other factors as well as s o i l texture and previous cropping are considered. E s s e n t i a l l y the Balance Sheet method involves c a l c u l a t i n g the desired y i e l d and associated N requirement and subtracting from t h i s a l l the estimated N inputs. Bertrand (1984, personal communication with S. Loewen, Coast Agri F e r t i l i z e r s , Abbotsford B.C.) suggested an N balance method f o r crop N requirements i n the LFV, however further research i s necessary to r e f i n e t h i s . A number of the areas using a Balance Sheet method also include either a f a l l or spring s o i l sample for N, perhaps producing the most comprehensive of a l l N f e r t i l i z e r recommendation systems. 2.2.4 COMPUTER MODELLING Computer modelling f o r use i n N f e r t i l i z e r predictions i s an approach being investigated i n a number of locations i n Western Europe. Most of the models have been designed to simulate the amount of mineral N i n the s o i l p r o f i l e i n spring (Willigen and Neeteson 1984). These models have evolved because of the l o g i s t i c a l problems concerning c o l l e c t i n g and analyzing s o i l 35 samples from many s i t e s In the spring and making recommendations in good time f o r f e r t i l i z e r application. Other models, s p e c i f i c a l l y i n the U.K. (Greenwood et a l . 1984, George 1982) have been designed to simulate crop response to N f e r t i l i z e r i n order to i d e n t i f y why there i s often l i t t l e c o r r e l a t i o n between the crop's N f e r t i l i z e r requirement and N a v a i l a b i l i t y indices. In 1983 a workshop i n the Netherlands brought together researchers i n Western Europe that were designing and developing N cycle simulation models, (Willigen and Neeteson 1984). At the workshop, the p a r t i c i p a n t s were asked to run t h e i r models with a data set of experimental r e s u l t s c o l l e c t e d between November 1977 and June 1978, from a N f i e l d experiment i n the central part of the Netherlands. Table 2.5 summarizes the s i x d i f f e r e n t models and the processes each of them consider. A l l the models calculate mineralization as a function of environmental conditions (temperature and/or water content) and aim to predict s o i l mineral N i n the p r o f i l e over winter and spring. They a l l deal with the fate of N i n the unsaturated zone of the s o i l p r o f i l e . Transport of water and solutes i s taken to be e s s e n t i a l l y i n the v e r t i c a l d i r e c t i o n . In a l l models the s o i l p r o f i l e i s divided into layers, i n which each layer i s considered to be uniform throughout, i . e . within a layer no gradients w i l l develop. Figure 2. shows the measured and simulated course of N03-N in the arable layer, and i n the upper 60cm, from the model proposed by Addiscott (Willigen and Neeteson 1984). This was one of the most accurate models. In general, the r e l a t i v e l y Table 2.5 Summary of processes considered in the 6 models presented at the N cycle simulation model workshop - Netherlands 1983. (Adapted from Willigen and Neeteson 1984) Model Process I II III VI V VI 1. Mineralization/immobilization + + + + + + 2. Growth and decay of biomass - _ + -3. N i t r i f i c a t i o n + - - - - -4. Denitrification _ -! 5. Flux of water + + + + - + 6. Leaching of nitrate + + + + + + 7. Adsorption of ammonium + - - - - -(+ = process considered; - = process ignored or input required) ! For denitrification a separate model has been developed. 1! In a newer version denitrification i s also considered. Model Institute Reference I Rothamsted Experimental Station Addiscott (1977,1982) II Nat. Veg. Research Station Burns (1974,1975,1976) Wellesbourne, UK III University of Leuven, Belgium Seligman and Van Keulen (1981) IV University of Hanover Richter et a l . (1978,1980) V ITAL Wageningen, Netherlands Van Veen and Fr i s s e l (1981) VI Institute for Soil F e r t i l i t y Zandt and De Willigen (1981) Haren, Netherlands Soil mineral N 120 r (kg ha") 80 40 A A A ~ A " \ TA " Model I 0-30cm 0-60cm measured A A • • simulated A o o A > A A A ^ -A- A - A ' I 0 80 160 days 240 Figure 2. Measured and simulated course of n i t r a t e -nitrogen i n the arable layer and i n the upper 60cm. (Willigen and Neeteson 1984) 38 simple models I,II,IV and VI were more accurate than the complex models III and V. The mean computed by each of these four models d i f f e r e d by l e s s than 10 kg h a - 1 of N from the experimental mean. Host of the problems found i n modelling the N cycle appeared to be caused by the microbiological processes. The discrepancies between predicted and measured N0a-N contents were due to overestimation of N mineralization. Greenwood et a l . (1984) r e i t e r a t e d the point that simpler simulation models tended to be more accurate. Their model for i n t e r p r e t i n g N - f e r t i l i z e r t r i a l s required only four out of a possible 60 input c o e f f i c i e n t s , these were; pote n t i a l maximum yi e l d , the mineralization rate, the d i s t r i b u t i o n of inorganic-N down the s o i l p r o f i l e , and the weight of dry plant material at the s t a r t of modelling. The researchers also admitted however, that t h i s s i m p l i f i c a t i o n l i m i t e d the range of conditions where the model could be applied. For instance, i t could not be expected to apply without further amendment where there was s i g n i f i c a n t spring leaching or d e n i t r i f i c a t i o n , or where the monthly incoming r a d i a t i o n varied considerably during the growing period. Nevertheless, Greenwood et a l . (1984) f e l t that t h e i r model has p o t e n t i a l f o r use i n adjusting N f e r t i l i z e r p r a c tice according to need and thereby improving the e f f i c i e n c y of f e r t i l i z e r use. The usefulness of computer modelling for predicting spring s o i l n i t r a t e i s probably of l i t t l e value i n the LFV, t h i s i s due to the high winter r a i n f a l l and consequent pote n t i a l f o r spring leaching and d e n i t r i f i c a t i o n . However, a computer model may be of considerable value i n combining information from worldwide l i t e r a t u r e and l o c a l research, to develop some form of Balance Sheet system for N recommendations i n the Valley. The Manure Management Model previously mentioned (Section 2.1.3, Bulley and Cappelaere 1978), already encompasses a nitrogen behaviour section within which there are programmes simulating growth f o r corn and grass. The model enables the farmer to use the Manure Management Guidelines (Bertrand and Bulley 1985) to predict how much manure i s required from a s p e c i f i c livestock/manure system i n order to supply adequate N to a forage crop which has one of three p o t e n t i a l y i e l d s . A simple conversion procedure i s shown to adapt the guidelines to crops other than forages. This foundation i n computer modelling of N i n the LFV could be of great value f o r improving recommendations for other N sources, besides manure. 2.3 APPROACH USED IN THIS STUDY In view of the current practices for N recommendations i n humid regions and the associated l i t e r a t u r e the approach taken i n t h i s study was to investigate the a p p l i c a b i l i t y of a spring s o i l t e s t and/or a s o i l N Index System f o r improving N f e r t i l i z e r recommendations i n the LFV. The approach used sweet corn (Zea Mays saccharata) as the t r i a l crop. Corn was chosen because i t i s a common and highly valuable crop i n the region of study, and a crop which i s generally responsive to N f e r t i l i z e r and r e l a t i v e l y simple to use f o r f i e l d t r i a l s , re. uniformity. harvesting etc.. Further research would be required to apply the r e s u l t s of the project to other crops i n the region. With respect to a spring s o i l test the project aimed to answer the following questions: a) Are s o i l N03-N or NH*-N or both, s u f f i c i e n t l y correlated with crop response to make a s o i l test worthwhile? b) If a s o i l test can be used, to what depth and on what date i s i t necessary to sample? The questions addressed regarding the N Index System were: a) Can the N supplied by the s o i l be i n d i r e c t l y estimated by s o i l c h a r a c t e r i s t i c s such as organic matter, previous cropping, s o i l texture? b) Which fact o r s have the greatest influence on corn uptake of s o i l and f e r t i l i z e r N? One further question posed i n the study was; Once a recommendation has been made, does the method of f e r t i l i z e r application, i e . broadcast preplant, or sidedressed when the crop i s about 30 cm t a l l , make a s i g n i f i c a n t difference to the crop use of f e r t i l i z e r N? In order to answer the questions above, the project was composed of two interconnected studies which were set up as follows: 1) The establishment of a 'Replicated F e r t i l i z e r Response T r i a l ' which aimed to: (a) Monitor s o i l NO,-N and NH«-N to a depth of 80cm at i n t e r v a l s of 0-20cm, 20-50cm and 50-80cm. (b) Investigate y i e l d response and N uptake e f f i c i e n c y at four d i f f e r e n t rates of sidedress applied 41 urea, (c) Compare the effectiveness of sidedress and preplant applied urea. 2) A 'Multifarm Survey' of sidedressed versus control plots at 28 locations i n the Ladner area over a 2 year period. This aimed to e s t a b l i s h the range of N supplying capacities of some LFV s o i l s and r e l a t e these to other s o i l properties and crop history. 3. METHODS The study, which covered two f i e l d seasons, 1984 and 1985, was located on Westham Island and i n the Ladner area at the mouth of the Fraser River, 35 km south of Vancouver, B r i t i s h Columbia (Fig.3.). The s o i l s i n t h i s area are mostly gleysols, s i l t loams to s i l t y clay loams with organic matter i n the plough layer varying from 2. 0 to 9. 5'/.. The region vas chosen f o r the study because of i t s proximity to Vancouver and because farmers w i l l i n g to cooperate i n the study were known i n the d i s t r i c t . The area produces high value vegetable crops i n need of improved N f e r t i l i z e r recommendations. Sweet corn, the crop chosen f o r the study, i s grown i n the region mainly for canning and freezing. Table 1. (Sec.1.1) showed the monthly p r e c i p i t a t i o n and temperature summaries for Vancouver International Airport, approximately 10 km from the study s i t e s . Summer r a i n f a l l i n both 1984 and 1985 was well below the 30 year average. Daily r a i n f a l l measurements over the growing season are recorded i n Appendix 1. 3.1 PROJECT DESIGN The project consisted of four i n t e r r e l a t e d parts: 1) S o i l N monitoring during spring. 2) A 'Replicated F e r t i l i z e r Response T r i a l ' with four rates of applied urea. M U L T I F A R M TRIAL: PLOT LOCATIONS Figure 3. Multifarm t r i a l plot locations , Delta Municipality, B r i t i s h Columbia. 3) A comparison of 'Preplant versus Sidedress' applied urea f e r t i l i z e r . 4) A 'Multifarm Survey' of sidedressed versus control plots. 3.2 FIELD METHODS 3.2.1 NITROGEN MONITORING STUDY. FERTILIZER RESPONSE TRIAL AND  PREPLANT VERSUS SIDEDRESS UREA STUDY These studies were conducted i n cooperation with Mr.Hugh Reynolds, at Reynelda Farms, Westham Island, B.C.. The f i e l d s used i n both 1984 (Site A) and 1985 (Site B) were contracted to grow sweet corn, variety 'Jubilee', f o r Royal Cit y Foods Ltd.. S i t e A was situated on medium to moderately f i n e textured d e l t a i c deposits of the Crescent series, i t had been i n peas i n 1983 followed by a cover crop of spring barley. The crops p r i o r to the peas were potatoes i n 1982 and corn i n 1981. S i t e B had been i n strawberries f o r f i v e years p r i o r to the experiment, i t was situated adjacent to S i t e A, separated by a drainage ditch and was also of the Crescent ser i e s . The two s i t e s d i f f e r e d somewhat i n s o i l c h a r a c t e r i s t i c s . S i t e A had a coarser s o i l texture, a lower organic matter content (2.4% compared to 3.8%, 0-20cm depth) and a higher bulk density. Both s i t e s had a r e l a t i v e l y low pH range, between 4 and 5, and S i t e B contained notably higher quantities of Na, S0 4-S, Fe and B plus a s u b s t a n t i a l l y greater e l e c t r i c a l conductivity (Appendix 2). PLOT LAYOUT The experimental design f o r both s i t e s was a randomized complete block design with s i x treatments and f i v e r e p l i c a t e s . Four of the s i x treatments belonged to the ' F e r t i l i z e r Response T r i a l ' and consisted of four rates of urea, 0,50,100 and 200 kg ha" 1 of N applied to 4m x 6m plots. The two remaining treatment: contained the 'Preplant versus Sidedress' urea t r i a l , which consisted of 100 kg ha~ 1 of N as urea applied preplant, and 100 kg ha~ 1 of urea N applied at sidedress time, when the corn was approximately 30cm t a l l (Appendix 3). In 1985 a second f i e l d t r i a l (Site C) was conducted i n a si m i l a r manner to those at Reynelda Farms. The t r i a l was set up in cooperation with Mr. John Malenstyn of Jowkema Farms and was situated on the mainland 7km East of Westham Island. The s o i l on S i t e C was of the Westham series, i t had been i n corn the previous year and was chosen for inv e s t i g a t i o n because i t contained l e s s N03-N than S i t e B at sidedress time. The plot layout was i d e n t i c a l to that used on Sites A and B with the omission of the Preplant versus Sidedress Urea T r i a l treatments, ie . there were four, not s i x treatments, r e p l i c a t e d f i v e times at 0,50,100 and 200 kg ha" 1 urea N. METHODS OF FERTILIZATION The urea applied at preplant was broadcast by hand on 29 May in 1984 and on 8 May i n 1985. The sidedressed urea was applied each year on a date when the corn was approximately 30cm t a l l , (13 July 1984, 20 June 1985). A push-plough was used to make a 46 5-10cm deep furrow 15cm away from the corn along the right-hand side of the row. The f e r t i l i z e r was placed into t h i s furrow and then covered with s o i l using a rake. In addition to the sidedress urea, 47 kg ha" 1 of N was d r i l l e d as a starter, 5cm below and to the side of the seed. The seed was custom planted by a single contractor (Mr. John Malenstyn) using a row width of 1.0 m. SOIL MEASUREMENTS A l l 30 plots were s o i l sampled before planting, (29 May 1984, 1 May 1985), at sidedress time, (13 July 1984, 20 June 1985) and again at harvest (18 Sept 1984, 25 August 1985). The ten plots comprising the Preplant versus Sidedress t r i a l were sampled f o r t n i g h t l y , from 25 A p r i l to 4 July 1984, and 8 May to 16 July 1985 f o r the S o i l N Monitoring Study. A sample consisted of ten composited s o i l cores from each plot, these were taken with an oak f i e l d sampling probe from between the corn rows at depths of 0-20, 20-50 and 50-80cm. The samples were transported i n coolers to the laboratory, where they were stored at 2°C u n t i l extraction, which was within 24 h of sampling. Six bulk density cores (volume = 510.5cm3) were taken at a depth of 10cm on every sampling date. Two cores were taken at depths of both 35cm and 65cm from a p i t dug on the f i r s t s o i l sampling date i n each season. S o i l temperatures were recorded throughout the 1984 experimental period with thermocouple probes at three depths; 10cm, 35cm and 65cm. These probes were attached to a recorder 47 which malfunctioned i n 1985, thus the s o i l temperature data used for 1985 are temperatures recorded at a depth of 10cm on a drained plot at the Boundary Bay drainage experiment, 10.5 km East of the t r i a l s i t e . The temperatures f o r each sampling date were calculated as a mean of the d a i l y temperatures over the f o r t n i g h t l y s o i l sampling i n t e r v a l s . A l l management practices on the experimental plots, except f e r t i l i z i n g and harvesting, were performed by the farmer or a farmer-hired contractor. CROP HARVEST Harvest of the experimental plots was done by hand, using a machete. Harvesting consisted of cutting two, 2m rows of corn i n each plot; from these, numbers of cobs, stalks, and t i l l e r s were t a l l i e d , and stalk and cob fresh weights were obtained. Following weighing, f i v e s t a l k s and f i v e cobs were randomly selected from each plot f o r moisture and t o t a l N determinations following oven drying at S5°C. About one month before harvest, farmers 'Top' t h e i r sweet corn to prevent plants tangling and slowing harvest operations. 'Topping', for the farmer, involves cutting the top 50 cm of the plant by machine. In order to avoid losing the tops of the experimental plants, topping was performed on each s i t e by hand using rose cutters before the f i e l d was mechanically topped. The tops were gathered, dried and weighed, and a subsample was l a t e r added to the s t a l k subsample c o l l e c t e d at harvest. 3.2.2 MULTIFARM SURVEY OF SOIL NITROGEN SUPPLYING ABILITY This study was c a r r i e d out i n close cooperation with Mr. Irvine Schinkel, Royal City Foods Ltd. on 28 s i t e s <17 i n 1984, 11 i n 1985) on farms contracted to grow sweet corn for processing. At each s i t e two treatments were applied: <1) A four-row wide 'control' s t r i p of corn receiving only the 47 kg ha - 1 of s t a r t e r N. (2) A paired comparison s t r i p , receiving i n addition to the s t a r t e r N, 135 kg ha - 1 of urea-N when the corn was 30cm t a l l . 20m from the headlands within each treatment s t r i p , a 6x4m plot was s o i l sampled at sidedress time and again at harvest. The s o i l sampling and harvesting methods were the same as those described for the F e r t i l i z e r Response T r i a l (Sec.3.2.1). In contrast to the Replicated F e r t i l i z e r Experiment where f e r t i l i z i n g was done manually using a push-plough, N sidedressing i n the Multifarm Study was car r i e d out on a l l plot by a custom operator. The remainder of the f i e l d management practices except the plot harvest, were performed by the contracted growers. In order to obtain crop and s i t e h i s t o r i e s , questionaires were sent to each cooperating farmer (Appendix 4). The following crops were found on the survey s i t e s the year pr i o r t corn: Peas (10), Potatoes (7), Beans (3), Spring barley (2), Corn (2), Strawberries (1), Unknown (3). 3.3 LABORATORY METHODS S o i l moisture determinations consisted of drying lOg of field-moist s o i l overnight at 105°C and reweighing. The s o i l for the bulk density determinations was treated i n a s i m i l a r manner. NH«-N and N03-N were extracted from the moist s o i l samples with 2M KCl using a 1:5 s o i l to extractant r a t i o (20g moist s o i l :100mL 2M KCl) and shaking f o r 1 h (Keeney 1982). After s e t t l i n g , the supernatant was f i l t e r e d through Whatman #42 f i l t e r paper, the extractions were stored at 2°C i n 60mL bottles containing a drop of toluene to i n h i b i t microbial growth. Concentrations of NH4-N and N03-N i n the f i l t e r e d extracts were determined using the Autoanalyser II (Technicon Autoanalyser II Methodology 1977), as was 'Total N', found i n the form of NH*-N, after the plant samples had been digested using the method of Parkinson and Allen (1975). The t o t a l N digestions were performed separately on the dried cob and stalk samples which had been ground i n a Wiley m i l l to pass a 2mm mesh sieve. The s o i l analyses f o r the s i t e s i n the Multifarm T r i a l ( S o i l texture. Total N, Organic matter, pH, Salts, P, K, Mg, Ca, Na, Total cations, Exchangeable sodium percent, SAR, SO*-S, B, Cu, Fe, Mn, and Zn) were performed by the B.C. Ministry of Agriculture s o i l s laboratory, Kelowna, using t h e i r standard techniques (Appendix 5). This laboratory also analysed the Multifarm T r i a l s o i l s f o r N03-N. In contrast to the technique 50 described above using 'Field-Moist' s o i l s , the 'Kelowna' method used a i r dried s o i l s which had been ground to pass through a 2mm mesh sieve. The extractant used for N03-N was the Kelowna Extractant (0.25N HOAc+0.015N»F) (van Lierop 1986) which was also used f o r extracting many of the other plant nutrients i n the standard analysis. The extraction procedure involved shaking a 1:10 v/v so i l : e x t r a c t a n t solution at 180 cycles min"1 f o r 5 minutes and then f i l t e r i n g through Whatman #2 f i l t e r s . 3.4 STATISTICAL ANALYSIS 1) N Monitoring Study: Mann-Whitney U (Mann and Whitney 1947) tests were used to compare s o i l N values on s p e c i f i c dates. Pearson's ' r ' c o r r e l a t i o n c o e f f i c i e n t s (Hicks 1982) were used for co r r e l a t i o n s between s o i l N and temperature. 2) Replicated F e r t i l i z e r Response T r i a l : Differences between treatments and blocks were i d e n t i f i e d with the Kruskal-Wallis One Way Analysis of Variance Technique (Kruskal and Wallis 1952). 