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An evaluation of four tillage systems on Pineview clay, a fine textured soil in the central interior… Grevers, Mike C.J. 1979

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cop. I AN EVALUATION OF FOUR TILLAGE SYSTEMS ON PINEVIEW CLAY, A FINE TEXTURED SOIL IN THE CENTRAL INTERIOR OF B.C. Sc., (Agr.) U n i v e r s i t y of B r i t i s h Columbia, 19 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF THE FACULTY OF GRADUATE STUDIES (Department of S o i l Science) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1979 (c% Mike C.J. Grevers, 1979 by Mike C.J. Grevers MASTER OF SCIENCE IN I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1W5 D E - 6 B P 75-51 ! E i i ABSTRACT Pineview c l a y o r i g i n a t e s from a l a c u s t r i n e deposit and has a c l a y content of approximately 55%. During the s p r i n g the s o i l i s g e n e r a l l y q u i t e moist due to m e l t i n g snow and r a i n f a l l , w h i l e ambient a i r temperatures are r e l a t i v e l y c o o l . These f a c t o r s cause s o i l warming on Pineview c l a y to be slow. Due to the slow s o i l warming process i n the s p r i n g and due to the f i n e t e x t u r e of t h i s s o i l , i t i s important that the Pineview c l a y maintains a good s o i l s t r u c t u r e . L i t t l e research has been c a r r i e d out on Pineview c l a y as to the e f f e c t of t i l l a g e p r a c t i c e s on s o i l s t r u c t u r e . I t was the purpose of t h i s p r o j e c t to study changes i n the p r o p e r t i e s of Pineview c l a y brought about by d i f f e r e n t t i l l a g e systems. In the f i r s t p a r t of the p r o j e c t major adverse s o i l c o n d i t i o n s that occur on Pineview c l a y were evaluated w i t h respect to the emergence of b a r l e y . In the l a b o r a t o r y the e f f e c t s of s o i l compaction and s o i l tempera-ture were evaluated i n terms of b a r l e y s e e d l i n g emergence. The second part of the study c o n s i s t e d of determining the f e a s i b i l i t y of s e v e r a l t i l l a g e systems and the use of a h e r b i c i d e p r i o r to t i l l a g e on Pineview c l a y . In the l a s t part of the study four f a l l sod breaking t i l l a g e systems were evaluated i n terms of t h e i r e f f e c t on s o i l p h y s i c a l p r o p e r t i e s , N t r a n s f o r -mations, crop growth and development, and economic r e t u r n s . Barley s e e d l i n g emergence i n the l a b o r a t o r y was found to be a f f e c t e d by s o i l compaction and s o i l temperature. Between 5 and 20 C the r a t e of b a r l e y emergence approximately doubled f o r every 5 C increment i n s o i l temperature. Applying the h e r b i c i d e Gramaxone p r i o r to t i l l a g e improved s o i l break-up and c o n t r o l of sod regrowth, but the cost of t h i s h e r b i c i d e may be p r o h i b i t i v e . For sod breaking operations a stubble plow proved to i i i be inadequate and a special sod breaking plow should be used. Rotovation prior to moldboard plowing improved s o i l break-up and control of sod re-growth. Chisel plowing resulted in a rough, mulched s o i l surface condition, which required many passes before a satisfactory level s o i l surface had been created. The four f a l l sod breaking systems were moldboard plowing (using a sod breaking plow) with and without prior rotovation, and chisel plowing with and without prior rotovation. The results indicate major differences due to the type of plow used (moldboard vs chisel) rather than the additional use of the rotovator prior to plowing. Moldboard plowing resulted in superior s o i l physical conditions, higher s o i l NO^ -N levels, higher crop yields and N uptake by the crop, and better economic returns than chisel plowing. The four tillage systems reached maximum profits under various f e r t i l i z e r rates; $208.00/ha for moldboard plowing at 112 kg N/ha, $104.00/ha for rotovating and moldboard plowing at 56 kg N/ha, $71.00/ha for chisel plowing at 168 kg N/ha, and $39.00/ha for rotovating and chisel plowing at 0 kg N/ha. TABLE OF CONTENTS ABSTRACT TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS ACKNOWLEDGEMENTS I INTRODUCTION I I LITERATURE REVIEW A. A General E v a l u a t i o n of T i l l a g e Systems 1. T i l l a g e Considerations 2. Conventional T i l l a g e 3. Minimum T i l l a g e 4. Mulch T i l l a g e 5. Zero T i l l a g e B. T i l l a g e on Fine Textured S o i l s C. The E f f e c t of T i l l a g e on S o i l Temperature D. The E f f e c t of T i l l a g e on S o i l P h y s i c a l P r o p e r t i e s E. The E f f e c t of T i l l a g e on Nitrogen Transformations F. Economic Analyses of T i l l a g e Systems G. Summary of L i t e r a t u r e Review I I I STUDY OBJECTIVES IV PROJECT OUTLINE V MATERIALS AND METHODS VI RESULTS AND DISCUSSION A. S o i l C h a r a c t e r i s t i c s B. Laboratory Studies Page c. P r e l i m i n a r y T i l l a g e Studies 56 D. 1977-1978 T i l l a g e Study 63 ( i ) P h y s i c a l S o i l P r o p e r t i e s 63 ( i i ) Nitrogen Transformations 74 ( i i i ) Crop Growth and Development 82 ( i v ) Economic A n a l y s i s 88 VII CONCLUSIONS 92 REFERENCES 95 APPENDICES A. S o i l Temperatures i n 19 77 1040404 B . P h y s i c a l S o i l P r o p e r t i e s 108 C. S o i l Temperatures i n 1978 H I D. M i n e r a l S o i l N 116 E. NH.-N l e v e l s 4 119 F. N0 3~N l e v e l s 121 G. NH./NO. r a t i o s 4 3 124 H. Barley y i e l d 127 I . T o t a l N Uptake by Barley 129 J . Percent N Content of Barl e y 1.31 K. Percent F e r t i l i z e r N Uptake 1132 L. T i l l a g e Costs 134 M. F e r t i l i z e r Costs 136 N. Miscellaneous Costs 137 0. Treatment Costs 138 v i LIST OF TABLES Table Page I Pineview c l a y , s o i l p r o f i l e d e s c r i p t i o n . 38 I I P h y s i c a l p r o p e r t i e s of Pineview c l a y . 47 I I I Mechanical p r o p e r t i e s of Pineview c l a y . 48 IV Chemical p r o p e r t i e s of Pineview c l a y . 49 V The p h y s i c a l s o i l c o n d i t i o n s of the two treatments i n the b a r l e y emergence study. 54 VI The emergence of b a r l e y seedlings under various temperatures. 58 VII P h y s i c a l s o i l p r o p e r t i e s of the s o i l s used i n the main t i l l a g e experiment. 64 V I I I Percent moisture and s o i l moisture p o t e n t i a l s of 4 t i l l a g e treatments during 1978. 70 IX Ba r l e y y i e l d as a f f e c t e d by t i l l a g e / f e r t i l i z e r treatments. 83 X T o t a l N uptake by b a r l e y . 84 XI Percent N of b a r l e y . 86 XII Economic a n a l y s i s of t i l l a g e / f e r t i l i z e r treatments. 89 v i i LIST OF FIGURES Figure Page 1 Radiation balance. 23 2 Particle size distribution of Pineview clay. 50 3 Soil-water retention curve of Pineview clay. 51 4 The emergence of barley seedlings under two different s o i l physical conditions. 53 5 The emergence of barley seedlings affected by different methods of f e r t i l i z e r placement. 55 6 The emergence of barley seedlings at different temperatures. 57 7 Soil temperatures of differently t i l l e d plots (1977). 61 8 Soil temperatures at 50 cm depth for differently t i l l e d plots (1977) . 62 9 Average weekly s o i l temperatures at 5 cm depth (1978). 67 10 Average weekly s o i l temperatures at 10 cm depth (1978). 69 11 Weekly degree days of tillage plots at depths of 5 and 10 cm (1978). 72 12 Average weekly s o i l temperatures at 50 cm depth (1978). 73 13 Soil mineral N at different f e r t i l i z e r rates. 75 14 Soil mineral N during the 1978 growing season for different f e r t i l i z e r treatments. 76 15 Soil NH^ -N during the 1978 growing season for different f e r t i l i z e r treatments. 77 16 Soil NO^ -N as affected by till a g e treatments. 79 17 Soil NO^ -N for t i l l a g e / f e r t i l i z e r treatments vs. time. 80 18 NH^ -N/NO -N ratios for different f e r t i l i z e r treatments during the 1978 growing season. 81 19 % f e r t i l i z e r N uptake for different t i l l a g e / f e r t i l i z e r treatments. 87 20 Total revenues and total costs of t i l l a g e / f e r t i l i z e r treatments. 91 LIST OF ABBREVIATIONS moldboard plowing rotovating and moldboard plowing chisel plowing rotovating and chisel plowing mean-weight diameter aeration porosity total porosity bulk density moisture content Pacific Standard time least significant difference The rate of growth at one temperature compared the rate of growth at a temperature 10 C highe ACKNOWLEDGEMENTS The author wishes to thank Dr. A r t Bomke f o r h i s advi c e , support and encouragement throughout the du r a t i o n of the p r o j e c t . A very s p e c i a l thanks to Tom Guthrie and Anne Macadam f o r t h e i r help and encouragement i n the l a b o r a t o r y . Thanks to the s t a f f of the A g r i c u l t u r e Canada Research S t a t i o n i n P r i n c e George, B.C., e s p e c i a l l y Mike van Adrichem, Pat K l i n e and Dr. Marion Lee. Thanks to A g r i c u l t u r e Canada f o r f i n a n c i a l support. 1 I. INTRODUCTION The Pineview Clay Association covers an area "of over 100,000 hectares, centering mainly around Prince George, B.C. This s o i l originates from lacustrine deposits and contains in excess of 50% clay. The Vanderhoof and Nulki soils are somewhat coarser in texture but are s t i l l relatively fine textured soils with similar tillage problems as the Pineview Clay. These three soils cover an area of over 1/4 million hectares. In the Prince George area the mean annual temperature i s 3.9°C. The mean temperature of the coldest month January is -10°C, that of the warmest month July is 16°C, (Kelley and Farstad, 1946). The mean annual precipi-tation for the area is 642 mm which is well distributed during the year. Melting snow, a well distributed r a i n f a l l pattern and cool spring tempera-tures (average temperatures for April and May are 5° and 9°C respectively, Kelley and Farstad, 1946) have a major effect on the character of the growing season in this area. Cold s o i l temperatures created in the winter months (average air temperatures for December and January are -8° and -10°C respectively, Kelley and Farstad, 1946) increase only slowly in April and May. Germination of seeds and vegetative growth in general early in the spring i s thus quite slow. Most growth occurs in June, July and August when the average air temperatures are between 13 * and 16*C, and the days are long with an average of 246 hours of sunshine per month (Kelley and Farstad, 1946). The cool and generally wet spring conditions, together with a high clay content make this s o i l d i f f i c u l t to manage. The number of days that this s o i l is workable can be very few and in some years i t is a matter of number of hours. 