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Winter wheat nitrogen management in south coastal British Columbia Yu, Shaobing 1990

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WINTER WHEAT NITROGEN MANAGEMENT IN SOUTH COASTAL BRITISH COLUMBIA by SHAOBING YU B. Sc. (Agron.), HUNAN AGRICULTURE COLLEGE, CHINA, 19 8 2 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF SOIL SCIENCE We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December 1990 © Shaobing Yu, 1990 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 of qpTT. R fl T F N P. F, The University of British Columbia Vancouver, Canada D a t e 7 Docombor 1990 DE-6 (2/88) ABSTRACT Nitrogen i s e s s e n t i a l to obtain high y i e l d s of winter wheat i n south coa s t a l B r i t i s h Columbia, which includes Vancouver Island and the lower Fraser V a l l e y . An accurate recommendation f o r N a p p l i c a t i o n i s required to keep input costs down f o r most economical returns and to l i m i t environmental problems r e l a t e d to leaching of excess N. The questions are how much, when and which form of N should be applied to winter wheat. The general objective of t h i s study i s to improve our understanding of winter wheat growth and N uptake. This study monitors the s o i l N supply and characterizes the plant development, dry matter accumulation, and N uptake of winter wheat i n South Coastal B.C.. Also, i t compares the effectiveness of conventional and intensive crop N management and urea and ammonium n i t r a t e sources of f e r t i l i z e r N under intensive crop management. A s e r i e s of f i e l d experiments was conducted i n 1986-87 and 1987-88 with winter wheat to evaluate conventional and intensive N management i n the area. A d d i t i o n a l l y , a N source i i study was c a r r i e d out i n the l a t t e r year to compare ammonium n i t r a t e and urea. S o i l N supply f o r winter wheat ranged from 52 to 151 kg N/ha through the two years of f i e l d experiments at f i v e s i t e s . A v a i l a b l e N i n the 0-50 cm s o i l depth var i e d from 10 to 100 kg N/ha through the growing season i n the d i f f e r e n t treatments. An accurate estimate of N behavior involves N accumulation i n the crop. During the ea r l y spring u n t i l harvest, the crop dry matter y i e l d and N uptake patterns were p l o t t e d . The grain y i e l d s ranged from 4 to 9 t/ha f o r the conventional management (75 kg N/ha) , and from 4 to 11 t/ha f o r the intensive crop management (I.CM. 225 kg N/ha) system. Between the conventional and I.CM., there was no s i g n i f i c a n t d i f f e r e n c e i n grain y i e l d but there was i n q u a l i t y , s p e c i f i c a l l y grain protein. Grain p r o t e i n ranged from 8.2 to 9.7% f o r the conventional and from 10 to 13.7% fo r the I.CM. treatment. Also, there was no d i f f e r e n c e i n grai n y i e l d or q u a l i t y between ammonium n i t r a t e and urea f e r t i l i z e d p l o t s at f i n a l harvest. However, i n the early stage at GS31, crop took up more N from ammonium n i t r a t e (97 kg N/ha) than from urea (75 kg N/ha) and s o i l mineral N l e v e l s with urea were higher than with ammonium n i t r a t e . i i i TABLE OF CONTENTS ABSTRACT . . II TABLE OF CONTENTS LIST OF TABLES VI LIST OF FIGURES. VII ACKNOWLEDGEMENTS VIII INTRODUCTION. 1 1.1 IMPORTANCE OF WINTER WHEAT IN SOUTH COASTAL B.C 1 1.2 FIELD STUDIES WITH N MANAGEMENT IN WINTER WHEAT 3 Nitrogen from S o i l 3 Determination of N Needs. 4 Nitrogen Uptake Pattern 6 Protein. 9 Nitrogen Source 9 C r i t i c a l N l e v e l 11 1.3 REASONS FOR INCREASING FERTILIZER N EFFICIENCY 12 1.4 PURPOSE OF THIS STUDY 14 Ob j e c t ives 14 S p e c i f i c objectives are the following 15 METHODS AND MATERIALS . 16 2.1 MATERIALS AND SITE DESCRIPTION 16 2.2 GROWTH STAGE 21 2.3 SAMPLING. 25 2 . 4 LABORATORY METHODS 2 8 2.5 STATISTICAL METHOD .29 RESULTS AND DISCUSSION 3 0 3.1 SITE DIFFERENCE .30 Weather Information 3 0 N-uptake and Dry Matter Y i e l d s i n Control P o l t s 31 3.2 FINAL HARVEST 3 6 Grain 3 6 Grain Protein 42 3.3 SOIL N SUPPLY 45 Eastern Fraser V a l l e y ..45 Oyster River 49 Delta 52 3.4 CROP N CONCENTRATIONS 55 3.5 PATTERNS OF DRY MATTER YIELDS AND N UPTAKE 58 Eastern Fraser V a l l e y 59 Oyster River. 67 i v Delta 73 3.6 NITROGEN IN THE SOIL/PLANT SYSTEM ....80 3.7 MODELS OF N-UPTAKE AND DRY MATTER YIELDS ...87 Control P l o t 87 Conventional N management 89 Intensive N management 91 SUMMARY AND CONCLUSIONS ....... 93 BIBLIOGRAPHY 97 APPENDIX I 104 APPENDIX II 105 APPENDIX I I I 106 APPENDIX IV. 107 APPENDIX V. . 108 APPENDIX VI 119 APPENDIX VII 110 APPENDIX VIII I l l APPENDIX IX 112 APPENDIX X 113 APPENDIX XI 114 APPENDIX XII 115 APPENDIX XIII ..116 APPENDIX XIV 117 v LIST OF TABLES INTRODUCTION 1.2.1 Nitrogen and dry matter accumulation by various growth stages f o r a 7.3 t/ha y i e l d i n Eastern Washington 6 METHODS AND MATERIALS 2.1.1 Nitrogen f e r t i l i z e r treatments i n 1986-87 18 2.1.2 Nitrogen f e r t i l i z e r treatments i n 1987-88 18 2.1.3 Selected p h y s i c a l and chemical properties at 0-20 and 20-50 cm depths f o r four s i t e s by the f i r s t sampling time i n spring. 22 2.2.1 A decimal code f o r the stages of cereals 24 2.3.1 Sampling dates and growth stages of winter wheat..26 RESULTS AND DISCUSSION 3.1.1 Dry matter y i e l d s and N uptake i n f i n a l harvest fo r c o n t r o l p l o t s during s i x s i t e years 34 3.2.1 Grain and N uptake and protein y i e l d s with 225 kg N/ha as urea or ammonium n i t r a t e 37 3.4.7 Crop N concentrations at d i f f e r e n t s i t e s --57 3.6.1 Difference i n crop N uptake between the co n t r o l and 75 kg N/ha treatments 80 3.6.2 Difference i n crop N uptake between the c o n t r o l and 225 kg N/ha treatments 82 3.6.3 Difference i n s o i l N (0-50 cm) between the co n t r o l and 75 kg N/ha treatments 83 3.6.4 Difference i n s o i l N (0-50 cm) between the co n t r o l and 225 kg N/ha treatments 85 3.6.5 Crop uptake of f e r t i l i z e r N added point to the indicated grow stages 86 v i LIST OF FIGURES METHODS AND MATERIALS 2.1.1 Experimental design 19 2.1.2 A map of the f i e l d s i t e s used i n the study 20 RESULTS AND DISCUSSION 3.1.1 Mean monthly temperature f o r the study s i t e s 32 3.1.2 P r e c i p i t a t i o n (mm) f o r the study s i t e s 33 3.2.1 Grain y i e l d s (13.5% moisture) at f i v e site-years..38 3.2.2 P r e c i p i t a t i o n (mm) during winter wheat growth 39 3.2.3 Grain p r o t e i n % i n winter wheat 44 3.3.1 S o i l N (0-50 cm) i n Agassiz 1986-87 47 3.3.2 S o i l N (0-50 cm) i n Chilliwack 1987-88. 48 3.3.3 S o i l N (0-50 cm) i n Oyster River 1986-87 50 3.3.4 S o i l N (0-50 cm) i n Oyster River 1987-88... ..51 3.3.5 S o i l N (0-50 cm) i n Delta 1986-87 53 3.3.6 S o i l N (0-50 cm) i n Delta 1987-88... 54 3.5.1 Dry matter y i e l d s i n Agassiz 1986-87 63 3.5.2 N uptake kg N/ha i n Agassiz 1986-87 64 3.5.3 Dry matter y i e l d s i n Chilliwack 1987-88. 65 3.5.4 N uptake kg N/ha i n Chilliwack 1987-88 66 3.5.5 Dry matter y i e l d s i n Oyster River 1986-87 69 3.5.6 N uptake kg N/ha i n Oyster River 1986-87 70 3.5.7 Dry matter y i e l d s i n Oyster River 1987-88 71 3.5.8 N uptake kg N/ha i n Oyster River 1987-88 72 3.5.9 Dry matter y i e l d s i n Delta 1986-87.. 76 . 3.5.10 N uptake kg N/ha i n Delta 1986-87.... 77 3.5.11 Dry matter y i e l d s i n Delta 1986-87 78 3.5.12 N uptake kg N/ha i n Delta 1986-87 79 3.7.1 Regression of N on dry matter f o r c o n t r o l . . . . •. .... 88 3.7.2 Regression of N on dry matter f o r conventional.... 90 3.7.3 Regression of N on dry matter f o r I.CM 92 v i i A C K N O W L E D G E M E N T S I n i t i a l l y , I would l i k e to thank Dr. Arthur A. Bomke, f o r h i s great enthusiasm to introduce me to t h i s t o p i c , and h i s work as my administrative advisor. I am p a r t i c u l a r l y g r a t e f u l f o r guidance and valuable suggestions from Dr. Shannon M. Berch. I would also l i k e to thank my committee members: Dr Les M. Lavkulich and Dr. James D. Beaton f o r t h e i r help. Special thank to Wayne, Rola, Barb, Aaron, Chuck, P a t r i c e , Eveline, Xiahun, and J e r r y f o r t h e i r f r i e n d s h i p and endless help i n the f i e l d and laboratory work. F i n a l l y , thanks are due to my sponsors from the Potash & Phosphate I n s t i t u t e of Canada, Canada International Development Agency, and A g r i c u l t u r e M i n i s t r y of China. v i i i INTRODUCTION Wheat i s the p r i n c i p a l crop grown i n Canada. About 9 5 % of a l l Canada's wheat i s grown i n the P r a i r i e provinces of Manitoba, Saskatchewan, and Alberta. Most wheat grown i n the P r a i r i e provinces i s spring wheat as winters are severe for winter wheat production. Some winter wheat i s grown i n southern Alberta and along the f o o t h i l l s of the Rocky Mountains. Winter wheat i s produced i n Ontario, and minor amounts are grown scattered across other eastern provinces. 1.1 IMPORTANCE OF WINTER WHEAT IN SOUTH COASTAL B.C. The introduction of winter wheat int o South Coastal B r i t i s h Columbia could a i d i n the conservation of s o i l and increase crop management f l e x i b i l i t y . The c e n t r a l concept i s to reduce s o i l degradation processes, such as ponding, subsurface compaction and surface erosion, by providing a f a l l seeded crop l i k e winter wheat. One of the benefits of introducing winter wheat i s the s h i f t of s o i l t r a f f i c and land preparation i n t o July, August and September, the d r i e r months of the year. This would minimize the necessity of f i e l d operations on wet s o i l s i n the l a t e f a l l and early 1 spring. Many farmers curren t l y carry out f i e l d operations on wet s o i l s because most spring crops must be seeded i n A p r i l or May (Temple and Bomke 1989). In south coa s t a l B. C. a g r i c u l t u r a l areas, the annual p r e c i p i t a t i o n ranges from 1000 to 1800 mm, most of which f a l l s during the winter months. The degree of leaching i s greater with higher r a i n f a l l and N i s c a r r i e d beyond the root zone of wheat during the winter and e a r l y spring. I t i s then l o s t f o r purposes of plant n u t r i t i o n and may eventually seep in t o water supplies that are u t i l i z e d f o r humans and li v e s t o c k . This may r e s u l t i n N d e f i c i e n c y i n the s o i l i n the next spring when crops need N f o r growth and development. Consequently, plant growth i s i n h i b i t e d i n the spring a r e s u l t of N leaching during winter. Most of the published f i e l d experiments with N management on winter wheat have been done i n the P a c i f i c Northwest and the A t l a n t i c Coastal P l a i n region of the U.S.A., and Europe. In south coa s t a l B.C., farmers lack information f o r growing the crop. 2 1.2 FIELD STUDIES WITH N MANAGEMENT ON WINTER WHEAT Nitrogen from S o i l The s o i l N comes from the decomposition of crop r e s i d u e s and s o i l o r g a n i c matter. I f m i n e r a l N i s produced i n autumn or e a r l y w i n t e r , i t may be leached t o such a depth t h a t the wheat cannot r e c o v e r i t . I f not leached, t h e r e i s a p o s s i b i l i t y of l o s s by d e n i t r i f i c a t i o n . S o i l a n a l y s i s i s a f i r s t guide t o e f f i c i e n t f e r t i l i z a t i o n . N i t r a t e - N i s mobile i n the s o i l and i s s u b j e c t t o l e a c h i n g and d e n i t r i f i c a t i o n l o s s e s . The l e v e l of N i n the s o i l can a l s o i n c r e a s e t e m p o r a r i l y through m i n e r a l i z a t i o n . Thus, s o i l t e s t s f o r r e s i d u a l N ( N O 3-N & NH4-N) r e q u i r e t h a t s o i l samples be c o l l e c t e d t o a depth of 50-60 cm t o estimate the l e v e l of p l a n t - a v a i l a b l e N. Sampling t o g r e a t e r depths (120-150 cm) i s recommended t o improve the accuracy of the N recommendation i n North Dakota (Halvorson e t a l , 1987). N i t r o g e n uptake depends on both a p l a n t ' s i n h e r e n t p h y s i o l o g y and the N a v a i l a b i l i t y t o the r o o t s . T h i s l a t t e r c o n s i d e r a t i o n i s mostly a consequence of s o i l environmental c o n d i t i o n s . Gregory e t a l . (1979) demonstrated t h a t w i n t e r 3 wheat growth rate was c l o s e l y r e l a t e d to N accumulation during the middle portion of the growing season. Under f i e l d conditions, without l a t e r a p p l i c a t i o n s of N f e r t i l i z e r , N uptake i s u s u a l l y low following heading (Simmons, 1982) I f adequate N i s not a v a i l a b l e at the time wheat i s t i l l e r i n g and e s t a b l i s h i n g i t s y i e l d p o t e n t i a l , y i e l d responses to N f e r t i l i z e r applied l a t e can be disappointing (Pumphrey and Rasmussen 1982). A f a l l a p p l i c a t i o n of N i s generally as e f f e c t i v e as a spring a p p l i c a t i o n on heavy-textured s o i l s i n the d r i e