3) Preplant versus Sidedress Study: Mann-Whitney U tests were used to i d e n t i f y s i g n i f i c a n t differences between treatments. 4) Multifarm T r i a l : Pearson's r c o r r e l a t i o n c o e f f i c i e n t s were used for scattergrams between s o i l parameters and corn y i e l d parameters. Three types of regression l i n e s were f i t t e d to these scattergrams: a) Linear (y = b 0 * b tx). b) Logarithmic (y = b« • bilogx + b Bx). This equation determines whether the graph of points f l a t t e n s out as the x component increases. c> Quadratic .(y = b 0 + bi x + b ex 8 ). This equation determines whether the shape of the curve i s parabolic, i e . y values begin to decrease when x values are high. Graphs of S o i l N03-N versus corn y i e l d parameters were also analyzed using the Cate-Nelson procedure (Cate and Nelson 1971). This procedure i s applied to logarithmic type graphs and s p l i t s the data into two populations using successive tentative ' C r i t i c a l Levels' to ascertain the p a r t i c u l a r l e v e l which w i l l maximize the o v e r a l l p r e d i c t i v e a b i l i t y of the graph. In t h i s study, a graphical version of the procedure was used, i t involved placing over a plot of the population, a transparency s p l i t into four quadrants by two l i n e s drawn at right-angles. The method for fin d i n g the C r i t i c a l Level was described i n Sec.2.2.2.. In r e a l i t y , there i s r a r e l y a precise C r i t i c a l Level, instead the v e r t i c a l l i n e could cross the X-axis at any number of points within a range which varies depending on the data set. The data i n t h i s study was s p l i t by t h i s graphical method into 'Responsive' and 'Unresponsive' populations which f e l l i n the lower l e f t and upper right quadrants respectively. 4.RESULTS AND DISCUSSION The design of the project, with four i n t e r r e l a t e d parts, allowed the r e s u l t s to be conveniently separated into four sections: 1) The Nitrogen Monitoring Study. This section produced information on s o i l N transformations during spring, and provided data regarding optimum sampling times and depths for use with a spring s o i l sample should i t be prove to be p r a c t i c a l . 2) & 3) The Replicated F e r t i l i z e r Response T r i a l s and the  Preplant versus Sidedress Urea Study. The r e s u l t s of these studies showed there to be no s i g n i f i c a n t crop response to eith e r d i f f e r e n t rates of f e r t i l i z e r or to d i f f e r e n t methods of f e r t i l i z e r application. Such findings, i n s p i t e of being negative, demonstrated the importance of N supplied by the s o i l . 4) The Multifarm Survey. This survey of 28 d i f f e r e n t s i t e s i n the Delta region of the LFV, generated the greatest amount of information p a r t i c u l a r l y regarding the response of corn plants to s o i l and f e r t i l i z e r N. The r e s u l t s could be used to assess how N f e r t i l i z e r recommendations i n the LFV might be improved. It must be borne i n mind that the r e s u l t s here apply s p e c i f i c a l l y to sweet corn i n the Delta region of the LFV however they do e s t a b l i s h p r i n c i p l e s that could be applied to other crops and other a g r i c u l t u r a l regions. 4. 1 NITROGEN MONITORING DURING SPRING 4.1.1 SOIL MINERAL NITROGEN. MAGNITUDE AND VARIABILITY Fig. 4.1 shows the accumulated s o i l N03-N (kg ha" 1 ) contents measured f o r t n i g h t l y i n the spring at the three depths; 0-20, 20-50 and 50-80cm i n both 1984 and 1985. Tables 4.1 and 4.2 emphasize the considerable differences between the two years i n both the magnitude and v a r i a b i l i t y of N03-N and NH*-N values. In s p i t e of these differences, a trend of N03-N increasing during spring can be seen, p a r t i c u l a r l y i n the 0-20cm depth. Although r e l i a b l e conclusions cannot be founded on the basis of just a couple of years research, two points can be drawn from the data. 1) That substantial quantities of mineral N are made available by the s o i l . 2) That when sampling f o r N03-N there are large amounts of s p a t i a l and temporal v a r i a b i l i t y . Results such as those i n 1985, which showed 130 kg ha - 1 i n the 0-80cm p r o f i l e at sidedress time (Table 4.1), suggest that s o i l N should be taken into consideration when f e r t i l i z e r recommendations are being made. However, the large differences i n N values, both between s i t e s and within s i t e s , not only emphasise the importance of s i t e sampling, but also underlines the d i f f i c u l t y i n doing t h i s accurately and then int e r p r e t i n g the r e s u l t s . The most obvious area of v a r i a t i o n i s the difference i n N03-N between S i t e A and S i t e B (Fig. 4.1). It i s not possible to i d e n t i f y the cause for t h i s difference because too many ' f t < t H t t t t f, » • T • ? ' T • - J | | r f T 1 , w „ f n 1 , . n . | r r . ^ „ . r . , . , APR MAY JUN JUL MAY JUN JUL I984(SITEA) 1985 (SITE B) Figure 4.1 S o i l n i t r a t e to a depth of 80cm d u r i n g s p r i n g . ui Table 4.1. Soil NOa-N during spring 1984 (Site A) and 1985 (Site B). Date 0-20cm Soi l N0,-N kg ha ' CV 20-50cm CV 50-80cm CV Total 0-80cm 1984 1984 Apr 25 2.6 15.4 10.0 16.0 8.5 11.8 21.1 May 9 11.1 6.3 16.5 15.2 17.6 32.4 45.1 May 23 11.6 12.9 19.7 16.2 14.2 15.5 45.5 June 7 18.1 5.5 21.9 29.7 13.5 21.5 53.4 June 20 35.7 19.6 28.9 48.8 15.5 25.2 79.8 July 4 34.4 18.9 33.0 11.2 22.6 9.3 89.9 1985 1985 May 8 14.0 33.6 37.5 28.0 40.3 36.0 91.8 May 22 19.2 17.2 42.1 27.3 42.1 23.0 103.4 June 5 28.9 30.4 39.1 23.5 36.4 30.0 104.6 June 19 42.3 21.7 48.2 26.8 42.8 37.4 133.3 July 2 40.6 13.5 48.5 19.2 38.1 28.1 127.2 July 16 31.5 7.3 42.8 22.0 31.1 43.1 105.3 Planting = 29 May 1984, 8 May 1985. Sidedress = 13 July 1984, 20 June 1985. Table 4.2 Soil NH^ -N during spring 1984 (Site A) and 1985 (Site B). Date 0-20cm CV So i l NH^ -N kg ha"1 20-50cm CV 50-80an CV Total 0-80cm NH^ -N as % of total Mineral N 1984 1984 1984 Apr 25 2.3 17.4 4.2 43.0 2.7 18.5 9.3 27 May 9 3.5 37.1 6.3 46.0 3.9 25.6 13.7 23 May 23 3.9 41.0 4.5 17.8 3.2 18.8 11.6 20 June 7 3.6 30.1 4.1 29.3 3.4 26.5 11.1 17 June 20 3.4 20.6 4.3 18.6 3.2 25.0 10.9 12 July 4 4.2 16.7 5.9 16.9 5.4 24.1 15.5 15 1985 1985 1985 May 8 6.7 37.3 11.5 46.1 9.8 41.8 28.0 23 May 22 2.6 61.5 2.8 3.6 3.7 99.0 9.1 8 June 5 6.3 30.2 9.9 15.2 10.0 17.0 26.2 20 June 19 3.9 79.5 3.3 45.5 4.8 62.5 12.0 10 July 2 1.8 83.3 0.5 48.0 1.6 93.8 4.0 4 July 16 2.9 51.7 5.6 24.0 3.0 70.0 11.6 9 Planting = 29 May 1984, 8 May 1985. Sidedress = 13 July 1984, 20 June 1985. 56 i n t e r e l a t e d f a c t o r s were involved. For example, there were both s i t e f a c t o r s and weather factors; some of the s i t e factors being, the d i f f e r e n t s o i l properties. S i t e A contained l e s s organic matter, more clay and had a lower pH than s i t e B. Si t e B had been i n strawberries f o r the past f i v e years, and the crop had been heavily treated with a f e r t i l i z e r mix composed partly of sewage sludge. In comparison, S i t e A had been i n peas the previous year and therefore the influence of crop and f e r t i l i z e r residues was minimal. The high mineral N contents found i n the lower depths on S i t e B (Table 4.1) may have a number of causes, eg. ploughing i n the strawberry plants i n the f a l l , the f e r t i l i z e r prcatices used on the strawberries, or perhaps the source and nutrient content of the water beneath S i t e B was di f f e r e n t from S i t e A. The high values may also have been due to the differences i n the weather between the two years, spring 1984 being much colder and wetter than 1985. Thus, the many factor s that a f f e c t s o i l mineral N cannot be unravelled to explain the d i f f e r e n t N l e v e l s between the two s i t e s . Such a complex system does however suggest the usefulness of a mineral N s o i l sample, p a r t i c u l a r l y as close to f e r t i l i z i n g time as possible i n order to override the many factors that can af f e c t s o i l mineral N values. 4.1.2 SOIL AMMONIUM On S i t e A (1984) s o i l NH*-N values were consistently low throughout the p r o f i l e (9-16 kg ha" 1 0-80cm depth. Table 4.2). In contrast, on S i t e B (1985) NH»-N values varied e r r a t i c a l l y 57 from 4-28 kg ha - 1 . As a proportion of t o t a l mineral N, NH*-N decreased throughout the spring, reaching values of below 15% i n 1984 and below 10% i n 1985 (Table 4.2). This decrease probably r e f l e c t s the increasingly favourable conditions for n i t r i f i c a t i o n , i e . warmer, d r i e r s o i l s . The low l e v e l s of NH*-N in comparison to N03-N imply that n i t r i f i c a t i o n was keeping pace with mineralization. The increase i n NH*-N as a proportion of t o t a l mineral N on the l a s t sampling date i n both years was probably due to the s t a r t of crop uptake of s o i l N03-N. 4.1.3 SOIL NITRATE AND SOIL TEMPERATURE S o i l N03-N i n the surface horizon showed a strong l i n e a r c o r r e l a t i o n with temperature, (Fig.4.2, r=0.92 »» (1984), r=0.73*» (1985)). This l i n e a r c o r r e l a t i o n i s seen to cease before the f i n a l sampling date and, i n a si m i l a r manner to the increase i n NH*-N as a proportion of mineral N, i s probably due to the beginning of detectable crop uptake of s o i l N03-N which appears to occur about f i v e to six weeks afte r planting i n both 1984 and 1985 (Table 4.1). 4.1.4 VARIABILITY OF BULK DENSITY MEASUREMENTS Six bulk density measurements were taken i n the 0-20cm depth at each sampling date of the N monitoring study. Table 4.3 shows the mean and CV values f o r bulk density and s o i l N03-N (mg kg - 1 ) at each date. The average CV for bulk density measurements was su b s t a n t i a l l y lower than for s o i l N03-N (mg kg - 1 ) e s p e c i a l l y i n 1985. This r e s u l t suggests that the error 58 Figure 4.2 Relationship between s o i l n i t r a t e (0-20cm) and s o i l temperature during spring. Table 4.3 Replicated F e r t i l i z e r Response T r i a l : Mean and coefficient of variation (CV) for ND.-N (mg kg"') and bulk density (t m"5). Date NCL-N 6 mg kg"' %CV Bulk density 0-20cm t m"* %CV 1984 Apr 25 0.8 15.9 1.24 6.8 May 9 3.2 6.3 1.31 5.3 May 23 3.7 12.1 1.18 10.5 June 7 5.2 5.3 1.38 6.6 June 20 8.9 20.0 1.50 11.1 July 4 10.2 18.5 1.34 9.1 1985 May 8 4.4 30.5 1.14 4.4 May 22 6.7 17.2 1.07 3.7 June 5 10.5 29.4 0.98 7.8 June 19 14.3 20.5 1.11 6.7 July 2 13.6 13.6 1.13 4.8 July 16 10.8 7.7 1.11 6.7 60 incurred by using sample date bulk densities to convert N03-N from mg k g - 1 to kg ha - 1 was acceptable, because the N03-N sampling error was greater than the bulk density measurement error. 4.2 FERTILIZER NITROGEN RESPONSE TRIAL AND PREPLANT VERSUS  SIDEDRESS UREA STUDY 4.2.1 CROP RESPONSE TO FERTILIZER One way analysis of variance showed no s i g n i f i c a n t differences i n corn y i e l d or crop N content among any of the four f e r t i l i z e r treatments (0,50,100 and 200 kg ha - 1 of N) on any of the s i t e s . A,B or C. Table 4.4 shows the average corn y i e l d s and N contents for these three s i t e s . S i m i l a r l y , Mann-Whitney U te s t s showed no s i g n i f i c a n t differences between the yi e l d s of crops which had been broadcast f e r t i l i z e d preplant and those which had been sidedressed when the corn was about 30cm t a l l . The t o t a l dry y i e l d s f o r both treatments averaged 12.3 t ha" 1 and 11.6 t ha" 1 i n 1984 and 1985 respectively and the t o t a l N uptake was 135 kg ha"» i n both years (Table 4.4). Sweet corn does not have the same large demand f o r N as si l a g e corn, hence the lack of response i n the Replicated F e r t i l i z e r Response T r i a l and the Preplant Versus Sidedress Study may have been due to the adequate supply of N from the s o i l and the s t a r t e r N f e r t i l i z e r . The t o t a l N uptake by corn i n the Replicated F e r t i l i z e r Response T r i a l was 171 and 143 kg ha - 1 (Table 4.4) and the average N03-N content (0-80cm) at 61 Table 4.4 Replicated f e r t i l i z e r response t r i a l , Preplant versus sidedress urea t r i a l 1984, 1985: Corn data, site means and coefficients of variation. Corn Yield Replicated f e r t i l i z e r response t r i a l 1984 1985 Preplant versus sidedress urea t r i a l 1984 1985 Fresh Yield (t ha-' ) Site A Site B Site C Preplant Sidedress Preplant Sidedress Stover Mean 37.9 32.3 38.9 36.7 36.8 29.2 29.1 CV 6.5 17.9 16.6 13.9 11.1 19.2 11.3 Cobs Mean 23.9 26.9 22.7 25.2 24.1 25.8 28.2 cv 8.2 11.2 16.3 12.3 8.3 11.2 11.7 Total Mean 61.8 59.2 61.6 61.9 60.9 55.0 57.3 Dry Yield (t ha"' ) Stover Mean 8.0 5.2 5.8 6.5 6.4 4.8 4.7 CV 9.1 13.5 20.3 13.8 7.8 14.6 21.3 Cobs Mean 6.1 5.9 4.5 5.3 5.1 5.6 6.2 cv 7.8 10.2 25.0 9.4 11.8 1.8 14.5 Total Mean 14.1 11.1 10.3 12.5 12.0 11.3 11.9 N Content (kg ha"' ) Stover Mean 97.5 63.8 N 73.6 79.2 54.2 56.8 cv 18.6 19.4 contents 10.7 16.6 19.0 19.5 not Cobs Mean 73.8 79.3 measured 57.0 59.3 77.2 81.4 cv 20.3 15.0 34.2 19.7 16.8 17.3 Total Mean 171.3 143.1 130.6 138.5 131.3 138.2 Table 4.5 Replicated F e r t i l i z e r Response T r i a l 1984,1985: So i l NOj-N, means and coefficients of variation before planting and at sidedress time. Date 0-20cm CV Soil N0j-N kg ha -' 20-50cm CV 50-80cm CV Total 0-80cm 1984 Site A Before planting Sidedress tiros 18.9 37.8 15.2 17.3 23.9 18.9 34.4 16.2 14.6 23.6 24.1 23.2 57.3 95.8 1985 Site B Before planting Sidedress time 10.0 30.7 18.0 16.9 36.4 17.6 43.8 31.4 43.4 40.2 9.2 14.2 89.7 114.6 Planting = 29 May 1984, 8 May 1985. Sidedress = 13 July 1984, 20 June 1985. 63 sidedress time was 95.8 and 114.6 kg ha - 1 for S i t e s A and B respectively, (Table 4.5). Therefore i t i s quite probable that the s o i l N at sidedress, the generous amount of s t a r t e r N (47 kg h a - 1 ) , and the amount of N mineralized over the growing season, supplied s u f f i c i e n t N f o r the crop's requirements under the p r e v a i l i n g weather and management conditions. D i l z (1981) i n the Netherlands, showed a s i m i l a r lack of reponse when he used spring barley as a test crop. He found no r e l a t i o n s h i p between N0 P and N. t„ as had been previously been found with winter wheat, sugar beet and potatoes. 4.3 MULTIFARM SURVEY 4.3.1 SOIL NITROGEN SUPPLYING CAPACITIES The Multifarm Survey provided the greatest amount of information relevant to the project's objectives. In s p i t e of the large amount of v a r i a b i l i t y due to using farmers' f i e l d s under a wide range of s o i l conditions, trends were found r e l a t i n g the N supplying capacity of the s o i l to s o i l c h a r a c t e r i s t i c s and crop response. Table 4.6 shows the Multifarm Survey's range and mean values for s o i l N03-N and NH*-N sampled at three depths at sidedress time. The maximum N03-N value i n any depth was 50 kg h a - 1 , the maximum NH4-N value i n any depth was 16 kg ha - 1 except f o r two s i t e s with unusually high quantities (Appendix 7). Table 4.6 Multifarm T r i a l : S o i l NOj-N and NH^ -N at sidedress time, mean and range over 27 sites. Depth 0 - 20 cm 20 - 50 cm 50 - 80 cm 0 - 80 cm NOg-N Mean 22.3 20.9 16.3 59.7 kg ha - 1 Range 3.2 - 46.8 0.9 - 49.5 0.2 - 48.2 4.3 - 141.6 NH4-N Mean 8.2 5.1 7.1 20.4 kg ha"' Range 0.7 - 25.9 0.6 - 16.8 0.5 - 23.9 2.8 - 37.1 Anomalous sit e NOj-N kg ha"' 70.2 28.3 38.7 137.2 NH+-N kg ha -' 8.8 2.9 2.5 14.2 65 4.3.2 BULK DENSITIES OF THE MULTIFARM TRIAL SITES The range and averages f o r bulk densities i n the Multifarm t r i a l are shown i n Table 4.7. The averages show that the means and medians tend to f a l l close to the 'Mid-point' of the ranges; the only exception was i n the 20-50cm depth where the values were skewed towards the high end, causing the median bulk density to be somewhat higher than the mean or range mid-point. In the Multifarm T r i a l s i t e bulk densities were used for converting N03-N from mg kg" 1 to kg ha - 1 i n a s i m i l a r manner to the N Monitoring Study. A paired T-test was ca r r i e d out comparing N03-N values calculated using the i n d i v i d u a l s i t e bulk densities to N03-N calculated using the mean bulk density from a l l 28 s i t e s at each depth. The r e s u l t s showed that the N03-N values calculated using i n d i v i d u a l s i t e bulk densities, were s i g n i f i c a n t l y d i f f e r e n t from values calculated using a mean bulk density at the 0-20cm depth, but not at depths 20-50cm, and 50-80cm. Such r e s u l t s suggest that where possible, plough layer bulk densities should be used f o r conversion purposes; at greater depths, average bulk densities f o r the region or the s o i l type under investigation, would probably be adequate. 4.3.3 SOIL NITROGEN AND PREVIOUS CROPPING The most common crops grown on the s i t e s , the year before corn, were peas, beans and potatoes (Appendix 6). When the previous crops were grouped into two categories and compared, ie . a leguminous crop (13 s i t e s ) versus potatoes (7 s i t e s ) , Table 4.7 Multifarm T r i a l : Bulk densities (t m - 3), range and averages. Depth 0 - 20 cm 20 - 50 cm 50 - 80 cm Bulk Range 0.76 - 1.43 0.85 - 1.60 0.87 - 1.53 Density tm"' Range 1.10 1.23 1.20 mid-point Mean 1.12 1.24 1.18 Median 1.14 1.31 1.20 there appeared to be no r e l a t i o n s h i p between previous crop and s o i l N03-N at side-dress time, nor previous crop and t o t a l s o i l plus crop N at harvest i e . 'Total N'. The mean Total N f o r peas and beans was 140 kg ha" 1 (CV = 52*/.) and for potatoes was 144 kg ha - 1(CV=59%). This apparent lack of r e l a t i o n s h i p between previous crop and s o i l N i s not s u r p r i s i n g since according to the UK N Index System <MAFF 1985-86) a l l the crops i n the Multifarm T r i a l apart from spring barley, f e l l into the Index 1 category. Furthermore, the high c o e f f i c i e n t s of v a r i a t i o n support the findings by Jungk and Wehrmann (1978) who found that the large differences i n s o i l N0 3 -N on s i t e s with the same previous crop outweighed differences among s i t e s with d i f f e r i n g previous crops. 4.3.4 SPRING SOIL NITROGEN AND SOIL PROPERTIES Correlations were calculated between s o i l N03-N at sidedress time and a l l the s o i l properties determined by the BCMAF S o i l and Feed Testing Laboratory, plus t o t a l s o i l N and s o i l texture, ie. V. s i l t , sand and clay. I n i t i a l l y , high c o r r e l a t i o n s were obtained for many of the parameters, e s p e c i a l l y s o i l N03-N versus organic matter. However a c a r e f u l examination of the graphs, showed that most of the c o r r e l a t i o n was accounted for by a s i n g l e o u t l i e r (Year 2, S i t e 3) which contained a large amount of N03-N (77 kg ha - 1 N03-N) and unusually high contents of organic matter (167.), P(358 mg L~ 1 ), K(3.48 me lOOmL"1), Mg(5.48 me lOOmL"1), and Zn(34.3 mg L" 1 1) i n the 0-20cm depth. This s i t e was behind a disused barn and had previously been manured for many years. The outlying s i t e was eliminated from the data, leaving 27 s i t e s for the Multifarm Survey analysis. Table 4. 8 shows the s i g n i f i c a n t c o r r e l a t i o n s between s o i l parameters and s o i l N03-N at sidedress time. NH*-N did not cor r e l a t e with any s o i l parameters. ORGANIC MATTER AND TOTAL NITROGEN Organic matter ranged from 2.2 - 9.5% i n the 0-20cm depth although a majority of s i t e s were within the narrow 2-5% range. S o i l N03-N did not correlate with organic matter at any depth. Maximum t o t a l s o i l N was 0.57. i n the 0-20cm depth (Table 4.8). Total s o i l N was p o s i t i v e l y correlated with organic matter i n the 0-20cm depth r=0.37(») and i n the 20-50cm depth r=0.32(*>. Many spring N sampling studies have shown l i t t l e , i f any r e l a t i o n s h i p between organic matter and N uptake or N mineralized, e s p e c i a l l y when the range of organic matter l e v e l s i s narrow (Linden 1984; Sylvester-Bradley 1984; Ostergaard, 1984). The reason for t h i s lack of r e l a t i o n s h i p i s generally given to be the inconsistent mineralization of organic N due to continuously changing s o i l conditions. SOIL TEXTURE The Multifarm T r i a l study area was situated i n the Delta region of the Fraser Valley where the s o i l textures are mainly s i l t loams to s i l t y clay loams. The % sand, s i l t and clay for the 27 study s i t e s ranged from 0-12, 58-75, and 19-37% respectively, i n the 0-20cm depth (Table 4.8). No s i g n i f i c a n t Table 4.8 Multifarm Trial: Soil parameter ranges and significant correlations at three depths between soil characteristics and 'Field Moist' extracted soil N0--N at sidedress time. Soil Parameter 0-20 Range cm r 20 -Range 50 an r 50 -Range 80 cm r % S i l t 58-75 - 67 - 81 - 55-80 -% Sand 0-12 - 0-14 - 0-35 -% Clay 19 - 37 - 14 - 31 - 10 - 27 -% Organic matter 2.2 - 9.5 - 0.8 - 4.4 - 0.7 - 4.6 -% Total Nitrogen 0.10 - 0.52 - 0.04 - 0.34 - 0.02 - 0.31 -0.341 * pH (Ht0) 4.1 - 6.9 - 3.6 - 6.7 0.447 ** 3.2 - 6.6 0.445 * Salts (E.C.) dS m" 0.32 - 5.0 - 0.24 - 6.1 -0.349 * 0.24 - 9.00 -N05-N kg ha - 1 4.1 - 143.0 0.720 ** 0.0 - 92.6 0.808 *• 0.0 - 87.0 0.878 ** P jjg mL-1 29.0 - 291.0 0.450 ** 2.0 - 116.0 - 2.0 - 61.0 -K me lOOmt,-1 0.25 - 0.97 - 0.09 - 0.76 - 0.08 - 0.76 -Mg me 100 L -' 0.65 - 5.67 -0.470 ** 0.39 - 5.43 - 0.32 - 4.11 -Ca me lOOmL-1 1.83 - 8.0 - 0.59 - 6.67 0.336 * 0.23 - 3.16 -Na me lOOmL-1 0.0 - 4.28 -0.406 * 0.0 - 5.35 - 0.0 - 7.17 -Total Cations me lOOraL-' 3.79 - 18.0 - 1.4 - 11.6 - 0.73 - 13.63 -- i SO^ -S *g mL 10.3 - 136.6 -0.369 * 12.4 - 171.5 - 13.0 - 340.0 -Significance: ** = 1% * = 5% 'Range' = Range of values ewer 27 sites. 