2 L i t t l e research has been done on the tillage aspect of managing this s o i l , and i t is partly because of this that the study was undertaken. The study is a two year project. In the f i r s t year preliminary research was carried out on tillage methods in general. The information obtained in the f i r s t year led to four f a l l sod breaking operations. In the second year these four tillage treatments were evaluated. 3 I I . LITERATURE REVIEW A. A General Evaluation of Tillage Systems 1. Tillage Considerations For tillage operations, there are a number of factors to be taken into consideration: a) The type of s o i l t i l t h . This can be very important with respect to the size of the seed and i t s depth, the crop rooting depth, hazards with s o i l erosion, and water i n f i l t r a t i o n capacity. Sipher (1932) suggested four basic requirements for a good seedbed-rootbed: (i) Permit rapid i n f i l t r a t i o n and satisfactory retention of usable r a i n f a l l , ( i i ) Afford an adequate air capacity and ready exchange of s o i l a i r with the atmosphere, ( i i i ) Offer l i t t l e resistance to root penetration, (iv) Resist erosion. b) The i n i t i a l s o i l conditions that we are dealing with. Different s o i l textures such as clays and sands require different til l a g e operations. Also the presence of pans, or dense s o i l layers w i l l influence the type of tillage that should be used. c) The presence of important climatic influences on the s o i l that are of primary concern when choosing tillage systems. Examples of these conditions are soils in arid, humid and cold environments. d) Problems with diseases, weeds or pests that may need to be con-trolled with t i l l a g e . Although the tendency in weed, disease and pest control i s to make more use of herbicides, we do not as yet have the necessary herbicides for a l l the cropping systems (Wiese and Staniforth, 1973). Subsequently tillage s t i l l has an important role to play. The best 4 weed control in soils under sod, which may harbour diseases and pests can be achieved with t i l l a g e . The control of perennial grass weeds with frequent discing prior to planting can result in the dessication of their roots and subsequently the control of those weeds. Tillage or cultivation between crops is another method for controlling weeds. e) The type of tillage systems that are available. There are four types of tillage systems: (i) Conventional t i l l a g e ; in this case the entire s o i l surface is affected by implements such as plows and harrows, ( i i ) Minimum ti l l a g e ; only a strip of s o i l is t i l l e d (such as in the case with row crops) or a minimum number of til l a g e operations is used, ( i i i ) Zero t i l l a g e ; the crop i s planted in untilled s o i l , herbicides are used for weed control, (iv) Mulch t i l l a g e ; tillage is carried out in such a manner that i t leaves the surface residue in order to reduce erosion and water evaporation. 1. Conventional Tillage Conventional tillage consists of primary t i l l a g e , which breaks up the s o i l , and secondary tillage which further modifies the s o i l surface to create a suitable seedbed. Primary til l a g e Records from ancient time indicate that a type of moldboard plow existed for thousands of years B.C. (Smith and Wilkes, 1976). Plowing is to turn down surface material and to cause a loosening of the s o i l surface as a result of the breaking loose and inversion of the furrow slice (Baver et_ al_., 1972). Subsequently, the importance of plowing lie s in i t s weed 5 c o n t r o l ( e . g . deep b u r y i n g o f c o u c h - g r a s s and c r e e p i n g t h i s t l e , Mouat and Coleman, 1954), and i t s s o i l d i s t u r b a n c e (improve a e r a t i o n and r e d u c e s o i l s t r e n g t h . There a r e a number o f a s p e c t s t o be t a k e n i n t o c o n s i d e r a t i o n i n o r d e r t o e v a l u a t e t h e p l o w i n g a c t i o n ; (a) Depth o f p l o w i n g Mouat and Coleman (1954) r e p o r t t h a t a d e p t h / w i d t h r a t i o o f 2/3 f o r the f u r r o w s l i c e w i l l g e n e r a l l y r e s u l t i n the b e s t s o i l c o n d i t i o n s when p l o w i n g w i t h g e n e r a l p urpose p l o w s . However t h e r e a r e two s o i l c o n d i t i o n s where the d e p t h of p l o w i n g i s o f p r i m a r y i m p o r t a n c e ( B a v e r e_t a l _ . , 1972): ( i ) Homogeneous p r o f i l e s ; t i l l a g e o f t h e s o i l a t t h e same d e p t h c a n r e s u l t i n plow pan f o r m a t i o n . S u b s e q u e n t l y by v a r y i n g t h e p l o w i n g d e p t h t h i s p r o b l e m can be r e d u c e d , ( i i ) H e terogeneous p r o f i l e s ; l a y e r s of t o p s o i l and s u b s o i l can be i n v e r t e d , m i x e d o r plowed such t h a t no m i x i n g o c c u r s . T h i s p r a c t i c e can be i m p o r t a n t when w o r k i n g w i t h s o i l s t h a t have u n f e r t i l e o r s a l i n e l a y e r s . Deep p l o w i n g g e n e r a l l y r e f e r s t o p l o w i n g a t depths e x c e e d i n g 20 cm (Baver et_ al., 1972). I t s p r i m a r y p u r p o s e i s t o e x t e n d the d e p t h of the r o o t b e d , r e s u l t i n g i n i n c r e a s e d r o o t e l o n g a t i o n and s o i l w a t e r s t o r a g e ( B a v e r et. al., 1972) . S u b s o i l i n g i s a form o f deep t i l l a g e w h i c h has a h i g h d r a u g h t r e q u i r e m e n t . The main r e a s o n f o r u s i n g s u b s o i l e r s i s t o . l o o s e n dense s u b s o i l s , however, B a v e r e t a l . , (1972) r e p o r t a n o t h e r use f o r s u b s o i l e r s ; as a p r e l u d e t o p l o w i n g i n o r d e r t o o b t a i n b e t t e r p e n e t r a t i o n and g r a n u l a t i o n a c t i o n of d i s c p l o w s , (b) Type o f plows Mol d b o a r d plows a r e t h e most p o p u l a r where weed c o n t r o l i s o f p r i m a r y c o n c e r n . The plow i n v e r t s t h e s o i l r i b b o n , r e s u l t i n g i n good weed and p e s t 6 control as well as considerable s o i l break up. There are a variety of designs of the moldboard plow, such as those with different degrees of curvature and those made of different materials. Moldboard plows, with excessive curvatures cause the furrow slice to be thrown over quickly, causing more pulverization (Smith and Wilkes, 1976). These plows can also be slatted to obtain better performance in cases where the s o i l is sticky. The material of the plow can also be varied to obtain better scouring conditions. Three materials are generally used; soft steel, crucible steel and chilled cast iron (Smith and Wilkes, 1976). Scouring w i l l be best with the soft centre type of plow while the chilled cast iron plow is more popular in gravelly and sandy soils where the wear resistance of the plow is important (Smith and Wilkes, 1976). The moldboard plow re-quires a large draught force and because of this i t i s replaced by disc and chisel plows in cases where the extent of weed control or s o i l break up is not c r i t i c a l . Recently the moldboard plow systems have had to compete with zero- and minimum tillage systems, due to the availability of efficient herbicides and the high cost of tractor fuel (Triplett et a l . , 1977). The disc plow uses an inclined, concave steel disc set at an angle to the direction of travel. The discs generally range from 60-90 cm in dia-meter (Mouat and Coleman, 1954). Their penetration is due to their weight or due to hydraulic pressure systems, and not due to the downward pull as with moldboard plows. According to Smith and Wilkes (1976), the disc plow is adapted to conditions where the moldboard plow w i l l not work, such as: (i) sticky, waxy, gumbo, nonscouring soils and soils having a hard-pan or plow sole. ( i i ) dry, hard ground that cannot be penetrated with a moldboard plow. 7 ( i i i ) rough, stony, and rooty ground, where the disc w i l l r i d e over the rocks. (iv) peaty and leaf-mold s o i l s , where the moldboard plow w i l l not turn the furrow s l i c e , (v) deep plowing. The draught requirement of the disc plow i s somewhat less than that of the moldboard plow when turning the same volume of s o i l (Smith and Wilkes, 1976). Chi s e l plows use r i g i d , curved or s t r a i g h t shanks with r e l a t i v e l y narrow shovel points (Smith and Wilkes, 1976). The s o i l i s broken by s t i r r i n g and i s not inverted or pulverized to the extent that the moldboard or di s c plows t i l l the s o i l s . I t i s often used to loosen hard, dry s o i l s before the regu-l a r plow i s "used. The c h i s e l plow can also be used i n breaking up hard layers of s o i l j u s t below the regular plowing depth, i . e . hard pans or plow soles (Smith and Wilkes, 1976). The c h i s e l plow generally requires more passes over the s o i l than the moldboard plow and does not r e s u l t i n any s a t i s f a c t o r y degree of trash b u r i a l (Chamen and Cope, 1976). The approach angle of the c h i s e l plow determines the amount of s o i l disturbance and p o s s i -ble s o i l compaction. Payne and Tanner (1959) showed that considerably more o o s o i l was disturbed when using an approach angle of 20 rather than 90 . The greater the approach angle, the greater the tendency for the c h i s e l thrust to r e s u l t i n a downward force thereby compacting the s o i l ( G i l l and Vanden Berg, 1968). In dense s o i l s the c h i s e l approach angle i s l i k e l y to be some-what greater e s p e c i a l l y i f i t meets high density pockets, the r e s u l t i n g phenomena i s that the c h i s e l point rides over the s o i l creating a plow pan. Subsoilers. Since these plows operate at depths from 50-90 cm they are b u i l t stronger than other plows. They also require more power to p u l l them. Smith and Wilkes (1976) report power requirements of 45-60 kW (60-80 hp) f o r 8 subsoiling operations. Subsoilers can be modified plows, where a subsoiling tine at 7.5 - 10 cm lower than the rear plow body is used (Mouat and Coleman, 1954). Double plowing is also used although i t is energy consuming. In this system two plows, following each other, are used at different depths. Sub-soilers can also be modified to become mole plows to improve drainage. Rotary t i l l e r s . 