r climates of the Northern Great P l a i n s of the USA. In higher r a i n f a l l areas, concern over winter NO3-N leaching has prompted top-dressed N a p p l i c a t i o n s i n l a t e winter or e a r l y spring. Gallagher 1 et a l . , (1973) report that topdressing N f o r winter wheat i n l a t e winter can improve N-use e f f i c i e n c y and y i e l d s i n sandy s o i l s i n Kansas r e c e i v i n g heavy f a l l p r e c i p i t a t i o n . Delayed N a p p l i c a t i o n s tend to have a greater e f f e c t on grain p r o t e i n and l e s s on y i e l d . Determination of N Needs Winter wheat, l i k e a l l crops, requires nitrogen for growth and reproduction. Nitrogen i s a constituent of a l l 4 protein, enzymes, many of the metabolic intermediates involved i n protein synthesis and energy t r a n s f e r , and f o r the deoxyribonucleic acids making up the genetic code i t s e l f . Of the elements necessary f o r winter wheat growth, N i s u s u a l l y required i n larger q u a n t i t i e s than any other element absorbed from the s o i l . For a 7.3 t/ha grain y i e l d of winter wheat on dryland i n Washington (Koehler 1985), the crop takes up a t o t a l of 176 kg N, 48 kg P, 134 kg K, 11 kg S, 22 kg Ca, and 15 kg Mg/ha. For an 11 t/ha y i e l d under i r r i g a t i o n i n Idaho 260 kg N, 43 kg P, 250 kg K, 34 kg S, 43 kg Ca, and 26 kg Mg/ha are taken up (Brown 1986) . The various sources i n d i c a t e that wheat requires 1 kg of N to produce 41 kg of good q u a l i t y grain. High y i e l d s require large amounts of nitrogen. Washington data (Table 1.2.1) ind i c a t e the amounts of N that accumulate i n the aboveground portions of a winter wheat y i e l d i n g 7.3 t/ha. For optimum winter wheat y i e l d s i n the Great P l a i n s and P a c i f i c Northwest, USA, estimates f o r the amount of N needed f o r a complete crop (roots, vegetative portion, and grain) range from 38-43 kg N/t of grain (Gardner & Goetze, 1980). In North and South Dakota, USA, Halvorson et a l . , (1977) reported a requirement of 40 kg N fo r one tonne of grain. I t i s important to remember that 5 both s o i l N and f e r t i l i z e r N can meet these needs, and farmers must consider inputs from a l l sources. Table 1.2.1 Nitrogen and dry matter accumulation by various growth stages f o r a 7.3 t/ha y i e l d i n Eastern Washington (Koehler, 1985). T i l l e r i n g Boot Milk Mature Tot a l GS*23 GS45 GS70 GS92 N (kg/ha) 42 78 56 0 176 DM (kg/ha) 885 6238 5029 2005 14157 N (%) 24 68 100 89 DM** (%) 6 50 86 100 * GS means Zadoks Growth Stage (See Pg 22) ** DM means dry matter Nitrogen Uptake Pattern High e f f i c i e n c y of f e r t i l i z e r N use by winter wheat should occur when the N a v a i l a b i l i t y matches the plant needs throughout the growing season. Understanding the N uptake 6 pattern of winter wheat i s important f o r improving N f e r t i l i z e r management (Harper et a l . , 1987). The determination of optimum N f e r t i l i z e r rates i s a major unsolved problem i n most humid regions of the world (Stanford, 1982). Information i s lack i n g on the N uptake pattern of i n t e n s i v e l y managed winter wheat i n southern c o a s t a l B.C.. Plant analysis might be most r e l i a b l e for p r e d i c t i n g optimum N f e r t i l i z e r rates i n humid climates. Evaluation of N concentration and uptake throughout the crop growing season provides information to p r e d i c t N f e r t i l i z e r requirements. In B r i t a i n , the winter wheat crop has only a small N requirement (20 kg N/ha at Woburn) i n the f a l l because of i t s r e l a t i v e l y small amount of growth p r i o r to winter dormancy (Widdowson, 1986). Also, the amount of N03-N i n the s o i l at the outset of growth i n autumn i s r e l a t e d to s o i l mineral N supply u n t i l A p r i l . Widdowson reported that winter wheat on a sandy s o i l given 22 0 kg N/ha i n spring yielded 9.3 t/ha of grain. The N uptake pattern was 66, 107, 172, and 198 kg N/ha by 21 A p r i l , 19 May, 24 June and 30 August at f i n a l harvest. 7 In the A t l a n t i c Coastal P l a i n region of V i r g i n i a , U.S.A., winter wheat f i e l d experiments were established during the 1981-82 through 1985-1986 period (Baethgen and A l l e y , 1989a). The treatments i n these experiments consisted of s i n g l e or s p l i t spring N a p p l i c a t i o n s at GS 25 and 30 t o t a l i n g 0, 90, or 135 kg N/ha. In the 1984-85 experiment, with 135 kg N/ha at G.S. 30, the grai n y i e l d was 6.04 t/ha and the f i n a l N uptake was 170 kg N/ha. The research i n V i r g i n i a (Baethgen and A l l e y , 1989b) showed that s p l i t t i n g N a p p l i c a t i o n enabled farmers to manipulate the winter wheat fo r higher y i e l d and greater N e f f i c i e n c y (55-60%). During the t i l l e r i n g phase (GS 20-25) of wheat growth, the plant produced more t i l l e r s with increasing amounts of N uptake. A d d i t i o n a l N was applied at the beginning of stem elongation (GS 30) to meet the crop needs during the major N uptake period. I t i s important to estimate an accurate amounts of N demand during that time. Under favorable conditions, 80% or more of the f e r t i l i z e r N may be recovered by the crop to which i t i s applied. However, under many s o i l and cropping conditions, e f f i c i e n c i e s of 50 % or l e s s are not uncommon ( Prasad et a l . , 1971). 8 Protein Adding more N than needed f o r optimum y i e l d w i l l generally r e s u l t i n an increase i n gr a i n p r o t e i n (Fowler and de l a Roche, 1984). In North Dakota, Goos (1984) found that a spring wheat grai n protein l e v e l below 14% indicates u n d e r f e r t i l i z a t i o n with N. Goos (1983) also found that a l e v e l of 12% protein i n grain indicated s u f f i c i e n t N f o r optimum y i e l d of winter wheat. In the P a c i f i c Northwest of the U.S.A., Altman (1983) indi c a t e d that a major constraint to growing hard red winter wheat i s the c o n s i s t e n t l y low grain protein observed. In an Oregon f i e l d study, Altman et a l . , (1983) found 4.55 t/ha of gra i n y i e l d had 10.93% protein f o r the c o n t r o l and 5.87 t/ha of g r a i n y i e l d had 11.46% pr o t e i n f o r a 100 kg N/ha f e r t i l i z e r topdress treatment. Thus, gra i n p r o t e i n can be used as an i n d i c a t o r to evaluate wheat N f e r t i l i z a t i o n programs. Nitrogen Source 9 The source of N f e r t i l i z e r can a f f e c t crop u t i l i z a t i o n by i n f l u e n c i n g N form, p o s i t i o n a l a v a i l a b i l i t y , leaching, and v o l a t i l i z a t i o n l o s s of N. Ammonium n i t r a t e normally contains between 33 and 35% of N. The N0 3 component of NH 4N0 3 i s r e a d i l y a v a i l a b l e to crops, but i t i s more prone to leaching and d e n i t r i f i c a t i o n . Urea [CO(NH 2) 2] i s acted upon by the enzyme urease, which hydrolyzes i t to unstable ammonium carbonate and NH3. The NH 4 + formed following urea hy d r o l y s i s i s r e s i s t a n t to leaching but also i s not r e a d i l y transported to the plant root by mass flow. Also, s o l u t i o n NH 4 + becoming e l e c t r i c a l l y balanced by 0H~ would favor NH3 l o s s as represented by the following r e a c t i o n : NH 4 + + OH" = NH4OH = NH3 + H 20 In north c e n t r a l Montana, Christensen and Meints (1982) reported that comparison of regression c o e f f i c i e n t s f o r e i t h e r winter wheat grain y i e l d or t o t a l N uptake revealed no s i g n i f i c a n t d i f f e r e n c e s between N source or timing combinations. Spring top-dressed urea and ammonium n i t r a t e were equally e f f e c t i v e i n supplying N to wheat plants. But i n the U.K., Chaney and Paulson (1988) have reported that winter wheat y i e l d was s i g n i f i c a n t l y greater when ammonium n i t r a t e was applied rather than urea. 10 During the winter and the e a r l y spring months i n South Coastal B.C., the s o i l temperature i s low and the a c t i v i t i e s of Urease, Nitrosomonas, and Nitrobacter are low. Some of the NH 4 + released by the processes of ammonification i s slowly converted to N03-N. To improve the effectiveness of N, i t i s necessary to get more information about the use of urea and ammonium n i t r a t e to supply N to winter wheat i n humid areas. C r i t i c a l N l e v e l D i f f i c u l t i e s with s o i l t e s t s f o r N under humid region conditions have led to several projects evaluating plant t i s s u e N concentration during spring growth as a means of assessing wheat N requirements. Nitrogen recommendations are often based on a plant t i s s u e sample obtained i n the spring when the wheat i s between GS 22 to 32. Whole plant N concentration recently has been suggested as i n d i c a t o r of N requirement f o r wheat. C r i t i c a l l e v e l s reported f o r N at GS 30 vary from 2.75% i n Arkansas (Adams and Chapman, 1984) to 4.2% i n North Dakota (Engel and Z u b r i s k i , 1982). In Pennsylvania, Roth (1989) found that the whole plant N concentration or c r i t i c a l l e v e l to produce 90% of the maximum y i e l d was 2.65% of N f o r GS 31. In V i r g i n i a , 11 a n a l y s i s of whole wheat plants c o l l e c t e d at GS 3 0 indicated an N s u f f i c i e n c y range from 4.0-5.0% f o r obtaining maximum y i e l d s (Donohue and Brann, 1984). Also, winter wheat f i e l d experiments conducted i n eastern Colorado (Westfall et a l . 1990) showed that spring a p p l i c a t i o n of N f e r t i l i z e r was superior to f a l l applied N i n increasing y i e l d and protein content. The t o t a l N content of the two most f u l l y developed leaves at GS 3 0 was the most accurate and p r a c t i c a l p r e d i c t o r of N needs using t i s s u e t e s t i n g . The c r i t i c a l l e v e l established was 3.2% t o t a l N. At GS 32 the c r i t i c a l l e v e l declined to 2.7% N. 1.3 REASONS FOR INCREASING FERTILIZER N EFFICIENCY There are three main reasons f o r improving the e f f i c i e n c y of N f e r t i l i z e r a p p l i c a t i o n s . F i r s t , p r e d i c t i o n of the best rate and times of N a p p l i c a t i o n i s e s s e n t i a l to obtain high y i e l d s . A high y i e l d i n g (7 t/ha) wheat contains large amounts ( > 200 kg N/ha) of N but over-application of N causes crop lodging and disease. The supply of s o i l N i s li m i t e d , mobile and e a s i l y l o s t , and the complex processes of replenishment are very weather dependent. 12 Second, increasing income i s very important from the farmer's viewpoint. Choosing the r i g h t source of N f e r t i l i z e r and optimal a p p l i c a t i o n methods increases N e f f i c i e n c y and economic e f f i c i e n c y . The costs of ammonium n i t r a t e and urea are d i f f e r e n t . In September 1989, the p r i c e of ammonium n i t r a t e quoted by the Green V a l l e y F e r t i l i z e r Ltd. Surrey, B r i t i s h Columbia was $ 307/t ($ 0.88 /kg N) as compared to urea at $ 315/t ($ 0.68/kg N) . In the past, farmers put on excess N to ensure optimum y i e l d s because N f e r t i l i z e r was r e l a t i v e l y inexpensive. For example, i n 1975, the p r i c e of urea i n B.C. was $ 105/t (Guthrie, 1981). Now, with the increased cost of N f e r t i l i z e r , farmers are becoming more cost conscious i n t h e i r N f e r t i l i z e r a p p l i c a t i o n rates and t h i s may reduce y i e l d or q u a l i t y i f the f e r t i l i z e r s are not managed e f f e c t i v e l y . Furthermore, an important reason f o r N e f f i c i e n c y i s the reduction of environmental problems. I f a v a i l a b l e N from s o i l and f e r t i l i z e r sources exceeds the t o t a l N demand of winter wheat, n i t r a t e may be leached from s o i l s leading to drinking water high i n N03-N. 13 1.4 PURPOSE OF THIS STUDY The q u e s t i o n s o f when, how much, and which form of N s h o u l d be a p p l i e d have been argued r e p e a t e d l y over the y e a r s . There i s p r o b a b l y no si m p l e answers. P l a i n l y , some N s h o u l d be a p p l i e d i n A p r i l a t about t h e time when t h e r a p i d i n c r e a s e s i n growth and N uptake o c c u r . Optimum r a t e s and t i m i n g o f N a p p l i c a t i o n s a t o t h e r times a r e not w e l l known. Knowledge o f t h e r e l a t i o n s h i p between c r o p N demand and s o i l s u p p l y i s e s s e n t i a l t o determine N management. In t h e humid South C o a s t a l B.C. r e g i o n , N f e r t i l i z e r recommendations f o r w i n t e r wheat must be based on l o c a l f i e l d experiments on d i f f e r e n t s o i l t y p e s and under l o c a l c l i m a t i c c o n d i t i o n s . E s t a b l i s h i n g b e s t N management p r a c t i c e s i s e s s e n t i a l t o s u c c e s s f u l p r o d u c t i o n o f w i n t e r wheat i n t h i s r e g i o n . O b j e c t i v e s The g e n e r a l o b j e c t i v e o f t h i s study i s t o improve our u n d e r s t a n d i n g o f w i n t e r wheat growth and N uptake. T h i s w i l l p r o v i d e a b a s i s f o r improving f e r t i l i z e r N r a t e and t i m i n g recommendations f o r w i n t e r wheat i n South C o a s t a l B.C.. 14 S p e c i f i c objectives are the following; 1) To observe the s o i l N supply and change through the crop growth periods. 