70 c o r r e l a t i o n s were found between s o i l N03 -N and 7. sand, s i l t or clay at any depth. Ostergaard (1985) noted that although s o i l mineral N i s affected by s o i l texture, s i g n i f i c a n t differences are only apparent when there i s a wide range of textures. In the study area, the range of s o i l textures was r e l a t i v e l y narrow, i e . s i l t y loams to s i l t y clay loams, t h i s may have been the reason for the lack of c o r r e l a t i o n between s o i l texture and s o i l N03-N at sidedress. pH. N03-N was p o s i t i v e l y correlated with pH which ranged from 4.1 to 6.9 i n the 0-20cm depth, and went as low as 3.6 and 3.2 i n the 20-50 and 50-80cm depths (Table 4.8). This r e s u l t r e f l e c t s the well known favourable e f f e c t of higher s o i l pH on n i t r i f i c a t i o n . The low pH observed on many of the s i t e s could be raised by liming, t h i s practice would probably increase the N supplied by the s o i l , however i t might also increase the p o t e n t i a l for d e n i t r i f i c a t i o n at times when the s o i l was very wet. MARINE EFFECTS E l e c t r i c a l conductivity, Na, Mg and S0«-S a l l showed s i g n i f i c a n t negative c o r r e l a t i o n s with s o i l N03-N (Table 4.8). These c o r r e l a t i o n s were caused mainly by four s i t e s (Yr.1, Sites 2,7,16. Yr.2, S i t e 6) which had been affected by marine conditions. These conditions caused them to have unusually high l e v e l s of exchangeable ions associated with sea water and high 71 soluble s a l t s i n the s o i l p r o f i l e (Table 4.8). Three of these s i t e s also displayed high NH*-N l e v e l s at sidedress and were on s o i l s that, when unimproved, are moderately poorly to poorly drained (Delta and Ladner s o i l s ) . Such findings suggest that f i e l d s with obvious management problems may have to be treated separately, or excluded from a N f e r t i l i z e r recommendation system. SOIL NITRATE MEASURED BY THE KELOWNA LABORATORY A c o r r e l a t i o n of the N03-N i n 'Kelowna' extracted s o i l s , with the N03-N i n the s o i l s extracted 'Field-Moist', showed that the Kelowna method extracted more N03-N over the 0-80cm depth than the Field-Moist method (r=0.88 (»*), slope=1.77). Some of the v a r i a b i l i t y and the difference i n magnitude between N03-N extracted by the two methods, may be due to the F i e l d Moist extracted s o i l s being l e f t i n p l a s t i c bags for some days before drying. However the higher l e v e l s found i n the Kelowna extracted s o i l s may also have been a product to some extent of the drying, grinding and d i f f e r e n t extracting procedures used. A proper comparison of the Field-Moist method and the Kelowna method fo r extracting s o i l N03-N would require a project i n i t s e l f , however some of the differences observed were worth noting (Table 4.9): a) The Kelowna N03-N values showed s i g n i f i c a n t c o rrelations at the IV. (»») l e v e l for pH at a l l three depths (Table 4.9). This was i n comparison to the Field-Moist extracts which showed t h i s l e v e l of s i g n i f i c a n c e at only one of the three depths. Table 4.9 Multifarm Trial: Significant correlations between soil/crop parameters and soil NOj-N (sidedress) extracted by the 'Kelowna' and 'Field Moist' methods. 0-20 cm 20 - 50 cm 50 - 80 cm Parameter Kelowna Field Moist r r Kelowna r Field Moist r Kelowna r Field Moist r Soil pH (HjO) 0.569 ** - 0.546 •* 0.447 ** 0.476 0.445 * Crop - Stalks Fresh yield t ha"' - 0.771 **(C) 0.334 *(L) 0.719 *(C) - 0.647 *(C) % Total N 0.522 *(C) - 0.495 *(C) 0.330 *(L) 0.497 *(C) 0.334 *(L) Total N kg ha -' 0.578 **(C) 0.567 **(C) 0.598 **(C) 0.610 **(C) 0.593 **(C) 0.605 **(C) Crop - Cobs Fresh yield t ha"' 0.602 **(L) 0.571 **(C) 0.615 **(L) 0.631 **(C) 0.633 **(L) 0.682 **(C) % Total N 0.407 *(L) - 0.411 *(L) _ 0.443 *(L) -Total N kg ha"' 0.581 **(L) 0.447 **(L) 0.587 **(L) 0.537 **(L) 0.594 **(L) 0.591 **(L) Crop - Whole plant Fresh yield t ha-' 0.491 *(C) 0.754 **(C) 0.510 *(C) 0.749 **(C) 0.515 *(C) 0.730 **(C) Total N kg ha-' 0.600 **(C) 0.541 *(C) 0.598 **(C) 0.595 **(C) 0.593 **(C) 0.619 **(C) Significance: ** = 1% * = 5% (L) = Linear correlation (C) = Logarithmic correlation b> The Kelowna values were not correlated with e l e c t r i c a l conductivity. c) Correlations between Kelowna N03-N and corn N were stronger than between F i e l d Moist N03-N and corn N. In contrast, c o r r e l a t i o n s between Kelowna ND3-N and corn y i e l d s were weaker than F i e l d Moist N03-N and corn y i e l d s (Table 4.9). A possible explanation for a l l these findings i s that the Kelowna s o i l s underwent a form of incubation, or at least had a longer period of mineralization than the F i e l d Moist extracted s o i l s . Thus the e f f e c t of pH on mineralization and on n i t r i f i c a t i o n , became more pronounced. Sim i l a r l y , as the s o i l s were dried, the r e s u l t i n g n i t r i f i c a t i o n eradicated the negative c o r r e l a t i o n between s o i l N03-N and e l e c t r i c a l conductivity. The stronger r e l a t i o n s h i p between Kelowna N03-N and corn N, suggests that some form of incubation, on top of a simple s o i l test, may improve the prediction of N uptake, but as mentioned previously, N03-N produced i n incubations does not seem to be related well to N03-N used for crop growth. 4.3.5 SPRING SOIL NITROGEN AND CORN RESPONSE Tables 4.10a,b and c show the corr e l a t i o n s between corn y i e l d parameters and control plot mineral N at sidedress time. 'Stalk' y i e l d s i n t h i s discussion re f e r to, sta l k s plus leaves plus tops. Correlations with both N03-N and NH4-N were consistently higher for fresh y i e l d s than for dry yi e l d s . The NH4-N i n the 0-20cm depth was correlated negatively with stalk and cob, fr e s 74 Table 4.10a Multifarm t r i a l : Significant correlations between soil N0S-N and NHV-N extracted 'Field Moist* and corn yield parameters. N0,-N extracted 'Field Moist' NHV-N Logarithmic (C) or Results for 0-20 Linear Correlation Quadratic (Q) cm depth oily Crop Part Depth correlations Yield Parameter (Mean) (cm) r Sig. R Sig. r Sig. # per plot Tillers 0-20 0.456 ** 0.573 (C) ** -0.356 * (22) 0-50 0.503 ** 0.598 (C) ** (4.1m) 0-80 0.524 ** 0.580 (C) ** Stalks 0-20 - NS (20) 0-50 - NS 0-80 - NS Cobs 0-20 - NS 0.484 (C) * (23) 0-50 0.356 * 0.529 (C) • 0-80 0.396 * 0.536 (C) • Fresh yield Stalks 0-20 0.445 ** 0.771 (C) ** -0.521 ** (29.9) 0-50 0.489 ** 0.719 (C) * t ha'1 0-80 0.466 ** 0.647 (C) * Cobs 0-20 0.530 ** 0.571 (C) ** -0.460 ** (19.6) 0-50 0.620 ** 0.631 (C) ** 0-80 0.680 ** 0.682 (C) ** Whole Plant 0-20 0.538 ** 0.754 (C) ** -0.557 ** (49.5) 0-50 0.608 0.749 (C) ** 0-80 0.620 ** 0.730 (C) ** Dry yield Stalks 0-20 0.393 • 0.567 (C) ** -0.498 ** (5.1) 0-50 0.409 * 0.564 (C) * t ha -' 0-80 0.381 * 0.530 (C) * Cobs 0-20 0.365 * -0.352 * (4.8) 0-50 0.418 • 0-80 0.456 ** 0.471 (C) * Whole Plant 0-20 0.383 * 0.505 (C) * -0.420 * (11.1) 0-50 0.412 ** 0.525 (C) ** 0-80 0.408 ** 0.526 (C) ** Significance: ** = 1% * = 5% NS = Not Significant Table 4.10b Multifarm t r i a l : Significant correlations between soil NOj-N and NH^ -N extracted 'Field Moist' and corn yield parameters. NOj-N extracted 'Field Moist' NH^ -N Logarithmic (C) or Results for 0-20 Linear Correlation Quadratic (Q) cm depth only Crop Part Depth correlations Yield Parameter (Mean) (cm) r Sig. R Sig. r Sig. % Dry matter Stalks 0-20 NS (0.17) 0-50 NS 0-80 NS Cobs 0-20 -0.331 * (0.25) 0-50 -0.386 * 0-80 -0.413 * % Total N Stalks 0-20 NS (1.00) 0-50 0.330 * 0-80 0.334 * Cobs 0-20 NS (1.33) 0-50 NS 0-80 NS Total N Stalks 0-20 0.455 ** 0.567 (C) ** (62.8) 0-50 0.472 ** 0.610 (C) ** kg ha"1 0-80 0.451 ** 0.605 (C) ** Cobs 0-20 0.447 ** (63.0) 0-50 0.537 ** 0-80 0.591 ** Whole Plant 0-20 0.499 ** 0.541 (C) * (125.7) 0-50 0.536 ** 0.595 (C) ** 0-80 0.548 ** 0.619 (C) ** Significance: ** = 1% * = 5% NS = Not Significant 76 Table 4.10c Multifarm t r i a l : Significant correlations between soil NOj-N and NH^ -N extracted 'Field Moist* and corn yield parameters. NOj-N extracted 'Field Moist* NH, -N Logarithmic (C) or Results for 0-20 Linear Correlation Quadratic (Q) cm depth only Crop Part Depth correlations Yield Parameter (Mean) (cm) r Sig. R Sig. r Sig. Relative Yield Stalks 0-20 NS (0.91) 0-50 - NS (Fresh) 0-80 - NS Cobs 0-20 0.836 * 0.458 (Q) * -0.476 ** (0.87) 0-50 0.393 * 0.487 (Q) * 0-80 0.393 * 0.505 (Q) * Whole Plant 0-20 0.394 * - (O NS -0.407 * (0.89) 0-50 0.394 * 0.472 (C) * 0-80 0.359 * 0.472 (C) * Relative Yield Stalks 0-20 _ NS 0.503 (Q) * (0.93) 0-50 - NS 0.485 (Q) * (Dry) 0-80 — NS — (Q) NS Cobs 0-20 0.480 ** 0.506 (C) * (0.92) 0-50 0.438 * 0.436 (C) NS 0-80 0.400 * 0.401 (C) NS Whole Plant 0-20 0.446 ** 0.480 (Q) * (0.91) 0-50 0.408 * 0.431 (C) NS 0-80 0.359 * 0.400 (C) NS Significance: ** = 1% * = 5% NS = Not Significant and dry y i e l d s and with numbers of t i l l e r s , t h i s r e s u l t suggest that the conditions which i n h i b i t e d n i t r i f i c a t i o n i n some s o i l s were also unfavourable fo r corn growth. NUMBERS OF TILLERS. COBS AND STALKS S i g n i f i c a n t logarithmic r e l a t i o n s h i p s (r=0.57**, r = 0.60»*, r=0.58*») were found when number of t i l l e r s was plotted against s o i l N03-N for the depths 0-20, 0-50, and 0-80cm respectively (Table 4.10a). A s i m i l a r r e l a t i o n s h i p was found between the number of cobs per plot and s o i l N03-N, although the l e v e l of s i g n i f i c a n c e was only 5% (•) Table 4.10a. The number of s t a l k s per plot was not s i g n i f i c a n t l y correlated with s o i l N03-N and nor was the number of cobs per stalk. The e f f e c t of N on cob y i e l d s and numbers i s d e l i c a t e l y balanced, e s p e c i a l l y with respect to t i l l e r production. The r e s u l t s showed that s o i l N03 N was s i g n i f i c a n t l y and p o s i t i v e l y correlated with t i l l e r s and that there was a corresponding increase i n cob numbers. It i s possible however, that available N could have been more e f f i c i e n t l y used to increase i n d i v i d u a l cob y i e l d s than to increase t i l l e r s which yielded smaller cobs. YIELDS OF STALKS. COBS. AND THE WHOLE PLANT Logarithmic r e l a t i o n s h i p s were found to account for the greatest amount of v a r i a t i o n f o r fresh y i e l d s of cobs and both fresh and dry y i e l d s of s t a l k s and the whole plant (Table 4.10a). Dry y i e l d of cobs showed a l i n e a r c o r r e l a t i o n with N03 N at sidedress time (r=0.46*», 0-80cm). For stalks, the N03-N i n the top 0-20cm accounted for the greatest amount of variation out of a l l three depths, but f o r cobs N03-N i n the whole 0-80cm p r o f i l e produced the largest c o r r e l a t i o n c o e f f i c i e n t s . The conclusion drawn from these l a s t observations i s that the stalks tended to obtain a majority of t h e i r N from the surface horizon, while the cob N, part of which was transferred from stalk N, was extracted from a greater depth of s o i l . This i s l o g i c a l because the s t a l k s develop f i r s t using N taken up by roots exploring the upper depths of s o i l , then, by the time the cobs begin to develop, the roots have penetrated deeper and are taking up N from lower depths. The strong r e l a t i o n s h i p between s o i l NQ 3-N and fresh weight of cobs (r=0.682«* 0-80cm depth, Table 4.10a) i s caused to a large extent by the way available N delays cob maturity. Percent dry matter of cobs was found to decline with increasing s o i l N0 3 - N content, or vice versa, moisture content increased with increasing s o i l N0 3-N (Table 4.10a). Since a l l the s i t e s were harvested at approximately the same time the less mature cobs contained proportionally more water at harvest. However, the experimental s i t e s were harvested at the same time as the farmer's f i e l d , thus s i t e s with higher available N w i l l produce greater fresh y i e l d s of sweet corn cobs due to higher cob moisture contents. Harvesting the crop at an immature stage may also provide an explanation for the consistently weaker rel a t i o n s h i p s between s o i l N03-N and dry y i e l d s than between s o i l N0 3 -N and fresh y i e l d s . This r e s u l t however, may also have been caused by the increased amount of experimental error incurred i n the procedure f o r obtaining the dry yields, i e . se l e c t i n g f i v e plants from the harvested area, weighing them, bringing them back to the laboratory, drying them and then reweighing. RELATIVE YIELD Relative y i e l d was calculated as: y i e l d of plot not side-dressed X 100 y i e l d of plot side-dressed Relative yi e l d s , which are i n d i r e c t estimates of the ef f e c t of applied f e r t i l i z e r , ranged from 70-120% fo r whole crop fresh yields. Quadratic equations best f i t t e d r e l a t i o n s h i p s between s o i l N03-N and y i e l d s of dry st a l k s and fresh cobs, and the logarithmic equation best f i t t e d the re l a t i o n s h i p between s o i l N03-N (0-20cm) and r e l a t i v e y i e l d of dry cobs. The correlations for r e l a t i v e y i e l d s were generally poor (r<0.51) Table 4.10c. The r e l a t i v e l y high range of r e l a t i v e y i e l d s (70-120%) may be a r e f l e c t i o n of the low N requirement of the corn, i t may also i ndicate that added f e r t i l i z e r was frequently of l i t t l e use and i n some cases may have been detrimental to crop growth, eg. where r e l a t i v e y i e l d was greater than 100% and where quadratic curves appeared. The poor response to f e r t i l i z e r may also have been due to the sidedressing technique used by the custom 80 sidedresser being i n e f f i c i e n t f o r unirrigated corn. The urea was dropped beside the corn plant and covered with s o i l by discs. Thus the shallow incorporation did not enable the f e r t i l i z e r to reach moist s o i l and furthermore there was no ra i n i n either 1984 or 1985 for at least a month af t e r sidedressing (Appendix 1). Sim i l a r l y , the manual method of urea application used i n the Replicated Response T r i a l and the Preplant versus Sidedress Urea T r i a l , may also have been i n e f f e c t u a l f o r the same reasons, i e . shallow incorporation and lack of water to wash the f e r t i l i z e r to the root zone. Therefore the lack of response to f e r t i l i z e r i n these two t r i a l s may not only have been due to the adequate s o i l N as previously suggested, but also due to the poor method of f e r t i l i z e r application. A comparison of the corn f e r t i l i z e d manually and the farmer's corn f e r t i l i z e d by machine, may have given an in d i c a t i o n of the e f f i c i e n c y of the manual method, however the farmer's rate of application did not correspond to any of the plot rates and, as mentioned, the machine technique was also i n question. STALK. COB. AND WHOLE PLANT NITROGEN Per cent N i n both st a l k s and cobs showed a l i n e a r r e l a t i o n s h i p with s o i l N03-N (Table 4.10b). The corr e l a t i o n s of s o i l N03 -N with t o t a l N (kg ha" 1 ) i n stal k s and cobs, i e . 7. N x Dry y i e l d , r e f l e c t e d the rel a t i o n s h i p s found with the dry y i e l d s rather than with the 7.K. Thus t o t a l N (kg ha" 1 ) i n the stalks t a i l e d o f f with increasing s o i l N03-N, while t o t a l N (kg ha" 1) i n the cobs continued to increase across the range of s o i l N03-N 81 values measured (Table 4.10b). Whole plant N, when correlated with s o i l N03-N, produced a logarithmic r e l a t i o n s h i p ; the greatest amount of va r i a t i o n was accounted f o r when N03-N i n the 0-80cm depth was considered (r=0.55**). A s i m i l a r r e s u l t was found f o r t o t a l cob N correlations, however fo r s t a l k s N03-N i n the top 0-50cm produced the highest r values, (Table 4.10b). 4.3.6 CORN RESPONSE ON PROBLEM SOILS Three categories of problem s o i l s were i d e n t i f i e d : 1) S i t e s with high e l e c t r i c a l c o n d u c t i v i t i e s (Year 1, Site s 2,7,16; Year 2, Si t e 7). 2) Si t e s with low pH. The f i v e lowest pH s i t e s were selected (Year 1, Sites 1,2,5,13,14). 3) Sites with noticeable compaction at the base of the plough layer (Year 1, Sites 5,14,15; Year 2, Si t e 1). Correlations between selected corn y i e l d parameters and sidedress N03-N were performed with the problem s i t e s excluded. Table 4.11 shows that excluding the s i t e s with high e l e c t r i c a l c o n d u c t i v i t i e s or low pH strengthened l i n e a r correlations, while excluding the compacted s i t e s , weakened them. When the s i t e s with high e l e c t r i c a l c o n d u c t i v i t i e s were excluded, the r value f o r the l i n e a r c o r r e l a t i o n between s o i l N03-N (0-80cm) and fresh y i e l d of cobs (r=0.78**), was su b s t a n t i a l l y improved over the value for a l l the s i t e s (r=0.68*«. Table 4.11). The four s i t e s with high e l e c t r i c a l conductivity ('marine s i t e s ' ) were a l l characterised by low s o i l N03-N l e v e l s at sidedress. 82 Table 4.11 Multifarm T r i a l , problem s o i l s : Selected correlations between crop parameters and s o i l NO.-N, problem sites excluded. Problem Sites Excluded Corn yield Depth (on) A l l Soils r Sig. High E l e c t r i c a l Conductivity r Sig. Low pH r Sig. Compact Soils r Sig. Stalks Fresh yield t ha"' 0-20 0.445 0.771(C) ** ** 0.475 0.787(C) * ** 0.490 * 0.317 NS Cobs Fresh yield t ha -' 0-80 0.680 0.682(C) ** ** 0.780 0.773(C) *+ ** 0.762 ** 0.644 ** Relative Yield Dry 0-20 0.480 ** 0.585 ** 0.469 * 0.458 * Whole plant Fresh yield t ha"' 0-20 0.538 0.754(C) ** 0.594 0.764(C) ** ** 0.556 ** 0.408 * Total N kg ha"' 0-80 0.548 ** 0.609 ** 0.572 ** 0.343 NS Relative Yield Dry 0-20 0.446 ** 0.520 ** 0.408 * 0.447 * Significance : ** = 1% * = 5% NS = Not significant (C) = Logarithmic correlation 83 5. NITROGEN FERTILIZER RECOMMENDATIONS IN THE LFV  -INTERPRETATION OF THE RESULTS By combining the r e s u l t s from the project's four parts, i t i s possible to provide estimates for some of the components i n the N Requirement Equation, and hence shed l i g h t on the questions posed at the s t a r t of the study. With respect to making N f e r t i l i z e r recommendations the N Requirement Equation can be rewritten as: e e <N provided by f e r t i l i z e r = N Requirement -and/or manure) e,(N supplied by the s o i l ) 5.1 NITROGEN REQUIREMENT FOR SWEET CORN The average N Requirement f o r the above-ground parts of sweet corn was given i n Table 2.1 (Sec. 2.1.1) to be 155 kg ha" 1 at a dry cob y i e l d of 4.1 t ha" 1. To simplify the discussion here, N contained i n corn roots i s not included i n the N Requirement, however some researchers (Magdoff et a l . 1984) suggest that the N requirement should be increased by 207. to account f o r N i n the roots. The average value of 155 kg ha" 1 i s a mean derived from a wide range of corn crops on a variety of s o i l types i n various parts of the USA. The actual amount of N taken up by a corn crop i n d i f f e r e n t regions w i l l obviously vary according to l o c a l s o i l and climate conditions. The amount of N taken up by the crops i n the Multifarm Study, i n the Delta Figure 5.1 Relationship between t o t a l corn nitrogen and cob y i e l d , fresh. 