'Although they are not plows, they are frequently used in primary tillage operations. They are relatively new in North America when compared with their use in Europe. Adams and Furlong (1959) report that patents on rotary t i l l e r s were issued as long ago as 1850. They can be separated into gyro-tillers and rotary hoes (Mouat and Coleman, 1954) . The gyro-tiller operates like a giant egg-whisk. The rotary hoe uses horizontal shafts set at right angles to the direction of travel, carrying a series of hoe blades or tines. The systems have a relatively high horsepower require-ment and have a tendency to overwork the s o i l (Adams and Furlong, 1959). The t i l t h produced by these implements usually can result in excellent germination of weed seeds, and subsequently the use of herbicides i s often required (Mouat and Coleman, 1954) . Rotary digger. Chamen and Cope (1976) have reported on a new type of tillage implement which f i l l s the gap between the moldboard and chisel plow. It consists of a rotor at 120-160 rev/min to be operated at approximately 10 cm depth, followed by tines set at 20 cm depth. The tines serve to absorb the thrust from the rotor and break pans that may be produced by the rotor. The tines also serve as an anchor at higher forward speeds. They found that the rotary digger resulted i n : (i) lower costs than the moldboard plow; ( i i ) twice the work rate compared to the moldboard plow; ( i i i ) l i t t l e or no smearing action beneath the rotor; 9 ( i v ) b e t t e r i n v e r s i o n of surface residues than w i t h the c h i s e l plow, but not matching the i n v e r s i o n achieved w i t h the moldboard plow; (v) y i e l d s were comparable with r e g u l a r systems; ( v i ) can be operated on heavy s o i l s ; Secondary t i l l a g e Secondary t i l l a g e means s t i r r i n g the s o i l a t comparably shallow depths. U s u a l l y i t f o l l o w s deeper primary t i l l a g e o perations. Smith and Wilkes (1976) l i s t 5 o b j e c t i v e s of secondary t i l l a g e operations: ( i ) To improve the seedbed by greater s o i l p u l v e r i z a t i o n . ( i i ) To conserve moisture by summer-fallow operations (to k i l l weeds and to reduce evaporation). ( i i i ) To cut up crop residue and cover crops, and mix vegetable matter w i t h the t o p s o i l . ( i v ) To break up c l o d s , f i r m the t o p s o i l and create a b e t t e r t i l t h f o r seeding and germination of seeds. (v) To destroy weeds on f a l l o w lands. There are b a s i c a l l y two types of secondary t i l l a g e implements; harrows and land r o l l e r s and p u l v e r i z e r s . 1. Harrows. Harrows are u s u a l l y involved i n the f i n a l p r e p a r a t i o n of the seedbed. Mouat and Coleman (1954) l i s t 9 uses f o r harrows: ( i ) To r e f i n e c u l t i v a t e d land to form a f i r m , l e v e l seedbed, ( i i ) To cover seeds. ( i i i ) For mixing f e r t i l i z e r s i n t o the s o i l as w e l l as spreading manure, ( i v ) To aerate top l a y e r s of winter sown land . (v) To encourage t i l l e r i n g . ( v i ) To aerate pastures and drag out moss and dead mat. 10 ( v i i ) For dragging weeds to the surface and c o l l e c t i n g them i n wind-rows . ( v i i i ) To c o n t r o l annual weeds. ( i x ) For c u t t i n g up the surface of grassland before plowing. There are three p r i n c i p a l types of harrows; the d i s c , s p i k e - t o o t h and the sp r i n g - t o o t h harrow (Smith and W i l k e s , 1976). a) Disc harrows This implement i s a m o d i f i c a t i o n of the p o l y d i s c plow, i n which gangs of d i s c s are d u p l i c a t e d so that the s o i l thrown to the l e f t by one gang i s brought back to i t s o r i g i n a l p o s i t i o n by the second, l e a v i n g a l e v e l f i e l d (Mouat and Coleman, 1954). The d i s c harrow has many uses; Smith and Wilkes (1976) l i s t the f o l l o w i n g : ( i ) Before plowing to cut up vegetable matter, ( i i ) A f t e r plowing to improve s o i l t i l t h , ( i i i ) To prepare a l l plowed land i n c o n d i t i o n f o r s p r i n g p l a n t i n g , ( i v ) To be used i n summer f a l l o w i n g , (v) To cover seeds that have been broadcast. There are d i f f e r e n t kinds of d i s c harrows, such as the t r a i l i n g and mounted ones. The d i s c s may have d i f f e r e n t c o n f i g u r a t i o n s f o r b e t t e r s u i t a b i l i t y under c e r t a i n c o n d i t i o n s . Discs g e n e r a l l y range i n s i z e from 40-70 cm, w i t h 4 major types of d i s c blades (Smith and Wil k e s , 1976): ( i ) Round, smooth-edged d i s c s are used on most d i s c harrows, ( i i ) Cutaway d i s c s are used where much residue i s to be c u t . ( i i i ) Notched d i s c s , ( i v ) S calloped d i s c s . 11 b) Spike-tooth harrows The principle use of this implement is for smoothing and leveling the s o i l after plowing. It w i l l s t i r the s o i l to a depth of approximately 5 cm i f weighted (Smith and Wilkes, 1976). There are different kinds of harrows, the major difference being the angle of the spike or tine (Mouat and Coleman, 1954) . The straight vertical tine w i l l only penetrate the s o i l to a shallow depth depending on i t s sharpness. It loosens the surface layers of the s o i l , but also has a consolidating effect on the layers beneath i t . Forward inclined tines w i l l tend to penetrate deeper. The main uses for this type is to loosen the s o i l and to comb the weeds out. Backward inclined tines do not penetrate the s o i l as deeply and tend to ride over the s o i l . They are used for breaking down surface clods and pressing long rubbish and stones into the s o i l (Mouat and Coleman, 1954) . c) Spring-tooth harrows The spring-tooth harrows are well adapted for rough and stony ground, since they w i l l tend to give when obstructions are struck. They are used to further loosen previously plowed s o i l . They penetrate the s o i l deeper than spike-tooth harrows. Frequently they are used for weed eradication, since the teeth penetrate deeply and tear out roots and bring them to the surface (Smith and Wilkes, 1976). 2. Land rollers and pulverizers These implements further prepare the seedbed through consolidating surface layers, crushing clods and smoothing the surface. There are two kinds; surface packers and subsurface packers (Smith and Wilkes, 1976). Surface packers thoroughly pulverize and firm the s o i l so that there w i l l not be any large air pockets. It presses the upper s o i l layers down against lower layers, thereby making a continuous seedbed in which moisture 12 is conserved (Smith and Wilkes, 1976). There are generally two types of packers (or r o l l e r s ) ; smooth cylinders giving a f l a t s o i l surface, and a gang of rings with wedge shaped edges leaving a series of small ridges (Mouat and Coleman, 1976) . Subsurface rollers are used when i t i s desirable to leave a good mulch on top. Rollers such as the crowfoot packer are designed such that they penetrate the s o i l surface while compacting lower surfaces (Smith and Wilkes, 1976) . 2. Minimum Tillage In this tillage practice the emphasis is in keeping the number of tillage treatments and the extent of s o i l disturbance to a minimum. In many cases no seedbed preparation is carried out other than in the row where the seed is to be placed. There are basically three methods; strip processing, wheel-track planting and plow-planting (Baver et a l , , 1972). Strip processing affects only a strip of s o i l . Discs, rotary hoes and harrows are used to prepare a good seedbed stri p . Wheel-track planting is a practice where after plowing, a loaded wheel crushes aggregates, preparing a smooth strip of seedbed. Plow-planting is essentially the same as strip processing. Plowing and planting are achieved in one operation, both implements (plow and planter) usually form one tillage-plant tool. Modifications of these methods that are often used are l i s t i n g and ridging. In l i s t i n g , furrows are made by double moldboard plow-type imple-ments and row crops are planted in the furrows to make use of higher moisture contents. In ridging, ridges are made with discs or plows, the crop is planted on the ridge to make use of lower moisture contents in the case of poorly drained s o i l s . Ridging is also practiced in arid regions where the 13 furrows are used as i r r i g a t i o n channels. Rao et_ a l _ . , (1960), s t u d i e s the e f f e c t of minimum t i l l a g e on the p h y s i c a l p r o p e r t i e s of s o i l s and crop response. They found c e r t a i n trends that are c h a r a c t e r i s t i c f o r minimum t i l l a g e when compared w i t h conventional t i l l a g e : ( i ) higher r a t e s of water i n f i l t r a t i o n ; ( i i ) saving on machinery time; ( i i i ) b e t t e r s u i t e d f o r medium-textured s o i l types, than f o r the more p l a s t i c s o i l s w i t h high c l a y contents; Minimum t i l l a g e a l s o reduces l o s s of s o i l moisture by reducing evapora-t i o n because a smaller area i s broken up and exposed to the atmosphere. Weed c o n t r o l a f t e r p l a n t i n g i s more c r i t i c a l than w i t h conventional t i l l a g e . 3. Mulch T i l l a g e Mulch t i l l a g e , or stubble mulching, t i l l s the s o i l w h i l e l e a v i n g the surface residue i n place (Baver e t a l . , 1972). Subsurface implements such as sweeps cut the ro o t s of the weeds and at the same time loosen the subsur-face. I t i s p r i m a r i l y used i n a r i d and semiarid r e g i o n s . McCalla and Army (1961) summarized the f o l l o w i n g trends of mulch t i l l a g e vs. s o i l p r o p e r t i e s and crop y i e l d s : ( i ) S o i l temperature: the i n s u l a t i n g and r e f l e c t i n g c h a r a c t e r i s t i c s of the mulch r e s u l t i n lower s o i l temperatures. ( i i ) S o i l s t r u c t u r e : the percentage of water s t a b l e aggregates increases under stubble mulching, the t o t a l number of aggregates decreases. S o i l c r u s t i n g can be b e t t e r c o n t r o l l e d r e s u l t i n g i n higher i n f i l t r a t i o n r a t e s , ( i i i ) E r o s i o n c o n t r o l : water e r o s i o n i s reduced by p r o t e c t i n g the s o i l s urface against the d i s p e r s i v e a c t i o n of f a l l i n g r a i n d r o p s . Wind 14 erosion is controlled due to the fact that the anchored crop residues reduce the force of the wind on the s o i l , (iv) Crop yields: in arid and semi-arid regions, higher crop yields may result from the higher moisture contents in mulched soi l s . In sub-humid and humid regions, lower crop yields may result from moisture contents that are too high due to the mulch. 