2) To characterize the plant development, dry matter accumulation, and N uptake of winter wheat i n South Coastal B.C.. 3) To compare the effectiveness of conventional and intensive crop N management. 4) To compare urea and ammonium n i t r a t e sources of f e r t i l i z e r N under intensive crop management. 15 METHODS AMD MATERIALS 2.1 MATERIALS AND SITE DESCRIPTIONS At each of the s i t e s , winter wheat (Triticunt aestivum L.) v a r i e t y Monopol was chosen f o r the experiment. In the 1986-87 experiment, plan t i n g dates were 30 September for Agassiz, 16 October f o r Oyster River, and 1 October for Delta (18 cm row spacing and 350 seed/m2 or 150 kg seed/ha). In the 1987-88 experiment, plan t i n g dates were 29 September fo r Chilliwack, 1 October f o r Delta, and 16 October f o r Oyster River (10 cm row spacing and 350 seed/m2 or 150 kg seed/ha). F e r t i l i z e r N treatments are described i n Table 2.1.1. fo r the 1986-87 study and Table 2.1.2 f o r the 1987-88 study. Treatment B r e c e i v i n g 75 kg N/ha at GS 31, i s representative of conventional wheat management i n the region while treatments C and D, each r e c e i v i n g 225 kg/ha of s p l i t applied N, are examples of Intensive Cereal Management (I.CM.). Treatment D, 225 kg N/ha as ammonium n i t r a t e , was only applied i n 1987-88. Nitrogen f e r t i l i z e r was c a r r i e d out by hand to 3 m x 3 m p l o t s along e i t h e r side of a 3 m wide set of tramlines i n a randomized complete block design with 16 four r e p l i c a t e s ( See F i g 2.1.1). For the 1986-87 study, each block was 9 m x 9 m, while i n 1987-88 p l o t dimensions were 12 m X 9 m. Research s i t e s were located i n south coa s t a l B r i t i s h Columbia, which includes Vancouver Island and the Lower Fraser V a l l e y (Fig 2.1.2). Three experimental s i t e s were used each year. The Agassiz s i t e on the A g r i c u l t u r e Canada Research Station (49° 15'lat., 121° 45'long.), Oyster River s i t e on the U.B.C. Oyster River Research Farm No 2 on Vancouver Island (49° 55', 123° 10') and Delta s i t e on the Montgomery Farm on River Road i n Delta M u n i c i p a l i t y were used f o r 1987 experimental s i t e s . The Oyster River s i t e was the same s i t e i n both years however the 1988 Delta s i t e was switched to Reynelda Farms on Westham Island (49° 10', 123° 10') and the 1988 Chilliwack s i t e , located near the south end of Bamford Road (49° 10', 121° 50'), replaced Agassiz as the eastern Fraser V a l l e y l o c a t i o n . 17 Table 2.1.1 Nitrogen f e r t i l i z e r treatments i n 1986-87 Treatment kg N/ha Growth Stage Source T o t a l A-Control 1 0 — 0 B-Conventional 75 31 urea 75 C-I.C.M.* 50 22 urea 125 31 urea 50 55 urea 225 * Intensive Crop Management. Table 2.1.2 Nitrogen f e r t i l i z e r treatments i n 1987-88 Treatment kg N/ha Growth Stage Source T o t a l A-Control 0 — 0 B-Conventional 75 31 urea 75 C-I.C.M. 50 22 urea 125 31 urea 50 37 urea 225 D-I.C.M. 50 22 AN* 125 31 AN 50 37 AN 225 *AN; ammonium n i t r a t e . 18 12m 3m 3m 3m 1 1 1 / \ / N 10 12 8 6 / \ / ^ / \ A b A 3 7 5 2 / \ / \ 4 9 /x y\ / \ / \ / X / X X X 12m Figure 2.1.1 Experimental Design 19 Figure 2.1.2 A map of the field sites used in this study 20 The s o i l s i n the study varied. The Agassiz s i t e had a s i l t loam s o i l with a moderate water holding capacity and good drainage. Silage corn was the previous crop. The Chilliwack s i t e also had a s i l t loam s o i l , but was poorly drained and had bush beans as the previous crop. Both Delta s o i l s were s i l t y c lay loams with underdrains. The p r i o r crop f o r 1986-87 Delta s i t e was spring barley and i n 1987-88 i t was potatoes. Oyster River had a well drained loamy sand s o i l . P r i o r to f a l l 1986, grass forage had been grown f o r 10 years. During that period the forage had been f e r t i l i z e d and had received dairy s l u r r y . Some of the important physical and chemical properties of the s o i l s used i n the study are l i s t e d i n Table (2.1.3). 2.2 GROWTH STAGE Timing of nitrogen a p p l i c a t i o n was based on the Zadoks growth stages (Zadoks et a l . , 1974). The, Zadoks decimal code i s described i n Table 2.2.1.. Detailed c l a s s i f i c a t i o n of the secondary growth stages uses a second d i g i t , coded from 0 to 9, f o r each p r i n c i p a l growth stage. As i t i s u n r e a l i s t i c to attempt to define the l a t t e r too c l o s e l y , not a l l positions are n e c e s s a r i l y used. 21 Table 2.1.3 Selected p h y s i c a l and chemical properties at 0-20 and 20-50 cm depths i n I.CM. p l o t s of four s i t e s by the f i r s t sampling time i n spring S i t e -Year* Depth B.D * pH OM N0 3 P K (cm) (kg/m3) (CaCl 2) (%) —kg/ha AG 87 0-20 1170 5.6 5.3 23 119 211 AG 87 20-50 1070 5.7 4.5 20 96 212 OY 87 0-20 970 5.7 9.0 58 90 139 OY 87 20-50 1270 5.6 8.5 48 64 178 DE 87 0-20 1223 5.2 6.2 17 228 374 DE 87 20-50 1240 4.9 3.9 35 109 354 CH 88 0-20 1124 5.7 10 27 130 227 CH 88 20-50 1360 6.1 3.6 18 26 250 OY 88 0-20 1031 5.6 6.8 37 112 182 OY 88 20-50 1270 5.3 7.5 22 102 188 DE 88 0-20 1223 5.3 5.3 36 184 330 DE 88 20-50 1240 4.8 3.9 35 67 167 * AG-Agassiz; OY-Oyster River; DE-Delta. ** Bulk Density. 22 For example, GS 22 means that the plant main shoot has two t i l l e r s . The f i r s t d i g i t of the code i n d i c a t e s that the crop i s t i l l e r i n g and the second the number of t i l l e r s formed. T i l l e r appearance i s c l o s e l y associated with leaf emergence. Primary t i l l e r buds can form i n the a x i l s of the f i r s t four or more true leaves of the main shoot. In addition, s u b t i l l e r s can develop from primary or secondary t i l l e r s . For winter wheat, the main shoot and e a r l i e r formed t i l l e r s are most l i k e l y to complete development and form gra i n (Kirby, 1983). In another example, GS 31 means that the f i r s t node i s detectable at elongation stage. Stem elongation coincides with the growth of leaves, t i l l e r s , roots, and the inflorescence. In winter wheat, a higher numbered internode i s f i r s t to elongate. When an internode has elongated to about h a l f i t s f i n a l length, the internode above i t begins elongating. 23 f Table 2.2.1 A decimal code f o r the stages of cereals (Zadoks et a l , 1974) 1- d i g i t code Description 0 Germination 1 Seedling growth 2 T i l l e r i n g 3 Stem elongation 4 Booting 5 Inflorescence emergence 6 Anthesis 7 Milk development 8 Dough development 9 Ripening 24 2 . 3 SAMPLING From the ea r l y spring to crop harvest, s o i l and plant samples were c o l l e c t e d p e r i o d i c a l l y within each of the 12 sub-plots (3.0 m X 1.5 m) from each treatment p l o t . Sampling dates and growth stages are shown i n Table (2.3.1). Plants i n a 1 m2 quadrat frame were harvested j u s t above the ground by a hand s i c k l e . In the f i e l d , the f r e s h f o l i a g e was weighed and notes made on any disease problems and growth stages. The s o i l samples were taken a f t e r the plant samples had been c o l l e c t e d and from the same 1 m2 area. At each sampling time, two depths of s o i l , 0-20 and 20-50 cm, were sampled using a 2.5 cm diameter Oakfield s o i l probe. Six s o i l cores were taken per p l o t , placed i n a labeled p l a s t i c bag and immediately put in t o a cooler. The s o i l samples were stored i n a r e f r i g e r a t o r (4°C) f o r 12-20 hours before NH4 and N0 3 extractions were done. 25 Table 2.3.1 Sampling dates and growth stages of winter wheat 1986-87 # Growth Stage Agassiz Oyster Yiver Delta 1 31 Mar.20 Mar.23 Mar.14 2 32 Apr.09 Apr.14 May 3 3 33 Apr.18 May 05 Apr.14 4 55 May 29 Jun.02 Jun. 4 5 68 Jun.11 Jun.17 Jun.24 6 78 Jun.27 Jul.01 Jul.17 7 95 Jul.20 Aug.07 *** 1987-88 # Growth Stage Chilliwack Oyster Yiver Delta 1 31 Mar.16 Mar.29 Apr.2 0 2 32 Apr.12 May 03 *** 3 33 May 05 May 19 May 19 4 55 May 30 Jun.13 Jun.07 5 68 Jun.15 Jul.13 Jun.27 6 78 Jul.07 Jul.11 Jul.19 7 95 Jul.27 Aug.07 Aug.15 *** no sample c o l l e c t e d 26 2.4 LABORATORY METHODS Plant samples were placed i n a drying oven at 65°C for 75 hours, a f t e r which they were removed from the oven f o r dry weight determination. Whole plant and straw samples were ground with a Wiley M i l l , whereas gra i n samples were ground with a rotary hammer m i l l . Samples were passed through a 1 mm screen. A f t e r t h i s preparation, the prepared plant samples were packaged and mailed to G r i f f i n Laboratories i n Kelowna, B.C.. In the laboratory, plant sample N concentrations were measured following a standard block digest method with 0.25 g of oven dry ground plant sample. The sample was added to 75 mL of di g e s t i o n mixture and digested f o r one hour a f t e r which, 5 mL of s u l f u r i c a c i d was added. The r e s u l t i n g d i g e s t i o n mixture was subsampled with f i n a l volumes f o r the d i l u t i o n being 75 mL. The r e s u l t i n g s o l u t i o n was analyzed f o r N using a Technicon autoanalyzer (Technicon Autoanalyzer II Methodology 1974). In the U.B.C. Department of S o i l Science laboratory, s o i l samples were thoroughly mixed by hand i n t h e i r p l a s t i c bags before extraction. S o i l moisture contents were determined by drying a 50 g subsample f o r 48 hours at 105°C and reweighing. The s o i l bulk density samples were treated 27 s i m i l a r l y . Ammonium was extracted by shaking 10 g of f i e l d moist s o i l f o r 1 hour with 50 mL of 1 M KCL i n a 120 mL p l a s t i c b o t t l e . A f t e r 5 minutes to allow s e t t l i n g , the supernatant was f i l t e r e d through Whatman #3 f i l t e r paper and 2 drops of toluene added to i n h i b i t m i c r o b i a l growth. After that, the s o i l extract was stored i n 60 mL b o t t l e s at 2°C u n t i l a n a l y s i s . The concentrations of NH4-N and N 0 3-N, as well as t o t a l N, were determined c o l o r i m e t r i c a l l y using the same type Technicon autoanalyzer as used f o r plant samples. N O 3 was reduced to NH4 using a Cd reduction column p r i o r to co l o r i m e t r i c a n a l y s i s . Grain y i e l d s and protein concentrations were ca l c u l a t e d at 13.5% moisture. Also, g r a i n p r o t e i n concentration was ca l c u l a t e d by mu l t i p l y i n g grain t o t a l N by 5.7, assuming grai n p r o t e i n has 17.5% N (Temple and Bomke 1989). F e r t i l i z e r N e f f i c i e n c y was c a l c u l a t e d by subtracting the N uptake by the co n t r o l (treatment A) from treatments B, C and D and then d i v i d i n g by the amount of applied f e r t i l i z e r N. For example, at GS 32 i n 1986-87 at Agassiz, treatment C had taken up 40 kg N/ha more than the control p l o t . The 40 kg N/ha divided by the 175 kg N/ha applied p r i o r to that date (50 kg N/ha at GS 22 plus 125 kg N/ha at 28 GS 31) gives a N e f f i c i e n c y or % uptake of f e r t i l i z e r N of 23% at GS 32 (See Table 3.6.2 and 3.6.5). 2.5 STATISTICAL METHOD S t a t i s t i c a l analyses were done with the Main Frame Analysis of Variance on the U.B.C. mainframe computer. To compare harvest times and treatments, each s i t e was subjected to analysis of variance using orthogonal contrasts and with p r o b a b i l i t y at 0.05 f o r s i g n i f i c a n c e . The time of harvest was the main f a c t o r with the treatment being the second f a c t o r . The N treatment data from f i n a l harvests within each s i t e was analyzed with the Kruskal-Wallis One Way Analysis of Variance Technique (Kruskal and Wallis 1952). S t a t i s t i c a l graphics were done using the STATGRAPHICS program and LOTUS-123 on a PACKARD BELL PB8810 personal computer. A m u l t i p l i c a t i v e model was chosen f o r regression a n a l y s i s . The independent v a r i a b l e i s dry matter y i e l d and the dependent v a r i a b l e i s N uptake. The data was c o l l e c t e d at 6-7 sample dates from s i x d i f f e r e n t s i t e - y e a r s f o r four treatments; A, B, C and D. 29 RESULTS AND DISCUSSION 3.1 SITE DIFFERENCES Weather Information A i r temperature and p r e c i p i t a t i o n data f o r the 1986-87 and 1987-88 growing seasons are presented i n Figures 3.1.1 and 3.1.2. They were obtained from the Vancouver o f f i c e of Environment Canada. In the Eastern Fraser V a l l e y , the coldest mean monthly temperature was 1°C i n January 1988 at Chilliwack. Also, there were high p r e c i p i t a t i o n and temperatures during the crop growing season i n the Eastern Fraser V a l l e y . Compared with the other s i t e s , Delta had much lower r a i n f a l l and l e s s extreme heat and cold. The average annual p r e c i p i t a t i o n at the s i t e s was 1353 mm f o r 1986-87, with 1013 mm occurring between November and A p r i l , almost a l l i n the form of r a i n . The mean annual a i r temperature was 10.3°C, with an average temperature of 6°C from November through A p r i l . For 1987-88, the average annual p r e c i p i t a t i o n at the three s i t e s was 1545 mm, with 1154 mm occurring i n the November to A p r i l period. The mean annual 30 a i r temperature during the 1987-88 crop year was 10.2 OC, with an average temperature of 5°C from November through A p r i l . Thus, 75% of the average annual p r e c i p i t a t i o n occurs during the 6 month period when p o t e n t i a l evapotranspiration was low. N-uptake and Dry Matter Y i e l d s i n Control P l o t s Nitrogen uptake and dry matter y i e l d s at f i n a l harvest from the co n t r o l p l o t s d i f f e r e d s i g n i f i c a n t l y among the s i x sit e - y e a r s (Table 3.1.1). The range f o r dry matter was 6.65 to 15.69 t/ha. The range f o r N uptake was 51 to 151 kg/ha; an i n d i c a t i o n of s o i l N supply at the s i t e s . The Delta 1988 s i t e (DE88) produced the highest values of dry matter and N uptake. The lowest values f o r the two v a r i a b l e s were recorded i n the Oyster River 1988 (OY88) experiment. 