85 region of the LFV, i s shown i n Fig.5.1. This graph, of the r e l a t i o n s h i p between marketable cob y i e l d and t o t a l corn N, can be used to predict approximately how much N would be required i n the above-ground parts f o r a s p e c i f i c cob y i e l d . For example, i f a target y i e l d was set at 20t ha - 1 fresh cobs (4t ha" 1 dry), the graph shows that approximately 125 kg ha - 1 N would be required i n the whole crop. 125 kg ha - 1 i s the amount of N act u a l l y found i n a crop which produced a y i e l d of 20 t ha - 1 fresh cobs; since sweet corn i s prone to 'luxury uptake', i e . uptake of N which does not increase y i e l d , t h i s f i g u r e does not indicate whether le s s N could have produced the same y i e l d . The amount of N that must be supplied to f u l f i l the N Requirement, either by the s o i l or by N addition, cannot be d i r e c t l y determined from Fig.5.1 because t h i s amount depends on the e f f i c i e n c y of the crop uptake of N. The graph does indicate however, the amount of N which i s adequate f o r a s p e c i f i c y i e l d of sweet corn i n the Delta region of the LFV. Therefore, i f a target y i e l d i s given, an approximation to the N Requirement i s not too d i f f i c u l t to obtain. The value of 125 kg ha - 1 f o r 4 t ha" 1 dry cobs i n the Multifarm t r i a l i s rather l e s s than the published averages (155 kg ha" 1, Table 2.1, Sec.2.1.1), t h i s r e l a t i v e l y low N uptake could have been due to poor s o i l conditions. A number of facto r s which i n h i b i t e d corn use of N were seen i n the f i e l d , the most obvious being s o i l compaction which i n h i b i t e d root penetration on many s i t e s . The majority of corn roots on compacted s i t e s were found i n the top 25cm, thus water and 86 nutrient uptake would have been limited. The uptake e f f i c i e n c y of both s o i l N and f e r t i l i z e r N may be increased by improved s o i l management. 5.2 NITROGEN SUPPLIED BY THE SOIL 5.2.1 SOIL SAMPLING VERSUS A NITROGEN INDEX SYSTEM S o i l N03-N sampling seems to be more useful than a N Index System i n the area of study. None of the groupings which are used to predict s o i l N supply i n the English N Index System (MAFF 1985-86) showed up i n t h i s study, i e . previous cropping, s o i l texture and manure influence; t h i s was due to the narrow range of crop types, and s o i l texture, and also because manure i s not routinely used i n the Delta Municipality area. It i s possible however, that the influence of manure was shown on the anomalous s i t e (Year 2, Si t e 3) which had high organic matter and a high spring s o i l N03-N content. The s i t e was situated behind a disused dairy barn and had received many years of manure application. However, i t was not possible to separate the e f f e c t s of manure on t h i s s i t e , from the e f f e c t s due to ploughing out the 30-year old pasture two years before the study. The one other factor that i s frequently used i n N Index or Budget systems i s organic matter. No s i g n i f i c a n t r e l a t i o n s h i p was found between organic matter and s o i l N03-N at sidedress time and a negative r e l a t i o n s h i p was even found with t o t a l N and s o i l N03 -N (Sec. 4.3.4). 87 An estimate of mineralization was calculated using the plots without sidedress N and the following assumptions; 1) Most mineralization i n the region of study occurs i n the 0-50cm depth. 2) There was no residual N from the previous year i n the top 0-50cm. 3) N i n the roots was i n s i g n i f i c a n t . MINZN = (N (kg ha" 1) i n cobs «- stalks) + (S o i l N03-N + NH*-N at harvest (kg ha" 1) 0-50cm) -st a r t e r N x ( e f f i c i e n c y of s t a r t e r = 0.7) A weak po s i t i v e r e l a t i o n s h i p (r=0.45*) was found between organic matter and mineralization. However, when mineralization as a proportion of organic matter content was plotted against organic matter, (Fig.5.2), the graph showed the proportion of organic matter mineralized to be inversely related to organic matter content (r=-0.51»»); a s i m i l a r f i n d i n g was recorded by Broadbent (1984). The reason f o r t h i s inverse r e l a t i o n s h i p could be that the higher organic matter l e v e l s were a r e s u l t of poor s o i l conditions which i n h i b i t e d mineralization, eg. poor drainage, s o i l a c i d i t y and/or marine influences. This suggestion was supported by the lowering of the r value to -0.41(») f o r the graph i n Fig.5.2 when the 'marine s i t e s ' were excluded. One notable exception to t h i s negative r e l a t i o n s h i p was again shown by the anomalous s i t e which displayed an unusually high organic matter l e v e l and a correspondingly high s o i l N0a-N content at sidedress time. The s i t e had been i n pasture f o r 30 years and was ploughed out only two years before N MINERALIZED 4 O.M. CONTENT(0-50cm) X ' ° 16.0 n ~» 1 1 1 1 1 1 1 0 100 200 300 ORGANIC MATTER thd' (0'50cm) Figure 5.2 Relationship between mineralization as a proportion of organic matter and organic matter (0-50cm). 89 the study, i t also had high pH and good drainage. Therefore s i t e history seems to be an important consideration when evaluating the pote n t i a l e f f e c t of organic matter on available s o i l N. It appears o v e r a l l , that i n a small area of the LFV such as Delta Municipality, a spring s o i l test would be of more use than a N Index System f o r improving N f e r t i l i z e r recommendations. 5.2.2 IMPLEMENTING A SPRING SQIL TEST DEPTH OF SAMPLING The r e s u l t s of the Multifarm T r i a l showed the correlations for response curves of stalk y i e l d s and stalk N with s o i l N03-N, to be greatest i n the 0-20cm depth, and for cob y i e l d s and cob N with s o i l N03-N, to be greatest i n the 0-80cm depth (Sec.4.3.5). These r e s u l t s cause the question of sampling depth to be unclear. If the sampling method uses co r r e l a t i o n s with stalk or whole plant yields, sampling to 20cm would seem to be s u f f i c i e n t . In fact sampling to t h i s depth i s probably more desirable i n most cases because i t i s the easiest and cheapest depth to sample. However, i f recommendations were made using c o r r e l a t i o n s involving cob y i e l d s or cob N contents, sampling to a depth greater than 20cm would be more accurate. Finances permitting, a compromise may be the best solution, i e . sampling to a depth of 50 or 60cm as i n many of the European countries. Obviously the suggested sampling depths here are s p e c i f i c to sweet corn i n the Delta region, and would be d i f f e r e n t for 90 d i f f e r e n t crops and also f o r d i f f e r e n t s o i l conditions. TIME OF SAMPLING As previously mentioned the best time f o r sampling i s as close to f e r t i l i z i n g as possible i n order to minimize environmental influences on the measured mineral N. The r e s u l t s of the N Monitoring Study (Sec. 4.1.3) supported t h i s suggestion by showing the s o i l N03-N contents to increase at a constant rate between the temperatures of 5 and 20°C and u n t i l the crop began to take up s o i l N, generally 5-6 weeks af t e r planting and a week or two before sidedressing. Therefore, although i t may be possible to predict s o i l N03-N at sidedress from s o i l measurements taken e a r l i e r i n the season combined with a knowledge of s o i l temperature, from the farmer's perspective i t i s easier to watch the crop and sample a couple of weeks before sidedressing, i e . when the crop i s almost 30cm t a l l . Sampling close to f e r t i l i z i n g would mean that the turnaround time for analysis and output of subsequent f e r t i l i z e r recommendations would have to be minimal. Since the N03-N test need not necessarily be extremely precise, a f i e l d test such as the Merck quick test (Hunt et al.1979; Scharpf and Grantzau 1985) or the s o i l N03-N electrode could be employed. 5.2.3 ESTIMATING SOIL AVAILABLE NITROGEN USING HARVEST-TIME  MEASUREMENTS As previously mentioned, estimates of avai l a b l e s o i l N i n humid regions are most accurate when based on two components; 1) A measure of mineral N i n the p r o f i l e on a s p e c i f i c date and, 2) An estimate of N mineralized over the growing season. Component (1) i n the study here, was simply s o i l N0 a-N and NH4-N at sidedress time. Component (2) can be estimated from the r e s u l t s i n a number of ways, the method described i n Sec. 5. 2. 1 being just one. It must be remembered at t h i s point, that a l l estimates of mineralization here are i n d i r e c t estimates (ie. extrapolated from the s o i l and crop data), and that the amount of N mineralized has been influenced to a greater or lesser extent by the growing corn crop. The mean amount of N mineralized, as determined i n Sec. 5.2.1, was 130 kg ha" 1, with a range of 40-275 kg ha - 1 over 27 s i t e s , (Appendix 6). These values for mineralization are somewhat higher than the mean of 80 kg ha" 1 and range of 30-140 kg ha" 1 recorded by Wehrmann et a l . (1982) on German s i t e s growing winter wheat. The difference may simply be due to the d i f f e r e n t environmental and crop conditions, however, the LFV values are possibly overestimates because the assumption that there was no residual N i n the 0-50cm depth may not be correct. For example, S i t e B i n the N Monitoring Study contained substantial amounts of both N0 3 -N and NH 4-N just a f t e r planting. A further sampling i n the Multifarm t r i a l , at planting or e a r l i e r , would have been able to determine the v a l i d i t y of the assumption. The residual N would not cause a problem i n estimating s o i l N i f i t was consistent year to year but i t i n e v i t a b l y varies due to cropping rotations and varying s o i l and weather conditions. For the purpose of estimating available s o i l N using the two component approach, another estimate of mineralization can be obtained from the re l a t i o n s h i p between Mineralization, as defined i n Sec. 5.2.1, and mineral N at sidedress time (0-50cm) as seen i n Fig. 5.3. The equation for the l i n e a r r e l a t i o n s h i p i s y = 66.5 + 1.3x (r=0.59**). From t h i s equation the amount of N mineralized between sidedress and harvest can be calculated. The intercept on the y-axis (ie. 66.5 kg ha - 1) corresponds to the quantity of N i n the s o i l and crop at harvest when there was zero N03-N at sidedress time. This amount of mineralization can be considered as the 'Basal Mineralization', unrelated to the amount of N found at sidedress time. If 'x' i s taken as the mean amount of mineral N (NH*-N + N03-N, 0-50cm) found at sidedress time on the 27 s i t e s , i e . 57 kg ha -* (Sec.4.3.1), an additi o n a l 1.3 X 57 = 74.1 kg ha - 1 mineral N above the basal quantity becomes av a i l a b l e between sidedress and harvest time. Therefore the estimate of mineralization derived t h i s way i s approximately 140 kg ha - 1 (66.5 + 74.1) i n comparison to 130 kg ha - 1 derived by the method i n Sec.5.2.1. Both these estimates of mineralization however have been derived using measurements taken at harvest-time; i n order to make N f e r t i l i z e r recommendations i t would be desirable to be able to predict a v a i l a b l e N from sidedress-time measurements. MINERALIZATION (kg ha"') 300-, 1 1 i 1 0 50 100 SOIL N0 3-N+ NH 4-N kg ha"1 (0"50cm) AT SIDEDRESS Figure 5.3 Relationship between mineralization and s o i l mineral nitrogen (0-50cm) at sidedress 94 5.2.4 PREDICTING SOIL AVAILABLE NITROGEN FROM NITRATE FOUND AT  SIDEDRESS TIME The graph of mineralization versus mineral N at sidedress, which was used to estimate basal mineralization i n Sec.5.2.3, could also be used for prediction purposes, however the r value was only 0.59(*»). By comparing regression values, i t was found that the r e l a t i o n s h i p between mineral N and t o t a l crop plus s o i l N at harvest, was stronger when NH4-N was omitted from the c a l c u l a t i o n s (Table 5.1). This may be due to the s i t e s containing s i g n i f i c a n t quantities of NH4-N being anomalies by being e i t h e r poorly drained and/or influenced by marine conditions. When the marine s i t e s were excluded, the r e l a t i o n s h i p between s o i l N03-N at sidedress and crop N plus s o i l N03-N at harvest was further improved (Table 5.1). Hence, although the most correct determinations of N mineralized should contain NH*-N, cal c u l a t i o n s considering only N03-N are used here due to the s i m p l i f i c a t i o n , and greater confidence found i n the predictions when t h i s i s done. Table 5.1 shows the r values, intercepts and slopes f o r the c o r r e l a t i o n s between sidedress N03-N and corn plus s o i l N03-N at harvest at the three d i f f e r e n t depths. The amount of s t a r t e r N taken up by the crop was assumed to be 33 kg h a - 1 , i e . 47 kg ha - 1 X 70'/., t h i s value was subtracted from the corn N. The r e l a t i o n s h i p s are seen to increase i n strength as more of the p r o f i l e N03-N i s considered, t h i s implies that the corn roots took up N03-N from as deep as the 0-80cm depth. Crop uptake from depth was also implied by paired T-tests comparing s o i l 95 Table 5.1 Multifarm T r i a l : Estimating N supplied by the s o i l . Linear regressions between crop N plus s o i l mineral N at harvest and s o i l mineral N at sidedress. (Mineral N = NOyN + NH^ -N or just NO,-N) Depth (cm) NCL-N and NH, -N considered NOj-N considered r r Sig. Intercept Slope r r Sig. Intercept Slope 0-20 0.467 0.218 ** 71.5 A l l 1.6 Sites 0.543 0.295 ** 73.3 1.7 0-50 0.592 0.350 ** 66.5 1.3 0.623 0.388 ** 69.3 1.3 0-80 0.685 0.469 ** 67.6 1.1 0.716 0.513 ** 68.9 1.2 Excluding Marine Sites 0-20 0.588 0.346 ** 49.0 2.2 0.635 0.403 ** 59.9 2.1 0-50 0.674 0.454 ** 38.2 1.7 0.705 0.497 ** 48.5 1.6 0-80 0.739 0.546 ** 44.4 1.3 0.787 0.619 ** 47.3 1.4 Significance : * * = ! % * = 5% NS = Not significant 96 N03-N at sidedress and harvest. The s o i l N03-N contents at harvest i n both the 0-50cm depth and the 0-80cm depth were s i g n i f i c a n t l y d i f f e r e n t from those at sidedress ( N O 3 - N kg ha - 1 : 0-50cm; sidedress = 43.2, harvest = 23.7. 0-80cm; sidedress = 59.5, harvest = 27.5. Appendix 14a and c). The strongest c o r r e l a t i o n i n Table 5.1 was between s o i l N03-N at sidedress (0-80cm> and crop N plus s o i l N03-N (0-80cm, harvest) when the marine s i t e s were excluded (r a=0. 62*»). The amount of N supplied by the s o i l can be predicted from the equation f o r t h i s c o r r e l a t i o n (Fig.5.4) i e . y = 47.3 + 1.4x. This equation estimates that for every kg ha -* N03-N (0-80cm) found i n the s o i l at sidedress, 47.3 +1.4 times t h i s amount, can be expected i n the s o i l and crop at harvest. The equation, in s p i t e of being s p e c i f i c to a p a r t i c u l a r crop and region, could be very useful f o r LFV N recommendations by accounting f o r the N supplied by the s o i l . As previously described, the intercepts shown i n Table 5. 1 provide an estimate of basal mineralization. The intercept changes noticeably from the 0-20cm depth to the 0-50cm depth but barely changes between the 0-50 and 0-80cm depths, t h i s suggests that more mineralization occurred i n the surface 0-50cm than i n the deeper horizon. The slope shows how much N at harvest can be expected f o r every kg ha" 1 of N03-N found at sidedress time. The slope values decrease down the p r o f i l e , a r e s u l t which i s probably due to the two inseparable reasons mentioned previously i e . a) more mineralization occurred higher up the p r o f i l e , and b) the crop took up mineral N from the whole 0-80cm depth. S O I L N O 3 N (0-80cm) -f CROP N kg ho"' AT HARVEST 300-r Figure 5.4 Relationship between s o i l n i t r a t e (0-80cm) plus crop nitrogen at harvest and s o i l n i t r a t e (0-80cm) at sidedress. 98 5.3 EFFICIENCY OF CROP UPTAKE OF SOIL MINERAL NITROGEN (e,) The r e s u l t s of the Multifarm T r i a l show that a reasonable estimate of N provided by the s o i l can be made from N03-N i n the s o i l at sidedress <r8=0.62** f o r the 0-80cm depth Table 5.1). However t h i s estimate does not indicate how much of the s o i l N i s a v a i l a b l e to the crop, i e . the e f f i c i e n c y of crop uptake of s o i l N. An estimate f o r e i can be made from the re l a t i o n s h i p between crop N uptake and t o t a l s o i l plus crop N at harvest (Fig.5.5). This estimate assumes that no N was l o s t from the 0-80cm depth during the growing season. The slope of the graph i n Fig.5.5, 0.5, can be taken as the average uptake e f f i c i e n c y for sweet corn i n the Multifarm T r i a l . This value i s somewhat lower than the estimate of 70% taken by Magdoff et a l . (1984) for sil a g e corn, i t possibly r e f l e c t s a lack of water due to the unusually dry summers and the shallow root penetration caused by s o i l compaction. Another estimate of e t could have been made from r e s u l t s i n the Replicated F e r t i l i z e r Response T r i a l had there been a response to f e r t i l i z e r . I f a more precise estimate than 50% for e» i s desired, further experiments would be necessary. However, i f t h i s estimate i s considered to be reasonable, three of the components of the N Requirement Equation are now s a t i s f i e d , i e . Crop N Requirement, e», and N supplied by the s o i l . In order to determine the f e r t i l i z e r component of the N Requirement Equation i t i s necessary to f i r s t estimate the e f f i c i e n c y factor for the applied N, i n t h i s case urea. Figure 5.5 Relationship between crop nitrogen uptake and t o t a l crop plus s o i l nitrogen (0-80cm) at harvest. 100 5.4 EFFICIENCY OF CROP UPTAKE OF FERTILIZER (ee> The e f f i c i e n c y factor f o r s t a r t e r f e r t i l i z e r , used above, was the l i t e r a t u r e value of 70%. However, three out of the four parts of t h i s study emphasised serious l i m i t a t i o n s to the e f f i c i e n c y of sidedress applied f e r t i l i z e r . An estimate of the e f f i c i e n c y of sidedress f e r t i l i z e r (e 3) was calculated as: e 3 = Y i e l d of Corn N on f e r t i l i z e d plot -Y i e l d of Corn N on control plot  Amount of f e r t i l i z e r N sidedressed = 135 kg ha - 1 N The f e r t i l i z e r e f f i c i e n c y values ranged from -26% to 52% (Appendix 6), they were probably low due to the unusually dry summers and also the i n e f f i c i e n t f e r t i l i z i n g techniques. A sidedress f e r t i l i z e r e f f i c i e n c y value of 50% w i l l be used i n following c a l c u l a t i o n s even though t h i s i s at the upper end of the range of values calculated experimentally. Relationships between f e r t i l i z e r e f f i c i e n c y and s o i l texture are sometimes observed. Dstergaard (1985) on some Danish s o i l s found a r e l a t i o n s h i p between % sand and the e f f i c i e n c y of f e r t i l i z e r use. In the study here, the only c o r r e l a t i o n between e e and s o i l texture was a weak re l a t i o n s h i p with s i l t (r = 0.40*), suggesting that s i l t y s o i l s somehow aided f e r t i l i z e r u t i l i z a t i o n . It i s possible that i n the two years of study, the s i l t y s o i l s were most e f f i c i e n t at providing water to the plants and thus i n d i r e c t l y improved use of f e r t i l i z e r . 101 5.5 NITROGEN SUPPLIED BY FERTILIZER AND/OR MANURE From the r e s u l t s of the project, three approaches can be taken to estimate the 'Added N' component i n the N Requirement equation: 1) Using the components of the N Requirement Equation. 2) Using the li n e a r r e l a t i o n s h i p between s o i l N03-N and crop response. 3) Using the logarithmic r e l a t i o n s h i p between s o i l N03-N and crop response plus the Cate-Nelson procedure of s p l i t t i n g the data into responsive and non responsive s i t e s . 5.5.1 ESTIMATING FERTILIZER REQUIREMENTS USING THE NITROGEN  REQUIREMENT EQUATION This approach uses the graphs i n Figs. 5. 1 and 5. 4. to estimate the N Requirement Equation components. To outline the approach an example using a target y i e l d of 20 t ha - 1 of marketable cobs s h a l l be taken. From the rel a t i o n s h i p between cob y i e l d and t o t a l plant N, or N Requirement (Fig. 5.1), i t was already noted that a cob fresh y i e l d of 20 t ha -* requires approximately 125 kg ha" 1 N i n the whole plant. If for example, 40 kg h a - 1 of N03-N i s found i n the s o i l at sidedress, the equation f o r the co r r e l a t i o n between N03-N (0-80cm) at sidedress and t o t a l crop plus s o i l N03-N (0-80cm) at harvest (Fig. 5.4, y = 47.3 + 1.4x) predicts that approximately 100 kg ha" 1 N i s made available by the s o i l . If e t i s taken as 50%, then 100 X 0. 5 = 50 kg h a - 1 N i s supplied by the s o i l . Therefore, the f e r t i l i z e r 102 or manure contribution must be the N Requirement (125 kg ha - 1 N) les s the N supplied by the s o i l (50 kg ha~ 1 ), i e . (75 kg ha - 1 N)/e e. With e e estimated at 50%, the amount of f e r t i l i z e r or manure N required to produce a fresh cob y i e l d of 20 t ha" 1 when s o i l N03-N at sidedress (0-80cm) i s 40 kg ha" 1, w i l l be 75/0.5 = 150 kg ha~ 1 . An approach such as t h i s i s easy to apply, however further experimentation would be required to v e r i f y the relationships, e s p e c i a l l y when s o i l s and growing season weather conditions vary. 5.5.2 ESTIMATING FERTILIZER REQUIREMENTS USING THE LINEAR AND LOGARITHMIC RELATIONSHIPS BETWEEN SOIL NITRATE AND CROP  RESPONSE Two d i f f e r e n t types of crop response to B o i l N03-N were found i n the project a) Linear and b) Logarithmic. After excluding s i t e s with high e l e c t r i c a l c o n d u c t i v i t i e s (marine influenced) a strong l i n e a r response was found between marketable cob y i e l d s and s o i l N03-N, 0-80cm (r =0.78 Sec. 4. 