4. Zero Tillage In this practice, the crop is planted in an untilled s o i l . Z e r o - t i l l planters are usually equipped with a fluted coulter or a rotary disc which makes a groove in which the seed i s placed, a packer then presses the seed into the s o i l for a good soil-seed contact. Fertilizers can be added to the s o i l at the time of seeding and herbicides can be sprayed on the vegetation surrounding the groove (i.e. a once-over operation). The advantages of zero tillage could be summarized as: (i) Sites where s o i l erosion is a problem due to sloping terrain or shallow soils are well suited for zero t i l l a g e . The reason is that the zero tillage implements only affect part of the s o i l surface and penetrates the s o i l to the seed depth only, ( i i ) In arid regions, the mulching characteristic of zero til l a g e results in moisture conservation, ( i i i ) Generally only one operation (seeding) is involved at the start of the season. The f i e l d in sod or covered with residue enables better t r a f f i c a b i l i t y at the higher moisture contents. These factors make zero tillage operations less dependent on periods of good plowing or planting weather such as is the case with conventional tillage operations, (iv) For pasture renovations, zero til l a g e implements can be useful. 15 Interseeding of grasses and/or legumes into old stands without interfering with the grazing of cattle for any substantial length of time is possible with zero t i l l a g e . (v) Where weeds or pests are not a problem, the lower equipment and fuel costs of zero tillage systems as compared with conven-tional tillage systems make i t economically attractive. The disadvantages of zero tillage are: (i) Zero til l a g e should not be practiced on fine textured s o i l s . These soils require s o i l "break up" and general loosening such as with conventional tillage practices in order to increase s o i l aeration and reduce s o i l strength, ( i i ) Soil compaction can s t i l l be caused by harvesting, seeding and spraying equipment, while zero tillage systems do not disrupt compacted s o i l layers, ( i i i ) Zero til l a g e generally results in higher s o i l moisture con-tents due to i t s mulching effect; in cold, heavy soils this could result in slower s o i l warming in the spring, thereby delaying or shortening the growing season, (iv) Perennial weeds can easily establish themselves i f weed control through herbicides is ineffective. Furthermore, problems may arise that are associated with the vegetative cover harbouring rodents and insects. There are situations where the advantages of zero tillage outweigh the disadvantages: (i) Sod planting of corn; in this case corn is directly planted in the sod which has been chemically suppressed. Sods successfully managed in this manner are fescue and al f a l f a (Baeumer and 16 Bakermans, 1973). ( i i ) Pasture renovation; interseeding grasses and/or legumes into old stands. ( i i i ) Multicropping; for example conventionally t i l l e d and planted wheat, followed by zero t i l l e d soybeans ( T r i p l e t t and van Doren, 1977) . B. T i l l a g e on Fine Textured S o i l s S o i l s of high clay content ( i n excess of 40% clay) are s u b s t a n t i a l l y d i f f e r e n t i n t h e i r management from coarser textured s o i l s , due to the influence of s o i l moisture content on t h e i r consistence. When these s o i l s are dry, t h e i r consistence i s harsh and the cementing e f f e c t s are large. Upon plowing i n t h i s condition hard cemented s o i l s w i l l r e s u l t with clods that are too hard to be broken down by c u l t i v a t o r s or harrows (Nichols and Reed, 1934; R u s s e l l , 1973). When these s o i l s are too wet p l a s t i c flow may occur instead of s o i l p u l v e r i z a t i o n and shattering. P l a s t i c flow i s des-cribed by G i l l and Vanden Berg (1968), "the en t i r e mass of s o i l i n the neighbourhood of the applied forces f a i l s by deforming without any d i s t i n c t separation on any surface". P l a s t i c flow occurs at s o i l moisture contents between the p l a s t i c and l i q u i d l i m i t s ( p l a s t i c index). The range of f r i a b l e consistence i s the range where the s o i l can be t i l l e d at the lowest draught requirement, and have the best e f f e c t s on s o i l granulation (Baver et a l . , 1972). To determine whether or not a clay s o i l i s i n a good condition to t i l l requires a c e r t a i n amount of knowledge or experience. In order to be le s s dependent on the s o i l moisture status for spring t i l l a g e operations and to benefit from f r o s t action during the winter months, many farmers use f a l l t i l l a g e . 17 Another problem with these fine textured soils i s their structural development. The cohesive nature of clay particles and their cementing action on larger particles cause aggregate formation. Organic matter and plant roots help produce a well granulated s o i l structure. The depletion of this organic matter by too many tillage operations, together with the absence of crops with extensive rooting systems can cause these soils to become compact with poor s o i l structure. Tillage can result in improving the s o i l structure, but can also result in i t s destruction. The c r i t i c a l factors for managing fine textured soils are the frequency, timeliness and kind of tillage operation. Over-tilling the s o i l can either lead to s o i l pulverization (which can result in s o i l crusting) or to plow pan formation. The mechanics of tillage has important ramifications as to the level of s o i l break-up, organic matter incorporation and mixing of natural s o i l layers. The hydraulic conductivity of clay soils is low compared to coarse textured soi l s . In wet springs the soils may take considerably longer to dry out than other soi l s , causing subsequent delay in t i l l a g e . There have been a number of studies done on the management of fine textured so i l s . Due to the effect of s o i l moisture on the consistence of these s o i l s , and on their s o i l warming rates in the spring, the experiments need to be of a long term nature. One such study was carried out on Pineview Clay during 1940-1949 by the Agriculture Canada staff in Prince George, B.C. They studied the effect of spring vs. f a l l plowing, and depth of plowing on the yields of barley and oats. In these sod breaking operations they found that spring plowing resulted in considerably lower yields of both oats and barley than f a l l plowing. Spring plowing l e f t the s o i l in a rough condition, which was d i f f i -cult to break down into a proper seedbed. Plowing at depths of 10 cm 18 resulted in better yields than plowing at 15 cm (Agriculture Canada, 1950) . Fal l plowing also proved to be a superior tillage treatment in a study done in Ohio by Taylor and Johnson (1956). The s o i l used, Hoytville s i l t y clay, is a lakebed s o i l which suffers from high s o i l moisture contents in the spring. They compared f a l l plowing, shallow plowing, wet plowing and rotary t i l l i n g . F a l l plowing resulted in a fine granular s o i l surface, which required a minimum amount of seedbed preparation in the spring and resulted in the highest corn yield. G r i f f i t h e_t £l., (1973) studied eight tillage planting systems on five Indiana s o i l s , ranging from sandy loam to s i l t y clay loam. Their findings were that on the poorly drained fine textured soils weed control after sod breaking operations was more of a problem with no-plow systems than with con-ventional t i l l a g e . For the s i l t loams and s i l t y clay loams the use of the moldboard plow resulted in higher yields of corn than did the use of the chisel plow. In Michigan, Cook et a l . , (1953) studied tillage methods on soils ranging from a sandy loam to a clay loam. On the fine textured soils the moldboard plow resulted in the best weed control and generally the highest yields of beans and beets. The rotary t i l l e r resulted in the lowest.yields and poorest weed control. An experiment on Brookston clay loam in Michigan, by Cook and Peikert (1950) showed that moldboard plowing resulted in superior weed control as compared to tillage systems that mixed the sod with the surface s o i l . The no-plow treatments required considerably more hoeing for weeds, and in some cases yields were substantially reduced by weed competition. 19 The new trend in zero and conservation tillage has resulted i n the re-evaluation of tillage practices. It appeared that quite frequently farmers have tended to overwork their s o i l (Triplett et a_l., 1977). They did this either out of habit or out of the belief that the finer they pulverized their s o i l , the better the seedbed. The merits of zero and conservation tillage practices have been reported by Triplett et^ a l . , (1977), Cannell et_ a l . , (1978), and Russell (1977). The general findings were that for clay s o i l s , reduced ti l l a g e methods can equal the yields of conventional tillage depending on a number of factors such as the s o i l structural development, climate and crop grown. Conventional til l a g e operations were compared with zero tillage opera-tions by Finney and Knight (1972). They found that direct d r i l l operations resulted in earlier lateral branching of the roots of winter wheat and the root system was also effectively shallower throughout the season than was the case with the conventional tillage operations. Pidgeon (1978) classified two contrasting s o i l types, one as suitable for long term direct d r i l l i n g and the other as non-suitable. The suitable s o i l was less compactable than the other s o i l . On the unsuitable s o i l , zero tillage resulted in spring barley yield reduction of 15% when compared with conventional t i l l a g e . Kupers and Ellen (1970) reported that the application of nitrogen f e r t i l i z e r to direct d r i l l e d soils resulted in a substantially reduced crop response as compared to the same rate applied to plowed plots. They attributed the lower response to the limited root system in the direct d r i l l e d plots which was substantially shallower. 