31 Mean monthly temperature for the study sites C" 2 0 -15 | k I 5 | 1 1 9 8 6 - 8 7 1 II I 1 9 8 7 - 8 8 ft •I isn i i mi m mm O N D J F M A M J J A S O N D J F M A M J J A m o n t h E.F. Valley Oyster River Del ta Figure 3.1.1 32 Precipitation (mm) for the study sites mm 400 1 9 8 6 - 8 7 1 9 8 7 - 8 8 300 200 100 -B I il ii I lhl\ m I aiLi to S O N D J F M A M J J A S O N D J F M A M J J m o n t h 1 H E : F . Valley Oyster River Del ta F i g u r e 3.1.2 33 Table 3.1.1 Dry matter y i e l d s and N uptake at f i n a l harvest from c o n t r o l p l o t s during s i x s i t e years. dry matter (t/ha) s i t e - y e a r average s i g . OY88 AG87 OY87 DE87 CH88 DE88 6. 65 9.41 10.29 13.81 15.26 15.69 a* a b a b b c c c N uptake (kg/ha) average s i g . 51.6 a 77.6 80.7 101.0 115.3 151. 3 a b a b c b c c d d * The means followed by the same l e t t e r (a, b and c) are not s i g n i f i c a n t l y d i f f e r e n t at P = 0.05. In Delta 1988, the growth was delayed about 3 weeks compared to Chilliwack i n the same year. The reason was that the plants were completely d e f o l i a t e d by wild ducks i n la t e December 1987. The root systems, however, remained undamaged. At Chilliwack the crop reached G.S. 31 on 16 March, while at Delta the same growth stage d i d not occur u n t i l 20 A p r i l (See Table 2.4.1). 34 The high values of 15.69 t/ha of dry matter y i e l d and 151 kg/ha of N uptake measured at the Delta 1987-88 s i t e might be due to the s o i l and weather or to the delayed crop growth and development. The Oyster River 1987-88 experiment had the lowest dry matter and N uptake (Refer to Table 3.1.1). The main reason was probably that the 1986-87 wheat crop on the same p l o t area depleted the mineralizable N from the s o i l . Although most of the 1986-87 crop straw was removed from the f i e l d , a s i g n i f i c a n t amount of high C/N crop residue may have immobilized an a d d i t i o n a l amount of nitrogen. 35 3.2 FINAL HARVEST Grain Winter wheat grain y i e l d s i n Southern Coastal B.C., which includes Oyster River 1986-87 and 1987-88 experiments, Agassiz 1986-87, Chilliwack 1987-88, and Delta 1987-88 are presented i n F i g 3.2.1. Also, F i g 3.2.1 i l l u s t r a t e s grain y i e l d s f o r three N treatment l e v e l s at the d i f f e r e n t study s i t e s . The two N sources, urea and ammonium n i t r a t e , applied at 225 kg N/ha were not s i g n i f i c a n t l y d i f f e r e n t (See Table 3.2.1). Under the 225 kg N/ha treatment, the grai n y i e l d was 8 t/ha i n the Oyster River 1986-87 experiment. The high y i e l d might be due to the f a c t that the s i t e had not been c u l t i v a t e d f o r 15 years. However, during the following year the gr a i n y i e l d f o r the same N a p p l i c a t i o n dropped to 6.9 t/ha. I t might be that the s o i l N i n the s i t e was depleted from the f i r s t year winter wheat. Also, p r e c i p i t a t i o n as shown i n Figure 3.2.2 indicated that the second year growing season was d r i e r than the f i r s t year i n Oyster River. 36 Table 3.2.1 Grain y i e l d s , N uptake, and pro t e i n concentration with 225 kg N/ha as e i t h e r urea or ammonium n i t r a t e (AN) i n the 1988 f i e l d season. S i t e N source Grain (t/ha) CH88-C urea 5.3 CH88-D AN 5.5 OY88-C urea 6.9 OY88-D AN 6.2 DE88-C urea 11.4 DE88-D AN 11.9 N uptake (kg/ha) Protein (%) 236 259 12 .8 13.7 174 164 11.4 11.3 287 324 11.2 11. 3 There are no dif f e r e n c e s at P = 5% s i g n i f i c a n c e within the same s i t e between urea and ammonium n i t r a t e . CH-Chilliwack, OY-Oyster River, and DE-Delta. 37 Grain yields (13.5% moisture) at five site-years t /ha AG87 OY87 C H 8 8 O Y 8 8 si te D E 8 8 0 kg N/ha 75 kg N/ha 225 kg N/ha F i g u r e 3.2.1 38 Precipitat ion mm during winter wheat growth mm (1000) 2 i OY87 DE87 AG87 OY88 DE88 CH88 s i t e Wffit 5 w i n t e r m o n t h s B P 3 3 v e g e t a t i v e m o n t h s fcftSl 2 r e p r o d u c t i v e m o n t h F i g u r e 3 .2 .2 39 The low grain y i e l d , 4 t/ha, at the Agassiz 1986-87 p l o t was r e l a t e d to the very high incidence of l e a f rust present at anthesis (GS 60) which reduced gr a i n f i l l i n g . Grain y i e l d , u l t i m ately, i s heavily influenced by f l a g leaf production and p a r t i t i o n i n g of plant photoassimilates and r e s p i r a t i o n . Estimates (Austin et a l . , 1977) suggest that from 70% to more than 90% of the grain y i e l d i s derived from photoassimilate produced a f t e r anthesis. Thus, crop p r o t e c t i o n against disease i s very important. Leaf r u s t and other diseases can be a major cause f o r low winter wheat grain y i e l d i n the area. The 5.3 t/ha grain y i e l d at the Chilliwack 1987-88 experiment was r e l a t e d to lodging at anthesis (GS 60) which l i m i t e d grain f i l l i n g . Carbon assimilated by a mature leaf can e i t h e r be translocated i n t o the kernel, retained within the l e a f or r e s p i r e d soon a f t e r f i x a t i o n . Plant lodging retards the process and pathway by which photosynthate moves out of the chloroplasts, across l e a f mesophyll and bundle sheath c e l l s and into the phloem (Giaquinta, 1983). A high f e r t i l i z e r N rate (225 kg N/ha) plus high s o i l a v a i l a b l e N (See s e c t i o n 3.3) might be r e l a t e d to crop lodging i n the p l o t . On the other hand, waterlogging probably accentuated crop lodging at the Chilliwack s i t e because high moisture 40 a f f e c t s crown r o t development by fungi such as B i p o l a r i s  sorokiniana (Ledingham et a l . , 1972). In 1988, the p r e c i p i t a t i o n at the Chilliwack s i t e (See F i g 3.2.2) was the highest of any l o c a t i o n . During March to May (3 vegetative months), the s i t e received 773 mm of r a i n f a l l . During the same period, the p r e c i p i t a t i o n was 282 mm at Oyster River. The f i n a l harvest data i n the 1986-87 Delta experiment was not c o l l e c t e d because the crop had been swathed by the farmer before sampling. In the 1987-88 f i e l d experiment, the crop growth was delayed about 3 weeks compared to Chilliwack. The 11.4 t/ha grain y i e l d was highest f o r the 225 kg N/ha treatment (Fig 3.2.1). The high y i e l d p o t e n t i a l at Delta probably indicates the combination of f e r t i l e s o i l and good climate f o r winter wheat growth i n the area. Also, i t might be the e f f e c t of the delayed growing season because the vegetative period of the crop was increased. Similar y i e l d s , however, were obtained at another l o c a t i o n i n Delta i n 1988-89 i n the absence of retarded crop development (Temple and Bomke 1989). At Oyster River i n 1986-87, the grain y i e l d was 8 t/ha f o r 225 kg N/ha treatment and 7 t/ha f o r 75 kg N/ha treatment. Dahnke (1983) suggests that a p r a c t i c a l range for 41 a y i e l d goal should be somewhere between above average to the highest y i e l d that has been obtained i n the area under s i m i l a r conditions such as s o i l , N f e r t i l i z e r , and climate. The 8 t/ha under 225 kg N/ha treatment was higher than 7.3 t/ha i n Washington (Koehler, 1985) and lower than 9.3 t/ha i n B r i t a i n (Widdowson, 1986). Also, winter wheat gra i n y i e l d reached 13.8 t/ha, i n the plant growth regulator (PGR) and fungicide t r i a l with 225 kg N/ha i n 1988 at Delta (Temple and Bomke 1989). Differences i n grai n y i e l d evidently indicated the s i t e e f f e c t with the highest y i e l d s observed i n Delta. Obviously, a number of fa c t o r s can a f f e c t the y i e l d goal, i n c l u d i n g moisture i n the f i e l d , pest c o n t r o l , weather conditions and rates of f e r t i l i z a t i o n . The Intensive Management (225 kg N/ha) treatments should probably r e s u l t i n c lose to the maximum y i e l d goal i n Southern Coastal B.C.. Grain Protein The highest grain protein was 12.8% f o r the 225 kg N/ha treatment i n the Chilliwack 1987-88 experiment and the lowest was 7.8% f o r the co n t r o l i n the Agassiz 1986-87 (See Fi g 3.2.3). Although, there was no s i g n i f i c a n t d i f f e r e n c e between the 75 kg N/ha and 225 kg N/ha treatment i n grain y i e l d s (See F i g 3.1.1), grain p r o t e i n concentrations were 42 strongly increased by the 225 kg N/ha r a t e . For a l l s i t e s 75 kg N/ha, representing the conventional management p r a c t i c e i n the area, produced grain p r o t e i n concentrations ranging from 8.2 to 9.7%. Goos (1982) found that 12% of protein i n g r a i n was s u f f i c i e n t f o r optimum y i e l d of winter wheat. Therefore, 75 kg N/ha was not s u f f i c i e n t f o r optimum protein concentrations of winter wheat. High l e v e l s of N f e r t i l i z a t i o n have more influence on q u a l i t y than on t o t a l g r a i n y i e l d . The grain pr otein might be used as an i n d i c a t o r to evaluate the N f e r t i l i z e r program f o r winter wheat. At Oyster River i n 1987-88, i t was found that 4.4 t/ha of g r a i n y i e l d had 7.8% of p rotein f o r the c o n t r o l , 7.3 t/ha of g r a i n y i e l d and 8.2% of p r o t e i n with 75 kg N /ha, and 8.1 t/ha of g r a i n y i e l d contained 11.4% of p r o t e i n with the 225 kg N /ha treatment. In high y i e l d i n g winter wheat, the 75 kg N/ha a p p l i c a t i o n had low grain p r o t e i n l e v e l s . Thus, the 225 kg N/ha treatment might be a better N recommendation for winter. wheat i n south coastal B.C. These experiments were not designed to e s t a b l i s h optimum N rates, which could vary from the 225 kg/ha N rate. 43 Grain protein % in winter wheat protein % AG87 OY87 C H 8 8 O Y 8 8 DE88 site H I 0 kg N/ha 75 kg N/ha 111 225 kg N/ha 3.2.3 44 3.3 SOIL N SUPPLY The s e a s o n a l p a t t e r n s o f s o i l N l e v e l s from d i f f e r e n t s i t e s a r e p r e s e n t e d below. A v a i l a b l e N i n c l u d e d NH4-N and N03-N summed over t h e 0-20 and 20-50 cm depths. Eastern Fraser V a l l e y S o i l s o f t h e A g a s s i z and C h i l l i w a c k s i t e s a r e s i l t loams. A t A g a s s i z t h e r e was l i t t l e d i f f e r e n c e i n s o i l N between t h e c o n t r o l and c o n v e n t i o n a l (75 kg N/ha) treatments ( F i g 3.3.1). A t cr o p GS 33, s o i l N was 101 kg/ha i n the 225 kg N/ha treatment, as compared t o 57 and 68 kg N/ha i n the c o n t r o l and c o n v e n t i o n a l p l o t s , r e s p e c t i v e l y . A t f i n a l h a r v e s t , t h e s o i l N c o n t e n t was 74 kg/ha f o r t h e 225 kg N/ha r a t e w h i l e o t h e r two trea t m e n t s were about 30 kg N/ha. A t t h e A g a s s i z s i t e , a v a i l a b l e s o i l N i n t h e 0-50 cm sampling depth a t t h e 225 kg N/ha I. C M . p l o t g e n e r a l l y i n c r e a s e d over t h e season w h i l e t h e 75 kg N/ha c o n v e n t i o n a l s o i l N d e c l i n e d . Between t h e c o n v e n t i o n a l and I. C M tre a t m e n t s had a s i g n i f i c a n t l i n e a r i n t e r a c t i o n (P=0.014) between f e r t i l i z e r N treatment and sampling d a t e . T h i s might 45 mean the l e v e l of s o i l N i n the conventional p l o t was s i m i l a r to the I.CM. treatment p l o t a f t e r the f i r s t 50 kg N/ha applied i n the ear l y season when the crop was small. A f t e r that, s o i l N i n the I.CM treatment p l o t was higher than i n the conventional p l o t . At Chilliwack i n 1988 (Fig 3.3.2), 225 kg N/ha applied as urea had 43 kg N/ha i n the s o i l at GS 31. I t was higher than other treatments which were about 22 kg N/ha at the same growth stage. Throughout GS 31 to 78, s o i l N contents i n the s i t e ranged from 22 to 54 kg N/ha. In the f i n a l harvest, s o i l N contents i n the 225 kg N/ha treatment pl o t s increased to 49 and 59 kg N/ha f o r urea and ammonium n i t r a t e r e s p e c t i v e l y . S o i l N content trends d i f f e r e d during the growth season at the Chilliwack s i t e following a p p l i c a t i o n of 225 kg N/ha as urea or ammonium n i t r a t e (quadratic P = 0.009). At GS 33 and 95, s o i l mineral nitrogen l e v e l s with urea f e r t i l i z a t i o n were higher than ammonium n i t r a t e . 