3. 6). The stalk, and whole crop y i e l d s i n contrast, showed logarithmic responses. These two types of response suggested that two d i f f e r e n t approaches could be taken to obtain f e r t i l i z e r requirements from the crop response to s o i l N03-N: 1) S o i l N03-N and l i n e a r crop response. 2) S o i l N03-N and logarithmic crop response. 103 ESTIMATING FERTILIZER REQUIREMENTS USING THE LINEAR  RELATIONSHIP BETWEEN SOIL NITRATE AND CROP RESPONSE Figure 5.6 shows the re l a t i o n s h i p between s o i l N03-N (0-80 cm) and cob fresh y i e l d with marine s i t e s excluded. From the regression l i n e f i t t i n g the r e l a t i o n s h i p i t can be predicted that a s o i l N03-N (0-80cm) content at sidedress of 40 kg ha - 1 (plus s t a r t e r N) w i l l r e s u l t i n a fresh cob y i e l d of approximately 17 t ha" 1. If a target y i e l d of 20 t ha - 1 i s aimed for, and e e i s taken as 50%, the sidedress f e r t i l i z e r requirement can be derived from the rel a t i o n s h i p between cob y i e l d and whole plant N (Fig. 5.1, y = 19.3 + 5.4x). The additi o n a l 3 t ha - 1 of cobs thus requires 35.5 kg N (19.3 + 16.2) which can be supplied by 35.5/0.5 = approx. 70 t ha" 1 f e r t i l i z e r N at sidedress. If the 47 kg ha" 1 s t a r t e r N i s added to t h i s , the t o t a l f e r t i l i z e r requirement i s almost 120 kg ha - 1 . Hence, from the l i n e a r r e l a t i o n s h i p betweem s o i l N03-N and fresh cob y i e l d , a farmer can be shown the y i e l d he can expect for a s p e c i f i c s o i l N03-N content at sidedress. If his f i e l d has no other l i m i t i n g conditions, the farmer can then decide to what extent he wishes to improve his y i e l d above that obtained s o l e l y with s o i l and s t a r t e r N. Both the 'N Requirement Equation' approach and the 'Linear Relationship' approach fo r estimating the F e r t i l i z e r N Requirement have appeared to be quite precise. However the v a r i a b i l i t y shown both i n obtaining s o i l N03-N values, and i n producing re l a t i o n s h i p s between corn response and s o i l N03-N, COB YIELD, FRESH (tha") 3 On Figure 5.6 Relationship between cob y i e l d , fresh and s o i l n i t r a t e (0-80cm) at sidedress. 105 suggest that such precise methods for predicting f e r t i l i z e r requirements may not be p r a c t i c a l . The r B for the r e l a t i o n s h i p between s o i l N03-N (0-80cm) and cob fresh y i e l d (marine s i t e s excluded) was 0.61»» which i s generally acceptable for prediction purposes. However Fig. 5.6 s t i l l showed a large amount of scatter around the regression l i n e (SE = 3.3 t ha" 1). The weakness of the r e l a t i o n s h i p was i n part due to the low N requirement of sweet corn r e l a t i v e to s i l a g e corn for example, and i n part because the r e l a t i o n s h i p considered just the sweet corn cobs and not the whole plant. In general, N tends to increase y i e l d s of vegetative plant parts rather than reproductive parts, which i n the case of sweet corn, are the parts which are harvested. Thus, the strongest co r r e l a t i o n s between crop y i e l d s and s o i l N0 3 -N i n the project (before excluding marine s i t e s ) , were fo r stalk and whole plant y i e l d s rather than for cob y i e l d s (Sec.4.3.5). The 'linear r e l a t i o n s h i p ' approach to estimating f e r t i l i z e r requirements i s probably more relevant for s i l a g e corn production than for sweet corn. When using s i l a g e corn, the whole plant i s harvested, and furthermore, the N demand of s i l a g e corn i s considerably higher than that of sweet corn. ESTIMATING FERTILIZER REQUIREMENTS USING THE LOGARITHMIC  RELATIONSHIP BETWEEN SOIL NITRATE AND CROP RESPONSE The previous two approaches to estimating N f e r t i l i z e r requirements were s p e c i f i c to the sweet corn i n the study area. From the strong logarithmic r e l a t i o n s h i p s between s o i l N03-N and s t a l k fresh y i e l d s and whole plant fresh y i e l d s (Table 4.10a, Sec-4.3.5), i t i s possible to derive a more general recommendation system which may be applied to other crops. The r e s u l t s showed that f o r stalk and whole plant fresh y i e l d s the strongest r e l a t i o n s h i p s were considering N03-N i n the 0-20cm depth i n contrast to 0-80cm depth fo r the cob fresh y i e l d s . Figs. 5.7 and 5.8 show the r e l a t i o n s h i p s between s o i l N03-(0-20cm), and s t a l k fresh y i e l d s and whole plant fresh y i e l d s respectively. The strong logarithmic c o r r e l a t i o n s lend themselves to the Cate-Nelson approach which p a r t i t i o n s the dat into two populations separated by a c r i t i c a l l e v e l (Cate and Nelson, 1971). Dahnke et al.(1977) and Magdoff et al.(1984) used the Cate-Nelson procedure for developing N f e r t i l i z e r recommendations i n Eastern USA; they applied t h i s graphical technique to the r e l a t i o n s h i p between s o i l N03-N and r e l a t i v e y i e l d (fresh wt.) of whole plants. Although, i n the study here the r e l a t i o n s h i p between whole plant r e l a t i v e y i e l d (fresh) and s o i l N03-N (0-50cm) was weak, (Fig.5.9, r=0.63(L>»*) i t can be used to i l l u s t r a t e how the Cate-Nelson procedure s p l i t s the graph into two populations, one with a high p r o b a b i l i t y of response to added f e r t i l i z e r and one with a low probability. The c r i t i c a l l e v e l i s found at 26 kg ha - 1 N03-N i n the 0-50cm depth, somewhat lower than the value of 39 kg ha" 1 N03-N in the 0-30cm depth derived by Magdoff et al.(1984) fo r s i l a g e corn i n Vermont. The amount of N required to increase crop y i e l d on N d e f i c i e n t plots could be derived from the equation of the l i n e STALK YIELD, FRESH (thd') 40-20-20 40 SOIL NO-N kg ha"' (0"20cm) AT SIDEDRESS Figure 5.7 Relationship between s t a l k y i e l d , fresh and s o i l n i t r a t e (0-20cm) at sidedress showing populations s p l i t using the Cate-Nelson method. WHOLE PLANT YIELD, FRESH (tha 1) 1 1 1 40 SOIL NOjN kg ha" (0~20cm) AT SIDEDRESS F i g u r e 5.8 R e l a t i o n s h i p between w h o l e p l a n t y i e l d , f r e s h and s o i l n i t r a t e (0-20cm) a t s i d e d r e s s s h o w i n g p o p u l a t i o n s s p l i t u s i n g t h e C a t e - N e l s o n method RELATIVE YIELD, FRESH (%) I20-, 604 • • • 40 -\ SOIL NOgN 50 kg ha" (0~50cm) AT 100 SIDEDRESS Figure 5.9 Relationship between r e l a t i v e y i e l d , fresh and s o i l n i t r a t e (0-50cm) at sidedress showing populations s p l i t using the Cate-Nelson method. 110 i n the 'responsive' quadrant. Fig. 5.9 shows only seven points i n t h i s quadrant, too few for prediction purposes. Magdoff et a l . (1984) however, demonstrated how f e r t i l i z e r recommendations could be made by s p l i t t i n g t h e i r ' r e l a t i v e y i e l d versus s o i l N0 3 -N graph' (containing 55 points) into two l i n e s separated by the c r i t i c a l l e v e l : 1) Where N03-N <0-30cm) < 39 kg ha" 1 y = 3. 2 + 0. 185x High p r o b a b i l i t y of response to f e r t i l i z e r . 2) Where N03-N (0-30cm) > 39 kg ha" 1 y = 9.57 + 0.023x Low p r o b a b i l i t y of response to f e r t i l i z e r . Using the slope of equation (1) the amount of N03-N needed to increase the y i e l d of N d e f i c i e n t plots was estimated at 5. 4 kg N03-N per tonne of y i e l d increase. The e f f i c i e n c y of f e r t i l i z e r uptake was taken as 707. and hence f e r t i l i z e r recommendations were made. Magdoff et al.(1984) found t h i s method made accurate predictions for the responsive s i t e s but not for the nonresponsive s i t e s . Nevertheless, the researchers showed f e r t i l i z e r recommendations to be su b s t a n t i a l l y improved over the previous system which did not incorporate a s o i l test. If the Cate-Nelson procedure i s also applied to the graphs i n Figs. 5.7 and 5.8 i t can be seen that the c r i t i c a l l e v e l can actually be drawn anywhere between two points, eg. between 18 and 23 kg ha - 1 for the whole plant fresh y i e l d (Fig.5.8). Thus a more correct separation of the Responsive and Unresponsive populations would be to use a c r i t i c a l 'Range' of 18 - 23 kg I l l ha" 1. This range could be termed a region of 'Possible Response' to f e r t i l i z e r . Table 5.2 shows the c r i t i c a l ranges of s o i l N03-N for crop response curves which could be s p l i t using the Cate-Nelson approach. From t h i s table i t can be seen how the c r i t i c a l ranges change with depth and with d i f f e r e n t crop parameters, i e . stalk s and whole plants. The Cate-Nelson approach could thus be used to s p l i t s o i l s with s p e c i f i c l e v e l s of N03-N at sidedress into three l e v e l s : Level 1 - Crop response probable. Level 2 - Crop response possible ( C r i t i c a l Range). Level 3 - Crop response unlikely. These Levels w i l l be s p e c i f i c to d i f f e r e n t crops as they were shown to be for the d i f f e r e n t plant parts, they w i l l also d i f f e r according to the depth of sampling. For example, for whole corn plants: Level 1 = < 18 (0-20cm), < 15 (0-50cm) kg ha" 1 N03-N. Level 2 = 18-23 (0-20cm), 15-23 <0-50cm) kg ha" 1 N03-N. Level 3 = > 23 (0-20cm and 0-50cm) kg ha" 1 N03-N. Further research would be necessary to develop t h i s approach for crops i n the Fraser Valley, however where the crop response to s o i l N i s logarithmic the approach would allow the farmer to decide whether or not he wishes to add f e r t i l i z e r according to his s o i l N03-N l e v e l at sidedress. 18-23 kg ha" 1 N03-N (0-20cm) may seem low fo r the c r i t i c a l range d i v i d i n g whole plant fresh y i e l d s into 'Responsive' and 'Unresponsive' populations. However i t must be remembered that Table 5.2 N F e r t i l i z e r Recomnendations: C r i t i c a l Ranges of NOj-N dividing Responsive and Unresponsive sites vising the Cate-Nelson method. C r i t i c a l Range of NOj-N (kg ha - 1) Crop Parameter 0-20 So i l Depth (cm) 0-50 0-80 Fresh Yield t ha"' Stalks 9 - 1 1 12 - 15 19 - 27 Whole Plant 18 - 23 15-23 Relative Yield Whole plant (Fresh) 16 - 22 26 - 27 28 - 29 Whole Plant (Dry) 18 - 22 28 - 30 33 - 40 47 kg ha" 1 N was applied at planting and also that the dry summers may have lim i t e d growth and subsequent N requirements. Nevertheless, the c r i t i c a l range of 18-23 kg ha" 1 does suggest that the whole plant requirement for N could have been met so l e l y by s o i l and s t a r t e r N on many of the s i t e s i n Delta, and that often added sidedress f e r t i l i z e r was not necessary. It i ; possible that i n the region of study an improvement i n s o i l conditions may prevent more wasted N f e r t i l i z e r than improved N recommendations, unless that i s , the recommendations were to allow f o r poor s o i l conditions. For example, the negative c o r r e l a t i o n of crop response with s o i l NH*-N, implied that unless the conditions which created the high NH*-N l e v e l s are r e c t i f i e d , added f e r t i l i z e r w i l l be of l i t t l e value. 114 6. CONCLUSIONS Conclusions can best be drawn from the project by r e f e r r i n g to the o r i g i n a l questions posed: 1> Are s o i l N03-N or s o i l NH4-N s u f f i c i e n t l y correlated with crop response to make a s o i l test worthwhile? It was not within the scope of t h i s project to determine the worth of a mineral N s o i l test f o r a l l LFV arable conditions. However, the r e s u l t s seem to indicate that i n a small a g r i c u l t u r a l region such as Delta, where neither cropping systems nor s o i l types vary appreciably, and where manure use i s limited, s o i l N03-N does appear to be s u f f i c i e n t l y correlated with t o t a l s o i l plus crop N at harvest, to make investigating the wider use of a s o i l test worthwhile. The project showed that s o i l s i n the Delta area supply a large proportion of the N required for sweet corn growth. Thus, when generous amounts of s t a r t e r N are used eg. 47 kg ha" 1, much of the additional sidedress N i s unnecessary. 2) If a s o i l test can be used, to what depth and on what date i s i t necessary to sample? The depth of sampling w i l l depend on f i n a n c i a l and human resources. For sweet corn, the r e s u l t s of the study imply that sampling down to 80 cm provides the best c o r r e l a t i o n between s o i l N03-N at sidedress and cob y i e l d . For other crops i t may not be necessary to sample so deep, i n fact, s t a l k and whole plant y i e l d s of sweet corn i n t h i s study were best correlated with s o i l N03-N to a depth of 20 cm. 115 The best time to sample i s as close as possible to sidedress time. For corn, t h i s i s when the crop i s almost 30 cm high, for other crops i t i s the point just p r i o r to the period of maximum growth and N uptake. 3) Can the N supplied by the s o i l be i n d i r e c t l y estimated by s o i l c h a r a c t e r i s t i c s such as organic matter, previous cropping, s o i l texture? The project showed that the range of s o i l types and cropping regimes i n Delta Municipality was too narrow to have a di r e c t influence on N supplied by the s o i l . N supplied by the s o i l may be related to organic matter, however a knowledge of s i t e history i s necessary before assuming a pos i t i v e relationship. If the organic matter percentage i s high due to conditions unfavourable f o r mineralization, there may i n fac t be a negative c o r r e l a t i o n between organic matter and the proportion of i t which i s converted to N03-N. S o i l pH was shown to be s i g n i f i c a n t l y p o s i t i v e l y correlated with s o i l N03-N, although pH cannot be used as an estimate of N supplied by the s o i l i t can be taken into consideration when s o i l N supply i s determined. N supplied by the s o i l may possibly be estimated from s o i l c h a r a c t e r i s t i c s , however further experimentation i n areas with widely varying s o i l textures and cropping regimes i s necessary before any such estimates can be established. 4) Which factors have the greatest influence on corn uptake of s o i l and f e r t i l i z e r N? In the Delta area, the three s i t e factors which had the greatest e f f e c t on crop uptake of s o i l N03-N were, poor l i s drainage, high l e v e l s of s a l t s associated with marine conditions, and low pH. These adverse s o i l conditions i n h i b i t e d n i t r i f i c a t i o n and a v a i l a b i l i t y of s o i l N to the crop. 5) Does the method of f e r t i l i z e r application, i e . broadcast preplant or sidedressed make a s i g n i f i c a n t difference to the crop use of f e r t i l i z e r N? This question cannot be answered from the r e s u l t s of the study. No s i g n i f i c a n t difference was found between y i e l d s of crops receiving urea N broadcast preplant or sidedressed. 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Haren: Inst. Bodemvruchtrbaarheid. Rapp 4-81. Appendix 1 D a i l y P r e c i p i t a t i o n (mm) A p r . - S e p t . 1984/1985. Vancouver I n t e r n a t i o n a l A i r p o r t . D a i l y P r e c i p i t a t i o n (mm) Date 1984 1985 Apr May Jun J u l Aug Sep Apr May Jun J u l Aug Sep 1 8 .7 22 .2 3.9 7 .2 TR 2 3.7 5.2 3 .0 0 .2 TR 3 5 .0 2 .4 4 .2 1.4 TR 4 . 0 4 TR 13 .0 TR 5.5 0 .6 0 .2 3.2 TR 1.4 5 1.4 6 .4 0 .4 TR 7.4 24 .0 TR TR 2 .0 6 .0 6 0 .6 TR 1.4 2 .6 1.2 TR 24.2 7 7.4 TR TR TR TR 0 .6 TR 12 .4 10.8 1.0 8 0 .4 6 .0 TR TR PP 3 1.1 1.2 9 21 .9 2 .6 0.4 1.7 4 .4 1.2 10 3.8 1.2 TR TR 2 .2 TR 11 9 .1 9 .9 0 .3 4 . 0 TR TR 12 16 .6 0 .8 TR TR TR 1.0 TR 13 5.3 5.3 SD TR 7.8 4 .7 2 .2 7.4 14 TR 0 .6 TR 0 .4 4 .8 5 .0 2 .6 15 1.4 TR TR 0 .2 0.2 16 0 .6 0 .3 2 .2 2 .0 2 .7 TR 12 .0 17 0 .4 TR TR 0 .4 1.3 18 1.8 3 .0 TR HARV 1.2 19 14 .6 TR SD TR 20 5 .6 TR 0 .4 TR 2 .0 1.6 TR 0 .6 21 7 .2 TR TR 22 12 .2 3.2 11 .8 TR 23 0 .2 TR TR 8 .2 2 .8 24 0 .5 2.4 TR 0.4 25 TR 7.4 TR TR 26 36.1 9 .4 6 .0 2 .8 22 .2 HARV 27 4 .8 0 .6 14 .6 28 19.8 1.2 29 PP 15.4 17 .6 0 .8 30 2 .0 TR 2 .8 TR 7 .2 31 2 .9 TR 0 .6 PP=Plan t ing SD=Sidedress HARV=Harvest TR=Trace Appendix 2 Soil characteristics of Reynelda farm sites. 1984 (Site A) 1985 (Site B) So i l Depth (cm) Depth (cm) Parameter 0-20 20-50 50-80 0-20 20-50 50-80 % S i l t 75.0 76.0 74.0 69.0 73.0 72.0 % Sand 5.0 6.0 13.0 1.0 6.0 4.0 % Clay 20.0 18.0 13.0 30.0 21.0 24.0 Bulk density at 1.43 1.46 1.22 1.13 1.28 1.18 sidedress (g 1 B L " 1 ) % Organic matter 2.4 1.9 1.9 3.8 2.1 2.6 Total N % 0.2 0.2 0.2 0.2 0.1 0.1 pH (H,0) 5.0 4.3 3.8 4.8 4.6 4.3 Salts (E.C.) 0.48 0.32 0.48 0.56 0.96 0.72 dS m"' Nitrates (NO,-N) Mg mL 13.0 5.0 3.0 11.0 8.0 11.0 Phosphorus (P) 144.0 22.0 7.0 97.0 13.0 21.0 jtg mL"' Potassium (K) 0.36 0.18 0.12 0.43 0.25 0.23 me lOOmL-1 Magnesium (Mg) 1.32 0.81 0.45 0.76 1.24 0.49 me lOOmL-Calcium (Ca) 4.69 2.38 0.62 2.4 0.85 0.91 me lOOmL Sodium (Na) 0.00 0.00 0.00 0.20 1.02 0.42 me lOOmL-1 Total Cations 6.37 3.37 1.19 3.79 3.37 2.05 me lOOmL-1 Exchangeable 0.00 0.00 0.00 5.40 30.40 20.60 sodium % Sodium adsorp- 0.00 0.00 0.00 0.16 1.00 0.50 tion r a t i o Sulphate (SO^-S) jig mL-1 18.1 24.3 58.5 61.0 177.0 131.0 Boron (B) 0.59 0.32 0.23 1.24 0.81 0.84 vg mL-' Copper (Cu) 6.8 8.7 7.3 7.9 4.7 5.6 Mg mL Iron (Fe) 160.2 241.7 333.2 312.2 358.1 329.2 Mg mL-' Manganese (Mn) 17.0 4.8 2.1 17.5 2.7 5.5 mL-' Zinc (Zn) 1.5 1.1 1.1 1.4 0.5 0.7 *tg mL1 S C A L E : lcm = 2m TREATMENT: 0,50,100,200 (kghcf'N) 7K SD = sidedress PP = preplant 4m 24m 6m 30 m I00PP 0 50 5 0 IOOPP IOOSD IOOPP 2 0 0 IOOSD 50 100 2 0 0 IOOSD IOOPP 100 50 IOOSD 100 100 2 0 0 2 0 0 100 IOOPP 0 0 0 50 0 2 0 0 IOOSD BLOCK I I E Appendix 3. F i e l d p l a n example: R e p l i c a t e d f e r t i l i z e r response t r i a l . S i t e A. 129 N i t r o g e n F e r t i l i z e r T r i a l on Sweet Corn F o r y o u r 1985 f i e l d ( s ) o f sweet c o r n c o n t a i n i n g t he " s i d e - d r e s s / n o s i d e - d r e s s " f i e l d t r i a l s t r i p s . ( P l e a s e complete t he q u e s t i o n s below as f a r as p o s s i b l e . ) YEAR 1981 1982 1983 1984 What c r o p ? Cover c r o p ? y o r x What s o r t ? Manure? / o r X Type and appro x i m a t e r a t e ? Lime? / o r X When? How much? How ( i f a t a l l ) i s t h i s f i e l d d r a i n e d and i r r i g a t e d ? What were t he r a t e s o f s t a r t e r and s i d e - d r e s s n i t r o g e n a p p l i e d t o the sweet cor n ? On what da t e was the co r n p l a n t e d ? Appendix 4. Multifarm t r i a l : Questionnaire sent to farmers to obtain s i t e information. Appendix 5 Methods used for s o i l analysis by B.C. Feed and tissue testing laboratory, Kelowna. S o i l Parameter Method of analysis Reference % S i l t , Sand, Clay Particle size analysis Day 1965 % Organic matter Loss on ignition Nelson and Somtners 1982 Total N % Kjeldahl N Brenner and Mulvaney 1982 pH (Ht0) 1:2 soil:water ratio Salts (E.C.) Conductivity Electrode NOj-N Kelowna extract Cadmium reduction + Autoanalyser van Lierop 1986 Technicon Autoanalyser 1977 P K Mg Ca Na SCy-S Kelowna extract ICPAES van Lierop 1986 Total Cations Sum of cations. B Cu Fe Mn Zn Hot water extract ICPAES DTPA extract ICPAES Black 1965 Page 1982 Appendix 6 Multifarm t r i a l : Previous crops, mineralization, crop + s o i l N (0-80cm), and f e r t i l i z e r efficiency estimates. Year Site Previous Mineralization Total crop + F e r t i l i z e r crop kg ha" s o i l N kg ha"' efficiency % 1 1 Corn 104.1 116.8 52 1 2 Beans 195.7 203.4 7 1 3 Beans 89.4 98.3 -9 1 4 Peas 88.3 94.3 18 1 5 Potatoes 42.3 46.9 27 1 6 Peas 122.1 137.5 10 1 7 Spring barley 81.3 96.5 -2 1 8 Potatoes 190.3 209.2 -26 1 9 Spring barley 172.2 189.3 -4 1 10 Potatoes 100.2 110.6 19 1 11 Beans 95.3 102.4 37 1 12 Potatoes 138.0 145.6 9 1 13 Peas 101.3 112.6 20 1 14 Potatoes 59.0 65.0 22 1 15 ? 154.3 169.4 6 1 16 Peas 115.1 123.2 34 1 17 Peas 148.7 168.3 10 2 1 Potatoes 305.1 349.1 42 2 2 Peas 192.0 218.5 4 2 3 Peas 302.3 321.7 0 2 4 Peas 190.5 215.3 25 2 5 ? 155.0 184.7 2 2 6 Peas 251.9 264.7 13 2 7 ? 118.6 130.4 38 2 8 Corn 184.2 212.9 10 2 9 Potatoes 168.2 217.4 26 2 10 Strawberries 144.2 167.2 13 2 11 Peas 103.8 120.4 7 Mineralization = Crop N + S o i l Mineral N (0-50cm) - starter x 0.7 Total crop + s o i l N = " (0-80cm) F e r t i l i z e r efficiency = N uptake f e r t i l i z e d plot - N uptake control plot Amount of f e r t i l i z e r N sidedressed = 135 kg ha' NOjNlkghd') NH^N(kghd') YR SITE 0-20 20-50 50-80 0~50 0"80 0"20 20-50 50-80 0-50 0"80 cm 1 1 13 55 23 36 20 .00 36 .91 56 .91 9. 16 16. .82 2 .00 25. 97 27. 97 1 2 7 36 3 .87 .95 1 1 . 23 12 . 18 1 . 84 7. 74 9 51 9. 58 19 09 1 3 46 b2 17 89 7 .06 64 .70 71 .77 14 . 78 76 12 46 15. 55 28. 01 1 4 8 65 6 99 5 82 15 .64 2 1 .46 10. 38 4 . 30 1 . 79 14 . 68 16 . 