20 Soane and Pidgeon (1977) state that cultivation should be retained on soils that are either poorly drained, of low structural sta b i l i t y or compacted, in order to ensure proper crop growth and reduce the occurrence of unfavourable physical conditions. Especially those crops with roots of large diameters require high levels of macropore space, which can often only be obtained with conventional t i l l a g e . In summary, tillage of fine textured soils is affected by the s o i l moisture content. There exists a narrow range between the dry and the wet s o i l condition, where the s o i l is in i t s optimum condition for t i l l a g e . Tillage practices can improve or destroy the s o i l structure depending on the frequency, timeliness and the kind of til l a g e operation. Minimum tillage can result in yields equal to those with conventional tillage de-pending on the s o i l structural development, climate and crop grown. Where so i l compaction or sod breaking operations occur, moldboard plowing i s superior to other tillage treatments. C. The Effect of Tillage on Soil Temperature The management of northern soils is often dictated by their climate, in particular their s o i l climate. These "cold" soils are limited in the range of crops that can be grown on them. The term "cold" generally refers to the low spring s o i l temperatures. These soils must absorb considerable amounts of radiative energy in order that they reach temperatures high enough for seed germination and crop growth in general. Pineview clay i s a cold s o i l because of poor drainage and cool spring temperatures common to the central interior of British Columbia. Management practices that result in faster s o i l warming can therefore have a considerable effect on the climate of these "cold" s o i l s . The 21 temperature of the s o i l has an important e f f e c t on the a c t i v i t y of s o i l micro-organisms, plant growth and phy s i c a l parameters such as gaseous , d i f f u s i o n and water movement. Latey et a l . , (1962) state that the rate of oxygen d i f f u s i o n increases by 1.8% for every degree c e l c i u s ri i s e i n temperature. Low s o i l temperatures r e s u l t i n a slow release of N and P from the s o i l organic matter (Tisdale and Nelson, 1966) . Seeds require s u f f i c i e n t l y high temperatures i n order to germinate. Once germinated the seedling w i l l grow very slowly at low s o i l temperatures, while being vulnerable to many p a r a s i t i c fungi which can grow r a p i d l y at low temperatures (Russell, 1973) It i s generally found that low s o i l temperatures reduce the rate of morphological development of a plant (Ito and Takeda, 1963; Nielsen and Humphries, 1967; R u s s e l l , 1973). Power et a l . , (1970) l i s t e d a s o i l tempera-ture of 15.5 C as the optimum temperature for barley growth. They found that below t h i s temperature the growth was s u b s t a n t i a l l y reduced. The morphology of roots at low temperatures i s characterized by thicke r , less branched roots r e s u l t i n g i n less root penetration into new regions of the s o i l (Russell, 1973) . Water absorption by the roots and transport of water from roots to shoots i s retarded at low temperatures due to the greater v i s c o s i t y of water and decreased permeability of the protoplasm (Kramer, 1973). Currie (1975) found that below optimum temperatures root r e s p i r a t i o n had a Q 1 Q= 3. In order to quantify the e f f e c t of s o i l temperatures on b i o l o g i c a l processes i n the s o i l , the temperatures can be expressed as growing degree days. Growing degree days are heat units that take into consideration both 22 the number of days and the number of degrees that the temperature is above a c r i t i c a l value. Growth can be expressed as a function of the sum of growing degree days: T where S = the sum of the growing degree days, T = the length of the period, v(t) = actual s o i l temperature degrees C, v^ = c r i t i c a l temperature at which growth stops (van Wijk, 1965) . The faster the s o i l warms in the spring, the more optimum the growing conditions w i l l be for the s o i l organisms and crop growth. The extent of s o i l warming is influenced by the amount of heat flow into the s o i l , the amount of heat storage, and the heat outflow. The processes involved are illustrated in Figure 1. The re f l e c t i v i t y or albedo of the s o i l surface determines how much solar radiation is reflected. A moist bare s o i l surface can have an albedo around 10-15% (Black, 1977), whereas a grey surface can have an albedo in the range of 20-35% (Sellers, 1965). The capacity of a s o i l to absorb heat is affected by the composition of the s o i l : C = CX + CX + CX s s ww a a where C = heat capacity, X = volume fraction, s = s o i l material, w = water, a = air (van Wijk, 1965). Average values for the heat capacities for water, 3 air and clay minerals are 4200, 1.2 and 2100 kJ/m C), respectively (Monteith, 1973). Consequently i t would take considerably more energy to warm up a wet s o i l than a dry one. The warming of the s o i l surface results in two phenomena; some of the heat is conducted deeper into the s o i l , and some of i t i s dissipated back to the atmosphere. The s o i l surface may have a low heat capacity as in the o i NET HEAT FLOW FIGURE 1 : Radiation^ balance 24 case with a dry mulched surface. However the s o i l below i t may receive l i t t l e of the heat from the surface i f the thermal conductivity i s low. In t h i s case most of the energy absorbed at the s o i l surface r e s u l t s i n higher surface temperatures. The higher the surface temperature of the s o i l , the greater the amount of energy l o s t from the s o i l surface i n the form of long wave r a d i a t i o n . Average values f o r the thermal conductivity for water, a i r and clay minerals are 0.57, 0.025, and 2.92 W m ^ C * re s p e c t i v e l y (Monteith, 1973). Consequently, the denser and wetter a s o i l , the higher i t s thermal conductivity and the more uniform s o i l warming rates are with depth. The r a t i o of the thermal conductivity to the heat capacity i s c a l l e d thermal d i f f u s i v i t y . The thermal d i f f u s i v i t y i s i n d i c a t i v e of the rate and depth of s o i l warming and i s highly dependent on the s o i l moisture content (Hay et a l . , 1978). Since t i l l a g e a f f e c t s the r a t i o s between s o i l mineral to s o i l water to s o i l a i r , i t can be expected to influence the s o i l temperature. T i l l a g e operations that r e s u l t i n improving any of the s o i l properties such as the albedo, heat capacity or thermal conductivity can benefit plant growth i n cold s o i l s (Spoor and G i l l s , 1973; Watts, 1975). In the United Kingdom, Hay (1977) studied the e f f e c t of conventional t i l l a g e and d i r e c t d r i l l i n g on s o i l temperature. He found that the stubble mulch on the uncultivated s o i l resulted i n less s o i l freezing at 1.0 cm than i n the c u l t i v a t e d s o i l , which had no mulch. He also found that the u n c u l t i -vated s o i l had fewer days above 5°C. Unger (1978) looked at the e f f e c t of wheat straw mulches on the s o i l temperature of Pullman clay loam i n Texas. He found that mulches of 8-12 t/ha s u b s t a n t i a l l y decreased the s o i l temperature at a depth of 10 cm. 25 The s o i l temperatures of the mulched plots were an average of 3°C below optimum for germination of sorghum. There was also a 2-5 day delay in emergence and slower early growth in the mulched plots. Hay e_t a l . , (1978) found that compared to a plowed s o i l , direct drilled s o i l had a higher albedo and a higher thermal diffusivity between the 5-10 cm depths. The result was fewer degree days above 5°C at depths of 1 and 5 cm during the f i r s t 20 days after sowing barley in the direct d r i l l e d s o i l . The general effect of conventional tillage is to create greater ex-tremes in s o i l temperature near the surface, more s o i l warming during the day and more s o i l cooling at night. The greater extent of s o i l cooling and in come cases s o i l freezing in cultivated plots can result in mortality amongst s o i l micro-organisms (Biederbeck and Campbell, 1973). Cycles of freezing and thawing also result in better s o i l t i l t h in the spring (Baver et a l . , 1972). Stubble-covered s o i l is protected from much of the frost action during the winter months. Hay et_ al_ (1977), in the UK, found that this protection contributed to the observed poor s o i l condition in the spring in direct d r i l l e d plots as compared with plowed plots. In summary, s o i l temperature has an important effect on s o i l biological processes. The rate of s o i l warming in the spring in cold soils is affected by tillage operations that change the albedo of a s o i l and/or the ratios of s o i l material to s o i l water to s o i l a i r . Conventional till a g e results in greater s o i l temperature extremes than reduced t i l l a g e . The greater tempera-ture extremes can produce better s o i l t i l t h but may also result in greater mortality amongst s o i l micro-organisms. 26 D. The Effect of Tillage on Soil Physical Properties One of the main purposes of tillage is to improve the s o i l t i l t h . The s o i l t i l t h is defined as the physical condition of the s o i l in relation to plant growth and hence must take into consideration a l l physical conditions that influence crop development (Buckman and Brady, 1969) . In order to determine the type and frequency of tillage to be used, a number of physical s o i l properties can be evaluated. Aggregate size distribution, bulk density, s o i l strength, s o i l temperature, soil-water status, aeration and total porosity can be measured in order to determine the tillage requirement (Larson, 1964; Soane and Pidgeon, 1975). The s o i l t i l t h has an optimum aggregate size distribution. Russell (1973) states that few aggregates should be finer than 0.5 - 1.0 mm and few should be coarser than 5.0 - 6.0 mm. Larson (1964) l i s t s as a c r i t i c a l upper limit for the secondary aggregate size a value of 5 mm. The aggregates must be small enough so that enough surface are exposed in order to provide adequate s o i l - s o i l solution or s o i l solution-root contact. They must also be large enough to prevent s o i l crusting and allow gaseous diffusion to deeper layers (Larson, 1964) . Methods that are often used for determining aggregate size analysis are dry sieving and wet sieving. Since dry sieving can result in the mechanical disruption of the aggregates, wet sieving is often preferred (van Bavel, 1953). A reduction in the mean aggregate size is achieved with tillage operations, which could either improve the s o i l t i l t h or destroy i t i f the aggregates are over-pulverized. Furthermore, as shown by Rovira and Graecen (1957), the reduction of aggregate size also exposes organic matter from inaccessible micropores, which can lead to an increase in organic matter decomposition. 