46 Soil N (0-50 cm) in Agassiz 1986-87 kg/ha GS68 f GS33 2 3 4 5 6 7 . 8 m o n t h 0 kg N/ha 75 kg N/ha - * - 225 kg N/ha F i g u r e 3.3.1 47 Soi l N ( 0 - 5 0 cm) in Chilliwack 1987-88 kg/ha f GS95 GS68 -1 l _ I , I I I X 2 3 4 5 6 7 8 m o n t h 75 kg N/ha UR 225 kg N/ha AN F i g u r e 3 .3 .2 0 kg N/ha 225 kg N/ha UR 48 Oyster River The Oyster River s i t e i s characterized by loamy sand s o i l . In 1986-87 the s i t e had high s o i l N contents (See F i g 3.3.3). There was 48 to 58 kg N/ha i n the c o n t r o l p l o t from GS 31 to 78. A f t e r that, i t dropped to 31 kg N/ha. The high mineral N contents i n the f i r s t year probably r e s u l t e d from the previous year's forage plowdown. In the second year of winter wheat growth at the same s i t e at Oyster River, mineral N i n s o i l decreased to 24 kg N/ha by the f i n a l i n c o n t r o l p l o t (See F i g 3.3.4). At Oyster River i n 1986-87, s o i l mineral N between the conventional and I.CM treatments had l i n e a r (P<0.001) and quadratic (P<0.05) i n t e r a c t i o n s i n 0-50 cm depth. In the e a r l y season, i n the conventional p l o t was higher than i n the I.CM. treatment p l o t . A f t e r f e r t i l i z e r N s p l i t t i n g , the l e v e l of s o i l N was increased i n the I. CM. p l o t which involved three s p l i t s t o t a l l i n g 225 kg N/ha. At crop GS 22, s o i l N was 56 and 43 kg/ha f o r the conventional and I.CM.. By f i n a l harvest, i t had decreased to 34 kg N/ha f o r the conventional and increased to 51 kg N/ha f o r I.CM.. 49 Soil N ( 0 - 5 0 cm) in Oyster River 1986-87 100 80 60 40 20 0 kg /ha GS32 GS33 GS68 GS78 GS22 GS31 GS95 J L. _1 1_ 5 6 m o n t h 0 kg N/ha — 7 5 kg N/ha - * ~ 225 kg N/ha F i g u r e . 3 . 3 . 3 50 Soil N ( 0 - 5 0 cm) in Oyster River 1987-88 0 2 i i 3 4 5 1 1 1 6 7 8 m o n t h — 0 kg N/ha 75 kg N/ha UR <- 225 kg N/ha UR - B - 225 kg N/ha AN F i g u r e 3 .3 .4 51 Delta S o i l s at both Delta s i t e s have s i l t y c l a y loam textures. In the Delta 1986-87 and 1987-88 experiments, the patterns of s o i l N i n the 0-50 cm depth through the growing season are presented i n F i g 3.3.5 and 3.3.6. From GS 31 to GS 55, s o i l N. i n a l l the 1986-87 treatments decreased. This coincided with the rapid accumulation of biomass. From GS 55 to harvest, s o i l N content i n the c o n t r o l and 75 kg N/ha treatment p l o t s were s i m i l a r . This might suggest that N was d e f i c i e n t i n the conventional (75 kg N/ha) treatment. At Delta 1987-88, there was a l i n e a r i n t e r a c t i o n (P<0.001) between con t r o l vs conventional and I.CM. (C and D) treatments i n s o i l 0-50 cm depth. However, there was no i n t e r a c t i o n between treatment C and D. S o i l mineral N contents at the f i r s t sampling at GS 31 were 81 and 97 kg N/ha f o r treatment C and D. At f i n a l sampling N l e v e l s were 28 and 37 kg/ha i n treatments C and D. 52 100 80 60 40 20 0 kg /ha F i g u r e 3 .3 .5 Soi l N ( 0 - 5 0 cm) in Delta 1986-87 GS31 GS55 GS78 GS68 GS95 5 m o n t h 0 kg N/ha 75 kg N/ha UR - * - 225 kg N/ha UR 53 Soil N ( 0 - 5 0 cm) in Delta 1987-88 experiment kg/ha 0 4 5 i i i 6 7 8 m o n t h i 9 0 kg N/ha 225 kg N/ha UR 75 kg N/ha UR - ° ~ 225 kg N/ha AN F i g u r e 3-3.6 54 3.4 CROP N CONCENTRATIONS Knowledge of nitrogen concentrations i n winter wheat can be usefu l f o r N f e r t i l i z e r management. Whole plant N concentrations f o r each of s i x s i t e s are presented i n Table 3.4.1. From GS 31 u n t i l GS 55, N concentrations decline quickly, while a f t e r GS 55 they decrease slowly. In comparison to the c r i t i c a l value of 3.2% t o t a l N at GS 31 necessary f o r maximum y i e l d s of hard red winter wheat i n Colorado, USA (Vaughan et a l . , 1990) the N concentrations fo r the 225 kg N/ha I. CM. treatment vary from 2.7% i n Agassiz 1986-87 to 5.1% i n Delta 1987-88. In the 225 kg N/ha I.CM. treatment where 50 kg N/ha was applied at GS 22, crop N concentrations were higher than the c o n t r o l and conventional treatments a f t e r GS 31. Nitrogen a p p l i c a t i o n should be made before crop elongation and t h i s i s a c r i t i c a l period f o r determining crop N concentration. At the c r i t i c a l GS 31, the Oyster River 1986-87 crop contained 4.0% N i n the 225 kg N/ha I.CM. treatment, and 3.2% N i n the c o n t r o l and 75 kg N/ha (conventional) treatments. The highest l e v e l of 5.1% N at GS 31 occurred i n 1988 at the Delta s i t e which produced the highest grain y i e l d of 11.9 t/ha. I t i s probably r e l a t e d to 55 the high y i e l d p o t e n t i a l at that s i t e . There i s a p o s s i b i l i t y that N concentration at GS 31 i s a useful i n d i c a t o r of crop needs f o r a d d i t i o n a l f e r t i l i z e r N required to optimize y i e l d s . 56 Table 3.4.1 Crop N concentrations at d i f f e r e n t s i t e s Site-Year Treatment Growth Stage 31 33 55 68 78 95 -% AG87 A 2.4 1.8 1.2 0.9 0.8 0.8 B 3.2 1.6 2.1 1.3 1.0 1.2 C 2.7 2.7 2.3 1.6 1.5 1.6 CH88 A 3.3 1.3 0.9 0.7 0.7 0.7 B 3.4 2.1 1.5 0.9 0.9 0.9 C 4.0 2.7 1.9 1.3 1.1 1.1 D 4.1 2.5 1.8 1.6 1.5 1.3 OY87 A 3.2 1.9 1.2 0.7 0.6 0.7 B 3.2 1.9 0.9 0.9 0.9 0.9 C 4.0 2.1 1.2 1.2 1.2 1.3 OY88 A 3.3 1.9 0.9 0.6 0.7 0.8 B 3.9 2.4 1.4 0.7 0.6 0.7 C 4.8 2.8 1.8 1.3 1.0 1.0 D 4.7 3.0 1.9 1.4 1.1 1.0 DE87 A 2.1 1.9 0.9 0.7 0.7 0.7 B 2.1 1.3 1.2 0.8 0.7 0.8 C 2.9 2.0 1.6 1.2 1.2 1.2 DE88 A 3 . 9 1.9 1.5 0.9 0.8 1.0 B 4.6 2 . 6 1.6 1.2 0.9 1.0 C 4.7 3.2 2.3 1.5 1.2 1.2 D 5.1 3.0 2 . 2 1.5 1.2 1.3 57 3.5 PATTERNS OF DRY MATTER YIELDS AND N UPTAKE Generally, dry matter accumulation and N uptake i n winter wheat increased with time (See Figures 3.5.1 to 3.5.12). In the e a r l y spring, crop dry matter accumulation and N uptake began slowly. A f t e r GS 32, dry matter y i e l d s began to show responses to d i f f e r e n t N treatments because the peak N demand occurs during elongation. By GS 33, the crop had accumulated one-half of the ultimate t o t a l dry matter y i e l d at each s i t e . The mass of dry matter was maximized at around l a t e milk stage (GS 78). A f t e r GS 78 the crop biomass at a l l s i t e s decreased s l i g h t l y u n t i l f i n a l harvest. Of the three N f e r t i l i z e r treatments, 225 kg N/ha gave the highest N uptake at a l l s i t e s i n d i c a t i n g that winter wheat i n the area had a high N requirement. There was l e s s N uptake from the 75 kg N/ha treatment than the 225 kg N/ha treatment, but dry matter production was s i m i l a r f o r the two N rates. The N uptake by u n f e r t i l i z e d winter wheat shows that the s i t e s had d i f f e r e n t p o t e n t i a l s for m i n e r a l i z i n g s o i l N. In the 1987-88 experiment, ammonium n i t r a t e and urea were compared at the Chilliwack, Delta, and Oyster River s i t e s . The trends of dry matter accumulation and N uptake 58 from ammonium n i t r a t e and urea were the same during crop growth. At f i n a l harvest, no s i g n i f i c a n t d i f f e r e n c e s were observed between ammonium n i t r a t e and urea except there were some dif f e r e n c e s during the e a r l y stage at Delta. Their r e s u l t s are s i m i l a r to those of Christensen and Meints (1982), i n north c e n t r a l Montana of the U.S.A., who reported that comparison of regression c o e f f i c i e n t s f o r e i t h e r grain y i e l d or t o t a l N uptake revealed no s i g n i f i c a n t differences between N sources. Spring top-dressed urea and ammonium n i t r a t e were equally e f f e c t i v e i n supplying N to wheat plants. The r e s u l t s of t h i s research suggest that urea i s s a t i s f a c t o r y f o r winter wheat i n Southern Coastal B.C. when the t o t a l N a p p l i c a t i o n approximates 225 kg N/ha (Temple and Bomke, 1990). Eastern Fraser V a l l e y At Agassiz i n 1987 there was l i t t l e d i f f e r e n c e i n dry matter accumulation among the f e r t i l i z e r treatments from GS 31 to 55 (See F i g 3.5.1). A f t e r GS 78, dry matter declined sharply i n the 225 kg N/ha treatment. At f i n a l harvest there was no s i g n i f i c a n t d i f f e r e n c e i n dry matter y i e l d s among the three N treatments. Leaf r u s t damaged almost a l l f l a g leaves at t h i s s i t e and prevented the increased N uptake and 59 vegetative growth response to f e r t i l i z e r N. Due to disease pressure, e f f i c i e n c y of N f e r t i l i z e r f o r the 225 kg N/ha (I.CM.) treatment was 29% i n Agassiz. Nitrogen uptake was highest i n the 225 kg N/ha treatment from GS 32 to GS 95 (See F i g 3.5.2). With r a p i d accumulation between GS 31 and 78, N uptake rates were approximately 0.45, 1.08, and 1.78 kg/ha/day i n the 0, 75, and 225 kg N/ha (I.CM.) treatments, r e s p e c t i v e l y . In the f i n a l harvest, the N uptakes were 78, 117 and 144 kg N/ha with 0, 75 and 225 kg/ha of f e r t i l i z e r N re s p e c t i v e l y . Dry matter accumulation and N uptake at Chilliwack i n 1987-88 are presented i n Figures 3.5.3 and 3.5.4. At t h i s l o c a t i o n there were only small d i f f e r e n c e s i n dry matter y i e l d among the f e r t i l i z e r treatments over the growing season (Fig 3.5.3). In ea r l y March 1988 during crop elongation (G.S. 31) the 2.0 t/ha of dry matter accumulation at Chilliwack was greater than 1.3 t/ha i n Agassiz 1986-87, 1.1 t/ha i n Oyster River 1986-87, 1.5 t/ha i n Delta 1986-87, and 0.6 t/ha i n Oyster River 1987-88. I t appears that s o i l and r a i n f a l l at Chilliwack (See F i g 3.1.2) were favorable fo r the ea r l y growth stage of winter wheat. Nitrogen uptake from the 225 kg N/ha applied as e i t h e r urea or ammonium n i t r a t e was c o n s i s t e n t l y higher than the wheat r e c e i v i n g 0 60 and 75 kg N/ha. However, there was no s i g n i f i c a n t d i f f e r e n c e between urea and ammonium n i t r a t e by f i n a l harvest. At Chilliwack i n 1987-88, N uptake i n l a t e March (GS 31) was 79 kg N/ha i n the 225 kg N/ha urea treatment and i t increased sharply from GS 31 to GS 33. A f t e r the middle of June, the crop lodged causing a 25 kg N/ha decline i n uptake. The high N l e v e l i n the e a r l y season plus poor drainage conditions caused the crop to lodge. At t h i s s i t e g rain y i e l d and N uptake were lower than at the other s i t e s . I t seems that a high N l e v e l e a r l y i n the season might cause a problem. However, dry matter accumulation increased u n t i l G.S. 78 and then declined (See F i g 3.5.3). During the growth season at the Chilliwack s i t e , there was a s i g n i f i c a n t l i n e a r i n t e r a c t i o n (P<0.05) i n N uptake between treatment C (I. CM. as urea) and D (I. CM. as ammonium n i t r a t e ) . The crop i n the ear l y stage at GS 31 took up more N from ammonium n i t r a t e (97 kg/ha) than from urea (79 kg/ha). Also, i t was higher i n the ammonium n i t r a t e p l o t than the urea p l o t l a t e i n season. At Eastern Fraser V a l l e y s i t e s , where growth conditions are warmer and wetter, the problems of disease and lodging 61 are c r i t i c a l i n N f e r t i l i z e r management. Lodging may also be a t t r i b u t e d to root r o t and eye spot disease i n poorly drained s i t e s . Leaf rust, septoria and powdery mildew were also common i n the area. Under high N f e r t i l i z a t i o n , i t i s necessary to apply fungicides f o r pr o t e c t i o n against these diseases. The choice of d i s e a s e - r e s i s t a n t v a r i e t i e s also deserves consideration. A d d i t i o n a l l y , the growth regulator Cycocel may prevent lodging (Temple and Bomke 1989). Under favorable growth, high rates of N f e r t i l i z a t i o n increase the r i s k of lodging and t h i s should be taken into account i n the N recommendation. 62 t/ha 15 10 0 Dry matter y ie lds in Agassiz 1986-87 GS68 GS5 GS78 GS95 GS31 Figure 3.5.1 5 6 m o n t h 0 kg N/ha — 7 5 kg N/ha 225 kg N/ha 63 2 5 0 2 0 0 150 100 50 0 kg /ha N uptake kg N / h a in Agassiz 1986-87 GS78 GS68 GS31 GS95 GS32 2 4 5 6 m o n t h 0 kg N/ha — 7 5 kg N/ha UR - * - 225 kg N/ha UR F i g u r e 3 .5 .2 64 Dry matter yields in Chilliwack 1987-88 25 20 . 