48 1 5 5 77 7 54 .51 7 81 8 .32 IO. 54 5 07 4 1 1 15 . 61 19 73 1 6 29 49 2 1 61 17 39 51 . 10 68 . 49 3. 77 8 .54 8 . 12 12. 32 20 43 1 7 4 17 ? ? 1 26 6 .68 6 94 8 59 .55 .52 9 14 9. 66 1 8 ?9 27 16 10 2 25 45 .37 47 .62 6. 57 5 19 8 .45 1 1 . , 76 20. 21 1 9 30 n 2 1 33 10 94 52 . 1 1 63 .06 7 . 5 1 9 54 5 .02 17 . 05 22 . 07 1 10 3 20 87 24 4 .07 4 32 25. 92 4 37 4 .87 30. . 29 35. 16 1 1 1 1 1 33 8 33 2 . 10 19 66 2 t . 76 67 56 1 .57 1 22 2 . 79 1 12 22 89 16 57 6 38 39 .46 45 .84 2 86 5 18 1 .59 8 . .04 9 63 1 13 18 18 25. 80 16 69 43 .98 60 .67 7 . 79 10 66 8 .81 18. 45 27. 26 1 14 10 77 5 03 3 2 1 15 .80 19 .02 3. 80 4 .02 2 . 29 7 . 83 10. 12 1 15 5 15 25 25 27 . .53 30 .4 1 57 .94 16 75 4 , .64 7 .7 1 21 . ,39 29. . 10 1 16 4 80 2 55 7 .54 7 .35 14 .90 5 . 10 5 . 47 14 .08 10. 57 24. 65 1 17 38 67 36 12 22 61 74 . 79 97 .39 3 .33 5. .76 5 .49 9. .09 14 .58 2 1 46 47 47 91 47 .21 94 .39 14 1 .59 7 . 15 7 .62 .92 14 , 77 15 .69 2 2 43 59 24 .95 19 .28 68 .54 87 .82 6 .23 3 .88 3 .06 10, . 1 1 13 . 17 2 3 70 23 28 27 38 . 73 98 .51 137 .24 B .78 2 .92 2 .45 11 .70 14 . 15 2 4 4 t 51 26 54 32 52 68 .05 100 .57 8 . 12 2 . 17 1 1 .83 10 . 29 22 . 1 1 2 5 27 00 26 29 19 93 53 . 29 73 .22 7. .50 2 .29 10 .63 9 .79 20 .42 2 6 16 39 •1? 7 1 35 92 59 . 10 95 .02 5 . 46 3 .88 1 1 .05 9. . 35 20 .40 2 7 12 60 1 1 84 1 35 24 .44 25 .80 22 .84 2 .49 1 1 .75 25 .33 37 .08 2 8 30 87 19 .73 27 54 50 .60 78 . 15 8. . 12 3 .29 8 .96 11 .41 20 .37 2 9 30 06 48 .63 48. , 23 78 .69 126 .92 7 . 12 3 . 19 7 .57 10 .31 17 .87 2 10 37 .91 49 .53 36 20 87 .44 123 .65 6 .24 7 .79 8 .05 14 .04 22 .08 2 11 25 .42 30 .5.1 19 93 55 .93 75. .87 2 .42 4 .72 23 .86 7 . 14 31 .OO Appendix 7. Multifarm T r i a l : S o i l n i t r a t e and ammonium ) at sidedress. (kg ha 1 (J 133 AB I) 2) C D E F G H 1 J 1 i 1 .80 80 0 80 5 0 1 . 24 1 1 2 .80 1 70 0 74 5 0 1 .40 i 1 3 .50 1 70 0 70 6 1 1 .08 1 2 1 .60 50 0 78 5 0 1 .24 1 2 2 .60 1 50 0 61 5 0 1 .40 1 2 3 .60 1 80 0 79 6 1 1 .08 1 3 1 .70 1 40 0 77 5 0 1 .24 1 3 2 .60 1 70 0 71 5 0 1 .40 1 3 3 .40 i 40 0 67 6 1 1 .08 1 4 1 .70 80 0 79 5 0 1 . 24 1 4 2 .50 1 50 0 73 5 0 1 .40 1 4 3 .50 1 90 0 67 6 1 1 .08 1 5 1 .60 90 0 76 5 0 1 .24 1 5 2 .70 2 20 0 69 5 0 1 .40 1 5 3 .50 1 90 0 64 6 1 1 .08 2 1 1 .70 .80 0 79 5 0 1 .24 2 1 2 1 .30 2 .20 0 75 5 0 1 .40 2 1 3 . 50 1 .70 0 69 6 . 1 1 .08 2 2 1 . 70 .70 0 79 5 . 0 1 .24 2 2 2 . 50 1 .70 0 71 5 .0 1 .40 2 2 3 .60 1 .60 0 67 6 . 1 1 .08 2 3 1 .90 .70 0 78 5 .0 1 .24 2 3 2 .80 1 .50 0 75 5 .0 1 .40 2 3 3 . 70 1 .90 0 65 6 . 1 1 .08 2 4 1 . 80 1 .00 0 77 5 .0 1 .24 2 4 2 .60 1 .80 0 71 5 .0 1 .40 2 4 3 .50 2 .00 0 67 6 . 1 1 .08 2 5 1 .60 .90 o 78 5 .0 1 .24 2 5 2 .50 1 .50 0 73 5 .0 1 .40 2 5 3 .50 1 .60 0 70 6 . 1 1 .08 1 2 1 1 1 1 .30 3 00 0 78 9 4 1 33 1 2 1 1 2 1 30 2 50 0 74 7 2 1 30 1 2 1 1 3 .60 2 OO 0 68 7 2 1 14 1 2 1 2 1 1 20 3 20 0 76 9 4 1 .33 1 2 1 2 2 1 .30 2 70 0 72 7 2 1 30 1 2 1 2 3 1 OO 2 50 0 68 7 2 1 14 1 2 1 3 1 80 3 20 0 77 9 4 1 33 1 2 1 3 2 1 00 3 10 0 72 7 2 1 30 1 2 1 3 3 80 2 60 0 68 7 2 1 14 1 2 1 4 1 1 30 3 20 0 78 9 4 1 33 1 2 1 4 2 90 2 90 0 75 7 2 1 30 1 2 1 4 3 60 2 90 0 68 7 2 1 14 1 2 1 5 1 1 10 4 60 0 75 9 4 1 33 1 2 1 5 2 1 10 4 20 0 71 7 2 1 30 1 2 1 5 3 1 20 3 70 0 66 7 2 1 14 1 2 2 1 1 1 10 3 30 0 78 9 4 1 33 1 2 2 1 2 1 10 2 50 0 75 7 2 1 30 1 2 2 1 3 70 2 20 0 69 7 2 1 14 1 2 2 2 1 60 3 10 0 76 9 4 1 33 1 2 2 2 2 2 10 3 10 0 73 7 2 1 30 1 2 2 2 3 1 00 5 20 0 67 7 2 1 14 1 2 2 3 1 1 00 3 OO 0 78 9 4 1 33 1 2 2 3 2 90 3 OO 0 76 7 2 1 30 1 2 2 3 3 90 3 50 0 72 7 2 1 14 1 2 2 4 1 1 60 3 50 0 77 9 4 1 33 1 2 2 4 2 1 10 3 50 0 72 7 2 1 30 1 2 2 4 3 80 3 50 0 68 7 2 1 14 1 2 2 5 1 80 3 10 0 76 9 4 1 33 1 2 2 5 2 . 70 3 40 0 71 7 2 1 30 1 2 2 5 3 .50 3 20 0 68 7 2 1 14 A = Year 1 = 1984 2 = 1985 B = Date of sampling C = Treatment 1 = preplant 2 = sidedress D = Block (1-5) E = Depth 1 = 0-20cm 2 = 20-50cm 3 = 50-80cm F = NH.-N 4 -1 . ^  .. g g moist s o i l G = N0 3-N 1 g g moist s o i l H = Dry weight of s o i l as proportion of moist weight I = Temperature °C 3 J = Bulk density g cm Appendix 8a. Nitrogen monitoring study: 1) 25 A p r i l 1984 2) 9 May 1984. 134 AB C D E F G H I J 1 3 i 1 1 1 .20 4 . 0 0 0. 78 9 . 4 1 , 22 1 3 1 1 2 .60 2 .50 0 . 70 7 . 2 1 . ,44 1 3 1 1 3 .50 2 . 0 0 O. 67 7 . 2 1 . . 10 1 3 1 2 1 1 . 10 4 . 0 0 0. .79 9 . 4 1 . 22 1 3 1 2 2 .90 3 .00 O .76 7. 2 1 44 1 3 1 2 3 .80 2 . 5 0 0. .67 7. 2 1 . 10 1 3 1 3 1 .90 3 .50 0. .76 9 . 4 1 . .22 1 3 1 3 2 .70 3 .00 0. .71 7 . 2 1 .44 1 3 1 3 3 .60 2 . 5 0 0 .67 7 . .2 1 , . 10 1 3 1 4 1 . 70 4 . 0 0 0 .77 9. 4 1 .22 1 3 1 4 2 .70 3 . 0 0 0 .75 7 . 2 1 . 44 1 3 1 4 3 .70 3 . 0 0 0 .65 7. 2 1 . 10 1 3 1 5 1 1 . 10 5 .00 0 . 76 9 .4 1 .22 1 3 1 5 2 .70 5 .00 0 .72 7 . .2 1 .44 1 3 1 5 3 .60 4 . 5 0 0 .66 7 . 2 1 . 10 1 3 2 1 1 1 .20 4 . 0 0 0 .79 9. .4 1 .22 1 3 2 1 2 1 .OO 3 .OO 0 .74 7 . 2 1 . 44 1 3 2 1 3 .70 2 . 5 0 0 .69 7. .2 1 . 10 1 3 2 2 1 .90 3 . 5 0 0 .80 9 .4 1 .22 1 3 2 2 2 .70 3 . 0 0 0 .75 7. .2 1 .44 1 3 2 2 3 .80 3 .00 0 .67 7 .2 1 . 10 1 3 2 3 1 1 .20 3 .00 0 .78 9 .4 1 .22 1 3 2 3 2 .70 3 . 0 0 0 . 75 7 .2 1 .44 1 3 2 3 3 .50 2 .50 0 .68 7 .2 1 . 10 1 3 2 4 1 2 . 10 4 . 0 0 0 .77 9 .4 1 .22 1 3 2 4 2 .80 4 .00 0 .75 7 .2 1 .44 1 3 2 4 3 .70 3 .50 o .67 7 .2 1 . 10 1 3 2 5 1 .80 4 . 0 0 0 .76 9 .4 1 .22 1 3 2 5 2 .70 4 . 0 0 0 .74 7 .2 1 .44 1 3 2 5 3 .60 3 .00 0 .66 7 .2 1 . 10 2) 1 4 1 1 1 4 1 1 1 4 1 1 1 4 1 2 1 4 1 2 1 4 1 2 1 4 1 3 1 4 1 3 1 4 1 3 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 5 1 4 1 5 1 4 1 5 1 4 2 1 1 4 2 1 1 4 2 1 1 4 2 2 1 4 2 2 1 4 2 2 1 4 2 3 1 4 2 3 1 4 2 3 1 4 2 4 1 4 2 4 1 4 2 4 1 4 2 5 1 4 2 5 1 4 2 5 1 15 .00 2 .80 3 1 . 10 1 10 .00 2 1 .20 3 1.10 1 2 0 . 0 0 2 1 .80 3 1 .50 1 16 .50 2 1 .60 3 .90 1 11 .00 2 1 .30 3 .90 1 1 .60 2 .80 3 .60 1 .80 2 .50 3 .60 1 1 .00 2 .60 3 .70 1 1 .OO 2 1 .OO 3 .60 1 .80 2 .60 3 1 .OO 7 . 0 0 0 . 7 9 3 .50 0 . 7 6 2 . 5 0 0 . 6 8 6 . 0 0 0 . 8 0 3 . 0 0 0 . 7 5 2 . 5 0 0 . 6 8 8 . 0 0 0 . 7 9 3 .50 0 . 7 3 2 . 5 0 0 . 6 9 7 . 0 0 0 . 8 0 3 .00 0 . 7 5 3 .00 0 . 6 8 8 . 0 0 0 . 7 8 4 . 0 0 0 . 7 0 3 . 0 0 0 . 6 6 5 .00 0 . 8 0 2 . 5 0 0 . 7 4 2 . 0 0 0 . 7 0 5 .50 0 . 7 9 3 . 5 0 0 . 7 3 2 . 5 0 0 . 6 8 5 .00 0 . 8 0 3 . 5 0 0 . 7 4 3 . 0 0 0 . 7 2 5 .50 0 . 7 9 5 .50 0 . 7 3 3 . 5 0 0 . 6 7 5 .00 0 . 7 9 3 . 5 0 0 . 7 2 3 . 0 0 0 . 6 6 11.1 1.38 10.0 1.44 9 .4 1.10 11.1 1.38 10 .0 1.44 9 .4 1 . 10 11.1 1 .38 10 .0 1.44 9 .4 1.10 11.1 1.38 10 .0 1.44 9 .4 1.10 11.1 1.38 10 .0 1.44 9 . 4 1.10 11.1 1.38 10 .0 1.44 9 . 4 1.10 11.1 1.38 10.0 1.44 9 . 4 1 . 10 11.1 1.38 10 .0 1.44 9 .4 1 . 10 11.1 1.38 10.0 1.44 9 .4 1.10 11.1 1.38 10.0 1.44 9 .4 1.10 Appendix 8b. Nitrogen monitoring study: 1) 23 May 1984 2) 7 June 1984. 135 AB C D E F G H I J 1 5 1 1 1 5 .00 24 .40 0 .82 13. 9 1 .61 1 5 1 1 2 1 .20 5 .OO 0 .75 12 8 1 .44 1 5 1 1 3 .70 3 .00 0 .68 12 .2 1 . 10 1 5 1 2 1 4 .OO 18 .40 0 .81 13. 9 1 .61 1 5 1 2 2 1 .20 4 .00 0 .75 12 . 8 1 .44 1 5 1 2 3 1 .00 4 .00 0 .70 12. .2 1 . 10 1 5 1 3 1 4 .00 18 .00 0 .80 13. .9 1 .61 1 5 1 3 2 1 .30 5 .00 0 .71 12. 8 1 .44  5 1 3 3 1 .00 4 .00 0. .68 12. .2 1 . 10 1 5 1 4 1 10 .00 22 .00 0 .81 13. 9 1 .61 1 5 1 4 2 1 . 10 5 .00 0 .77 12. .8 1 .44 1 5 1 4 3 1 .20 5 .00 0 .70 12. 2 1 . 10 1 5 1 5 1 3 .00 18 .oo 0 .80 13. .9 1 .61 1 5 1 5 2 1 . 10 7 .00 0 .71 12. 8 1 .44 1 5 1 5 3 1 . 10 6 .00 0 .66 12 .2 1 . 10 1 5 2 1 1 .90 11 .20 0 .81 13, .9 1 .61 1 5 2 1 2 .60 3 .00 0 .75 12 8 1 .44 1 5 2 1 3 .60 2 .00 0 .68 12. 2 1 . 10 1 5 2 2 1 1 . 10 7 .oo 0 .81 13. .9 1 .61 1 5 2 2 2 .80 3 .50 0 .72 12 8 1 .44 1 5 2 2 3 .80 3 .00 0 .67 12 .2 1 . 10 1 5 2 3 1 .70 10 .40 0 .81 13 .9 1 .61  5 2 3 2 .80 5 .00 0 .74 12 8 1 .44 1 5 2 3 3 .90 4 .00 0 .70 12 .2 1 . 10 1 5 2 4 1 .80 8 .00 0 .79 13 .9 1 .61 1 5 2 4 2 .60 9 .oo 0 .74 12 .8 1 .44 1 5 2 4 3 .50 4 .00 0 .68 12 .2 1 . 10 1 5 2 5 1 .70 8 .00 0 .80 13 .9 1 .61 1 5 2 5 2 .90 4 .00 0 .75 12 .8 1 .44 1 5 2 5 3 .50 3 .00 0 .68 12 .2 1 . 10 1 6 1 1 1 3 .70 26 .OO 0. .80 15 .6 1 .35 1 6 1 1 2 1 .20 7 .40 0. .74 12 .8 1 .44 1 6 1 1 3 1 .60 5 .50 0. .68 12 .8 1 . 10 1 6 1 2 1 1 .50 15 .OO 0. .80 15 .6 1 .35 1 6 1 2 2 1 .00 5 .20 O. .73 12 .8 1 .44 1 6 1 2 3 1 .00 3 .80 0. .68 12 .8 1 . 10 1 6 1 3 1 2 .40 16 .40 0. .79 15 .6 1 .35 1 6 1 3 2 1 .40 7 .50 0 .74 12 .8 1 .44 1 6 1 3 3 1 .20 5 .20 0, .67 12 .8 1 . 10 1 6 1 4 1 1 .50 16 . IO 0 .80 15 .6 1 .35 1 6 1 4 2 .80 5 .20 0. 74 12 .8 1 .44 1 6 1 4 3 1 .00 4 .80 0. .67 12 .8 1 . 10 1 6 1 5 1 2 .90 24 .80 0. ,79 15 .6 1 .35 1 6 1 5 2 1 . 00 8 .60 0. .73 12 .8 1 .44 1 6 1 5 3 .80 4 .90 0. .66 12 .8 1 . 10 1 6 2 1 1 1 .50 8 .OO 0. 81 15 .6 1 .35 1 6 2 1 2 1 .00 5 .OO 0. .76 12 .8 1 .44 1 6 2 1 3 1 .50 4 .40 0. .71 12 .8 1 . 10 1 6 2 2 1 1 .30 8 .40 o. .60 15 .6 1 .35 1 6 2 2 2 1 . 10 5 .OO 0. .73 12 .8 1 .44 1 6 2 2 3 1 .OO 4 .20 o. .66 12 .8 1 . 10 1 6 2 3 1 1 . 10 10 .80 0 .80 15 .6 1 .35 1 6 2 3 2 1 . 10 5 .90 0 .74 12 .8 1 .44 1 6 2 3 3 1 . 10 4 .50 o. 68 12 .8 1 . 10 1 6 2 4 1 1 .40 11 . 80 0. 80 15. 6 1 . ,35 1 6 2 4 2 1 . 10 6. .00 0. 71 12. 8 1 . 44 1 6 2 4 3 .70 5. .00 0. 67 12. 8 1 . , 10 1 6 2 5 1 1 .00 12, .OO 0. 80 15 . 6 1 , .35 1 6 2 5 2 .70 6. OO 0. 72 12. 8 1 , .44 1 6 2 5 3 1 .20 5, .00 0 . 66 12. 8 1 , . 10 Appendix 8c. Nitrogen monitoring study: 1) 20 June 1984 2) 4 July 1984 136 A B c D E F G H I « J 2 1 1 1 1 2 .00 4 . 00 0. 73 12 .  5 1 .  14 2 1 1 1 2 2 .00 4 . 00 0. 66 1 . . 28 2 1 1 1 3 2 .00 3 . 50 0. 64 1 .  18 2 1 1 2 1 2 .00 4 . 00 0. 74 12 . 5 1 . , 14 2 1 1 2 2 2 .00 8 . 00 0. 67 1 . 28 2 1 1 2 3 2 .00 10. . 50 0. 62 1 . . 18 2 1 1 3 1 2 .50 4 . 50 0. 74 12 . 5 1 . 14 2 1 1 3 2 2 .50 8 . 00 0. 68 1 . 28 2 1 1 3 3 2 .50 8 . 50 0 69 1 . . 18 2 1 1 4 1 2 .50 3. .50 0. 71 12 . 5 1 . 14 2 1 1 4 2 2 .50 7 . 00 0. 70 1 .28 2 1 1 4 3 2 .00 7 . 50 0. .71 1 . 18 2 1 1 5 1 2 .50 3. .50 0, .63 12 . 5 1 . 14 2 1 1 5 2 2 .50 7 . 50 0. .66 1 .28 2 1 M 5 3 2 .00 10. .50 0. 65 1 . . 18 2 1 2 1 1 2 .00 3 .00 0. .69 12 .5 1 . 14 2 1 2 1 2 2 .00 4 .00 0. .64 1 .28 2 1 2 1 3 2 .00 3. .50 0. .64 1 . 18 2 1 2 2 1 2 .00 4 . 50 0 . 74 12 .5 1 . 14 2 1 2 2 2 2 .50 e. .00 0 .67 1 .28 2 1 2 2 3 2 .00 6 .00 0, .63 1 . 18 2 1 2 3 1 3 .00 6 .50 0 .68 12 .5 1 . 14 2 1 2 3 2 2 .00 9 .00 0 67 1 . 28 2 1 2 3 3 2 .00 9. .50 0. .62 1 . 18 2 1 2 4 1 2 .50 3 .50 0 .75 12 .5 1 . 14 2 1 2 4 2 3 .00 6 .00 0 .68 1 .28 2 1 2 4 3 2 . 50 8 .00 0 .69 1 . 18 2 1 2 5 1 1 .00 4 .50 0 .75 12 .5 1 . 14 2 1 2 5 2 .50 8 .00 0 . 70 1 .28 2 1 2 5 3 .50 10 .50 0 .70 1 . 18 2 2 1 1 1 7 .50 5 .OO 0 .73 15 .9 1 .07 2 2 1 1 2 1 .00 4 .50 0 .66 1 .28 2 2 1 1 3 1 .00 8 .50 0 .62 1 . 18 2 2 1 2 1 9 .50 8 . 50 0 .75 15 .9 1 .07 2 2 1 2 2 2 .00 9 .50 0 .67 1 .28 2 2 1 2 3 2 .00 10 .00 0 .62 1 . 18 2 2 1 3 1 20 .50 8 .00 0 . 75 15 .9 1 .07 2 2 1 3 2 1 .50 9 .50 0 .67 1 .28 2 2 1 3 3 .00 9 .00 0 .69 1 . 18 2 2 1 4 1 3 .00 7 .50 0 .75 15 .9 1 .07 2 2 1 4 2 1 .00 8 .50 0 .70 1 .28 2 2 1 4 3 2 .00 10 .00 0 .70 1 . 18 2 2 1 5 1 4 .50 5 .50 0 .75 15 .9 1 .07 2 2 1 5 2 1 .00 7 .50 0 .68 1 .28 2 2 1 5 3 1 .00 8 .50 0 .67 1 . 18 2 2 2 1 1 .50 5 .00 0 .74 15 .9 1 .07 2 2 2 1 2 .50 4 .00 0 .67 1 .28 2 2 2 1 3 1 .00 5 .00 0 .65 1 . 18 2 2 2 2 1 . 50 6 .50 0 . 74 15 .9 1 .07 2 2 2 2 2 .50 7 .00 0 .66 1 .28 2 2 2 2 3 .50 7 .50 0 .66 1 . 18 2 2 2 3 1 .50 8 .00 0 .75 15 .9 1 .07 2 2 2 3 2 50 9. OO 0. 69 1 . 28 2 2 2 3 3 50 9. 50 0. 63 1 . 18 2 2 2 4 1 1 . 50 7 . 50 0. 74 15 . 9 1 . 07 2 2 2 4 2 50 8 . 00 0. 68 1 . 28 2 2 2 4 3 1 . 00 8 . 50 0. 70 1 . 18 2 2 2 5 1 1 . 50 6 . 50 0. 76 15 . 9 1 . 07 2 2 2 5 2 50 9. 50 0. 71 1 . 28 2 2 2 5 3 50 9 . 50 0. 72 1 . 18 Appendix 8d. Nitrogen monitoring study: 1) 8 May 1985 2) 22 May 1985. 137 AB C D E F G H I J 2 3 1 1 1 4 . 50 9 . 50 0 . 72 15 .8 0 . 98 2 3 1 1 2 2 .50 4 .00 0 .64 1 . 28 2 3 1 1 3 2 .00 3 .50 0 .62 1 . 18 2 3 1 2 1 2 .50 9 .50 0 .73 15 . 8 0 .98 2 3 1 2 2 2 .00 8 .50 0 .66 1 . 28 2 3 1 2 3 3 .00 6 .00 0 .63 1 . 18 2 3 1 3 1 9 .00 20 .00 0. . 72 15 .8 0. .98 2 3 1 3 2 7 .50 10 .50 0. 68 1 . . 28 2 3 1 3 3 5 .00 7. .00 0. ,67 1 . . 18 2 3 1 4 1 4 .00 1 1 .00 0. ,71 15 ,8 0. .98 2 3 1 4 2 2 .00 6 .50 0. 68 1. . 28 2 3 1 4 3 2 .00 7 .00 0. , 74 1. . 18 2 3 1 5 1 8 .50 1 1 .00 0. ,71 15, .8 0. .98 2 3 1 5 2 2 .50 8 .00 0. 65 1. . 28 2 3 1 5 3 3 . 50 10 .00 0. 65 1. 18 2 3 2 1 1 1 .50 7. .00 0. 71 15 , .8 0. 98 2 3 2 1 2 1 . 50 4 . 00 0. 65 1. 28 2 3 2 1 3 1 . .50 4 . 00 0. 6G 1. 18 2 3 2 2 1 2 . 00 10. .00 0. 71 15, .8 0. 98 2 3 2 2 2 2. .00 7 . 00 0. 64 1. 28 2 3 2 2 3 2 . ,00 5. .50 0. 65 1. 18 2 3 2 3 1 3 . 00 15. .50 0. 70 15 . 8 0. 98 2 3 2 3 2 1 . ,50 7 , .50 0. 64 1. 28 2 3 2 3 3 1 . 50 7. .50 0. 62 1. 18 2 3 2 4 1 3. 00 10. 00 0. 72 15. .8 0. 98 2 3 2 4 2 1 . 50 7 . 00 0. 68 1. 28 2 3 2 4 3 2 . 00 7 . 50 0. 69 1. 18 2 3 2 5 1 2. 00 10. .00 0. 73 15. .8 0. 98 2 3 2 5 2 2. 00 8. 50 0. 70 1. 28 2 3 2 5 3 2 . 50 10. OO 0. 72 1. 18 2 4 1 1 1 2 .50 21 . 00 0. 75 18 . 8 1 . 1 1 2 4 1 1 2 .50 7 . 00 0. 69 1 . 28 2 4 1 1 3 3, .00 10. 00 0. 63 1 . 18 2 4 1 2 1 .50 10. 50 0. 74 18 . 8 1 . , 1 1 2 4 1 2 2 2 .00 12 . 50 0. 75 1 . , 28 2 4 1 2 3 1 .50 8 . 00 0. 64 1 . , 18 2 4 1 3 1 7 .50 25. .00 0. 77 18. 8 1 . . 1 1 2 4 1 3 2 .50 1 1 . .00 0. 72 1 . 28 2 4 1 3 3 2 .00 8 . 50 0. 70 1 . 18 2 4 1 4 1 6 .00 20. .00 0. 76 18 . 8 1 , . 1 1 2 4 1 4 2 1 .50 1 1 . .00 0. 70 1 . 28 2 4 1 4 3 2 .00 14 , 00 0. 71 1 , . 18 2 4 1 5 1 6 .00 25. .00 0. .76 18 .8 1 . 1 1 2 4 1 5 2 1 .00 10, ,50 0. 70 1 .28 2 4 1 5 3 .50 1 1 .00 0. .67 1 . 18 2 4 2 1 1 1 . 50 1 1 . 50 0 . 75 18 .8 1 . 1 1 2 4 2 1 2 .50 5 .00 0. .74 1 .28 2 4 2 1 3 1 .00 3 .00 0. .69 1 . 18 2 4 2 2 1 .50 18 .50 0, , 74 18 .8 1 . 1 1 2 4 2 2 2 1 .00 8 .50 o. .66 1 . 28 2 4 2 2 3 1 . 50 8 .OO 0. .65 1 . 18 2 4 2 3 1 1 .00 15 .00 0. .76 18 .8 1 . 1 1 2 4 2 3 2 .50 10 .50 0 .69 1 .28 2 4 2 3 3 1 .00 10 .00 0. .63 1 . 18 2 4 2 4 1 3 .00 15 .00 0 .74 18 .8 1 . 1 1 2 4 2 4 2 1 .00 10 .00 0. .70 1 .28 2 4 2 4 3 1 .00 9 .50 0 .71 1 . 18 2 4 2 5 1 . 50 1 1 .50 0 . 77 18 .8 1 . 1 1 2 4 2 5 2 .OO 9 .50 0 . 70 1 . 28 2 4 2 5 3 .00 10 .50 0 .72 1 . 18 Appendix 8e. Nitrogen monitoring study: 1) 5 June 1985 2) 19 June 1985. 138 AB c DE F G H J 1 ) 2 5 1 1 1 .50 14 50 0 76 18 5 1 13 2 5 1 1 2 . 50 5 50 o 73 1 .28 2 5 1 1 3 .oo 3 50 0 62 1 18 2 5 1 2 1 2 .00 23 50 0 76 18 5 1 13 2 5 1 2 2 .50 1 1 00 0 69 1 28 2 5 1 2 3 6.00 2 50 0 63 1 18 2 5 1 3 1 .50 16 50 0 77 18 5 1 13 2 5 1 3 2 .OO 9 50 o 70 1 28 2 5 1 3 3 2.50 6 50 0 69 1 18 2 5 1 4 1 1 .50 17 50 0 76 18 5 1 13 2 5 1 4 2 .50 9 OO 0 69 1 28 2 5 1 4 3 1 . 50 10 50 0 72 1 18 2 5 1 5 1 3.50 20 50 0 76 18 5 1 13 2 5 1 5 2 1 .00 1 1 50 0 68 1 28 2 5 1 5 3 1 .50 10 OO o 67 1 18 2 5 2 1 1 .00 12 00 0 75 18 5 1 13 2 5 2 1 2 .00 7 00 0 66 1 28 2 5 2 1 3 .50 5 00 0 62 1 18 2 5 2 2 1 2.50 14 00 0 75 18 5 1 13 2 5 2 2 2 .00 7 00 0 70 1 28 2 5 2 2 3 .OO 5 00 o 69 1 18 2 5 2 3 1 .50 16 50 0 76 18 5 1 13 2 5 2 3 2 .OO 10 50 0 68 1 28 2 5 2 3 3 .50 9 00 0 65 1 18 2 5 2 4 1 .00 12 00 0 77 18 5 1 13 2 5 2 4 2 .50 8 50 0 69 1 28 2 5 2 4 3 .50 9 50 0 71 1 18 2 5 2 5 1 .00 13 50 0 76 18 5 1 13 2 5 2 5 2 .00 10 50 o 71 1 28 2 5 2 5 3 .00 8 OO 0 71 1 18 o\ 2 6 1 1 1 1 .OO 16 50 O 76 19 9 1 . 11 2) 2 6 1 1 2 .50 5 50 0 69 1 .28 2 6 1 1 3 3 .00 4 50 0 63 1 . 18 2 6 1 2 1 1 .50 20 OO 0 77 19 9 1 . 11 2 6 1 2 2 .50 9 00 0 69 1 .28 2 6 1 2 3 2 .00 7 50 0 63 1 18 2 6 1 3 1 1 .50 17 00 0 77 19 9 1 .11 2 6 1 3 2 1 .OO 9 50 0 71 1 .28 2 6 1 3 3 .50 5 00 0 72 1 . 18 2 6 1 4 1 2 .00 19 OO 0 73 19 9 1 . 1 1 2 6 1 4 2 .50 9 50 0 70 1 28 2 6 1 4 3 .50 10 50 0 69 1 18 2 6 1 5 1 .50 18 OO 0 77 19 9 1 11 2 6 1 5 2 1 .50 13 50 0 69 1 .28 2 6 1 5 3 .50 10 OO 0 68 1 18 2 6 2 1 1 1 .00 10 50 O 74 19 9 1 11 2 6 2 1 2 1 .50 5 50 0 68 1 .28 2 6 2 1 3 .50 4 00 0 64 1 . 18 2 6 2 2 1 1 50 1 1 . OO o. 74 19 9 1 11 2 6 2 2 2 50 7 OO o. 72 1 28 2 6 2 2 3 1 OO 3 50 0 69 1 18 2 6 2 3 1 50 1 1 50 0 81 19 9 1 1 1 2 6 2 3 2 2 00 9 50 0 68 1 28 2 6 2 3 3 00 7 50 0 66 1 18 2 6 2 4 1 50 9 50 0 76 19 9 1 1 1 2 6 2 4 2 1 OO 7 50 0 70 1 28 2 6 2 4 3 50 5 50 0 77 1 18 2 6 2 5 1 1 50 1 1 50 0 76 19 9 1 1 1 2 6 2 5 2 00 9 50 0 72 1 28 2 6 2 5 3 1 00 10 00 0 71 1 18 Appendix 8f. Nitrogen monitoring study: 1) 2 July 1985 2) 16 July 1985. 139 AB c D E F G H i 1 1 2 . 10 4 .80 0. 79 1. 44 0, .80 1 1 2 1 .20 3 .70 0. 80 1. 44 0, .90 1 1 3 1 .00 4 .80 0. 81 1. 44 1, .20 1 1 4 1 .90 4 .30 0. .80 1. 44 1, .50 1 2 1 2 .40 4 . 10 0. .79 1. 44 0, .70 1 2 2 0 .90 5 .80 0. .78 1. 44 0 .70 1 2 3 1 . 10 5 .20 0. . 79 1. 44 0, .60 1 2 4 0 .95 5 . 10 0. 80 1. 44 0, .90 1 3 1 1 .00 5 .20 0. 76 1. 44 0, .70 1 3 2 0 .75 5 .40 0. 79 1. 44 0, .60 1 3 3 1 .30 5 .70 0, ,78 1. 44 0 .65 1 3 4 0 .80 6 .00 0. 75 1. 44 0, .60 1 4 1 1 .55 5 .30 0. ,78 1. 44 0, .75 1 4 2 1 . 10 4 .30 0. ,79 1. 44 0, .90 1 4 3 1 .35 5 .40 0. ,79 1. 44 1, .35 1 4 4 0 .80 5 .70 0. . 79 1. 44 0 .60 1 5 1 0 . 55 4 .70 0. ,78 1. 44 0, .65 1 5 2 0 .85 7 .20 0. .78 1. 44 0 .65 1 5 3 0 .95 4 .80 0. 79 1. 44 0. .55 1 5 4 0 .90 5 .60 0. , 78 1. 44 0. .80 2 1 1 2 .00 2 .50 0. 72 1. 14 2. .00 2 1 2 2 .00 2 .50 0. ,72 1. 14 2 .00 2 1 3 2 .00 2 .50 0. 72 1. 14 2 . 00 2 1 4 2 . 00 2 .50 0. 72 1. 14 2 , .00 2 2 1 2 . 00 4 .00 0. 73 1. 14 1 . 50 2 2 2 2. .00 4 .00 0. 73 1. 14 1 . 50 2 2 3 2. .00 4 .00 0. 73 1. 14 1 , .50 2 2 4 2 . 00 4 .00 0. 73 1. 14 1 . , 50 2 3 1 2 . 5 3 . 5 0. 73 1. 14 1 . 5 2 3 2 2 . 5 3 .5 0. 73 1. 14 1 . 5 2 3 3 2 . ,5 3. . 5 0. 73 1. 14 1 . ,5 2 3 4 2. .5 3 .5 0. 73 1. 14 1 . 5 2 4 1 3. .0 3. .0 0. 74 1. 14 1 . 0 2 4 2 3 . 0 3. .0 0. 74 1. 14 1 . 0 2 4 3 3. .0 3. .0 0. 74 1. 14 1 . 0 2 4 4 3 . 0 3 . 0 0. 74 1. 14 1 . 0 2 5 1 3 . 5 3. .0 0. 74 1. 14 2. 5 2 5 2 3. .5 3 . 0 0. 74 1. 14 2. 5 2 5 3 3. 5 3. 0 0. 74 1. 14 2. 5 2 5 4 3. 5 3. ,0 0. 74 1. 14 2. 5 I J K L M N 0 3 .20 0. 74 1 .46 0. 55 2. 00 0. 66 1 , 22 3 .30 0. 74 1 . 46 0. 75 2. . 10 0. 68 1 , , 22 3 .80 0. 75 1 . 46 0. 95 2 . 40 0. 64 1 . 22 3 .00 0. ,73 1 . 46 1, . 10 1 . , 90 0. 67 1 , . 22 6 .70 0. 72 1 .46 0. 60 2 . ,90 0. 68 1 . 22 3 .OO 0. ,72 1 . 46 1. ,25 2 .40 0. 68 1 . 22 3 .60 0. 75 1 .46 0. ,80 2 , .60 0. 70 1 .22 4 . 10 0. 75 1 .46 0. 55 2 . 90 0. 70 1 , . 22 3 .70 0. .71 1 . 46 0. .50 2 . 30 0. 67 1 . 22 4 . 10 0. ,72 1 . 46 0. ,55 3 .40 0. 67 1 . 22 3 .70 0. ,72 1 . 46 0. ,60 1 .20 0. 68 1 .22 3 .60 0. 73 1 .46 0. ,65 3 .00 0. 67 1 .22 4 .00 0. .73 1 .46 0. ,50 2 .60 0. 69 1 .22 3 .90 0. .72 1 .46 0. ,65 3 . 10 0. 68 1 .22 3 .90 0. , 74 1 .46 1. ,30 2 .40 0. 68 1 .22 4 .00 0. .71 1 .46 0, . 50 2 . 10 0. 68 1 . 22 4 . 20 0. ,70 1 .46 0, .70 3 .80 0. 68 1 . 22 5 . 10 0, .71 1 .46 0 .80 3 .60 0. .67 1 .22 4 .40 0, , 74 1 .46 0 .65 4 .00 0. .69 1 .22 3 .90 0, .72 1 . 46 0 . 50 3 .20 0, .70 1 . 22 6 .00 0, ,67 1 . 28 2 .00 8 .00 0. .60 1 . 18 6 .OO 0, .67 1 . 28 2 .00 8 .00 0. .60 1 . 18 6 .00 0. .67 1 . 28 2 .00 8 .00 0. .60 1 . 18 6 .00 0. 67 1 . 28 2 .00 8 .00 0, .60 1 . 18 7 .00 0. 66 1 .28 2 , .00 8 .50 0. .66 1 . 18 7 .00 0. .66 1 . 28 2 , .00 8 . 50 0. ,66 1 . 18 7 .00 0. ,66 1 .28 2 .00 8 .50 0, ,66 1 . 18 7 .OO 0. ,66 1 .28 2 , .00 8 . 50 0, ,66 1 . 18 6 .0 0. 67 1 .28 1 , .5 7 .5 0, ,68 1 . 18 6 .0 0. ,67 1 .28 1 , .5 7 . 5 0, ,68 1 . 18 6 .0 0. 67 1 .28 1 , 5 7 .5 0. .68 1 . 18 6 .0 0. ,67 1 .28 1 , . 5 7 . 5 0, 68 1 . 18 5 .0 0. 69 1 . 28 2 , 0 7 .5 0, 68 1 . 18 5 .0 0. 69 1 . 28 2 , .0 7 .5 0, .68 1 . 18 5 .0 0. 69 1 .28 2 , .0 7 .5 0. .68 1 . 18 5 .0 0. 69 1 .28 2. .0 7 . 5 0. 68 1 . 18 8 .0 0. 69 1 . 28 2 . 5 9 .0 0. ,69 1 . 18 8 .0 0. 69 1 .28 2. . 5 9 .0 0. 69 1 . 18 8 .0 0. 69 1 .28 2 . 5 9 .0 0. ,69 1 . 18 8 .0 0. 69 1 .28 2. .5 9. .0 0. 69 1 . 18 A = B = C = D-G H-K L-O D, H, E, I, F, J, G, K, 3=100, 4=200 kg ha N) Year (1=1984, 2=1985) Block (1-5) Treatment (1=0, 2=50, = Depth 1 (0-20cm) = Depth 2 (20-50cm) = Depth 3 (50-80cm) L = NH -N ( ~ 1 M = NCXT-N ( g g N = Dry s o i l as a proportion of moist s o i l g g _ ^ moist s o i l ) moist s o i l ) = Bulk density ( g cm ) Appendix 9a. Replicated f e r t i l i z e r response t r i a l : S o i l data, preplant. 140 A B c D E F G H 1 J K L M N 0 1 1 1 1 30 08 7 0 80 1 . 30 0 60 4 6 0 73 1 .46 0 55 3 0 0 68 1 . 22 1 1 2 0 85 08 8 0 .80 1 .30 0 60 4 1 0 75 1 .46 0 45 3 2 0 68 1 .22 1 1 3 0 85 10 1 0 82 1 .30 0 90 5 2 0 74 1 .46 1 05 4 3 0 69 1 .22 1 1 4 0 80 09 0 0 81 1 . 3 0 0 65 3 8 0 75 1 .46 0 50 2 6 0 66 1 . 22 1 2 1 0 95 12 0 0 .81 1 . 3 0 0 . 7 0 6 1 0 76 1 .46 0 70 5 4 0 68 1 .22 1 2 2 0 90 12 3 0 . 8 0 1 .30 1 45 6 0 0 74 1 . 46 0 55 4 5 0 68 1 . 22 1 2 3 0 75 12 1 0 .80 1 . 30 0 70 6 0 0 74 1 .46 0 60 4 3 0 69 1 .22 1 2 4 0 95 12 4 0 81 1 . 30 0 85 6 0 0 76 1 .46 0 40 6 2 0 72 1 .22 1 3 1 0 95 15 2 0 80 1 .30 0 85 7 1 0 73 1 .46 0 85 4 2 0 69 1 .22 1 3 2 0 70 13 5 0 80 1 .30 0 50 5 7 0 73 1 .46 1 00 4 0 0 66 1 . 22 1 3 3 0 85 10 6 0 82 1 .30 0 85 6 0 0 73 1 .46 0 85 4 2 0 69 1 .22 1 3 4 1 20 15 5 0 81 1 .30 0 75 5 7 0 73 1 .46 0 45 4 3 0 68 1 . 22 1 4 1 1 15 10 4 0 80 1 . 3 0 2 05 6 1 0 75 1 .46 2 40 3 8 0 69 1 . 22 1 4 2 1 25 1 1 4 0 81 1 . 3 0 0 80 6 8 0 73 1 .46 0 55 4 2 0 68 1 .22 1 4 3 0 75 10 2 0 .81 1 . 30 0 75 5 0 0 76 1 . 46 0 65 3 6 0 69 1 .22 1 4 4 1 05 13 2 0 . 8 0 1 . 30 1 15 5 1 0 71 1 . 46 1 15 6 3 0 68 1 . 22 1 5 1 0 65 1 1 0 0 81 1 . 3 0 0 60 6 2 0 74 1 .46 0 60 4 5 0 68 1 .22 1 5 2 2 60 14 8 0 80 1 . 3 0 0 90 8 9 0 71 1 .46 0 85 3 4 0 67 1 .22 1 5 3 0 85 1 1 8 0 81 1 . 3 0 0 60 6 7 0 75 1 .46 0 75 6 6 0 68 1 .22 1 5 4 0 75 1 1 4 0 81 1 . 3 0 0 65 5 0 0 75 1 .46 0 75 5 3 0 67 1 .22 2 1 1 0 75 7 3 0 76 1 . 