27 The shear strength of a s o i l can be used to evaluate the degree of di f f i c u l t y that the roots have in forcing their way into a s o i l . The shear strength is the maximum internal resistance of a s o i l to the movement of i t s particles. It can be broken down into a component of cohesion and one of f r i c t i o n : S = C + tan 0 P where S = shear strength, C = cohesion, 0 = angle of f r i c t i o n , P = effective pressure normal to the shear plane (Baver et a l , 1972). Roots, once they enter a pore, expand and thereby widen the pore. When the s o i l strength exceeds the maximum amount of pressure that a root can exert (from 500 -1000 kPa for large seeded plants such as peas, Russell, 1973) root growth is reduced. Field methods for simulating s o i l resistance involve the use of penetrometers and penetrating cones (Eavis and Payne, 1969; Harrod, 1975). There are problems relating root penetration to laboratory or f i e l d measure-ments of s o i l strength. Lubrication by root exudates, drying of surrounding s o i l by water uptake by roots and the ab i l i t y of roots to take the path of least resistance, are hard to account for (Soane and Pidgeon, 1975) . Harrod (1975) found that the cone resistance method was better correlated with root growth in soils with poor structure where compression i s the dominant mode of failure, than with soils where crack formation is dominant. The loosening effect of tillage reduces the s o i l shear strength. Gowman et a l . , (1978) found shear strength values for direct d r i l l e d clay soils to be around 49 kPa at 5 cm depth, while the plowed soils had values around 15 kPa. The s o i l bulk density (B.D.) i s perhaps the most frequently used para-meter for evaluating ti l l a g e needs and performance. There are a number of methods available for measuring the B.D., ranging from gamma radiation tech-niques to s o i l core sampling (Blake, 1965). C r i t i c a l limits for B.D. vary 28 w i t h s o i l t e x t u r e . R u s s e l l (1973) i n d i c a t e d severe root r e s t r i c t i o n i f the 3 B.D. reached values of 1700 - 1800 kg/m f o r coarse textured s o i l s , and 1500 -3 3 1600 kg/m f o r f i n e textured s o i l s . Larson (1964) s t a t e d that 1400 kg/m i s the c r i t i c a l l i m i t f o r the s i l t loams of the Corn B e l t r e g i o n . T i l l a g e g e n e r a l l y r e s u l t s i n lowering the B.D. In a study on a loam s o i l , Hay et a l . , 3 (1978), found B.D. values around 1160 kg/m i n plowed s o i l s and around 1320 3 kg/m i n d i r e c t d r i l l e d s o i l s . Pidgeon and Soane (1977) compared s o i l B.D. of p l o t s a f t e r moldboard plowing, c h i s e l plowing and d i r e c t d r i l l i n g on a loam s o i l . In the top 10 cm the moldboard plow treatments had the lowest 3 3 value of around 1250 kg/m , the c h i s e l plow p l o t s 1320 kg/m and the d i r e c t 3 d r i l l e d p l o t s 1400 kg/m . In a t i l l a g e study on a sandy loam, Finney and Knight (1973) found s i m i l a r s o i l B.D. i n moldboard and c h i s e l plowed p l o t s 3 3 (1110 kg/m between depths of 5 - 10 cm), but higher values (1180 kg/m ) i n d i r e c t d r i l l e d p l o t s . The a e r a t i o n p o r o s i t y (A.P.) of a s o i l i s i n d i c a t i v e of the macro-pore space of a s o i l . I t can be determined by f i r s t s a t u r a t i n g a cored s o i l sample, and subsequently d r a i n i n g the sample under a s p e c i f i e d water t e n s i o n . The l o s s of water from the sample expressed as a percentage of the t o t a l volume i s the A.P. (Vomocil, 1965). Although water tensions used range between 5 and 50 kPa, most s c i e n t i s t s now use e i t h e r 6 or 10 kPa (Baver, e_t a l . , 1948; Kohmke, 1946; Vomocil, 1965; Wesseling and van Wijk, 1957). A.P. i s a u s e f u l t o o l i n e v a l u a t i n g both the p h y s i c a l and chemical c o n d i t i o n s of a s o i l . D i f f u s i o n of 0^ and CO2 i s r e s t r i c t e d when the A.P. i s low. An-aerobic c o n d i t i o n s may occur when the CO2 l e v e l i n the s o i l i s allowed to b u i l d up and the 0^ l e v e l to be depleted. At low 0^ and high CO2 l e v e l s i n the s o i l , root growth i s r e s t r i c t e d (Baver et a l . , 1972). S o i l micro-organisms that are e i t h e r o b l i g a t e aerobes or anaerobes are a l s o a f f e c t e d by 29 different levels of s o i l aeration (Russell, 1973). In soils with low A.P.'s there i s a greater occurrence of mechanical restriction to root growth, when growing roots encounter pores which are smaller than their own diameter (Viehmeyer and Hendrickson, 1948; Russell, 1977) . C r i t i c a l values for the minimum A.P.'s are between 10 and 20%. Baver and Farnsworth (1940) and Wesseling and van Wijk (1957) use 10% as a c r i t i c a l value for adequate root growth. Kopecky (1927) found that for crops such as barley minimum values range between 15 and 20%. Grable and Siemer (1968) report that 10% is too low and a value between 12 and 15% would be a safer l i m i t . The A.P. of a so i l can be improved with tillage practices. When comparing direct d r i l l i n g with conventional t i l l a g e , Gowman et a l . , (1978) found that the A.P.'s of the cultivated plots were around 40% higher than those in the direct d r i l l e d plots for the top 5 cm. Soane and Pidgeon (1977) evaluated A.P. profiles after moldboard plowing, chisel plowing and direct d r i l l i n g . Greatest differences were at a depth of 6 cm, where the moldboard plow treatment had an A.P. of 21.5%, the chisel plow treatment 17.2% and the direct d r i l l treat-ment 8.0%. The practice of green manuring results in substantial changes in the A.P. of a s o i l as shown by Baver and Farnsworth (1940). They found that between depths of 0 and 7.5 cm the A.P.'s were around 16.8% in green manured plots and 8.7% in control plots. The water status of a s o i l is an important parameter in clay soils during tillage operations. Tillage i t s e l f affects the s o i l water status by destroying the continuity of s o i l pores, thus reducing the s o i l hydraulic conductivity. The total pore volume may be increased with t i l l a g e , however this may be only on a short term basis (Finney and Knight, 1973). In situ-ations where dense, poorly structured soils restrict drainage, till a g e can increase the depth of water percolation. 30 The surface roughness of a s o i l can be an important parameter in areas where s o i l erosion or s o i l moisture storage are a problem. Tillage practices can increase the surface roughness as in the case with disc plowing and chisel plowing, but may reduce i t with rotovation. There are various instruments that can be used to measure surface roughness. Most of them involve measuring the s o i l microrelief of a small area and subsequently re-plicating this measurement over the entire f i e l d . Kuipers and van Ouwerkerk (1963) used a reliefmeter which measured the mean height of the s o i l surface relative to level marks under a plowed layer, before and after plowing. Burwell et a l . , (1963) used a point quadrant instrument which measured the surface microrelief in a 5 cm x 5 cm grid over a 100 cm x 100 cm area. As an index of random roughness, they used the standard error among logarithm of the elevation heights. Currence and Lovely (1970, 1971) used a profilo-meter, which was a similar instrument as the one used by Burwell et a l . , (1963). They measured the s o i l microrelief in a 2.5 cm x 2.5 cm grid over a 150 cm x 150 cm area. They used 5 different indices of surface roughness ranging from the one used by Burwell et_ al_., (1963) to a method that involved calculating the standard deviation of the height readings obtained with the profilometer. In summary, the s o i l t i l t h can be evaluated by a number of physical parameters such as aggregate size distribution, shear strength, bulk density, aeration porosity and s o i l water status. Tillage practices affect these physical parameters, and consequently the performance of tillage tools can be evaluated by studying the resulting changes in these parameters. 31 E. The Effect of Tillage on N Transformations As earlier discussed, tillage affects a number of s o i l physical proper-ties. Changes in these properties affect the N cycle of the s o i l . Different levels of s o i l aeration substantially affect n i t r i f i c a t i o n , since the nitro-bacteria are obligate autotrophic aerobes. Amer and Bartholomew (1951) found very l i t t l e n i t r i f i c a t i o n when the s o i l 0^ levels were low and high rates of ni t r i f i c a t i o n when the s o i l 0^  concentration reached 20%. Tillage practices that loosen the s o i l or provide improved s o i l drying result in better s o i l aeration which can lead to increased n i t r i f i c a t i o n . N i t r i f i c a t i o n has been reported to react to the s o i l water potential of a s o i l . Provided there is adequate aeration, s o i l water potentials around 10 kPa result in maximum ni t r i f i c a t i o n (Sabey, 1969; Miller and Johnson, 1964; Reichman et a l . , 1966; Justice and Smith, 1962). Increased s o i l warming in the spring due to tillage practices can i n -crease s o i l n i t r i f i c a t i o n . When early spring s o i l temperatures are around 4 and 5 C, the rate of n i t r i f i c a t i o n is very slow (Anderson and Boswell, 1964; Frederick, 1956) . At these low s o i l temperatures a relatively small increase in temperature can result in a substantial increase in the rate of ni t r i f i c a t i o n . Anderson and Purvis (1955) found a virtual doubling in the rate of nitrate accumulation between s o i l temperatures of 5.6 and 8.3 C, after 6 weeks of incubation. Maximum n i t r i f i c a t i o n has been reported to occur between 20 and 30 C (Parker and Larson, 1962; Sabey et al_., 1959; Mahendrappa et a l . , 1966). Tillage practices that incorporate surface residues, having C/N ratios in excess of 20-25, may result in temporary immobilization of mineral nitrogen (Harmsen and Van Schreven, 1955; Ferguson and Gorby, 1964). Russell (1973) reports that when these residues contain less than 1.2 to 1.3% N, 32 immobilization is l i k e l y to occur. Breaking virgin soils and subsequently cultivating them has been found to result in substantial reductions in the total amount of s o i l N (Shutt, 1905; Caldwell et a l . , 1939; Newton et a l . , 1945; Doughty et a l . , 1954; H i l l , 1954). Campbell et^ a l . , (1975) found that after t i l l i n g these virgin s o i l s , there was an increase in N mineralization and subsequent n i t r i f i c a t i o n resulted in the loss of NO^ -N through leaching. When comparing direct d r i l l operations with conventional t i l l a g e , N mineral-ization appears to be more prominent in the conventionally t i l l e d soils (Dowdell and Cannell, 1975) . The usually more compacted state of unculti-vated soils as compared to plowed