15 10 5 0 t /ha GS68 GS55 GS78 GS95 GS31 2 3 4 i 5 I 1 1 6 7 8 m o n t h 0 k g N/ha — 75 k g N/ha UR - * - 225 k g N/ha UR — B — 225 k g N/ha AN F i g u r e 3 .5 .3 65 300 250 200 150 100 50 0 kg/ha N uptake kg N / h a GS78 in Chilliwack 1987-88 GS68 GS33 G S 5 5 GS31 GS95 5 6 m o n t h 0 kg N/ha 225 kg N/ha UR — 7 5 kg N/ha UR - ° - 225 kg N/ha AN F i g u r e 3 .5 .4 66 Oyster River The average N uptake at Oyster River i n 1987 was 22 kg N/ha by GS 22 (Fig 3.5.6). This i n d i c a t e s that small amounts of N are needed by the crop during the f a l l and winter months. There were di f f e r e n c e s among the f e r t i l i z e r treatments i n 1986-87. At f i n a l harvest, there were no s i g n i f i c a n t d i f f erences between 225 and 75 kg N/ha treatments i n dry matter y i e l d (Fig 3.5.5) but N uptake was s i g n i f i c a n t l y higher i n the 225 kg N/ha treatment. (Fig 3.5.6). Between the conventional and I.CM treatments, there was a s i g n i f i c a n t l i n e a r i n t e r a c t i o n (P=0.00) f o r N uptake suggesting that N uptake i n the ea r l y growth stages was s i m i l a r f o r the conventional and I.CM. treatments. Following the s p l i t a p p l i c a t i o n of the high N rate i n the I.CM. treatment, N uptake increased more than where the crop received the conventional rate of 75 kg of N/ha. In 1987-88, the dry matter accumulation increased up to G.S. 78 and then declined (Fig 3.5.7). Regardless of N source, 225 kg N/ha c o n s i s t e n t l y y i e l d e d higher than both the c o n t r o l and 75 kg N/ha treatments. There was no s i g n i f i c a n t d i f f e r e n c e between the t o t a l dry matter y i e l d s 67 of 16.9 and 15.7 t/ha obtained with urea and ammonium n i t r a t e , r e s p e c t i v e l y . In the second year of cropping s o i l N declined. In co n t r o l p l o t s , the f i n a l dry matter y i e l d s were 6.6 t/ha for the 1987-88 experiment compared to 10.3 t/ha f o r the 1986-87 experiment. The N uptake without f e r t i l i z e r was 81 and 52 kg N/ha f o r the 1986-87 and 1987-88 crop years r e s p e c t i v e l y . N de f i c i e n c y symptoms such as yellowing of lower leaves ( c h l o r o t i c leaves) were evident by A p r i l 1988 i n pl o t s r e c e i v i n g 0 and 75 kg N/ha. These r e s u l t s i n d i c a t e that N de f i c i e n c y l i m i t e d winter wheat development throughout the growing season. N uptake increased l i t t l e a f t e r GS 32 i n the con t r o l and 75 kg N/ha treatments. At Oyster River i n 1987-88, there was a quadratic i n t e r a c t i o n (P<0.01) i n crop N uptake between treatments C (I.CM. as urea) and D (I.CM. as ammonium n i t r a t e ) . Nitrogen uptake i n the treatment D had exceeded that i n treatment C during the GS 3 3 to 78 period, however, the two f e r t i l i z e r N sources d i d not d i f f e r e a r l y i n the spring at GS 31-32 nor at f i n a l harvest (Figure 3.5.8). 68 Dry matter yields in Oyster River 1986-87 2 3 4 5 6 7 8 m o n t h 0 kg N/ha — 7 5 kg N/ha —«~ 225 kg N/ha F i g u r e 3 .5 .5 69 N uptake kg N / h a in Oyster River 1986-87 F i g u r e 3 .5 .6 t /ha 20 15 10 5 0 Dry matter yields in Oyster River 1987-88 G S 6 8 G S 7 8 GS95 GS33 GS32 I - I 2 3 4 i 5 1 1 1 6 7 8 m o n t h —— 0 kg N/ha —i— 7 5 kg N/ha UR - * - 225 kg N/ha UR — B — 225 kg N/ha AN F i g u r e 3 .5 .7 71 N uptake kg N / h a in Oyster River 1987-88 2 5 0 200 150 100 50 0 kg/ha GS33 G S 5 5 G S 6 8 G S 7 8 G S 9 5 GS31 2 3 4 i 5 i i i 6 7 8 m o n t h — 0 kg N/ha — 75 kg N/ha UR — 2 2 5 kg N/ha UR 225 kg N/ha AN F i g u r e 3 .5 .8 72 Delta At the l o c a t i o n i n 1986-87, there was a serious weed problem a f t e r GS 68, and as a consequence only two blocks were used f o r sampling a f t e r that stage. Differences i n dry matter y i e l d s were minor among treatments i n the early stages (Fig 3.5.9). Nitrogen uptake i n the 225 kg N/ha (I.C.M.) treatment was high a f t e r GS 32 (Fig 3.5.10). The trends of dry matter y i e l d s f o r the three N l e v e l s (0, 75 and 225 kg N/ha) throughout the 1987-88 growing season are shown i n F i g (3.5.4). Unlike other s i t e s , the Delta 1987-88 experiment only s t a r t e d to accumulate dry matter during May. From GS'31 to 68, a l l treatments showed a s i m i l a r pattern. By the milk development stage (GS 78) , dif f e r e n c e s were evident. In the f i n a l harvest, a l l treatments here y i e l d e d more than at other s i t e s . Control p l o t y i e l d of 15.7 t/ha at f i n a l harvest was higher than the 14 t/ha f o r the con t r o l p l o t at Chilliwack i n 1988. The y i e l d of 20.6 t/ha obtained with 75 kg N/ha treatment i n 1988 was higher than the 16.8 t/ha at Chilliwack. In addition, the 22.5 t/ha y i e l d r e s u l t i n g from the 225 kg N/ha treatment here was higher than 18.5 t/ha f o r the same rate at Oyster River i n 1986-87. 73 In 1987-88, when the growing season was delayed f o r about 3 weeks, there were only small d i f f e r e n c e s i n dry matter y i e l d s among the f e r t i l i z e r treatments from G.S. 31 to GS 78 (Fig 3.5.11). This i n d i c a t e s to that a v a i l a b l e s o i l N was not l i m i t i n g dry matter production. However, there were large d i f f e r e n c e s i n N uptake (Fig 3.5.12). At f i n a l harvest there were s i g n i f i c a n t d i f f e r e n c e s i n dry matter y i e l d s and N uptake between the c o n t r o l and I. CM. treatments. Also, during the growing season i n Delta 1987-88, there was no s i g n i f i c a n t l y l i n e a r (P=0.304) quadratic (P=0.567) i n t e r a c t i o n s between the I.CM urea and ammonium n i t r a t e treatments. In the presence of a r i c h N supply i n s o i l at the Delta s i t e , there were no di f f e r e n c e s between the two N sources. In the co n t r o l the f i n a l N uptake was 151 kg N/ha, the highest s o i l N m i n e r a l i z a t i o n i n the study. The 24.6 t/ha dry matter y i e l d and 323 kg/ha of N uptake with 225 kg N/ha as ammonium n i t r a t e was the highest t o t a l y i e l d and N uptake at any s i t e i n the two years of research. This might be r e l a t e d to several f a c t o r s . The crop was heavily grazed by birds i n the ea r l y stage (December) so that crop vegetative growth was delayed during the following spring. A le s s severe winter i n Delta might be b e n e f i c i a l to crop growth and dry matter and N accumulation. Also, the lower 74 temperatures during the g r a i n f i l l i n g period might contribute to a much higher y i e l d (Stoskopf 1981). there were other important f a c t o r s such as low disease and lodging pressure combined the deep and f e r t i l e s o i l i n Delta makes i t i d e a l f o r winter wheat growth. High y i e l d i n g crops take up more N than low y i e l d i n g ones. The I.CM. treatment r e c e i v i n g 225 kg N/ha r e f l e c t s t h i s . However, supplying adequate N i s only one aspect of achieving the desired high y i e l d . Apart from crop N management, s o i l type and climate are the main fact o r s i n f l u e n c i n g y i e l d p o t e n t i a l . The higher N recommendations should only be used where high y i e l d s can be r e a l i s t i c a l l y achieved. Use of N i n excess of that appropriate to a r e a l i s t i c y i e l d l e v e l w i l l decrease p r o f i t and increase p o l l u t i o n r i s k . 75 Dry matter yields in Delta 1986-87 experiment 0 N/ha 75 N/ha 225 N/ha F i g u r e 3 .5 .9 76 N uptake In Delta 1986-87 experiment GS78 GS95 3 4 5 6 7 m o n t h O N 7 5 N / h a - * ~ 2 2 5 N / h a F i g u r e 3.5.10 77 Dry matter y ields in Delta 1987-88 experiment t /ha 30 25 20 15 h 10 5 0 GS31 GS78 GS95 GS68 S 3 * ! I I I I 4 5 6 m o n t h 7 8 9 — 0 kg N/ha - * - 225 kg N/ha UR — B — 75 kg N/ha UR 225 kg N/ha AN F i g u r e 3.5.11 78 N uptake in Delta 1987-88 experiment F i g u r e 3.5.12 3.6 NITROGEN IN THE SOIL/PLANT SYSTEM Nitrogen was monitored i n the s o i l / p l a n t system of winter wheat i n Southern Coastal B.C.. Both s o i l s and crops were analyzed f o r N. The increases i n crop N uptake over the co n t r o l f o r the conventional N a p p l i c a t i o n (75 kg N/ha by GS 31) are presented i n Table 3.6.1.. Also, Table 3.6.2 summarizes the r e s u l t s of the intensive crop management (I. CM.) treatment with a t o t a l of 225 kg N/h applied i n three s p l i t s . TABLE 3.6.1 Difference of crop N-uptake between co n t r o l and 75 kg N/ha treatments GS AG87 CH88 OY87 OY88 DE87 DE88 kg N / h a — 32 -11 -3 5 47 -24 40 33 2 85 29 50 -4 30 55 41 86 30 41 15 42 68 60 33 53 45 50 67 78 66 37 55 29 56 67 95 39 64 57 39 12 57 80 In the Netherlands, D i l z (1988) reported that with the large amount of N required by winter wheat, s p l i t t i n g the N a p p l i c a t i o n reduced N leaching, e s p e c i a l l y i n areas with wet conditions. At Chilliwack i n 1988, the I.CM. treatment r e s u l t e d i n a uniform increase i n N uptake throughout the growing season. Although the experiment was not designed to t e s t a p p l i c a t i o n method, s p l i t t i n g N a p p l i c a t i o n s added N close to the time of crop N uptake and reduced the r i s k of lose. A f t e r the early 50 kg N/ha at GS 22 f o r I.CM., N uptake with ammonium n i t r a t e at GS 31 was 20-37 kg/ha as compared to 5-19 kg N/ha with urea (Table 3.6.2). This indicated that higher N uptake i n I.CM. occured with ammonium n i t r a t e . 81 Table 3.6.2 Difference of crop N-uptake between co n t r o l and 225 kg N/ha treatments Urea GS AG87 CH88 OY87 OY88 DE87 DE88 kg N/ha— 31 -2 19 5 17 2 5 32 40 35 21 94 32 69 33 52 128 82 117 77 51 55 74 153 82 99 77 77 68 80 104 112 141 98 109 78 142 108 83 142 135 109 95 66 121 154 123 137 136 Ammonium N i t r a t e GS AG87 CH88 OY87 0Y88 DE87 DE88 -• kg N/ha 31 37 20 33 32 31 106 58 33 139 135 113 55 148 158 118 68 138 164 162 78 128 171 163 95 108 113 172 82 Table 3.6.3 Difference of s o i l N (0-50cm) between con t r o l and 75 kg N/ha treatment GS AG87 CH88 OY87 OY88 DE87 DE88 — k g N/ha : 31 3 1 -3 1 4 21 32 2 4 28 9 2 1 33 11 4 15 1 17 6 55 2 10 -9 8 -6 3 68 -3 -1 16 22 13 -3 78 1 3 0 -2 3 -2 95 3 8 3 1 1 0 In the 0-50 cm depth, s o i l N contents i n a l l treated p l o t s decreased and were close to the co n t r o l p l o t s from GS 31 to GS 55. This coincided with the rapid biomass accumulation period. The s o i l mineral N i n the conventional 75 kg N/ha treatment hardly d i f f e r e d from the c o n t r o l (Table 3.6.3). From GS 55 to harvest, s o i l N contents i n the co n t r o l and 75 kg N/ha treatments were s i m i l a r . That might i n d i c a t e N d e f i c i e n c y i n the 75 kg N/ha treatment. 83 The I. C M N-application r e s u l t e d i n a considerable increase i n N-uptake, whereas the e f f e c t on s o i l N was r e l a t i v e l y small. The 225 kg N/ha (I.CM.) treatment gave a moderate increase of mineral s o i l N (Table 3.6.4). Also, the I.CM. treatment not only increased N uptake i n the crop, but also r a i s e d the a v a i l a b l e N l e v e l during the season. Approximately, N uptake rates from GS 31 to 78 were 0.5, 0. 9, and 1.5 kg/ha/day fo r the c o n t r o l , conventional and 1. CM., r e s p e c t i v e l y . Nitrogen use e f f i c i e n c y i s important from an environmental point of view, since any nitrogen that i s not recovered by the crop can be l o s t from the s o i l / p l a n t system. I t i s important to know to what extent N i s recovered by the crop and whether N i s l e f t i n the s o i l . The r e s u l t s are shown i n Table 3.6.5. The f i n a l harvest data showed the N e f f i c i e n c y ranged from 48 to 85%, except f o r two low values caused by disease and weeds i n Agassiz and Delta i n 1987. Under I.CM. treatments, the ranges were -4-74%, 26-73%, and 37-76% by GS 31, 33, and 78 r e s p e c t i v e l y . That i n d i c a t e s the large amounts of f e r t i l i z e r N recovered by winter wheat through the season. 84 Table 3.6.4 Difference of s o i l N (0-50 cm) between co n t r o l and 225 kg N/ha treatment Urea GS AG87 CH88 0Y87 OY88 DE87 DE88 kg N/ha 31 14 21 7 13 -29 40 32 9 5 34 15 3 46 33 44 11 35 -3 30 17 55 62 12 -13 18 6 24 68 48 -4 24 11 20 11 78 32 4 25 14 8 10 95 43 26 20 16 26 3 Ammonium N i t r a t e GS AG87 CH88 OY87 OY88 DE87 DE88 kg N/ha 31 15 14 56 32 -1 18 43 33 15 -5 29 55 19 11 20 68 -2 22 7 78 18 14 9 95 36 13 12 85 Table 3.6.5 Crop uptake of f e r t i l i z e r N added point to the indicated growth stages 75 kg N/ha treatment GS AG87 CH88 OY87 OY88 DE87 DE88 % 32 -15 -4 7 63 -32 53 33 3 111 39 67 -5 40 55 55 115 40 55 20 56 68 8 44 71 60 7 89 78 88 49 73 39 75 89 95 52 85 76 52 16 76 225 kg N/ha treatment as urea % 31 -4 38 10 34 4 10 32 23 20 12 54 18 39 33 30 73 47 67 44 26 55 33 68 36 44 34 34 68 36 46 50 63 44 48 78 60 48 37 63 60 48 95 29 54 68 55 61 60 225 kg N/ha treatment as ammonium n i t r a t e % 31 74 40 66 32 14 47 26 33 62 60 50 55 66 70 52 68 61 73 72 78 57 76 72 95 48 50 76 86 3.7 MODELS OF N-UPTAKE AND DRY MATTER YIELDS Control P l o t The M u l t i p l i c a t i v e model f o r the t o t a l dry matter y i e l d and the amount of N uptake i n the 0 kg N/ha treatment are shown i n Figure (3.7.1). lnY = ln3.047 + 0.6481nX, Y = 21.05 X 0 ' 6 4 8 , Where Y = N uptake i n kg/ha and X = dry matter y i e l d i n t/ha. The regression model was also the one that presented the best f i t (R-squared =77%), standard error (0.397) , and c o r r e l a t i o n c o e f f i c i e n t (0.88). The model f o r c o n t r o l would show the N accumulation f o r winter wheat i n South Coastal B.C. with only s o i l N a v a i l a b l e . Obviously, N accumulation was slow and N content was low. I f the dry matter y i e l d was 15 t/ha at harvest time, N content might only be 110 kg/ha f o r the c o n t r o l . 