11 0 80 5 5 0 69 1 . 28 0 60 4 5 0 66 1 . 18 2 1 2 0 80 7 3 0 76 1 . 1 1 0 50 4 8 0 68 1 .28 0 60 5 0 0 63 1 . 18 2 1 3 1 30 10 3 0 75 1 . 11 0 90 5 0 0 75 1 .28 0 60 3 a 0 63 1 . 18 2 1 4 1 00 9 8 0 80 1 . 1 1 0 50 3 8 0 66 1 .28 0 50 3 2 0 65 1 . 18 2 2 1 0 80 9 7 0 75 1 . 1 1 o 40 6 2 0 69 1 .28 0 30 4 5 0 69 1 . 18 2 2 2 1 30 8 3 0 75 1 . 1 1 0 70 6 3 0 66 1 .28 0 70 6 9 0 66 1 . 18 2 2 3 1 00 10 2 0 76 1 . 1 1 0 60 7 2 0 70 1 .28 0 60 6 9 0 65 1 . 18 2 2 4 0 70 9 8 0 75 1 . 11 0 60 7 0 0 67 1 .28 0 60 6 9 0 64 1 . 18 2 3 1 0 7 12 50 0 75 1 . 11 0 40 8 5 0 66 1 .28 0 70 1 1 4 0 66 1 . 18 2 3 2 0 6 8 15 0 70 1 . 1 1 0 40 6 8 0 75 1 . 28 0 20 7 0 0 66 1 . 18 2 3 3 0 7 10 20 0 76 1 . 11 0 40 9 0 0 75 1 . 28 0 20 7 5 0 65 1 . 18 2 3 4 0 8 1 1 65 0 76 1 . 1 1 0 40 9 9 0 70 1 . 28 0 30 6 2 0 70 1 . 18 2 4 1 0 8 10 75 0 74 1 . 1 1 1 OO 7 2 0 68 1 . 28 0 80 9 . 4 0 7 1 1 . 18 2 4 2 2 1 12 75 0 74 1 . 1 1 1 40 8 9 0 72 1 . 28 0 30 6 8 0 71 1 . 18 2 4 3 0 5 10 50 0 76 1 . 1 1 0 30 8 3 0 66 1 . 28 0 60 10 0 0 64 1 . 18 2 4 4 0 8 10 65 0 76 1 . 11 1 00 9 0 0 67 1 .28 0 20 1 1 0 0 '66 1 . 18 2 5 1 0 5 1 1 90 0 78 1 . 11 0 70 10 5 0 71 1 .28 0 20 1 1 3 0 72 1 . 18 2 5 2 0 5 1 1 65 0 77 1 . 1 1 0 50 9 7 0 70 1 . 28 0 20 10 4 0 69 1 . 18 2 5 3 0 6 13 40 0 73 1 . 1 1 1 00 15 2 0 75 1 . 28 0 40 10 3 0 69 1 . 18 2 5 4 0 4 1 1 00 0 71 1 . 1 1 0 40 10 9 0 71 1 .28 0 40 9 8 0 71 1 . 18 Appendix 9 b . R e p l i c a t e d S o i l d a ta. f e r t i l i z e r response t r i a l : s i d e d r e s s . 141 AB c D E F G H 1 < J K L M N 0 i 1 1 1 .8 3 .0 0 .79 1 .03 1 .6 1 . 3 0 .71 1 .46 1 .6 1 .0 0 .67 1 .22 1 1 2 1 . 5 8 . 5 0 .80 1 .03 1 . 3 1 .8 0 . 75 1 .46 1 .6 1 . 7 0 .71 1 . 22 1 1 3 1 .5 14 .0 0 .80 1 .03 1 . 2 3 .7 0 . 77 1 .46 1 .4 2 .2 0 .71 1 .22 1 1 411 .0 8 .0 0 .80 1 .03 2 .4 1 .8 0 .73 1 .46 4 .6 1 .8 0 .68 1 .22 1 2 1 1 .8 6 .5 0 .80 1 .03 1 .4 1 .8 0. . 78 1 . 46 1 . 4 2 . 3 0 .69 1 .22 1 2 2 2 .5 8 .0 0 .79 1 .03 1 . 2 2 . 1 0 .72 1 .46 2 . 7 1 .6 0 .66 1 . 22 1 2 3 2 . 4 13 .0 0 . 79 1 .03 1 .0 2 . 4 0 .73 1 .46 2 .0 3 . 3 0 .69 1 .22 1 2 4 2 .0 22 .5 0 .81 1 .03 1 .4 2 . 9 0. . 75 1 .46 1 .2 3 .0 0 .71 1 . 22 1 3 1 2 .8 6 .0 0 . 78 1 .03 2 . 1 1 .8 0 . 72 1 .46 3 .0 1 .5 0 .68 1 .22 1 3 210 . 4 1 1 .0 0 .79 1 .03 1 .6 2 .3 0, .72 1 .46 2 .0 2 .7 0 .65 1 .22 1 3 3 2 .4 8 .0 0 .80 1 .03 2 .0 2 . 2 0. . 72 1 .46 2 . 2 2 . 1 0 .69 1 .22 1 3 4 2 . 5 18 .0 0 .80 1 .03 1 .6 2 .5 0. .72 1 .46 3 .3 2 .3 0 .67 1 .22 1 4 1 1 .8 7 .0 0 .80 1 .03 1 .2 1 .8 0. .74 1 .46 0 .9 1 .9 0 .69 1 .22 1 4 2 1 .8 8 .5 0 .79 1 .03 1 .5 2 .4 0 .73 1 .46 1 .4 3 .4 0 .68 1 .22 1 4 3 2 .0 8 .0 0 .81 1 .03 1 . 1 2. . 5 0, . 76 1 .46 1 . 3 2 . 7 0 .70 1 . 22 1 4 4 1 .6 9 .0 0 .79 1 .03 1 .6 2 .7 0. .73 1 .46 1 .4 2 . 1 0 .68 1 . 22 1 5 1 2 . 1 9 .0 0 . 79 1 .03 0 . 7 1 .7 0. .73 1 .46 1 .9 1 .8 0 .69 1 .22 1 5 2 3 .0 8 .0 0 . 78 1 .03 1 .3 1 . .5 0. .70 1 .46 2 . 1 1 .8 0 .66 1 .22 1 5 3 3 .5 15 .0 0 .80 1 .03 1 .5 3. .4 0. .75 1 .46 2 .2 2 .2 0 .68 1 .22 1 5 4 2 .4 15 .0 O .80 1 .03 0 .8 3 . 7 0. . 74 1 .46 1 . 1 2 .3 0 .68 1 .22 2 1 1 1 .0 1 .9 0 . 77 1 . 13 2 .0 2. .9 0. .70 1 .28 0 .8 1 .8 0 .65 1 . 18 2 1 2 2 .3 2 .3 0 .79 1 . 13 1 .0 4. .4 0. ,82 1 .28 1 .0 2 .9 0 .85 1 . 18 2 1 3 1 .2 6 .8 0 .75 1 . 13 0 .9 2. . 5 0. .68 1 .28 0 .8 1 .3 0 .65 1 . 18 2 1 4 1 .0 2 .8 0 .75 1 . 13 1 .5 7 , 5 0. .67 1 .28 1 .5 2 .5 0 .63 1 . 18 2 2 1 0 .8 4 . 4 0 .77 1 . 13 1 . 2 4 . 9 0. ,71 1 .28 0 . 5 1 . 5 0 .68 1 . 18 2 2 2 0 .9 5 .0 0 .77 1 . 13 0 .8 6. .3 0. .69 1 .28 0 .8 2 .2 0 .68 1 . 18 2 2 3 0 . 6 1 .4 0 . 75 1 . 13 1 . 1 3. . 5 0. ,71 1 . 28 0 .8 1 .5 0 .63 1 . 18 2 2 4 1 .3 3 . 4 0 .75 1 . 13 1 . 1 5 . 9 0. ,69 1 .28 1 .0 2 .8 0 .63 1 . 18 2 3 1 0 . 7 1 .9 0, . 76 1 . 13 0 . 7 4 . 5 0. ,67 1 .28 0 .5 3 . 3 0 .66 1 . 18 2 3 2 1 .0 2 .4 0. . 77 1 . 13 0 . 7 4. 8 0. 71 1 .28 0 . 5 1 . 3 0 .68 1 . 18 2 3 3 0 . 7 1 .5 0 . 77 1 . 13 0 .8 5 . 0 0. .69 1 .28 0 . 4 3 .6 0 .65 1 . 18 2 3 4 1 . 2 2 . 8 0, . 77 1 . 13 0 .9 4. 9 0. .70 1 .28 0 .6 1 . 1 0 .66 1 . 18 2 4 1 2 . 2 1 . 3 0 .78 1 . 13 0 .6 4. 6 0. 69 1 .28 2 .8 2 . 1 0 . 72 1 . 18 2 4 2 3 . 2 4 .8 0 .78 1 . 13 0 .8 6. .4 0. .70 1 .28 0 .6 4 . 3 0 .72 1 . 18 2 4 3 1 .7 4 . 5 0. . 73 1 . 13 0 .8 6 . 3 0. .66 1 .28 0 .4 3 .3 0 .63 1 . 18 2 4 4 1 . 2 5 . 5 0, . 78 1 . 13 1 . 3 8 . 4 0. 68 1 .28 0 .5 5 .2 0 .65 1 . 18 2 5 1 1 . 4 3 .8 0. . 78 1 . 13 1 .9 6. .4 0. .71 1 .28 3 .5 4 .9 0 .72 1 . 18 2 5 2 0 .9 2 . 3 0. . 78 1 . 13 1 .0 5 . 8 0. .73 1 .28 0 .6 3 .8 0 .73 1 . 18 2 5 3 2 . 1 4 . 8 0. . 78 1 . 13 0 .8 7. ,9 0. 73 1 .28 1 .4 8 .9 0 .70 1 . 18 2 5 4 1 .3 2 .5 0. .79 1 . 13 0 . 7 7 . 8 0. 71 1 . 28 0 . 7 8 .5 0 .70 1 . 18 Appendix 9c. R e p l i c a t e d f e r t i l i z e r response t r i a l : S o i l d a t a , h a r v e s t . AB CD E F 1 1 1 24 18 23 1 1 2 22 15 27 1 1 3 29 15 21 i 1 4 26 19 20 1 2 1 24 19 24 1 2 2 27 18 29 1 2 3 27 20 27 1 2 4 28 17 25 1 3 1 28 18 28 1 3 2 25 19 26 1 3 3 25 20 32 1 3 4 24 19 29 1 4 1 30 19 31 1 4 2 24 18 25 1 4 3 27 19 30 1 4 4 28 19 29 1 5 1 28 21 36 1 5 2 34 20 33 1 5 3 34 19 36 1 5 4 26 16 27 2 1 1 19 22 22 2 1 2 20 22 20 2 1 3 22 25 24 2 1 4 21 27 15 2 2 1 25 19 30 2 2 2 26 22 34 2 2 3 26 16 23 2 2 4 26 22 37 2 3 1 28 19 40 2 3 2 25 18 33 2 3 3 23 18 33 2 3 4 26 18 35 2 4 1 28 22 33 2 4 2 30 17 34 2 4 3 30 21 38 2 4 4 27 17 36 2 5 1 25 21 41 2 5 2 25 18 26 2 5 3 21 18 34 2 5 4 24 19 26 G H 1 35 .41 7 . 37 0. 17 32 .07 6 . 29 0. 17 36 . 59 7 . 56 0. 18 42 .59 8 .61 0. 17 39 . 27 8 . 10 0. 17 37 .61 7 .49 0. 17 37 .61 8 . 17 0. 17 36 .59 7 .49 0. 17 40 .93 9 .34 0. 19 35 .95 7 . 54 0. 18 40 .24 7 .95 0. 18 38 . 73 9 .83 0. 20 40 .93 8. .78 0. 19 35 . 4 1 7 . 24 0. 17 36 . 59 7 .95 0. 18 38 . 17 7 . 10 0. 16 40. .93 8. .51 0. 18 39 .83 8 .37 0. 18 36, .59 8 . 15 0. 19 34 .85 6 .83 0. 16 36 .54 6 .21 0. 17 37, .65 6. .02 0. 16 37, ,65 6. .02 0. 16 32. .67 5 , . 55 0. 17 27 . 68 4 , .98 0. 18 35 . 99 5 . 76 0. 16 26. .58 4 , .25 0. 16 35 . 43 5. .31 0. 15 34 . 33 4, ,46 0. 13 29 . ,90 4. . 78 0. 16 32, . 1 1 5 . 14 0. 16 29. .90 5 , .08 0. 17 29. ,90 4. , 19 0. 14 24 . 36 3 . , 90 o. 16 36 . 00 6 . , 12 0. 17 32. , 1 1 5 . 14 o . 16 34 . 33 5 . 84 0. 17 28 . , 24 4 . 80 0. 17 33 . 22 5 . ,32 0. 16 32 . 1 1 5. ,46 o. 17 J K L 0 .748 23 . 24 6 .34 o .917 20 . 76 4 . 98 1 . 358 26 .00 5 .98 1 .223 23 .78 6 . 15 1 .273 21 . 29 5 .61 1 . 256 26 .00 6 .54 1, . 173 23 .24 5 .56 1, .092 26 .00 6 .63 0, .972 24 .07 6 .29 1 . 184 21 .29 5 .37 1 .082 23 .78 5 .93 1, . 268 22 .68 5 .98 0, .970 24 .07 6 .63 1, .205 21 , . 29 6 . 00 0, . 723 22 .95 5. .93 1, . 121 23 .78 5, .93 1, ,015 25, .80 6. .95 1, . 186 26 .83 6, .83 1. .200 27 .93 6 .27 1, . 188 23 .78 6 .20 0. .715 21 .87 5, .25 0. .780 21 , . 32 5, . 12 0. .764 24, . 36 5, .60 0. .918 22 .98 5 , .28 0. .691 24, .91 5, .23 0. . 94 1 27 .41 6, .03 0, .975 26, .58 5, .58 1. .062 30, .73 6, .45 0. .898 29. .90 6 .88 0. ,874 26 . 02 5 , . 72 1. .096 27 .41 6, .85 1, , 153 26 . 58 6. . 1 1 0. ,903 29. .07 5, .81 1. , 142 29. .62 5 . 63 0. ,927 31 . 28 7 . , 19 1. . 189 30 .73 6, .76 1. .276 27 .41 5, .76 1. , 186 25. . 75 5, . 15 1. ,403 25, .75 5, .92 1. , 153 27 , .68 5. ,81 M N 0 0 . 23 1 .051 0 .80 0 .21 1 . 348 0 . 78 0 .22 1 .096 0 .64 0 .22 1 . 183 0 .98 0 . 23 1 .220 0 .89 0 .22 1 .079 1 . 17 0 .20 1 .010 0 .97 0 .22 1 . 140 0 .95 0 .23 1 .342 0 .94 0 .22 1 . 181 0 .71 0 . 25 1 . 397 0 .87 0 . 23 1 . 183 1 .62 0 .23 1 .488 0 .93 0 . 22 0 .451 1 .OO 0 .22 1 . 181 0 .91 0 .21 1 . 136 0 .40 0 .24 1 , .485 0 . 79 0 . 22 1 , .472 0 .69 0 .20 1 , . 304 0, .51 0 .23 1 .325 0 .52 0 .24 1 .221 0 .83 0 .24 1 , . 27 1 0, .69 0 .23 1 , . 286 0, .92 0 .23 1 , . 333 1, .08 0 .21 1 . 182 1, .35 0 . 22 1 .296 1, .29 0 .21 1 .267 1, . 13 0 .21 1 , .411 1, .40 0 .23 1 , . 359 1 .68 0 . 22 1 . 166 1, .06 0 . 25 1 .358 1 .04 0 .23 1 , . 195 1 .30 0 . 20 1 , .298 1, . 18 o . 19 1 , . 380 0, .91 0 . 23 1 , .465 1 .49 o .22 1 .515 1 .48 0 .21 1 , .375 1 .06 0 .20 1 , .543 1, . 16 0 .23 1 , .408 1, .25 0 .21 1 , . 424 1, .01 A = Year (1=1984, 2=1985) B = Block (1-5) _ 1 C = Treatment (1=0, 2=50, 3=100, 4=200 kg ha N) D = Number st a l k s E = Number of cobs F = Number of t i l l e r s _1 G = Stalk weight, fresh (t ha ) H = Stalk weight, dry (t ha > I = Stalk dry matter (proportion) J = Stalk %N _ 1 K = Cob weight, fresh (t ha ) L = Cob weight, dry (t ha ) M = Cob dry matter (proportion) N = Cob %N _ 1 0 = Tops weight, dry (t ha ) Appendix 10. Replicated f e r t i l i z e r response t r i a l : Com data. 143 A B c D E F G H I J K L M N 0 i 1 1 1 . 2 4 . 0 0 78 1 . 27 0 . 6 2 5 o 70 1 46 0 . 5 2 . 0 O 67 1 .05 1 1 2 1 . 1 4 . 0 0 79 1 . 28 0 . 9 3 0 0 76 1 41 0 .8 2 . 5 0 67 1 . 15 1 1 3 0 . 9 3 . 5 0 76 1 .00 0 . 7 3 0 0 71 1 46 0 .6 2 . 5 0 67 1 .05 1 1 4 0 . 7 4 .0 0 77 1 . 10 0 . 7 3 0 0 75 1 41 0 . 7 3 . 0 0 65 1 . 15 1 1 5 1 . 1 5 . 0 0 76 1 . 25 0 . 7 5 0 0 72 1 46 0 .6 4 . 5 0 66 1 .05 1 2 1 1 . 2 4 . 0 0 79 1 . 39 1 . 0 3 0 0 74 1 41 0 . 7 2 . 5 0 69 1 . 15 1 2 2 0 . 9 3 . 5 0 80 1 . 27 0 . 7 3 0 0 75 1 46 0 .8 3 . 0 0 67 1 .05 1 2 3 1 . 2 3 . 0 0 78 1 . 28 0 . 7 3 0 0 75 1 41 0 . 5 2 . 5 0 68 1 . 15 1 2 4 2 . 1 4 .0 0 77 1 .OO 0 . 8 4 0 0 75 1 46 0 . 7 3 . 5 0 67 1 .05 1 2 5 0 . 8 4 .0 0 76 1 . 10 0 . 7 4 0 0 74 1 .41 0 .6 3 . 0 0 66 1 . 15 2 1 1 2 . 0 4 .0 0 74 1 .09 2 . 0 4 0 0 66 1 .25 2 . 0 3 .5 0 64 1 . 18 2 1 2 2 . 0 4 .0 0 74 1 . 14 2 . 0 8 0 0 67 1 .31 2 . 0 10 .5 0 62 1 . 17 2 1 3 2 . 5 4 . 5 0 74 1 .09 2 . 5 8 0 0 68 1 .25 2 . 5 8 . 5 0 69 1 . 18 2 1 4 2 . 5 3 .5 0 71 1 . 14 2 . 5 7 0 0 70 1 .31 2 . 0 7 . 5 0 71 1 . 17 2 1 5 2 . 5 3 . 5 0 63 1 .21 2 . 5 7 5 0 66 1 . 25 2 . 0 10. 5 0 65 1 . 18 2 2 1 2 . 0 4 .5 0 69 1 . 18 2 . 0 4 0 0 64 1 .31 2 . 0 3 . 5 0 64 1 . 17 2 2 2 3 . 0 6 .5 0 74 1 .09 2 . 5 6 0 0 67 1 . 25 2 . 0 6 . 0 0 63 1 . 18 2 2 3 3 . 0 6 .5 0 68 1 . 14 2 . 0 9 0 0 67 1 .31 2 . 0 9 . 5 0 62 1 . 17 2 2 4 2 . 5 3 .5 0 75 1 .09 3 . 0 6 0 0 68 1 . 25 2 . 5 8 . 0 0 69 1 . 18 2 2 5 1 .0 4 . 5 0 75 1 . 14 0 . 5 8 0 0 70 1 .31 0 .5 10 .5 0 70 1 . 17 A = Year (1=1984, 2=1985) B = Block (1-5) C = Treatment (1=0, 2=50, 3=100, 4=200 kg ha N j D-G H - K L - O Depth 1 Depth 2 Depth 3 D, H , L E, I, M F, J , N G, K , C (0-20cm) (20-50cm) (50-80cm) -1 g g_,j moist s o i l ) moist s o i l ) g g = N H - N = N O ^ - N = Dry s o i l as a proportion of moist s o i l = Bulk density (g cm ) Appendix 11a. Preplant versus sidedress urea t r i a l : S o i l data, preplant. 144 AB c D E F G H I J K L M N 0 1 1 1 3.7 11 2 0 80 1 .60 1 2 7 4 0 74 1 . 46 1 .6 05 5 0 68 1 .05 1 1 2 1 . 5 15 0 0 80 1 .46 1 0 5 2 0 73 1 .41 1 .0 3 8 0 68 1 . 15 1 1 3 2.4 16 4 0 79 1 .23 1 4 7 5 0 74 1 .46 1 . 2 5 2 0 67 1 .05 1 1 4 1 .5 16 1 0 80 1 .32 0 8 5 2 0 74 1 .41 1 .0 4 8 0 67 1 . 15 1 1 5 2.9 24 8 O 79 1 .29 1 0 8 6 0 73 1 .46 0.8 4 9 0 66 1 .05 1 2 1 1 . 5 8 0 0 .81 1 . 37 1 0 5 0 0 76 1 .41 1 . 5 4 4 0 71 1 . 15 1 2 2 1 . 3 8 4 0 .80 1 .45 1 1 5 0 0 73 1 .46 1 .0 4 2 0 66 1 .05 1 2 3 1 . 1 10 8 0 .80 1 .46 1 1 5 9 0 74 1 .41 1 . 1 4 5 0 68 1 . 15 1 2 4 1 .4 1 1 8 0 .80 1 . 23 1 1 6 0 0 71 1 .46 0.7 5 0 0 67 1 .05 1 2 5 1 .0 12 0 0 .80 1 . 32 0 7 6 0 0 72 1 .41 1 . 2 5 0 0 66 1 . 15 2 1 1 2.5 21 0 0 .72 1 . 10 0 5 7 0 0 64 1 .25 3.0 10 0 0 62 1 . 18 2 1 2 0.5 10 5 0 .73 1 . 14 2 0 12 5 0 66 1 .31 1 .5 8 0 0 63 1 . 17 2 1 3 7.5 25 0 0 .72 1 . 18 0 5 1 1 0 0 68 1 .25 2.0 8 5 0 67 1 . 18 2 1 4 6.0 20 0 0 .71 1 . 18 1 5 1 1 0 0 68 1 .31 2.0 14 0 0 74 1 . 17 2 1 5 6.0 25 0 0 .71 1 .04 1 0 10 5 0 65 1 .25 0.5 1 1 0 0 65 1 . 18 2 2 1 1 .5 1 1 5 0 .71 1 .00 0 5 5 0 0 65 1 .25 1 .0 3 0 0 66 1 . 18 2 2 2 0.5 18 5 0 .71 1 . 10 1 0 8 5 0 64 1 .31 1 .5 8 0 0 65 1 . 17 2 2 3 1 .0 15 0 0 .70 1 . 14 0 5 10 .5 0 65 1 .25 1 .0 10 0 0 .62 1 . 18 2 2 4 3.0 15 . 0 0 72 1 18 1 . 0 10 0 0. 68 1 31 1 .0 9. 5 0 69 1 17 2 2 5 0.5 1 1 . 5 0 73 1 18 0. 0 9 5 0. 70 1 25 0.0 10. 5 0 72 1 18 Appendix 11b. Preplant versus sidedress urea t r i a l : S o i l data, sidedress. 145 AB c D E F G H 1 J K L M N 0 1 1 1 2.0 30 0 0 81 1 .25 1 4 2 6 0 75 1 .46 4.0 2 9 0 68 1 .22 1 1 2 3 . 5 33 0 0 .81 1 . 25 1 0 2 4 0 74 1 . 46 2.0 2 9 0 69 1 . 22 1 1 3 3.8 18 0 0 . 78 1 . 25 2 7 2 7 0 72 1 .46 3.5 1 9 0 67 1 .22 1 1 4 2.4 21 0 0 .81 1 . 25 1 7 3 7 0 76 1 . 46 1 . 5 3 9 0 68 1 .22 1 1 5 2.0 20 0 0 . 79 1 . 25 2 9 4 5 0 71 1 . 46 1 . 2 2 1 0 65 1 .22 1 2 1 2.0 1 1 5 0 .80 1 . 25 1 2 1 7 0 74 1 .46 1 .9 1 4 0 70 1 . 22 1 2 2 1 . G 3 0 0 . 76 1 .25 1 7 2 8 0 76 1 .46 1 .7 2 4 0 68 1 . 22 1 2 3 5.6 16 0 0 .81 1 .25 4 5 3 5 0 74 1 .46 2 . 2 2 6 0 68 1 .22 1 2 4 2 . 5 15 0 0 .80 1 .25 1 3 4 3 0 84 1 .46 1 .5 3 7 0 70 1 . 22 1 2 5 2 . 9 12 0 0 78 1 . 25 2 7 2 4 0 71 1 . 46 1 .9 1 1 0 66 1 .22 2 1 1 1 . 5 5 5 . 75 1 . 13 2 0 2 0 66 1 . 28 1 . 5 1 0 62 1 . 18 2 1 2 3.0 21 5 .73 1 . 13 1 5 7 5 68 1 . 28 2.0 7 0 63 1 . 18 2 1 3 2.0 10 5 77 1 . 13 1 5 8 0 71 1 . 28 1 .0 3 5 67 1 . 18 2 1 4 3 . 5 8 5 .79 1 . 13 1 0 7 5 71 1 . 28 1 .0 6 0 72 1 . 18 2 1 5 7.0 29 0 79 1 . 13 3 0 1 1 5 70 1 . 28 1 .0 5 0 62 1 . 18 2 2 1 2.0 4 5 75 1 . 13 2 0 2 5 66 1 . 28 1 .0 1 0 64 1 . 18 2 2 2 1 .0 9 0 73 1 . 13 2 5 5 5 68 1 . 28 1 .5 3 0 65 1 . 18 2 2 3 1 .0 3 5 72 1 . 13 5 4 0 69 1 . 28 1 .0 2 5 64 1 . 18 2 2 4 2 . 5 7 5 .77 1 . 13 1 0 8 0 71 1 . 28 1 . 5 3 0 68 1 . 18 2 2 5 3.0 15 5 .79 1 . 13 1 0 8 5 72 1 . 28 1.0 5 5 72 1 . 18 Appendix 11c. P r e p l a n t versus s i d e d r e s s urea t r i a l : S o i l data, h a r v e s t . 146 AB c D E F G H I J K L M N 0 1 1 1 32 19 20 30 93 5 .41 0 18 1 016 29 32 5 . 57 0 19 0 . 59 0. 78 1 1 2 18 18 23 33 73 5 . 73 0 17 1 087 21 85 4 .81 0 22 1 .22 0. 56 1 1 3 27 19 28 38 73 6 .97 0 18 0 967 24 90 5 . 23 0 21 1 .22 0.80 1 1 4 29 20 29 35 95 6 .83 0 19 1 1 18 22 68 4 .76 0 21 0 .95 0.44 1 1 5 33 19 34 44 24 7 . 52 0 17 0 961 27 39 6 .03 0 22 1 .40 0. 85 1 2 1 26 13 27 34 24 6 . 16 0 18 1 105 26 56 5 .31 0 20 1 . 10 0. 73 1 2 2 25 13 21 34 29 5 .83 0 17 1 141 21 93 4 .60 0 21 1 .31 0. 39 1 2 3 23 20 34 37 61 6 . 77 0 18 0 905 22 41 4 .71 0 21 0 .94 0.49 1 2 4 29 18 26 34 29 6 . 17 0 18 1 266 23 78 4 . 76 0 20 1 . 19 0.46 1 2 5 30 21 36 43 71 6 .99 0 16 1 315 25 73 5 .92 0 23 1 . 30 0.56 2 1 1 22 21 22 30 42 4 .87 0 16 0 679 23 23 5 . 1 1 0 22 1 . 25 1 .05 2 1 2 26 21 29 28 76 4 .89 0 17 1 054 25 45 5 .60 0 22 1 .49 0.74 2 1 3 28 18 36 27 1 1 4 .61 0 17 0 985 26 83 6 . 17 0 23 1 . 39 0.77 2 1 4 28 21 39 37 62 5 .64 0 15 1 001 30 15 6 .63 0 22 1 . 36 1.13 2 1 5 20 17 28 22 13 3 .76 0 17 1 109 23 51 4 .70 0 20 1 . 33 0.79 2 2 1 22 20 20 28 21 4 .80 0 17 0 817 22 68 4 . 76 0 21 1 .22 0. 89 2 2 2 30 22 41 34 30 6 . 17 0. 18 1 021 30 70 7 .06 0 23 1 .30 0.92 2 2 3 25 21 36 30 42 4 .56 0 15 1 058 27 66 6 . 36 0 23 1 . 46 1 .01 2 2 4 25 19 26 24 34 3 .41 0. 14 1 031 30 15 6 .63 0 22 1 .27 1 .01 2 2 5 28 19 26 28 21 4 .80 0 17 1 086 29 59 6 .21 0 21 1 .29 0. 76 A = Year (1=1984, 2=1985) B = Treatment (1=Preplant, 2=sidedress) C = Block (1-5) D = Number stal k s E = Number of cobs F = Number of t i l l e r s _ 1 G = Stalk weight, fresh (t ha ) H = Stalk weight, dry (t ha ) I = Stalk dry matter (proportion) J = Stalk %N _ n K = Cob weight, fresh (t ha ) L = Cob weight, dry (t ha ) M = Cob dry matter (proportion) N = Cob %N _., O = Tops weight, dry (t ha ) Appendix 12. Preplant versus sidedress urea t r i a l : Corn data. YR S I T E 0M1 0M2 0M3 SON) SONS S 0 N 3 PHH201 P H H 2 0 2 P H H 2 0 3 SA1 SA2 S A 3 SI 1 SI2 S I 3 C l . 1 CL2 CL3 1 1 2 3 2 5 3 4 . 3 . 1 . 1 4 9 3 9 3 5 0 0 4 0 76 0 73 0 76 0 24 0 27 0 20 0 1 2 2 3 2 0 1 8 .2 . 1 . 1 4 5 3 7 1 O 4 2 0 6 O 2 0 69 0 72 0 80 O 29 0 22 0 18 0 1 3 2 2 4 1 1 5 . 3 . 2 . 1 4 8 4 4 4 2 O 4 O 4 0 68 O 70 0 74 0 32 0 26 0 22 0 1 4 3 0 1 9 4 1 .2 . 1 . 1 5 2 4 5 3 4 2 0 0 0 70 O 75 0 76 0 28 0 25 0 24 0 1 5 3 7 4 4 3 6 .2 . 1 . 1 4 3 3 8 3 5 0 14 0 32 0 63 0 7 1 0 57 0 37 0 15 0 1 1 0 1 6 4 4 3 8 3 6 . 3 . 1 . 1 4 9 5 3 5 3 9 0 8 0 14 0 65 0 68 0 69 0 26 0 24 0 17 0 1 7 3 6 3 G 4 6 . 3 . 1 . 1 5 6 5 7 5 5 6 0 14 0 17 0 72 O 70 0 67 0 22 0 16 0 1G 0 1 8 3 8 4 0 4 2 . 4 . 3 . 2 5 0 4 5 4 1 12 0 8 0 26 0 60 0 67 0 60 0 28 0 25 0 14 0 1 9 4 7 3 8 3 6 . 4 . 3 .2 4 8 4 0 4 2 1 1 0 6 0 35 0 59 0 67 0 55 0 30 0 27 0 10 0 1 10 3 6 3 7 4 2 .4 . 3 . 3 4 7 4 0 3 6 12 0 6 0 9 0 61 O 69 0 73 0 27 0 25 0 18 O 1 11 4 4 1 6 1 5 .4 . 3 . 3 4 7 4 5 4 3 8 0 14 0 17 0 65 0 72 0 70 0 27 0 14 0 13 0 1 12 7 4 2 2 1 7 .5 . 3 . 3 4 4 4 3 4 5 6 O 3 0 6 O 64 O 69 O 77 0 30 0 28 0 17 0 1 13 3 9 3 0 1 8 . 4 . 3 . 1 4 3 3 8 3 5 6 0 4 0 6 O 74 0 75 0 76 0 20 0 2 1 0 18 0 1 14 3 2 3 2 2 6 . 1 . 1 . 1 4 1 3 6 3 2 8 0 6 0 15 O 73 0 74 0 69 0 19 0 20 0 16 0 1 15 3 6 8 7 . 2 . 0 . 2 5 2 6 6 6 6 9 0 6 0 26 0 7 1 0 78 0 60 0 20 0 16 0 14 0 1 16 9 5 1 7 1 7 . 4 . 2 .2 5 6 4 1 3 9 8 0 3 0 10 0 72 O 8 1 0 77 0 20 0 16 0 13 0 1 17 2 4 1 9 1 9 .2 . 2 . 2 5 0 4 3 3 8 5 0 6 0 13 0 75 0 76 0 74 0 20 0 18 0 13 0 2 1 4 4 1 8 1 5 . 2 . 1 . 1 6 1 5 8 5 2 4 0 9 0 9 O 7 1 0 74 0 7 1 0 25 0 20 0 20 0 2 2 7 0 3 3 2 3 . 3 . | . 1 5 0 5 8 5 8 4 O 2 0 4 0 70 0 72 O 72 0 26 0 26 0 24 0 2 3 16 0 1 8 1 9 . 7 . 1 . 1 6 4 6 4 5 9 36 0 6 0 14 0 49 0 72 0 68 0 15 0 22 0 18 0 2 4 3 4 2 3 3 0 . 1 . 1 . 1 5 8 6 2 4 8 5 0 2 0 5 0 73 0 72 0 7 1 0 22 0 26 0 24 0 2 5 7 8 3 6 2 8 . 2 . 1 . 1 6 9 5 8 4 4 6 0 3 0 8 0 68 0 72 0 70 0 26 0 25 0 22 0 2 6 6 8 1 6 1 0 . 3 . l .0 5 8 6 7 5 9 10 0 14 0 18 0 66 0 62 0 62 0 24 0 20 0 20 0 2 7 5 4 2 0 1 8 . 2 . 1 . 0 6 0 5 0 4 5 8 0 10 0 17 0 70 0 72 0 70 0 22 0 18 0 13 0 2 8 5 1 2 8 2 5 . 2 . 1 . 1 6 0 6 5 5 9 12 0 2 0 2 0 58 0 67 0 7 1 0 30 0 31 0 27 0 2 9 4 0 3 1 2 5 . 2 . 1 . 1 6 1 5 1 4 2 2 0 0 IO 0 64 0 70 0 70 0 34 0 30 0 20 0 2 10 3 8 2 1 2 6 . 2 . 1 . 1 4 8 4 6 4 3 1 0 6 0 4 0 69 0 73 0 72 0 30 0 2 1 0 24 0 2 1 1 4 1 2 2 2 0 . 2 • 1 .1 5 8 5 8 5 4 2 0 5 0 0 62 o 7 1 o 74 0 36 0 24 o 26 0 YR = Year (1=1984, 2=1985) 1 = Depth 1 (0-20cm) 2 = Depth 2 (20-50cm) 3 = Depth 3 (50-80cm) OM = Organic matter (%) SON = Total s o i l N (%) P H = P H ( H 2 0 ) SA = Sand t%) SI = S i l t (%) CL = Clay (%) Appendix 13a. Multifarm t r i a l : S i t e properties. YR SITE NA 1 MA 2 NA3 , 1 .05 02 .00 1 2 . 88 90 1.13 1 3 .05 29 . 56 1 4 . 27 2 2 .09 1 5 .01 OO .00 1 6 .00 14 .84 1 7 2 . 66 4 97 7.17 1 8 .00 05 .05 1 9 .OO 15 .54 1 10 .00 00 .01 1 1 1 .00 00 .00 1 12 .00 00 .02 1 13 .03 36 . 13 1 14 .00 23 .01 1 15 . 49 2 45 3.15 1 16 4 . 28 5 35 6 . 43 1 17 .00 00 .00 2 1 . 16 16 .2 1 2 2 . 17 33 . 93 2 3 .21 37 . 46 2 4 .21 . 20 .40 2 5 . 44 1 34 3.76 2 e . 33 1 14 2 . 79 2 7 1 .94 2 92 4 . 65 2 8 . 17 1 1 . 10 2 9 . 26 17 . 17 2 10 . 20 1 02 .42 2 1 1 .06 10 . 12 CA TS 1 CATS2 CATS3 XNAI 8 40 1 28 73 6 7 84 2 79 3 1 1 1 1 2 7 3 1 2 50 3 13 7 8 05 3 28 1 82 3 3 4 25' 1 40 1 63 3 8 12 7 95 5 94 0 1 1 39 1 1 62 13 63 23 4 6 98 4 22 2 34 1 5 85 2 07 3 54 0 5 75 1 49 96 0 5 14 3 57 3 72 o 5 19 4 22 4 50 0 5 1 1 2 56 1 23 5 5 48 1 58 1 02 0 9 7 1 10 38 8 65 5 1 17 97 10 16 1 1 03 23 8 6 37 3 37 1 19 0 9 17 6 40 4 27 1 8 3 93 5 56 5 76 4 4 15 54 7 19 6 43 1 4 7 39 6 55 2 74 2 8 16 89 9 95 6 68 2 6 8 96 8 96 8 44 3 6 10 06 6 76 7 88 19 3 10 4 1 8 15 5 90 1 6 8 69 3 7 1 1 08 3 0 3 79 3 37 2 05 5 4 7 33 4 92 4 43 8 XNA 2 XNA3 SAR 1 SAR2 1 4 0 .024 .023 32 4 36 2 . 485 .980 1 1 7 17 9 .029 . 296 6 8 4 8 . 138 . 184 0 0 .009 .OOO 1 8 14 1 .000 .075 42 8 52 6 1 . 320 2 . 833 1 2 2 0 .002 .030 7 4 15 2 .000 . 163 0 1 4 .000 .000 0 1 .000 .000 1 5 .000 .003 14 1 10 6 .017 . 365 14 3 8 .000 .291 23 6 36 4 . 234 1 . 252 52 7 58 3 1 .686 3 .627 0 0 .000 .000 2 5 4 9 .079 .093 5 9 6 2 . 1 38 . 209 5 1 7 1 .088 .241 3 1 14 7 .114 .115 13 5 56 3 . 157 .656 12 7 33 0 . 160 .581 43 2 59 0 .990 2 . 200 1 3 1 6 .07 7 .057 4 6 16 1 . 129 .13 1 30 4 20 6 . 163 . 999 2 0 2 7 .033 .066 SAR3 S04S1 S04S2 S04S3 000 14 6 22 3 77 9 2 120 1 16 5 150 2 188 4 528 24 7 32 6 47 3 097 10 3 17 4 36 4 000 59 9 89 8 190 O 547 16 6 12 8 13 0 4 156 94 4 146 3 236 5 048 18 8 15 7 39 2 457 14 3 33 6 49 1 02 1 21 7 33 9 98 1 003 15 3 15 6 2 1 7 015 14 1 12 4 14 2 19 1 18 9 45 2 7 5 4 013 31 3 60 9 192 2 1 946 19 2 25 8 54 7 4 4 14 136 6 17 1 5 202 4 000 18 1 24 3 58 5 149 34 0 2 1 0 46 0 624 23 O 23 0 30 O 290 57 0 37 0 66 0 395 26 0 19 0 7 1 O 3 236 64 0 92 0 160 0 1 698 32 0 30 0 198 0 3 838 1 1 1 0 14 1 0 340 0 06O 26 0 20 0 38 O 272 32 0 46 0 84 O 504 61 0 177 0 13 1 0 082 33 0 30 0 39 0 YR = Year (1=1984, 2=1985) 1 = Depth 1 (0-20cm) 2 = Depth 2 (20-50cm) 3 = Depth 3 (50-80cm) NA = Na (me 100ml ) _ 1 CATS = Total cations (me 100ml ) XNA = Exchangeable sodium (%) SAR = Sodium Adsorption Ratio SO.-S = Sulphates ( g mL ) 4 Appendix 13b. Multifarm t r i a l : S i t e properties. 03 5 SITE EC 1 EC2 EC3 P1 P2 P3 K 1 K2 K3 MG 1 MG2 MG3 CA 1 CA2 CA3 , 1 . 32 .40 .60 56 00 14 00 14 00 . 33 . 10 . 12 2 53 . 55 . 38 5 48 .61 . 23 1 2 1 . 32 1 . 48 2.20 77 00 13 00 14 OO . 39 . 18 . 23 1 80 91 1 . 10 4 76 .80 .66 1 3 . 48 . 40 .48139 OO 19 00 18 00 . 66 . 27 . 3 1 1 02 7 1 1 24 5 57 1 . 23 1 .02 1 4 . 36 . 28 .36 72 00 11 00 11 00 .40 . 15 . 13 1 82 1 . 24 84 5 57 1 66 .76 1 5 . 56 .68 1.68 70 00 9 00 11 00 .43 . 14 . 16 1 22 67 95 2 60 59 .51 1 6 . 44 . 36 .40 82 00 1 1 00 8 00 .75 .47 . 39 2 28 4 . 39 3 55 5 09 2 95 1 . 16 1 7 1 .40 2 . 40 7.50 89 00 5 00 6 00 .58 .50 .51 3 74 3 84 4 1 1 4 39 2 32 1 .83 1 8 .40 . 24 .32 72 00 31 00 13 00 .75 . 38 . 30 2 44 2 . 17 1 34 3 79 1 .62 .64 1 9 . 40 .56 .88 80 00 10 00 9 00 .56 . 17 .21 81 .60 1 56 4 49 1 15 1 . 24 1 10 .40 . 40 .84161 00 10 00 15 00 .51 . 