soils together with generally higher mois-ture contents favour denitrification (van Ouwerkerk and Boone, 1970; Van Doren and Triplett, 1969). Direct d r i l l e d soils tend to have pores that are more continuous than those in cultivated s o i l s , resulting in better drainage which could lead to losses of nitrates through leaching (Baeumer, 1970) . In summary, N mineralization is indirectly affected by til l a g e practices. Tillage can induce changes in s o i l aeration, s o i l water status, s o i l warming and incorporation of organic matter. The level of N mineralization i s affected by these physical properties. N i t r i f i c a t i o n in particular is quite sensitive to s o i l aeration and s o i l temperature. F. Economic Analyses of Tillage Systems The limiting factor of many tilla g e systems is often their economic return. Conventional systems generally have a high energy consumption where-as reduced tillage systems do not. Triplett and Van Doren (1977) reported on studies which showed that systems using the moldboard plow required in excess of 800 l i t e r s of fuel per 50 hectares, compared to 94 for n o - t i l l 33 p l a n t i n g . P a t t e r s o n (1975) d i d an economic a n a l y s i s on t i l l a g e work on a c l a y loam i n B r i t a i n . He found t h a t r e d u c e d c u l t i v a t i o n was around $23.00/ha cheaper t h a n c o n v e n t i o n a l c u l t i v a t i o n u s i n g the moldboard plow. However, t h e p r o f i t a b i l i t y o f r e d u c e d c u l t i v a t i o n i n terms o f y i e l d o f w i n t e r wheat was $37.00/ha l e s s t h a n f o r t h e c o n v e n t i o n a l system. C o n s e q u e n t l y f o r s o i l s w i t h a h i g h t i l l a g e r e q u i r e m e n t , r e d u c e d t i l l a g e systems s h o u l s be e v a l u a t e d n o t j u s t by t h e i r o p e r a t i n g c o s t s b u t on a t o t a l economic r e t u r n b a s i s . I n many ca s e s heavy s o i l s r e q u i r e c o n v e n t i o n a l t i l l a g e o p e r a t i o n s i n o r d e r t o produce adequate c r o p y i e l d s . G. Summary o f L i t e r a t u r e Review C o n v e n t i o n a l t i l l a g e p r a c t i c e s s u c h as moldboard and d i s c p l o w i n g a r e b e t t e r a d a p t e d f o r sod b r e a k i n g o p e r a t i o n s t h a n minimum t i l l a g e p r a c t i c e s , e s p e c i a l l y i n f i n e t e x t u r e d s o i l s . I n t h e s e s o i l s , s o i l c o n d i t i o n s f o l l o w i n g t i l l a g e a r e h i g h l y dependent on t h e s o i l m o i s t u r e c o n t e n t . The s o i l t e m p e r a t u r e regime i s a f f e c t e d by t i l l a g e when i t changes s o i l p a r a m e t e r s s u c h as t h e s o i l ' s t h e r m a l d i f f u s i v i t y and a l b e d o . C o n v e n t i o n a l t i l l a g e g e n e r a l l y r e s u l t s i n g r e a t e r s o i l t e m p e r a t u r e extremes t h a n minimum t i l l a g e . The t e m p e r a t u r e o f t h e s o i l i n t u r n a f f e c t s s o i l b i o l o g i c a l p r o -c e s s e s such as s o i l o r g a n i c m a t t e r d e c o m p o s i t i o n . I t a l s o a f f e c t s s e e d g e r m i n a t i o n and r o o t g r o w t h . T i l l a g e g e n e r a l l y changes o r i n d u c e s changes i n t h e s o i l s t r u c t u r e . P h y s i c a l s o i l p a r a m e t e r s s u c h as a g g r e g a t e s i z e d i s t r i b u t i o n and a e r a t i o n p o r o s i t y a r e a f f e c t e d by t i l l a g e p r a c t i c e s . I n f i n e t e x t u r e d s o i l s c o nven-t i o n a l t i l l a g e p r a c t i c e s g e n e r a l l y r e s u l t i n a more open s o i l s t r u c t u r e , e.g. l o w e r s o i l b u l k d e n s i t i e s and h i g h e r a e r a t i o n p o r o s i t i e s , t h a n minimum t i l l a g e p r a c t i c e s . Due t o changes b r o u g h t about i n t h e s o i l s t r u c t u r e , 34 improved s o i l aeration and improved s o i l warming can result in higher s o i l n i t r i f i c a t i o n rates, thereby improving the s o i l f e r t i l i t y . In order to economically assess tillage systems both the cost of till a g e and the subsequent crop yield should be analyzed, preferably on a long term basis. 35 I I I . STUDY OBJECTIVES The absence of t i l l a g e g u i d e l i n e s f o r the area, the p h y s i c a l character of the Pineview c l a y , the c o o l s p r i n g temperatures and wet s o i l c o n d i t i o n s r e s u l t e d i n the f o l l o w i n g o b j e c t i v e s : ( i ) To study the e f f e c t of s o i l temperature on the r a t e of emergence of b a r l e y s e e d l i n g s . ( i i ) To determine which t i l l a g e treatments are s u i t a b l e f o r sod breaking operations on Pineview c l a y , ( i i i ) To evaluate these t i l l a g e systems by studying the f o l l o w i n g : a) s o i l p h y s i c a l p r o p e r t i e s b) s o i l N-transformations c) s o i l temperatures d) growth of a b a r l e y crop e) economics of the treatments 36 IV. PROJECT OUTLINE During the winter of 1976-1977, a growth chamber study was carried out at U.B.C. Soil temperatures of 5°, 10*, 12.5*, 15°, and 20*C were used to determine the rate and percent of emergence of barley seedlings. In separate studies the effect of f e r t i l i z e r placement and the effect of adverse s o i l physical conditions on barley emergence were also studied. During the summer of 1977, a number of tillage studies were carried out at the Agriculture Canada Experimental Farm in Prince George, B.C. They were: a) the effect of moldboard plowing at different dates on sod control. b) the effect of rotovating prior to moldboard plowing on s o i l break-up and sod control. c) a comparison of moldboard plowing, rotovating & moldboard plowing, disc plowing, and chisel plowing. d) evaluating the use of herbicides prior to till a g e as in (c). e) the effect of tillage treatments on the temperature of the so i l at 5, 10 and 50 cm depths. The major tillage study was started at the same experimental farm in August 1977. Four tillage treatments were carried out as f a l l t i l l a g e operations and the treatments were evaluated during the spring and summer of 1978. Evaluation consisted of studying the physical s o i l properties (including s o i l warming), nitrogen transformations, crop growth and development and the economical returns of the treatments. 37 V. MATERIALS AND METHODS A. Soil Description The Pineview Clay Association is characterized by a level to undulating topography. In i t s native state the s o i l is mainly covered with pine and spruce forests. The s o i l is an Orthic Gray Luvisol and one of i t s major characteristics is i t s high clay content, which is in excess of 50% (Farstad, 1947) . The Bt horizon has a clay content of around 70% and is located roughly between 15 and 35 cm. This horizon severely restricts root penetration and water drainage (Farstad, 1947). A s o i l description is given in Table I. The fields used for the tillage studies were old forage stands, con-sisting of mostly perennial grasses. The fields had not been f e r t i l i z e d or t i l l e d for over 12 years. A very dense thatch layer (L-F) had developed, ranging from 4-6 cm in depth. Primary tillage operations on these fields could therefore be classified as sod breaking operations. B. Growth Chamber Studies Three laboratory experiments were designed to evaluate the effects of so i l compaction, temperature and f e r t i l i z e r placement on the emergence of barley seedlings. Six metal rings were used in the s o i l compaction study, they were 7.5 cm wide and 7.5 cm high, 3 of the rings were loosely f i l l e d with Pineview clay, the other 3 were f i l l e d with the same s o i l , but were compacted during the f i l l i n g process. Compaction was carried out by f i l l i n g the core in layers and tapping each layer with a cylindrical tamper 4 cm in diameter. N and P were added to the soils at 29 and 64 kg/ha, respectively, with a NH^ H^ PO^  solution. The samples were saturated to approximately 60% of their f i e l d capacity through capillary action. They were stored at room temperature and 38 TABLE I Pineview c l a y , s o i l p r o f i l e d e s c r i p t i o n . Horizon Depth (cm) D e s c r i p t i o n L-F 5- 0 Dark brown (7.5 YR 4/2 d) semidecom-posed organic matter; f i b r o u s , common, f i n e and medium ro o t s ; abrupt, smooth boundary; 4-6 cm t h i c k . Ap 0- 10 Gray (10 YR 6/1 d) c l a y ; medium blocky; very hard; p l e n t i f u l ; c l e a r , wavy boun-dary; 5-15 cm t h i c k ; pH 5.1. Ae 10- 15 Light gray (10 YR 7/2 d) c l a y ; coarse blocky; very hard; very few; gradual i r r e g u l a r boundary; 3-7 cm t h i c k ; pH 5.1. Bt 15- 35 Grayish brown (10 YR 5/2 d) c l a y ; very coarse blocky; very hard; d i f f u s e i r r e g u l a r boundary; 15-25 cm t h i c k ; pH 6.0. BC 35-•40 Gray (7.5 YR 6/ d) c l a y ; s t r u c t u r e l e s s ; very hard; c l e a r , wavy boundary; 3-7 cm t h i c k ; pH 6.3. C 4 0+ Gray (7.5 YR 6/ d), with a l t e r n a t i o n of l i g h t and dark l a y e r s with range of co l o r from l i g h t gray (10 YR 7/1 d) to grayish brown (10 YR 5/2 d), c l a y ; f i n e p l a t y ; very hard; pH 7.0. 39 the emergence of barley was evaluated by daily counting. The total and aeration porosity, as well as the bulk density of the samples were measured at the termination of the experiment. The analyses were carried out by f i r s t weighing the samples, saturating them in three stages taking approximately 6 hours, and placing them on a tension table (6 kPa) for 12 hours. The samples were then weighed and placed in a drying oven at 105 C. After drying for 48 hours, the samples were weighed again and subsequently separated from their metal rings, which were weighed separately. Total porosity was deter-mined from the difference in weight of the saturated s o i l sample and that of the oven dried s o i l sample. Aeration porosity was calculated from the saturated weight of the sample and from the weight after the sample had been placed on a tension table at 6 kPa for 10 hours. Bulk density was determined by dividing the oven dried weight from the core volume. A f e r t i l i z e r placement study was carried out in order to determine how f e r t i l i z e r was to be added in the s o i l temperature vs. barley emergence study. The study was done in a tray, 32 x 50 x 7.5 cm f i l l e d with Pineview clay. The tray was divided into 4 compartments, each having a different f e r t i l i z e r treatment and a l l were seeded to two rows of barley (Gait). The treatments were; (i) placing the f e r t i l i z e r 2.5 cm below and to the side of the seed, ( i i ) placing the f e r t i l i z e r with the seed, ( i i i ) no f e r t i l i z e r and (iv) broad-casting the f e r t i l i z e r and incorporating i t in the top 2.5 cm. The f e r t i l i z e r was analytical grade NH^ H^ PO^ , at approximately 29 kg/ha of N and 64 kg/ha of P. The seeds were placed at a depth of 2.5 cm. After f e r t i l i z a t i o n and seeding had been carried out, the s o i l was saturated to approximately 60% of the f i e l d capacity through capillary action. The tray was stored at room temp-erature and the emergence of barley seedlings was evaluated by daily counting. 