87 Regi esjitxi ol II on ft-ij miter For 8 H ll/ha tn>>tn*it - j — | — | — , — , — j — i — i i — i — f — i — i — i — i — | — i — i — r ~ - r — | — i r i i — | — i i i r " j -• * • i I i i i i I i i i i I i i i i I i—i—i—i—I—i—i—i—i—L 88 Conventional N management The M u l t i p l i c a t i v e model f o r the t o t a l dry matter y i e l d and the amount of N uptake present i n 75 kg N/ha treatment i s shown i n Figure (3.7.2). lnY = ln3.546 + 0.5311nX, Y = 34.69 X 0 ' 5 3 1 ' The regression model was also the one that presented the best f i t (R-squared =79%), the standard error (0.282), and c o r r e l a t i o n c o e f f i c i e n t (0.89). The model f o r 75 kg N/ha treatment would p r e d i c t the N required during the growing season f o r conventional N management i n South Coastal B.C. I f the dry matter y i e l d was 5 t/ha at G.S. 33, when crop elongated, N uptake might be 90 kg/ha which was much higher than the c o n t r o l s i t e . Late season crop dry matter increase N accumulated slowly. The slope i n the 75 kg N/ha conventional treatment was 34.69. I t was higher than 21.05 f o r the c o n t r o l and lower than 40.95 f o r I.CM.. I t might i n d i c a t e that a N shortage happened i n l a t e season f o r the 75 kg N/ha conventional N management. 89 Regression of II MI Dry natter For 7j k9 ll ' lu treitnnit Ma 90 Intensive N management Under the 225 kg N/ha treatment, the m u l t i p l i c a t i v e model f o r the t o t a l dry matter y i e l d and the amount of N uptake i s shown i n F i g (3.7.3). lnY = ln3.712 + 0.5991nX, Y = 40.95 X 0 , 5 9 9 , The regression model was also the one that presented the best f i t (R-squared = 88%), standard error (0.227) and c o r r e l a t i o n c o e f f i c i e n t (0.94). Compared to the conventional N management model (75 kg N/ha) , the model f o r intensive N management (225 kg N/ha) suggests a large amount of N uptake throughout the season. For example, 5 t/ha of dry matter contained 90 kg N/ha i n the conventional N management and 100 kg N/ha i n the intensive N management. Another example, i f crop dry matter accumulated 15 t/ha a f t e r 4 months growth, N uptake would amounts to 12 0, 146 and 2 07 kg/ha f o r the control, conventional and I.CM. regimes, r e s p e c t i v e l y . This l a t t e r model also represents the p o t e n t i a l f o r N uptake when s o i l N i s not l i m i t i n g . 91 Regression of II on fry ostler For 2J5 Ig H/hi 92 SUMMARY AND CONCLUSIONS Winter wheat i s used as the i n i t i a l t e s t crop f o r assessing intensive crop management of over-winter crops i n south coa s t a l B.C.. The aim of t h i s t h e s i s was to evaluate crop and s o i l N behavior under conventional and intensive N management. • The study was conducted at f i e l d s i t e s at Agassiz, Chilliwack, Oyster River, and Delta during 1986-87 and 1987-88. Wheat received three treatments; A (0 kg N/ha) for c o n t r o l , B (75 kg N/ha) f o r conventional, and C (225 kg N/ha) f o r I.CM.. In 1986-87, the source of f e r t i l i z e r N was urea f o r a l l treatments. In 1987-88, the 225 kg N/ha rate was also added as ammonium n i t r a t e (D) . From the early spring to crop harvest, 0-20 and 20-50 cm s o i l and above ground plant samples were c o l l e c t e d from a subplot within each treatment. Samples of s o i l and plant were taken at a s e r i e s of dates and growth stages. The following information on winter wheat might be u s e f u l i n understanding crop y i e l d , s o i l N supply, and N f e r t i l i z e r response under l o c a l conditions; 93 1) In the 0-50 cm depth, s o i l N i n a l l treatment p l o t s decreased from GS 31 to GS 55. This coincided with the rapid biomass accumulation period. From GS 55 to harvest, s o i l N contents i n the cont r o l and 75 kg N/ha treatments were s i m i l a r . That might i n d i c a t e N d e f i c i e n c y i n the 75 kg N/ha treatment. 2) In the early spring, crop dry matter and N uptake begins slowly. A f t e r G.S. 32, dry matter y i e l d s began to respond to f e r t i l i z e r N a p p l i c a t i o n . The mass of dry matter was maximized at around l a t e milk stage (GS 78). A f t e r GS 78 the crop biomass at a l l s i t e s decreased s l i g h t l y u n t i l f i n a l harvest. With ra p i d accumulation between GS 31 and 78, N uptake rates are approximately 0.5, 0.9, and 1.5 kg/ha/day i n the c o n t r o l , conventional, and I.CM., r e s p e c t i v e l y . 3) Relative to the c o n t r o l , I.CM. gave a high response i n dry matter and N uptake y i e l d s i n a l l s i t e s regardless of source of N. I t indicates that winter wheat i n the area has a high N requirement. The conventional treatment gave considerably l e s s N uptake response than the I. CM. treatment but was usually s i m i l a r i n dry matter y i e l d s . By the f i n a l harvest, there was no d i f f e r e n c e i n grain y i e l d and N uptake between ammonium n i t r a t e and urea under I.CM.. 94 4) Nitrogen d e f i c i e n c i e s occur due to inadequate rates of N f e r t i l i z a t i o n , excessive r a i n f a l l or inappropriate N a p p l i c a t i o n . In t h i s area, N d e f i c i e n c i e s showed up i n the conventional N management. In addition, I.CM. r e s u l t e d i n a higher crop t o t a l N-recovery and higher grain protein contents. There was no s i g n i f i c a n t d i f f e r e n c e i n grain y i e l d at f i n a l harvest between 75 and 225 kg N/ha, but protein concentrations were increased by the higher N rate. The grain p r o t e i n ranged from 10 to 13.7% f o r I.CM. and 8.2 to 9.7 f o r the conventional. 5) The N uptake by u n f e r t i l i z e d winter wheat i n the area shows that the s i t e s have d i f f e r e n t p o t e n t i a l s f o r mi n e r a l i z i n g N. In the con t r o l p l o t s at f i n a l harvest, the t o t a l dry matter y i e l d and N uptake i n Delta and Chilliwack 1987-88 were s i g n i f i c a n t l y higher than Agassiz 1986-87 and Oyster River 1986-87 and 1987-88. Nitrogen uptake i n the co n t r o l p l o t s ranged from 52 to 151 kg/ha f o r the study. 6) The r e l a t i o n s h i p s between N uptake and dry matter y i e l d f o r the three l e v e l s of N management i n south coastal B.C. are as follows; Y = 21.05 X 0 , 6 4 8 , (0 kg N/ha) 95 Y = 34.69 X 0 , 5 3 1 , (75 kg N/ha) Y = 40.95 X 0 , 5 9 9 , (225 kg N/ha) where Y = N uptake kg/ha, X = d r y matter y i e l d t/ha. These show t h a t N uptake i n c r e a s e s w i t h d r y matter a c c u m u l a t i o n . F o r t h e 75 kg N/ha, i t i n d i c a t e s t h a t a N s h o r t a g e happened i n t h e l a t e season. A l s o , t h e model f o r th e 225 kg N/ha treatment r e p r e s e n t s t h e p o t e n t i a l f o r N uptake when s o i l N i s not l i m i t i n g , and shows a l a r g e amount of N uptake through t h e season. 96 BIBLIOGRAPHY Adams, D. , and S. L. Chapman, 1984. Monitoring wheat fo r n u t r i t i o n a l and disease l e v e l s as a management decision a i d . p. 20. Agronomy Abstracts ASA, Madison, WI. Altman, D.W., W.L. McCuistion, and W.E. Kronstad 1983. Grain p r o t e i n percentage, kernel hardness, and gra i n y i e l d of winter wheat with f o l i a r applied urea. Agron. J . 75:87-89. Austin, R.B., J.A. Edrich, M.A. Ford, and R.D. Blackwell. 1977. The fate of dry matter, carbohydrates and 14C l o s t from the leaves and stems of wheat during grain f i l l i n g . Ann. Bot. 41:1309-1321. Baethgen, W.E., and M.M. A l l e y , 1989a. Optimizing s o i l and f e r t i l i z e r nitrogen use by i n t e n s i v e l y managed winter wheat. I. crop nitrogen uptake. Agron. J . 81:116-120. Baethgen, W.E., and M.M. A l l e y , 1989b. Optimizing s o i l and f e r t i l i z e r nitrogen use by i n t e n s i v e l y managed winter wheat. I I . c r i t i c a l l e v e l s and optimum rates of nitrogen f e r t i l i z e r Agron. J . 81:120-125. 97 Beringer, V. H., and G. Hess. 1979. Braauchbarkeit der pflanzenanlze zur bemessung spater N-gaben zu winterweizen. Landwirtsh. Forsch. 32:384-394. Brown B.D. 1986. Nutrient Uptake i n High-Yielding Wheat Better Crops/Spring 1986-27. Chaney, K. , and G.A. Paulson. 1988. F i e l d experiments comparing ammonium n i t r a t e and urea top-dressing f o r winter cereals and grassland i n the U.K.. J . Agr i c . S c i . Camb. 110:285-299. Christensen, N.W., and V.W. Meints, 1982. Evaluating N f e r t i l i z e r source and timing f o r winter wheat. Agr. J. 70:840-844. Dahnke, W.C. 1983. Choosing a crop y i e l d goal. p.69-70, In 1984 Crop production guide. North Dakota" State Univ., Fargo. D i l z , K. 1988. E f f i c i e n c y of uptake and u t i l i z a t i o n of f e r t i l i z e r N by plants. In D.S. Jenkinson (ed) N e f f i c i e n c e i n a g r i c u l t u r a l s o i l . E l s . Sc. Pub. Inc. London. 98 Donohue, S.J., and D.E. Brann. 1984. Optimum N concentration i n winter wheat grown i n the Coastal P l a i n region of V i r g i n i a . Commun. S o i l S c i . Plant Anal. 15:651-661. Engel, R. E., and J . C. Zu b r i s k i . 1982. Nitrogen concentrations i n spring wheat at several growth stages. Commun. S o i l S c i . Plant Anal. 15:651-666. Fowler, D.B., and I.A. de l a Roche. 1984. Winter wheat production on the north c e n t r a l Canadian P r a i r i e s : Protein q u a l i t y c l a sses. Crop S c i . 24:873-876. Gallagher, P.J., L.S. Murphy, C.L. Harms, and W.A. Moore. 1973. Comparisons of e f f e c t s of nitrogen c a r r i e r s , rates and time of a p p l i c a t i o n on y i e l d and q u a l i t y of winter wheat. Kansas Fert. Res. Rep. Prog. 202:59-60. Gardner, E.H., and N.R. Goetze. 1980. Oregon State U n i v e r s i t y f e r t i l i z e r guide f o r winter wheat(non-irrigated Columbia Plateau). FG 54. Oregon State Univ. Ext. Serv., C o r v a l l i s . 99 Giaquinta, R.T. 1983. Phloem loading of Source. Ann. Rev. Plant P h y s i o l . 34:347-387. Goos, R.J. 1983. Small gr a i n s o i l f e r t i l i t y i n v e s t i g a t i o n s , 1979-1983. North Dakota Farm Res. 41(1) '.21-29, 33. Goos, R.J. 1984. Post-harvest evaluation of nitrogen management-a new approach f o r " s e l l i n g " s o i l t e s t i n g to wheat farmers. J . Agron. Educ. 13:103-106. Gregory, P.J., D.V. Crawford, and M.McGowan. 1979. Nutrient r e l a t i o n s of winter wheat. I I . Movement of nutrie n t s to the root and t h e i r uptake. J . Ag r i c . S c i . 93:495-504. Guthrie, T.F., 1981. Evaluation of the n i t r i f i c a t i o n i n h i b i t o r s N-serve and ATC with urea f e r t i l i z e r . Ph.D. t h e s i s i n Dept. of S o i l S c i . UBC. Halvorson A.D., M.M. A l l e y and L.S. Murphy. 1987. Nutrient requirements and f e r t i l i z e r use.In E.G. Heyne (ed) 2nd Wheat and wheat improvement. Madison, Wisconsin, USA. p345-395. 100 Harper,. L.A., R.R. Sharpe, G.W. Langdale, and J.E. Giddens. 1987. Nitrogen c y c l i n g i n a wheat crop: S o i l , plant, and a e r i a l nitrogen transport. Agron. J . 79:965-973. Kirby, E.J.M. 1983. Development of the c e r e a l plant, pp. 1-3. In D.W. Wright (ed.) The y i e l d of c e r e a l s . Royal A g r i c u l t r u e Society of England, London. Koehler, F.E. 1985. Wheat takes up much plant food. Potash and Phosphate I n s t i t u t e Pamphlet. Ledingham, R.J., T.G. Atkinson, J.S. Horricks, J.T. M i l l s , L.J. Piening, and R.D. T i n l i n e . 1972. Wheat losses due to common root r o t i n the P r a i r i e provinces of Canada 1969-1971. Can Plant Dis. Surv. 53:113-112. Prasad, R., G.B. Rajale, and B.A. Lakhdive. 1971. N i t r i f i c a t i o n retarders and slow-release nitrogen f e r t i l i z e r s . Adv. Agron. 23: 337-383. Pumphrey, F.V., and P.E. Rasmussen. 1982. Winter wheat f e r t i l i z a t i o n i n the northeast intermountain region of Oregon. Oregon State Univ. Agric. Exp. Stn. C i r c . 691. 101 Simmons, R.G.. 1982. T i l l e r and ear production of winter wheat. F i e l d Crop Abstr. 35:875-870. Stanford, G. 1982. Assessment of s o i l nitrogen a v a i l a b i l i t y . In F.J. Stevenson (ed.) Nitrogen i n a g r i c u l t u r a l s o i l s . Agronomy 22:651-688. Stoskopf, N.C. 1981. Undersatanding crop production. Reston Pub. Con. Inc. V i r g i n i a USA. Technology Transfer. 1974. Manual of methods for chemical analysis of water and wastes. US Environmental Protection Agency. p l l 6 4 . Temple, W.D. and A.A. Bomke. 1989. U.B.C. progress report on intensive winter c e r e a l production system f o r south coa s t a l B.C.. Vaughan, B., K. A. Barbarick, D. G. Wes t f a l l and P. L. Chapman. 1990. Tissue N l e v e l s of dryland hard red winter wheat. Agron. J . 82 (3):561-565. 