19 . 15 1 19 . 49 41 4 05 .80 . 38 1 1 1 .40 .32 .36 65 00 8 00 7 00 .58 . 15 . 10 81 1 .00 1 .53 3 75 2 .42 2 .08 1 12 . 48 . 32 .24 32 00 2 00 2 00 .25 .09 .08 91 1 .46 2 . 19 4 02 2 .66 2 . 20 1 13 . 36 . 48 .64 59 00 12 00 1 1 00 .42 . 24 . 17 1 39 . 72 52 3 26 1 .23 .41 1 14 . 48 .60 1.92 97 00 22 00 1 1 00 .51 . 15 . 16 1 28 . 39 .42 3 .68 .82 .44 1 15 .44 . 56 .96 29 00 2 00 4 00 . 36 .25 . 26 4 23 5 .43 3 .83 4 63 2 . 25 1 .41 1 16 5.00 6. 10 9.00113 00 8 00 8 00 .77 .46 . 36 5 67 3 .06 3 . 19 7 25 1 . 29 1 .05 1 17 . 48 . 32 .48144 00 22 00 7 00 .36 . 18 . 12 1 32 .81 .45 4 69 2 .38 .62 2 1 1.12 . 36 .36192 00 49 00 16 00 .64 . 29 . 16 1 18 2 .06 2 .05 7 19 3 .89 1 .85 2 2 .56 . 32 .321 15 00 27 00 12 00 . 58 .37 . 38 1 35 2 . 77 3 .06 1 83 2 . 10 1 . 38 2 3 1 . 32 . 52 .68358 00 27 oo 22 00 3.48 2 . 22 1 .00 5 48 2 .89 3 .41 6 36 1 .71 1 .56 2 4 . 56 .24 .40170 00 62 00 21 00 .44 .31 . 25 1 50 2 .25 1 . 26 5 24 3 .78 .83 2 5 1 .00 1 . 76 5.30131 00 23 00 10 00 . 50 .26 . 22 1 68 1 . 68 1 .50 14 26 6 .67 1 . 20 2 6 . 84 . 36 1.84 30 00 13 00 13 00 .30 . 19 .26 2 92 4 .95 3 .92 5 .41 2 .68 1 .48 2 7 1 . 76 4 .00 6.50119 00 24 00 9 00 .40 .30 . 30 2 2 1 1 .66 1 .95 5 51 1 .87 . 98 2 8 .76 . 32 .40291 001 16 00 61 00 .97 . 76 . 76 1 47 1 .90 2 . 13 7 .80 5 . 38 2 .91 2 9 . 72 . 40 .44 121 00 18 00 14 00 .51 . 18 .09 1 64 1 .OO . 32 6 28 2 . 37 .49 2 10 . 56 .96 .72 97 00 13 00 21 00 .43 . 25 . 23 76 1 . 24 .49 2 .40 .85 .91 2 1 1 .44 .40 .32105 00 22 00 13 00 .52 . 25 . 17 65 .71 .98 6 . 10 3 .87 3 . 16 YR = Year (1=1984, 2=1985) 1 = Depth 1 (0-20cm) 2 = Depth 2 (20-50cm) 3 = Depth 3 (50-80cm) P = P mL ) K = K (me 100mL ) MG = Mg (me 100ml_J) CA = Ca (me 100mL ) Appendix 13c. Multifarm t r i a l : S i t e properties. YR SITE B 1 B2 B3 CU 1 CU2 CU3 FE 1 1 1 59 27 30 5 5 6 8 4 9 123 .O 1 2 84 47 51 9 0 3 7 2 8 354 . 1 1 3 7 1 33 34 9 3 8 7 6 0 34 1 . 5 1 4 55 15 13 7 5 8 9 8 4 142 .6 1 5 39 24 17 1 1 0 6 8 7 5 507 .0 1 6 1 69 1 2 1 72 3 3 6 5 12 3 436.2 1 7 2 47 1 64 1 97 6 7 10 2 8 8 294.5 1 8 2 05 96 64 2 7 9 9 6 6 650.0 1 9 40 35 29 6 3 5 7 2 2 440.5 1 10 3 1 39 42 6 3 3 9 1 8 448.8 1 1 1 1 1 00 00 8 4 8 6 9 0 310.6 1 12 07 00 00 6 3 1 1 3 10 5 337.0 1 13 64 39 55 8 0 7 3. 2 8 650.0 1 14 42 25 28 1 1 6 6 1 2 9 452 . 3 1 15 89 1 26 1 28 4 0 5 7 3 1 463. 1 1 16 2 04 99 1 09 6 4 17 2 9 7 321 .9 1 17 59 32 23 6 8 8 7 7 3 160. 2 2 1 58 40 .47 3 7 5 3 7 1 240.0 2 2 1 41 1 34 1 13 2 3 6 0 12 2 371 .3 2 3 1 89 .84 .96 3 6 6 0 12 9 338 . 1 2 4 1 14 1 . 19 1 .01 3 9 5 0 8 3 177.4 2 5 58 56 88 3 7 7 4 6 6 155.5 2 6 1 54 1 .64 1 94 1 6 4 8 5 9 500.0 2 7 1 97 1 .21 1 .45 5 0 8 2 4 4 231 .6 2 8 83 .52 .55 4 8 6 9 8 7 206 . 3 2 9 .61 .52 .84 7 0 7 8 6 0 126.2 2 10 1 . 24 .81 .84 7 9 4 7 5 6 312.2 2 1 1 . 43 . 36 48 6 4 6 9 6 9 244 . 4 YR = Year (1=1984. 2= 1 = Depth 1 (0-20cm) 2 = Depth 2 (20-50cm) 3 = Depth 3 (50-80cm) B = B (*/g mL ) CU = Cu (-*/g mL^ ) FE = Fe (^Q mL_ ) MN = Mn (^g mL_ ) ZN = Zn (^g mL ) FE2 F E 3 MN1 MN2 MN3 ZN1 ZN2 ZN3 297 8 301 8 22 1 1 6 2 5 1 2 5 6 315 4 315 2 9 7 3 1 3 9 1 3 5 9 374 5 334 0 4 1 1 9 2 5 9 5 6 163 6 282 6 38 2 3 8 4 6 1 3 1 3 1 0 345 5 335 7 1 1 0 2 3 2 9 1 3 7 3 0 163 5 209 0 2 4 1 3 2 5 1 6 8 1 2 69 1 155 3 2 6 1 4 1 1 1 3 1 7 2 0 336 8 324 1 7 2 5 2 4 3 2 3 2 0 1 1 329 7 228 2 2 8 1 6 9 1 2 6 4 465 7 444 1 9 0 1 7 2 1 1 9 5 5 210 0 263 9 5 3 1 7 1 6 8 7 1 1 315 5 309 6 5 6 1 4 1 9 1 0 1 0 1 3 420 4 367 4 6 4 1 6 1 6 1 3 6 4 390 6 402 7 9 3 9 4 6 1 8 5 9 67 7 47 8 3 1 1 1 1 9 1 3 2 2 392 2 494 2 14 7 5 5 5 4 13 9 5 9 4 1 241 7 333 2 17 0 4 8 2 1 1 5 1 1 1 0 133 8 189 2 1 5 8 8 6 6 9 227 6 196 1 3 3 1 3 1 9 1 2 9 1 5 136 7 164 2 7 2 5 8 34 3 8 9 139 6 293 6 7 4 3 9 3 1 1 2 1 1 1 2 267 8 363 7 1 3 1 1 1 1 1 2 8 1 1 193 9 98 0 1 8 8 4 6 1 3 4 1 8 235 3 290 7 1 5 1 3 7 1 4 2 2 1 4 172 0 320 8 20 5 5 7 1 0 4 7 1 4 6 313 0 273 O 18 9 4 3 1 5 1 1 7 4 358 1 329 2 17 5 2 7 5 5 1 4 5 7 215 9 2 18 1 2 7 1 3 9 8 6 7 Appendix 13d. Multifarm t r i a l : S i t e properties ui o YR SITE NH4N1S0 N03N1SO DW1 SO BD1 SO NH4N2S0 N03N2SO DW2SO BD2S0 NH4N3S0 N03N3S0 DW3S0 BD3S0 1 1 2 50 3 70 . 77 1 41 3 60 5 00 . 70 1 09 40 4 00 .63 1 05 1 2 50 2 00 . 75 1 38 1 60 80 .67 1 08 2 00 20 .65 1 03 1 3 4 20 13 30 . 75 1 32 20 4 70 .67 85 3 00 1 70 .65 90 1 4 3 00 2 50 . 78 1 35 80 1 30 . 72 1 29 40 1 30 .67 1 00 1 5 2 60 1 30 . 75 1 52 80 40 . 70 1 48 80 10 .70 1 .20 1 6 1 10 8 60 . 77 1 32 1 70 4 30 . 77 1 29 1 40 3 00 . 74 1 43 1 7 2 50 1 30 . 78 1 34 10 40 . 77 1 42 10 05 .70 1 21 i . 8 2 20 9 80 . 75 1 12 1 00 3 10 . 78 1 35 1 50 40 . 73 1 37 1 9 2 00 8 20 . 73 1 37 1 70 3 80 . 70 1 31 1 10 2 40 .75 1 14 1 10 8 10 1 00 .75 1 20 1 00 20 .68 99 1 00 05 .64 1 04 1 1 1 20 3 40 . 75 1 25 10 1 50 . 74 1 37 30 40 .71 1 24 1 12 1 00 8 00 .72 1 03 1 00 3 20 . 73 1 26 30 1 20 . 70 1 24 1 13 2 40 5 60 . 77 1 25 1 90 4 60 .69 1 29 1 90 3 60 .66 1 02 1 14 1 20 3 40 . 77 1 22 80 1 00 .68 1 14 50 70 .68 1 04 1 15 5 20 1 60 . 77 1 24 90 4 90 . 78 1 34 1 40 5 00 .79 1 45 1 16 1 70 1 60 . 72 1 08 1 50 70 . 74 90 2 80 1 50 .71 1 19 1 17 1 00 1 1 60 . 78 1 30 96 6 02 . 73 1 46 1 02 4 20 .68 1 22 2 1 2 00 13 00 . 80 1 43 1 40 8 80 .81 1 47 20 10 25 .71 1 09 2 2 2 00 14 00 . 79 1 23 70 4 50 .79 1 46 50 3 15 .75 1 53 2 3 3 25 26 00 . 77 1 04 60 5 80 . 80 1 30 60 9 50 .78 1 06 2 4 2 25 1 1 50 . 82 1 48 40 4 90 . 77 1 39 2 00 5 50 .69 1 36 2 5 2 50 9 00 . 78 1 17 40 4 60 . 74 1 41 2 00 3 75 .70 1 24 2 6 2 00 6 00 .82 1 12 60 6 60 . 70 1 51 2 00 6 50 .76 1 40 2 7 7 25 4 00 . 80 1 26 40 1 90 . 77 1 60 2 00 23 . 72 1 4 1 2 8 2 50 9 50 .80 1 30 70 4 20 . 76 1 19 2 00 6 15 .69 1 03 2 9 2 25 9 50 . 79 1 25 80 12 20 . 70 93 2 00 12 75 .69 87 2 10 2 10 12 75 . 76 1 13 1 40 8 90 . 69 1 28 1 50 6 75 .66 1 18 2 1 1 80 8 40 . 76 1 15 85 5 50 . 73 1 35 4 25 3 55 .70 1 31 YR = Year (1=1984. 2=1985) 1 = Depth 1 (0-20cm) 2 = Depth 2 (20-50cm) 3 = Depth 3 (50-80cm) NH4N = NH -N (AKJ g~} ) N03N = NO^-N (<"cj g ) DW = Dry weight (as a proportion of moist) BD = Bulk density (g cm ) Appendix 14a. Multifarm t r i a l : S o i l data from control plots (0) at sidedress (S). ui YR SITE NH4N1S1 N03N1S1 DW1S1 BD1S1 NH4N2S1 N03N2S1 DW2S1 BD2S1 NH4N3S1 N03N3S1 DW3S1 BD3S1 1 1 40 5 00 . 75 1 41 20 5 20 .69 1 09 20 4 10 . 63 1 05 1 2 3 60 1 80 . 74 1 38 80 80 .68 1 08 1 80 20 .65 1 04 1 3 4 20 12 70 . 74 1 32 1 40 5 30 . 67 84 1 40 1 40 . 65 90 1 4 1 80 4 00 .78 1 35 1 60 2 00 .72 1 29 20 1 30 .67 1 00 1 5 1 10 1 40 . 76 1 52 60 90 .73 1 48 1 70 20 .71 1 20 1 6 1 10 10 60 . 76 1 31 40 4 30 . 78 1 29 2 60 2 00 . 76 1 43 1 7 5 00 1 30 .77 1 34 10 10 . 77 1 42 2 20 05 .71 1 21 1 8 3 80 10 60 . 77 1 12 1 80 2 80 .78 1 35 1 00 1 80 .73 1 37 1 9 1 80 11 70 . 73 1 37 1 30 5 10 . 70 1 31 1 40 3 30 .75 1 14 1 10 8 10 2 10 . 75 1 20 1 10 20 .68 99 80 05 .65 1 04 1 1 1 40 3 90 . 75 1 25 30 2 00 . 72 1 37 30 70 . 73 1 24 1 12 30 10 00 . 72 1 03 30 3 40 . 72 1 26 30 1 40 . 69 1 24 1 13 3 60 10 30 . 77 1 25 1 80 5 70 .67 1 29 2 20 3 60 .64 1 02 1 14 2 20 4 90 . 77 1 22 2 10 1 00 .67 1 14 1 40 1 40 .63 1 04 1 15 6 40 2 10 . 75 1 24 1 50 5 80 . 79 1 34 40 5 00 . 78 1 45 1 16 3 00 3 20 . 75 1 08 6 50 3 70 .74 90 70 1 00 .71 1 19 1 17 95 12 30 . 72 1 33 81 5 12 . 73 1 46 65 4 94 .68 1 22 2 1 2 OO 13 00 . 80 1 43 1 40 8 80 .81 1 47 20 10 25 .71 1 09 2 2 20 14 00 . 79 1 23 70 4 50 . 79 1 46 50 3 15 . 75 1 53 2 3 3 25 26 00 . 77 1 04 60 5 86 . 80 1 30 60 9 50 . 78 1 06 2 4 2 25 1 1 50 .82 1 48 40 4 90 . 77 1 39 40 5 50 .69 1 36 2 5 2 50 9 00 .78 1 17 40 4 60 . 74 1 41 40 3 75 . 70 1 24 2 6 2 00 6 00 . 82 1 12 60 1 32 .70 1 51 40 6 50 . 76 1 40 2 7 7 25 4 00 .80 1 26 40 6 90 .77 1 60 40 1 15 . 72 1 41 2 8 2 50 9 50 .80 1 30 70 4 20 .76 1 19 40 6 15 .69 1 03 2 9 2 25 9 50 . 79 1 25 80 12 20 .70 93 40 12 75 .69 87 1 10 2 10 12 75 . 76 1 13 1 40 8 90 .69 1 28 30 6 75 . 66 1 18 2 1 1 50 9 40 .76 1 15 30 5 25 . 73 1 .35 10 4 95 .70 1 31 Appendix 14b. M u l t i f a r m t r i a l : S o i l d a t a from f e r t i l i z e d p l o t s (1) a t s i d e d r e s s ( S ) . ui YR SITE NH4N1H0 N03N1H0 DW1H0 BD1H0 NH4N2H0 N03N2HO DW2H0 BD2H0 NH4N3H0 N03N3HO DW3H0 BD3H0 1 1 1 5 5 0 . 76 1 22 1 0 3 0 .71 1 09 9 2 .0 .72 1 05 1 2 1 9 13 5 . 74 1 17 8 2 0 .68 1 08 8 .9 .68 1 03 1 3 1 5 4 0 .69 1 17 1 1 1 1 .70 85 1 1 1 .O .64 90 1 4 1 1 3 5 .80 1 13 9 5 . 74 1 29 7 . 7 .70 1 00 1 5 1 4 2 0 . 75 1 09 8 3 . 7 1 1 48 6 . 3 .71 1 20 1 6 1 2 5 4 .81 89 2 1 9 .81 1 29 2 1 . 7 .78 1 43 1 7 2 1 3 0 . 73 1 18 1 3 9 . 78 1 42 2 0 1 .0 . 72 1 21 1 8 1 4 6 1 . 77 98 8 1 6 .79 1 35 1 9 1 .6 .76 1 37 1 9 2 5 4 9 . 73 91 1 9 2 2 .70 1 31 2 2 1 .5 .74 1 14 1 10 5 2 3 3 .74 1 00 5 6 1 7 .69 99 5 1 .7 .66 1 04 1 1 1 2 7 1 8 .69 1 03 1 9 7 . 73 1 37 6 .7 .68 1 24 1 12 2 3 5 8 . 70 76 1 4 5 . 72 1 26 1 2 . 2 .69 1 24 1 13 1 0 3 7 . 78 1 01 1 9 1 4 .69 1 29 6 1 .8 .65 1 02 1 14 8 1 8 . 76 1 03 9 7 . 70 1 14 6 .6 .63 1 04 1 15 1 7 3 6 . 76 1 08 1 4 2 7 . 78 1 34 7 2 .0 . 78 1 45 1 16 1 1 6 0 . 72 93 1 9 1 1 . 74 90 6 1 .O . 70 1 19 1 17 2 1 6 5 .79 1 .25 1 4 1 8 .73 1 46 1 8 1 .9 .69 1 22 2 1 5 5 19 5 .81 1 . 43 1 0 9 0 .83 1 47 1 O 9 .5 .78 1 09 2 2 4 5 6 0 .82 1 .23 1 5 5 5 .83 1 46 1 5 3 .0 .78 1 53 2 3 6 5 21 5 . 79 1 06 1 5 2 5 .86 1 30 5 4 . 5 .82 1 06 2 4 4 0 13 0 .81 1 42 1 0 2 5 .82 1 39 1 0 3 .5 . 74 1 36 2 5 4 0 5 5 .75 1 17 5 3 5 .74 1 41 1 5 4 .0 .69 1 24 2 6 4 0 2 0 .70 1 12 1 5 17 0 .80 1 51 1 0 1 .5 .82 1 40 2 7 4 5 6 0 . 76 1 26 5 1 0 . 77 1 60 1 0 1 .0 . 72 1 41 2 8 4 0 15 0 . 78 1 30 5 4 5 . 77 1 19 1 0 5 .5 .70 1 03 2 9 3 5 1 1 5 . 75 1 25 1 0 5 5 .71 93 5 12 .5 .69 87 2 10 1 5 3 0 . 77 1 27 1 0 4 5 .69 1 28 1 5 3 .0 .69 1 18 2 1 1 1 5 2 5 . 76 1 15 1 5 1 5 . 73 1 35 1 5 1 . 5 .71 1 31 Appendix 14c. Multifarm t r i a l : S o i l data from control plots (0) at harvest (H). ui YR SITE NH4N1H1 N03N1H1 DW1H1 BD1H1 NH4N2H1 N03N2H1 DW2H1 BD2H1 NH4N3H1 N03N3H1 DW3H1 BD3H1 1 1 1 5 2 5 .76 1 .22 1 5 3 0 .71 1 09 1 0 2 3 .65 1 05 1 2 3 8 13 5 .75 1 17 9 3 4 6 .70 1 08 8 5 3 9 .67 1 03 1 3 3 8 1 0 . 73 1 17 1 0 1 0 .67 85 1 0 9 .66 90 1 4 3 3 8 0 . 79 1 13 1 0 6 . 76 1 29 2 7 1 0 .68 1 00 1 5 1 3 2 0 .76 1 .09 9 4 .73 1 .48 1 0 4 .71 1 20 1 6 10 5 10 3 . 79 .89 1 3 1 2 .80 1 . 29 7 1 5 . 76 1 43 1 7 2 5 6 3 .77 1 . 18 2 4 1 3 .77 1 42 2 3 1 1 .72 1 21 1 8 2 1 6 7 . 79 98 1 3 1 6 .80 1 35 1 7 5 .76 1 37 1 9 1 9 12 0 .75 91 1 1 3 6 .71 1 31 1 3 1 8 .73 1 14 1 10 1 1 0 7 2 . 76 1 00 1 1 1 7 . 72 99 2 3 2 4 .66 1 04 1 1 1 9 4 0 . 74 1 03 1 3 5 .73 1 37 9 3 . 74 1 24 1 12 12 0 10 2 . 72 1 01 1 6 9 .71 1 26 8 3 . 75 1 24 1 13 10 3 7 2 . 78 1 .03 1 7 2 3 .70 1 29 7 1 8 .63 1 02 1 14 9 2 1 .76 1 .08 8 8 .66 1 14 7 6 .64 1 04 1 15 3 9 10 0 .82 93 7 2 5 . 78 1 34 1 8 2 6 . 78 1 45 1 16 9 4 14 2 . 70 1 25 8 9 . 76 90 7 9 .70 1 19 1 17 3 9 14 5 . 77 1 25 1 6 2 7 . 73 1 46 2 3 2 3 .66 1 22 2 1 7 5 24 5 . 78 1 43 1 0 9 0 . 77 1 47 1 0 12 5 . 70 1 09 2 2 5 5 9 5 . 79 1 23 1 0 4 0 .82 1 46 1 0 9 0 .78 1 53 2 3 5 5 99 8 . 78 1 06 1 5 15 5 .85 1 30 1 5 1 5 .85 1 06 2 4 19 0 23 0 .80 1 .42 1 5 5 5 .80 1 39 5 6 0 . 74 1 36 2 5 10 5 7 0 .75 1 17 1 5 3 5 . 73 1 4 1 1 0 5 0 . 70 1 24 2 6 5 5 5 0 . 76 1 12 2 0 1 5 .83 1 81 1 0 4 0 . 78 1 40 2 7 1 1 0 1 1 5 . 78 1 26 5 1 0 .75 1 60 1 0 1 0 . 72 1 41 2 8 10 0 32 0 . 79 1 30 1 0 4 5 . 78 1 19 1 0 1 0 .70 1 03 2 9 7 5 23 5 . 75 1 25 2 0 8 5 .72 93 2 0 5 5 .67 87 2 10 1 0 3 5 . 77 1 27 1 0 7 0 .69 . 1 28 1 0 4 0 .65 1 18 2 1 1 1 5 2 5 . 76 1 15 1 0 1 0 . 73 1 35 1 0 1 0 . 7 1 1 31 Appendix 14d. Mu l t i f a r m t r i a l : S o i l d a t a from f e r t i l i z e d P l o t s (1) at harv e s t (H). YR SITE 0-20 20-50 50"80 1 1 21 . 97 23 . 36 20. OO 1 2 7 . 36 00 00 1 3 63 .36 22 . 84 4 . 15 1 4 13 . 85 00 .00 1 5 4 .05 00 .00 1 6 37 .71 20. 10 23. . 19 1 7 20 .62 00 00 1 8 47 . 79 20. 77 .00 1 9 4 1 . 29 22 . 45 4 .56 1 10 19 . 20 00 .00 1 11 10 .00 00 .00 1 12 40 .06 15 . .53 .00 1 13 25 .97 56. .09 9 .27 1 14 12 .68 15 . .09 .00 1 15 16 . . 10 30. .92 27 .53 1 16 15 , .00 .00 .00 1 17 43 . 33 30 .00 16 . 15 2 1 143 . .00 92 . 56 78 . 30 2 2 62 . 28 55 . 44 55 .08 2 3 124 . 26 48 . 75 48 .92 2 4 108 . 29 48 . 74 53 . 22 2 5 48 . 00 5 1 .45 37 . 20 2 6 92 . 88 38 . 83 33 . 16 2 7 40. 95 37 .40 35 . 25 2 8 87 . 75 51 .67 49 .26 2 9 85. 44 55 .80 87 .00 2 10 32 . 71 44 . 52 59 .00 2 1 1 30. 26 55 . 48 44 .91 155 0-50 0-80 45 . 33 65 . 33 7 . 36 7 . 36 86 . 20 90 . 35 13 .85 13 .85 4 .05 4 .05 57 .82 81 .01 20 . 62 20 .62 68 . 56 68 .56 63 .74 68 .30 19 .20 19 .20 10 .00 10 .00 55 .59 55 .59 82 .06 91 . 33 27 . 76 27 . 76 47 .03 . 74. . 56 15 .00 15 . 00 73 . 33 89 .48 235 . 56 3 13 . 85 117 . 72 172 . 80 173 . 01 221 . 93 157 . .03 2 10 25 99 . 45 136 . 65 131 . 7 1 164 . 86 78 . 35 113. 60 139. 42 188 . 68 14 1. 24 228 . 24 77 . 23 136 . 23 85 . 74 130. 66 Appendix 15. Multifarm t r i a l : Kelowna s o i l n i t r a t e _ i values (kg ha ). 156 R S ITE STSO STS1 STWO STW1 STDO 1 19 18 26 56 33 73 5 58 2 22 18 40 39 40 93 6 46 3 19 14 22 68 24 34 3 86 4 18 16 25 44 32 07 4 32 5 22 21 20 46 27 65 3 88 6 18 23 30 98 30 41 5 89 7 16 18 19 37 18 80 4 07 8 21 19 40 39 33 20 8 48 9 19 19 43 15 45 90 6 47 10 19 18 16 05 19 90 2 89 11 19 24 34 29 40 39 4 80 12 19 19 37 61 37 05 6 02 13 19 20 29 32 34 29 4 69 14 17 16 26 56 29 32 5 05 15 22 20 21 59 20 46 4 53 16 17 19 14 93 25 44 3 28 17 19 20 39 05 38 20 7 03 2 1 27 37 38 17 49 79 7 63 2 2 20 20 28 21 29 87 4 51 2 3 18 19 53 10 57 53 6 90 2 4 17 20 29 87 34 30 5 08 2 5 23 20 31 53 32 08 4 73 2 6 20 18 37 06 39 83 5 93 2 7 19 18 29 .87 35 40 3 88 2 8 17 20 23 .79 26 .00 4 .28 2 9 20 20 33 .74 40 .93 3 .71 2 10 21 21 32 .53 32 .42 5 . 14 2 1 1 37 34 33 .85 35 . 18 5 . 15 STD1 STDMO STDM1 STNO STN1 TODO T0D1 6 41 .21 . 19 .51 1 .21 1 .22 2 .00 7 37 . 16 . 18 1 . 16 1 .03 1 .90 2 .20 3 89 . 17 . 16 1 . 18 .82 .83 1 .80 5 77 . 17 . 18 .85 .84 .63 .73 4 43 . 19 . 16 .54 .90 .49 .83 5 47 . 19 . 18 .79 .88 1 .85 1 .85 3 01 .21 . 16 .90 1 .07 .78 .59 5 98 .21 . 18 1 .03 .94 2 .68 1 .85 6 89 . 15 . 15 1 . 12 1 .20 1 46 1 27 3 78 . 18 . 19 .77 .89 1 32 2 05 6 46 . 14 . 16 .83 1 .22 1 17 1 51 5 93 . 16 . 16 .89 1 02 2 44 2 34 5 83 . 16 . 17 81 81 2 34 2 29 6 45 . 19 .22 52 77 2 10 68 5 12 .21 .25 1 .31 1 .40 1 07 1 17 5 60 . 18 .21 1 24 1 04 24 88 6 65 . 18 . 17 1 00 1 18 87 95 8 46 .20 . 17 1 02 1 50 1 55 1 68 4 78 . 16 . 16 1 35 1 34 87 1 05 8 05 . 13 . 14 1 44 1 38 1 74 2 02 4 80 . 17 . 14 1 11 1 50 1 29 1 42 4 81 . 15 . 15 1 16 1 10 78 1 17 5 58 . 16 . 14 1 19 1 34 1 20 1 64 4 60 . 13 . 13 1 36 1 57 1 06 1 72 4 .68 . 18 . 18 1 07 1 28 1 05 82 5 32 . 11 . 13 1 27 1 20 1 03 1 14 5 32 . 16 . 16 90 1 10 1 22 1 25 5 .35 . 15 . 15 99 88 65 1 39 YR = Year (1=1984, 2=1985) SITE = S i t e (1-17 i n 1984, 1-11 i n 1985) • 0 = C o n t r o l p l o t 1 = F e r t i l i z e d p l o t STS = Number o f s t a l k s _. STW = S t a l k y i e l d , f r e s h ( t ha~ ) STD = S t a l k y i e l d , f r e s h ( t ha" ) STDM = S t a l k dry matter ( p r o p o r t i o n o f f r e s h ) STN = S t a l k n i t r o g e n (%) _ 1 TOD = Top y i e l d , dry ( t ha ) Appendix 16a. M u l t i f a r m t r i a l : C o m d a t a . 157 YR S ITE COSO COS1 COWO COW1 CODO 1 1 24 24 19. 63 21 . 56 5. 69 1 2 24 21 21 . 56 18. 54 5. 17 1 3 17 18 12 . 17 12. 73 2. 80 1 4 22 28 18. 24 26 . 00 4. 74 1 5 2 1 23 1 1 . 07 17 . 15 2. 77 1 6 26 28 20. 20 22 . 68 5. 45 1 7 15 22 10. 51 14 . 66 2. 73 1 8 30 26 24 . 60 21 . 85 6. 40 1 9 20 21 18. 80 20 . 46 6. 39 1 10 20 19 1 1 . 61 16. 59 3. 83 1 1 1 24 29 17. 71 22. ,41 4. 25 1 12 26 26 21 . .59 22. 95 5. 18 1 13 20 23 14. . 10 21 . .85 3. .81 1 14 18 25 14 , . 10 19 .63 3 .53 1 15 26 29 21 .29 22, .41 5, .75 1 16 20 23 19. .90 19. .37 5, .37 1 17 27 26 23 .92 24, .00 5, .55 2 1 25 31 29 .32 28 .21 7 .33 2 2 25 31 21 .85 26 .55 5 .03 2 3 32 32 31 .25 30 .98 7 .50 2 4 23 30 24 .34 26 .55 4 .87 2 5 32 30 23 .23 25 .67 5 . 11 2 6 32 30 26 .55 28 .21 5 .58 2 7 20 28 12 .45 24 .89 2 .49 2 8 24 28 23 .01 25 . 78 5 .75 2 9 24 33 23 .79 29 .32 4 .04 2 10 25 25 26 .61 27 .71 5 .80 2 1 1 24 28 18 .31 20 . 19 3 .74 C0D1 CODMO C00M1 CONO C0N1 TISO TIS1 6 . 47 .29 .30 1 . 10 1 .38 20 26 4 . 82 . 24 .26 1 .35 1 .65 24 33 2. 29 .23 . 18 1 .43 1 .40 12 16 5 . 98 .26 .23 1 .24 1 .30 28 23 4 . 12 .25 .24 1 .25 1 .44 14 13 6 . 12 .27 .27 1 . 19 1 .29 24 21 3 . 66 .26 .25 1 .54 1 . 19 1 1 10 5 . 68 . 26 .26 1 . 19 1 .28 31 16 4 . 91 .34 .24 1 . 18 1 . 18 16 17 4 . 48 .33 .27 1 .21 1 .37 4 6 4. 71 .24 .21 1 . 19 1 .49 21 13 6. .43 .24 .28 1 .32 1 . 17 17 24 5, .90 .27 .27 1 .22 1 .25 6 13 5, . 10 .25 .26 1 . 12 1 . 19 25 27 5, .38 .27 .24 1 .35 1 .37 22 12 5. .81 .27 .30 1 .40 1 .96 8 12 5 .33 .23 .22 1 .02 1 . 19 28 26 6 .77 .25 .24 1 .40 1 .78 44 53 5 .04 .23 . 19 1 .67 1 .68 29 24 6 .82 .24 .22 1 .57 1 .50 34 31 5 .58 .20 .21 1 .55 1 .75 17 26 4 .62 .22 . 18 1 .40 1 .57 30 32 6 .21 .21 .22 1 .37 1 .40 29 31 4 .73 .20 . 19 1 .62 1 .62 21 26 5 . 16 .25 .20 1 .28 1 .50 34 28 5 .86 . 17 .20 1 .62 1 .64 17 28 6 . 10 .22 .22 1 .29 1 .38 33 32 4 .04 .20 .20 1 .35 1 .52 28 21 YR = Year (1=1984, 2=1985) SITE = S i t e (1-17 i n 1984, 1-11 i n 1985) 0 = Control p l o t 1 = F e r t i l i z e d p l o t COS = Number of cobs . COW = Cob y i e l d , fresh (t ha ) COD = Cob y i e l d , dry (t ha ) CODM = Cob dry matter (proportion of fresh) CON = Cob nitrogen (%) TIS = Number of t i l l e r s Appendix 16b. Multifarm t r i a l : C o m data. 158 YR SITE STNODW STNIDW CONODW CON 1DW 1 1 34 95 101 . 5 1 62 82 89 6 1 1 2 96 8 1 99 05 69 85 79 58 1 3 55 58 46 77 40 18 32 1 1 1 4 42 32 54 53 58 63 77 98 1 5 23 82 47 55 34 76 53 20 1 6 6 1 38 64 7 1 64 85 78 95 1 7 43 84 38 66 4 1 99 43 63 1 8 1 15 5 1 73 45 76 35 72 48 1 9 88 50 98 00 75 27 57 89 1 10 32 42 51 83 46 42 6 1 47 1 1 1 49 6 1 97 3 1 50 57 69 99 1 12 75 04 84 77 68 43 75 42 1 13 57 08 65 93 46 56 74 04 1 14 37 54 55 26 39 64 60 64 1 15 73 36 88 06 77 74 73 65 1 16 43 54 67 20 75 23 1 13 64 1 17 78 68 89 53 56 6 1 63 59 2 1 94 09 152 10 102 62 120 7 1 2 2 72 68 78 12 83 85 84 82 2 3 124 50 139 17 117 52 102 30 2 4 70 58 93 1 1 75 48 97 65 2 5 63 97 65 73 71 54 72 67 2 6 84 70 96 75 76 28 86 94 2 7 67 18 98 97 40 26 76 48 2 8 56 87 70 45 73 77 77 50 2 9 60 20 77 26 65 45 96 05 2 10 57 05 72 01 74 65 83 94 2 1 1 57 65 59 33 50 38 6 1 37 RSTW RSTD RCOW RCOD R Y I E L D W R Y I E L D D . 79 .87 . 9 1 .88 . 84 . 84 .99 . 88 1 . 16 1 07 1 .04 .94 93 .99 .96 1 22 .94 . 94 . 79 .75 . 70 79 .75 . 78 74 .88 .65 67 .70 . 76 1 02 1 .08 .89 89 . 96 . 98 1 03 1 . 35 . 72 75 .89 1 .04 1 22 1.42 1.13 1 13 1 . 18 1 . 30 94 .94 .92 1 30 . 93 1 . 10 8 1 . 76 .70 85 . 76 . 78 85 .74 .79 90 .33 .8 1 1 02 1 .02 .94 81 .99 .93 86 .80 .65 65 . 77 . 77 9 1 .78 .72 69 .83 .87 1 06 . 88 .95 1 07 1 OO . 97 59 .59 1 .03 92 78 .72 1 02 1 .06 1 .00 1 04 1 01 1 .04 77 . 90 1 .04 1 08 87 .98 94 .94 . 82 1 00 89 .96 92 . 86 1.01 1 10 95 . 96 87 1 .06 . 92 87 89 . 95 98 .98 .90 1 . 1 1 95 1 .00 93 1 .06 .94 .90 93 . 95 84 .84 . 50 .53 70 . 67 9 1 .91 . 89 1 . 1 1 90 1 .04 . 82 .70 .81 .69 82 . 7 1 1 .OO . 97 .96 . 95 98 . 96 . 96 .96 .91 .93 94 .88 YR = Year (1=1984, 2=1985) SITE = S i t e (1-17 i n 1984, 1-11 i n 1985) 0 = Control p l o t 1 = F e r t i l i z e d p l o t STNODW STN1DW CONODW RSTW = RSTD = RCOW = RCOD = -1 = Stalk nitrogen (kg ha_.| ) = Stalk nitrogen (kg ha ) = Cob nitrogen (kg ha ) Control p l o t (0) Relative y i e l d , s t a l k s fresh Relative y i e l d , s t a l k s dry Relative y i e l d , cobs fresh Relative y i e l d , cobs dry RYIELDW = Relative y i e l d , whole plant fresh RYIELDD = Relative y i e l d , whole plant dry Appendix 16c. Multifarm t r i a l : Corn data. 159 YR SITE CORNWO t 1 46 19 1 2 61 95 1 3 34 85 t 4 43 68 t 5 31 53 1 6 51 18 1 7 29 88 ! S 64 99 9 6 1 95 10 27 66 1 11 52 00 1 12 59 20 13 43 42 14 40 66 15 42 88 16 34 83 1 17 62 97 2 1 67 49 2 2 50 06 2 3 84 35 2 4 54 2 1 2 5 54 76 2 6 63 61 2 7 42 32 2 8 46 80 2 9 57 53 2 10 59 14 2 1 1 52 16 C0RNW1 CORNOO 55 29 12 49 59 47 13 53 37 07 7 49 58 07 9 69 44 80 7 14 53 09 13 19 33 46 7 58 55 05 17 56 66 36 14 32 3G 49 8 04 62 80 10 22 60 00 13 64 56 14 10 84 48 95 10 88 42 87 1 1 35 44 81 8 89 62 20 13 45 78 OO 16 51 56 42 10 4 1 88 51 16 14 60 85 1 1 24 57 75 10 62 68 04 12 7 1 60 29 7 43 51 78 1 1 08 70 25 8 78 60 13 12 16 55 37 9 54 C0RND1 CORNO 14 88 8 1 14 39 1 25 7 98 1 31 12 48 1 05 9 38 90 13 44 99 7 26 1 22 13 5 1 1 1 1 13 07 1 15 10 31 99 12 68 1 01 14 70 1 10 14 02 1 02 12 23 82 1 1 67 1 33 12 29 1 32 12 93 1 01 16 91 1 21 10 87 1 51 16 89 1 .50 1 1 80 1 . 33 10 60 1 28 13 43 1 28 1 1 05 1 . 49 10 66 1 17 12 32 1 44 12 67 1 09 10 78 1 . 17 CORNNO C0RNN1 97 77 19 1 . 12 166 66 178 63 95 76 78 88 100 96 132 5 1 58 58 106 75 126 23 143 66 85 83 82 29 191 86 145 92 163 77 155 89 78 84 1 13 29 100 19 167 30 143 47 160 19 103 64 139 98 77 18 1 15 90 151 10 16 1 7 1 1 18 78 180 84 135 29 153 1 1 196 7 1 272 8 1 156 53 162 95 242 03 24 1 47 146 06 190 76 135 51 138 45 160 98 183 69 107 45 175 46 130 64 147 96 125 65 173 31 13 1 70 155 94 108 03 120 75 YR = Year (1=1984, 2=1985) SITE = S i t e (1-17 i n 1984, 1-11 i n 1985) 0 = Control p l o t 1 = F e r t i l i z e d p l o t CORNW = Whole plant y i e l d , fresh (t ha 1) CORND = Whole plant y i e l d , dry (t ha ) CORN = Whole plant nitrogen (%) _1_ CORNN = Whole plant nitrogen (kg ha ) Appendix 16d. Multifarm t r i a l : Corn data. 

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