102 Widdowson F. V., A. Penny, R. J . Darby, E. B i r d and M. V. Hewitt 1986. Amounts of N03-N and NH4-N i n s o i l , from autumun to spring, under winter wheat and t h e i r r e l a t i o n s h i p to s o i l type, sowing date, previous crop and N uptake at Rothamsted, Woburn and Saxmundham, 1979-85. J . A g r i . S c i . , Camb. 108:73-95. Zadoks, J . C. , Chang, T. T. and Konzak, C. F. 1974 A decimal code f o r the growth stages of cer e a l s . Weed Res. 14, 415-421. 103 APPENDIX I Weather data of study s i t e s Monthly mean temperatures and p r e c i p i t a t i o n Agassiz Oyster River Delta 1986-87 month C* 0 (mm) C A0 i (mm) C" 0 (mm) Sep 15 . 1 101. 3 13. 1 38. 3 13 .9 67. 4 Oct 12 . 1 113. 0 9. 5 44. 4 10 .1 35. 9 Nov 5 .3 361. 0 4. 9 248. 1 5 .7 162. 0 Dec 4 . 1 136. 9 3. 6 290. 8 3 .9 129. 3 Jan 3 .4 238. 4 3. 9 248. 6 3 .8 138. 4 Feb 6 .4 67. 6 5. 4 174. 3 6 .3 66. 6 Mar 8 .5 164. 6 5. 9 171. 2 7 .9 118. 8 Apr 11 .4 173 . 6 7. 6 70. 5 10 .5 78. 8 May 13 .4 145. 5 12. 1 86. 7 13 .0 68. 0 Jun 16 .7 39. 2 14. 7 19. 8 15 .8 10. 4 J u l 17 .6 106. 2 16. 5 71. 1 17 .3 32. 9 Aug 18 .6 13. 8 16. 0 12. 6 16 .9 14. 0 Chilliwack Oyster River Delta 1987-88 month C" 0 (mm) C A0 (mm) C" 0 (mm) Sep 17 .0 66. 2 14. 2 25. 4 15 .2 18. 0 Oct 12 .5 35. 2 8. 8 31. 0 9 .8 26. 4 Nov 7 .5 181. 9 5. 8 204. 8 8 . 1 117. 4 Dec 1 .6 292. 0 2. 8 216. 4 3 .4 145. 1 Jan 0 .9 221. 0 2. 9 187. 7 3 .2 80. 2 Feb 4 .8 194. 8 4. 2 76. 7 5 . 3 60. 2 Mar 6 .7 325. 6 5. 6 140. 2 6 .9 121. 2 Apr 10 .0 255. 8 8. 4 79. 2 10 .0 94. 3 May 13 .4 192 . 6 10. 9 63 . 1 12 .7 127. 1 Jun 15 . 6 66. 2 13. 9 40. 8 15 .3 36. 0 J u l 18 .5 119. 4 16. 9 25. 6 18 .0 31. 0 Aug 18 .5 64. 8 16. 9 21. 4 17 .6 27. 8 104 Appendix II Analysis of variance f o r the f i n a l dry matter y i e l d s i n treatment A Source of var. Sum of Sq. d.f. Mean Sq. F - r a t i o S i g . l e v e l Between groups 254.13907 5 50.827 12.896 0.0000 Within groups 63.06267 16 3.941417 Total(corrected) 317.20 21 2 missing values have been excluded. Confidence l e v e l : 95% Mu l t i p l e range analysis f o r the f i n a l DM i n treatment A by s i t e s S i t e Count Average Homogeneous Groups OY88 4 6.645000 * AG87 4 9.405000 * * OY87 4 10.29074 * * DE87 2 13.80500 * * CH88 4 15.25500 * DE88 4 15.68500 * 105 Appendix I I I Analysis of variance f o r the f i n a l N uptake i n treatment A Source of var. Sum of Sq. d.f. Mean Sq. F - r a t i o S i g . l e v e l Between groups 23940.092 5 4788.02 16.129 0.0000 Within groups 4749.783 16 296.8614 Total(corrected) 28689.9 21 2 missing values have been excluded. Confidence l e v e l : 95% Mul t i p l e range analysis f o r the f i n a l N uptake i n treatment A by s i t e s S i t e Count Average Homogeneous Groups OY88 4 51.62450 * AG87 4 77.59500 * * OY87 4 80.71319 * * * DE87 2 101.0000 * * CH88 4 115.2800 * * DE88 4 151.3115 * 106 APPENDIX IV Mean, standard deviations and contrast f o r gra i n y i e l d s on d i f f e r e n t s i t e s Agassiz 1986-87 Treatment A B C Contrast F P r o b a b i l i t y MN 4.2 4.4 3.8 A vs B + C 3. 28 0.120 SD 0.46 0.62 0.712 B vs C 3 . 82 0.098 Oyster River 1986-87 Treatment A B C Contrast F P r o b a b i l i t y MN 4.5 7.3 8.1 A vs B + C 13 .5 0.010 SD 0.84 0.81 1.61 B vs C 0. 58 0.476 Chilliwack 1987-88 Treatment A B C D Contrast F P r o b a b i l i t y MN 4.2 5.8 5.3. 5. 5 A vs B+C+D 19 . 8 0.002 SD 0.39 0.49 0.58 0. 26 B vs C+D 1. 29 0. 285 C vs D 0. 16 0.703 Oyster River 1987-88 Treatment A B C D Contrast F P r o b a b i l i t y MN 2.9 5.1 6.9 6. 2 A vs B+C+D 23 .4 0. 001 SD 0.94 1.31 1.29 0. 35 B vs C+D 4. 75 0. 057 C vs D 0. 77 0.403 Delta 1987-88 Treatment A B C D Contrast F P r o b a b i l i t y MN 7.8 9.9 11.4 11 .9 A vs B+C+D 17 . 2 0. 003 SD 1.35 1.31 1.98 1. 03 B vs C+D 3. 52 0.094 C vs D 0. 29 0.603 107 APPENDIX V Mean, standard deviations and contrast f o r grain p r o t e i n on d i f f e r e n t s i t e s Agassiz 1986-87 Treatment A B C Contrast F P r o b a b i l i t y MN 7.8 8.4 10.0 A vs B + C 142.4 0.000 SD 0.29 0.65 0.50 B vs C 89.9 0. 000 Oyster River 1986-87 Treatment A B C Contrast F P r o b a b i l i t y MN 7.8 8.2 10.9 A vs B + C 13.5 0. 010 SD 0.84 0.81 1.61 B vs C 0.58 0.476 Chilliwack 1987-88 Treatment A B C MN 7.8 9.7 12.8 SD 0.45 0.29 0.85 D Contrast F 13.7 A VS B+C+D 106.4 1.03 B VS C+D 66.4 C vs D 3.00 Pr o b a b i l i t y 0.000 0. 000 0.117 Oyster River 1987-88 Treatment A B C MN 8.0 9.7 11.4 SD 0.75 0.45 0.70 D Contrast F 11.3 A vs B+C+D 2 6.2 0.85 B vs C+D 65.4 C vs D 0.06 P r o b a b i l i t y 0. 000 0.000 0.810 Delta 1987-88 Treatment A B C MN 8.8 9.7 11.2 SD 0.85 0.95 0.86 D Contrast F 11.3 A vs B+C+D 16.0 0.25 B V S C+D 9.49 C vs D 0.04 P r o b a b i l i t y 0. 003 0.013 0.838 108 APPENDIX VI T o t a l s o i l N (0-50 mm) i n A g a s s i z 1986-87 Treatment A B C C o n t r a s t F-value P r o b a b i l i t y kg N/ha GS31 28 31 42 L i n e a r GS32 31 33 40 A vs B,C 1 .45 0. 232 GS33 57 68 101 B vs C 6 .42 0. 014 GS55 40 42 59 GS68 40 37 102 Q u a d r a t i c GS78 32 33 64 A vs B,,C 0 . 34 0. 560 GS95 31 33 74 B vs C 0 .87 0. 353 Dry matter y i e l d s i n A g a s s i z 1986- 87 Treatment A B C t/ha GS31 1.6 1.2 1.3 L i n e a r GS32 3.0 2.6 3.6 A vs B,C 11 .10 0 . 001 GS33 6.9 4.3 6.0 B vs C 0 .12 0. 727 GS55 7.2 9.3 9 . 8 GS68 11.5 10.0 12.6 Q u a d r a t i c GS78 11.0 12.7 14 . 5 A vs B,C 3 .13 0 . 082 GS95 9 . 4 12.2 11.1 B vs C 4 .74 0. 033 N uptake i n A g a s s i z 1986-87 Treatment A B C kg N/ha GS31 37 35 35 L i n e a r GS32 55 44 95 A vs B,C 19. 01 0. 000 GS33 86 88 138 B vs C 0 . 51 0 . 476 GS55 84 125 158 GS68 105 111 185 Quadrat i c GS78 86 152 228 A vs B,C 5. 31 0. 025 GS95 78 117 144 B vs C 14 . 43 0. 000 109 APPENDIX VII Tot a l s o i l N (0-50 mm) i n Oyster River 1986-87 Treatment A B C Contrast F-value P r o b a b i l i t y kg N/ha GS22 48 56 43 GS31 53 50 60 Linear GS32 56 84 89 A vs B,C 0. 59 0. 441 GS33 51 66 86 B vs C 7. 91 0. 006 GS55 59 50 46 GS68 53 69 77 Quadratic GS78 58 58 83 A vs B,C 1. 55 0. 216 GS95 31 34 51 B vs C 5. 23 0. 024 Dry matter y i e l d s i n Oyster River 1986-87 Treatment A B C t/ha GS22 0.5 0.7 0.5 GS31 1.2 1.1 1.1 Linear GS32 3.0 2.5 2.7 A VS B,C 71. 49 0. 000 GS33 4.6 4.4 6.6 B vs C 7. 09 0. 009 GS55 9.1 10.2 12.4 GS68 11.7 13.7 14.6 Quadratic GS78 11.4 14.4 16.2 A vs B,C 1. 98 0. 162 GS95 10.3 16. 0 18.5 B vs C 0. 08 0. 771 N uptake i n Oyster River 1986-87 Treatment A B C kg N/ha GS22 20 27 21 GS31 38 3 6 43 Linear GS32 57 72 88 A vs B,C 51. 58 0. 000 GS33 56 85 138 B vs C 24. 39 0. 000 GS55 67 97 146 GS68 73 126 186 Quadratic GS78 78 133 161 A vs B,C 4. 46 0. 037 GS95 81 138 206 B vs C 0. 35 0. 551 110 APPENDIX VIII T o t a l s o i l N (0-50 mm) i n C h i l l i w a c k 1987-88 Treatment A B C D C o n t r a s t F-value P r o b a b i l i kg N/ha GS31 22 23 43 37 L i n e a r GS32 22 26 27 21 A vs B,C,D 0.96 0.330 GS33 17 21 28 32 B vs C,D 0.62 0.432 GS55 21 31 33 40 C vs D 5.32 0.023 GS68 25 24 21 23 Q u a d r a t i c . GS78 21 24 25 39 A vs B,C,D 3 . 37 0.070 GS95 23 31 49 59 B vs C,D 7. 09 0.009 C vs D 0.17 0 .677 Dry matter y i e l d s i n Chi 11iwack 1987-88 Treatment A B C D C o n t r a s t F-value ] P r o b a b i l i t/ha GS31 1.8 2. 0 2. 0 2 .3 L i n e a r GS32 3.6 3. 7 4 . 2 4 .0 A vs B,C,D 13 .02 0.000 GS33 8.3 9. 1 9. 7 9 .9 B vs C,D 0.71 0 .400 GS55 12 . 7 13 . 3 14 . 6 14 . 4 C vs D 1.02 0.313 GS68 15.9 16 . 8 17. 6 17 .9 Q u a d r a t i c GS78 18.0 18. 7 20. 5 19 .3 A vs B,C,D 0.17 0 . 678 GS95 14 .0 16. 8 17. 4 17 .1 B vs C,D C vs D 1.75 0.02 0.189 0.878 N uptake i n C h i l l i w a c k 1987-88 Treatment A B C D C o n t r a s t F-value P r o b a b i l i t y kg N/ha GS31 60 67 79 97 L i n e a r GS32 81 7 8 116 112 A vs B,C,D 36 . 56 0 . 000 GS3 3 110 195 262 249 B vs C,D 14. 52 0. 000 GS55 108 194 273 264 C vs D 4 . 34 0. 040 GS68 112 154 232 285 Q u a d r a t i c GS7 8 122 159 230 284 A vs B,C,D 14 . 54 0. 000 GS9 5 115 179 236 259 B vs C,D 5. 89 0. 017 C vs D 0 . 56 0. 453 111 APPENDIX IX T o t a l s o i l N (0-50 Treatment A B C D kg N/ha GS31 19 17 32 33 GS32 15 24 30 33 GS33 32 33 29 27 GS55 32 40 50 43 GS68 27 49 38 49 GS78 19 17 33 33 GS95 24 25 40 37 ) i n Oyster R i v e r 1987-88 C o n t r a s t F-value P r o b a b i l i t y L i n e a r A vs B,C,D 0 . 16 0 .688 B vs C,D 0 . 05 0 .821 C vs D 0 .01 0 .890 Q u a d r a t i c A vs B,C,D 0 .00 0 .947 B vs C,D 4 .13 0 .045 C vs D 0 .01 0 . 896 Dry matter y i e l d s i n Oyster R i v e r 1987-88 Treatment A B C D C o n t r a s t F-value 1 P r o b a b i 1 i t/ha GS31 0.5 0. 6 0 .7 0. 8 L i n e a r GS32 2.0 3. 5 4 .6 4. 8 A vs B,C,D 103.10 0.001 GS33 4.4 6. 5 8 .8 9. 4 B vs C,D 19 .63 0. 354 GS55 6.8 10. 0 13 .3 14 . 4 C vs D 0.39 0.150 GS68 5.0 12. 5 14 .6 15. 1 Q u a d r a t i c GS78 7.6 13 . 8 17 .9 18 . 7 A vs B,C,D 7.18 0 .000 GS95 6 . 6 11. 8 16 .9 15. 7 B vs C,D C vs D 0 . 86 2.11 0.354 0.936 N uptake i n Oyster R i v e r 1987-88 Treatment A B C D C o n t r a s t F-value ] P r o b a b i 1 i kg N/ha GS31 16 25 33 36 L i n e a r GS32 38 85 132 144 A vs B,C,D 36.02 0 .000 GS33 42 92 159 177 B vs C,D 47.71 0.000 GS55 45 85 161 202 C vs D 0.01 0.936 GS68 42 87 183 206 Q u a d r a t i c GS78 59 87 200 229 A vs B,C,D 39 .40 0 .000 GS95 52 90 174 164 B vs C,D 25.49 0.000 C vs D 8.30 0.005 112 APPENDIX X T o t a l s o i l N (0-50 mm) i n D e l t a 1987-88 Treatment A B C D C o n t r a s t F-value P r o b a b i l i t y kg N/ha GS31 41 62 81 97 L i n e a r GS33 20 21 66 63 A vs B,C,D 12.16 0 . 000 GS55 11 17 28 40 B vs C,D 6 .42 0 . 013 GS68 16 19 40 36 C vs D 0. 30 0. 581 GS78 25 22 36 32 Q u a d r a t i c GS95 25 25 28 37 A vs B,C,D 0.49 0. 485 B vs C,D 0.11 0. 736 C vs D 1.20 0. 277 Dry matter y i e l d s i n D e l t a 1987-88 Treatment A B C D C o n t r a s t F-value i P r o b a b i l i t/ha GS31 0.5 0 .8 0 .5 1 .1 L i n e a r GS33 4.5 5 . 5 4 .9 5 A vs B,C,D 24 . 27 0.000 GS55 8.5 9 . 4 8 .2 11 .1 B vs C,D 4.77 0 .032 GS68 14.1 13 .9 13 .8 16 . 5 C vs D 2 . 55 0.115 GS78 20 23 . 3 22 . 5 25 .6 Quadrat i c GS95 15.7 20 .6 22 .5 24 .6 A vs B,C,D 7.11 0.009 B vs C,D 0.83 0.364 C vs D 1.20 0.277 N uptake i n D e l t a 1987-88 Treatment A B C D C o n t r a s t F-value P r o b a b i l i t y kg N/ha GS31 20 34 25 53 L i n e a r GS33 87 127 156 145 A vs B,C,D 18 . 59 0 . 000 GS55 127 157 178 240 B vs C,D 12 .05 0. 001 GS68 130 172 207 248 C vs D 1 .07 0 . 304 GS78 151 218 260 313 Q u a d r a t i c GS95 151 208 287 324 A vs B,C,D 0 .08 0. 771 B vs C,D 0 .01 0. 944 C vs D 0 . 33 0. 567 113 APPENDIX XI T o t a l soi-1 N (0-50 mm) i n Delta 1986-87 Treatment A B C kg N/ha GS31 74 78 45 GS32 49 51 52 GS33 29 46 59 GS55 33 27 39 GS68 19 32 39 GS78 15 18 23 GS95 17 18 43 Dry matter y i e l d s i n D e l t a 1986-87 Treatment A B C t/ha GS31 0 . 8 1. 0 0 .9 GS32 3.2 3. 0 3 .4 GS33 8.8 4. 1 7 .1 GS55 8.7 7 . 5 9 .6 GS6 8 11.9 11. 2 15 .7 GS78 15.8 21. 3 20 .1 GS95 13. 8 14 . 7 19 .3 N uptake i n D e l t a 1986-87 Treatment A B C kg N/ha GS31 17 21 19 GS32 62 38 94 GS33 67 63 144 GS55 78 93 155 GS68 83 88 181 GS78 101 157 236 GS95 101 113 238 114 APPENDIX XII Regression Analysis f o r Control M u l t i p l i c a t i v e model: Y = a X f o r co n t r o l treatment Dependent v a r i a b l e : N uptake (kg/ha) Independent v a r i a b l e : Dry matter y i e l d s (t/ha) Parameter Estimate Standard Error T-value S i g . l e v e l Intercept* 3.04709 0.0608643 50.0637 0.00000 Slope 0.648091 0.0295005 21.9688 0.00000 *: The Intercept i s equal to Log a. Analysis of variance Source Sum of Squares Df Mean Squares F - r a t i o S i g . l e v e l Model 76.04899 1 76.04889 482.627 0.00000 Error 22.21778 141 0.15757 To t a l 98.26677 142 C o r r e l a t i o n C o e f f i c i e n t =0.879718 R-squared = 77.39% Stnd. Error of Est. = 0.396955 115 APPENDIX XIII Regression Analysis f o r Conventional M u l t i p l i c a t i v e model: Y = a X f o r conventional treatment Dependent v a r i a b l e : N uptake (kg/ha) Independent v a r i a b l e : Dry matter y i e l d s (t/ha) Parameter Estimate Standard Error T-value S i g . l e v e l Intercept* 3.5463 0.0504001 70.363 0.00000 Slope 0.530981 0.0233497 22.7404 0.00000 *: The Intercept i s equal to Log a. Analysis of variance Source Sum of Squares Df Mean Squares F - r a t i o S i g . l e v e l Model 41.09419 1 41.09419 517.1269 0.00000 Error 11.20475 141 0.07947 To t a l 52.29894 142 Co r r e l a t i o n C o e f f i c i e n t =0.886429 R-squared = 78.58% Stnd. Error of Est. = 0.281898 116 APPENDIX XIV Regression Analysis f o r I.CM. M u l t i p l i c a t i v e model: Y = a X f o r I.CM. treatment Dependent v a r i a b l e : N uptake (kg/ha) Independent v a r i a b l e : Dry matter y i e l d s (t/ha) Parameter Estimate Standard Error T-value S i g . l e v e l Intercept* 3.71231 0.0413732 89 .7273 0.00000 Slope 0.598711 0.0181997 32 .8967 0.00000 *: The Intercept i s equal to Log a. Analysis of variance Source Sum of Squares Df Mean Squares F - r a t i o S i g . l e v e l Model 55.9793 1 55.9793 1082.192 0.00000 Error 7.29361 141 0.05173 Tota l 63.27290 142 Co r r e l a t i o n C o e f f i c i e n t =0.9406 R-squared = 88.47% Stnd. Error df Est. = 0.227437 117 

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