40 In the f i n a l l a b o r a t o r y study a P e r c i v a l growth chamber was used to achieve constant temperatures of 5°, 10*, 12.5°, 15° and 20°C, the temperature v a r i a t i o n was 0.2 C. Each temperature treatment c o n s i s t e d of two trays f i l l e d w i t h Pineview c l a y , each w i t h 12 rows of b a r l e y seeds at 10 seeds per row. F e r t i l i z e r and water was added as i n the f e r t i l i z e r placement study. The temperatures were recorded w i t h a hygrothermograph (Weather Measure Corp.). The emergence of b a r l e y was measured by d a i l y counting. C. F i e l d Studies Two t i l l a g e s t u d i e s were undertaken during the summer of 1977. They were both c a r r i e d out on a f i e l d i n sod which had not been t i l l e d or f e r t i l i z e d i n at l e a s t 12 years. Study 1 The f i r s t study evaluated the e f f e c t of moldboard plowing at d i f f e r e n t dates and the e f f e c t of r o t o v a t i n g p r i o r to moldboard plowing on sod c o n t r o l . The moldboard plow treatments were 7.5 x 35 m and were c a r r i e d out at weekly i n t e r v a l s . One h a l f of a l l the moldboard plow p l o t s were rotovated twice to a depth of 3.5 cm p r i o r to plowing. The depth of plowing was 10 cm. For the plowed p l o t s , a John Deere 2 bottom stubble plow was used, f o r the r o t o -vated p l o t s a 1.2m width Howard r o t o v a t o r . A David Brown 990 t r a c t o r of approximately 37 kW (55 hp) was used f o r a l l the t i l l a g e work. Sod c o n t r o l was evaluated by v i s u a l o b s e r v a t i o n . Study 2 The second study was a comparison of moldboard plowing, r o t o v a t i n g & moldboard plowing, d i s c plowing and c h i s e l plowing. The e f f e c t of using a h e r b i c i d e p r i o r to t i l l a g e operations was a l s o evaluated. The s i t e was adjacent to that used i n study #1, and was d i v i d e d i n t o e i g h t p l o t s each 41 7.5 x 35 m, forming a randomized block design. One h a l f of each p l o t was sprayed w i t h Gramaxone (Paraquat) at 12 l i t r e s per ha one week before t i l l a g e . The t i l l a g e treatments were d u p l i c a t e d and used the same equipment as i n study //l, as w e l l as a John Deere double d i s c plow, and a 4.3 m Minneapolis Moline c h i s e l plow. Rotovation c o n s i s t e d of one pass at a depth of 5 cm, a l l plowed treatments were to a depth of 10 cm. The c h i s e l plow treatment r e q u i r e d 5 passes before a s a t i s f a c t o r y s o i l t i l t h had been created. The d i s c plow treatment had to be abandoned due to the extremely rough surface c o n d i t i o n s that i t created which could not be broken down w i t h harrows. A l l treatments were d i s c harrowed twice and spike tooth harrowed once. S o i l temperature measurements were made using S i l i c o n (FD 300) diodes and a constant current voltmeter box. The diodes were i n s e r t e d at s o i l depths of 5, 10 and 50 cm through s o i l excavation. Two s e t s of diodes were used i n each p l o t , as w e l l as two s e t s i n an u n f i l l e d p l o t adjacent to the t i l l a g e p l o t s . S o i l temperatures were measured twice d a i l y , at 0700 P.S.T. and at o 1230 P.S.T. (the accuracy of the system was estimated to be 0.5 C). Sod c o n t r o l and s o i l break up were evaluated by v i s u a l o b s e r v a t i o n . T i l l a g e cost was analyzed using a 1978 A l b e r t a A g r i c u l t u r e farm machinery guide ( A l b e r t a A g r i c u l t u r e , 1978) . From the i n f o r m a t i o n obtained from the two t i l l a g e s t u d i e s , four t i l l a g e methods were s e l e c t e d and were a p p l i e d as f a l l sod breaking operations i n August 1977. They were: moldboard plowing (M), r o t o v a t i n g & moldboard plowing (R + M), c h i s e l plowing (Ch), and r o t o v a t i n g and c h i s e l plowing (R + Ch). The implements c o n s i s t e d of a three bottom Overum sod breaking plow, and a r o t o v a t o r and c h i s e l plow that were used i n s t u d i e s 1 and 2. Depth and frequency of moldboard plowing were the same as i n study 2. The Ch p l o t s were plowed 4 times at r i g h t angles and worked at diagonals w i t h a 42 disc harrow a month l a t e r . The R + Ch p l o t s were plowed twice, at r i g h t angles, followed with two passes with a disc harrow a month l a t e r . S o i l moisture contents were determined at the same time that the t i l l a g e operations were ca r r i e d out, using the gravimetric method (Gardner, 1969) . The s i t e was adjacent to the ones used i n studies 1 and 2, and consisted of three blocks 35 x 140 m. Two of these blocks were on a s l i g h t slope facing east, the t h i r d was on a somewhat l e v e l surface. The blocks were separated into four 35 x 35 m plots and t i l l a g e treatments were randomly arranged amongst the 4 p l o t s . Each t i l l a g e p l o t a f t e r allowing for a border zone around i t s edges contained 4 subplots of 4.6 x 18.3 m. Four f e r t i l i z e r treatments were randomly arranged i n the 4 subplots. F e r t i l i z e r was applied a f t e r a l l the plots were disc harrowed and spike tooth harrowed. The f e r t i l i z e r consisted of four rates; 0, 56, 112, and 168 kg N/ha i n the form of urea (46-0-0), which was broadcast using a 1.2 m Gandy f e r t i l -i z e r spreader. Subsequent to f e r t i l i z a t i o n a l l pl o t s were disc harrowed i n a d i r e c t i o n which minimized contamination between subplots. The plots were seeded to c e r t i f i e d barley seed (Gait) at 112 kg/ha with a Massey Ferguson seeder. Along with the seed 75 kg/ha of ammonium phosphate (11-48-0) was applied. Diodes were i n s t a l l e d at depths of 5, 10, and 50 cm i n each t i l l a g e p l o t as well as i n the u n t i l l e d sod plots adjacent to the t i l l a g e p l o t s . The diodes were i n s t a l l e d by f i r s t pushing a metal rod of s i m i l a r diameter into the s o i l at an angle of 45°. The diode with i t s cable was then led into the hollow, while a mud s l u r r y was added i n order to prevent a i r pockets. The cable (4 conductor, p l a s t i c shielded cable) attached to the diode was hooked up to one of two switch boxes located i n Stevenson screens 1.2 m above ground. The diodes were FD 300 ( F a i r c h i l d Semi-conductor), and were coated with 43 electrical resin (Scotchcast #8) . Soil temperatures were measured daily at 0/00 and at 12*50.,. The jsame constant current voltmeter box as in study #2 was o used allowing for an overall accuracy of + 0.5 C. Air temperatures were measured at the same times, using min/max thermometers and a hygrothermograph. The thermometers and the hygrothermograph were located in the Stevenson screens. The surface roughness was measured immediately after the f a l l t i l l a g e treatments were carried out. The measurement was carried out by f i r s t spanning a rope tightly along the s o i l surface, diagonally across each till a g e plot. Subsequently at 1 m intervals the vertical distance between the rope (datum) and the s o i l surface was measured. The average distance between the rope and the s o i l surface was used as an index of the surface roughness. The barley crop was sampled twice during the summer of 1978, once in July (9 weeks after seeding) and once in August (13 weeks after seeding). After harvesting the barley crop for silage, the root development of the barley grown in differently t i l l e d plots was evaluated by visual inspection. Mixing of horizons was also evaluated at this time. An economic analysis was carried out using the farm machinery guide as in study #2. Tillage costs, f e r t i l i z e r and harvesting costs were compared with the yield of the barley. D. Laboratory Procedures 1. Physical Analyses Samples for aeration porosity, total porosity, bulk density, and moisture content were obtained by using a bulk density core sampler. , The samples should ideally be taken when the s o i l is near f i e l d capacity, or at least at the same moisture content at each sampling date. This w i l l 44 reduce the effect of s o i l swelling or shrinking on bulk density and aeration porosity determinations. However in this study this was not possible since the s o i l had i t s highest moisture content early in the spring and i t s lowest moisture content during the summer. (In other words the s o i l dried out during the study.) The samples were analyzed in the laboratory as previously described, (page 37) The samples for the particle density determination were collected from the top 10 cm and were analyzed by the pycnometer method (Blake, 1969). The samples for the particle size distribution were also taken from the top 10 cm and the analysis done by the hygrometer method (Day, 1969) . Atterberg Limits were determined on samples such as above using the procedure described by Sowers (1969). 2. Chemical Analyses A composite s o i l sample was taken from each subplot between depths of 0 - 10 cm. The samples were collected in a plastic bag, stored overnight in a cooler and sent by air freight to the laboratory at U.B.C. the following morning. In the laboratory at U.B.C. the samples were analyzed at their, natural moisture content. The samples were f i r s t crushed and then analyzed for various chemical properties. Total N, % organic matter, pH and mineral N levels were determined. Total N was determined colorimetrically by a Technicon Autoanalyzer II Methodology, (1975) following acid digestion in a block digestor at 420 C. Nitrate and ammonium N were extracted using 2N KC1 at approximately 10:1 KC1 solution to dry weight of s o i l (Bremner and Keeney, 1963) . Subsequently they were analyzed colorimetrically as in the case with total N. pH was determined using a 1:2 s o i l to 0.01 M CaC^ ratio (Peech, 1969). The % organic matter was determined with a carbon analyzer after combustion of the sample (Laboratory Equipment Corp., 1959, 1966). 45 A composite plant sample was taken from each subplot. The samples were weighed, placed i n a forced d r a f t oven f o r 48 hours at 70 C, and then weighed again. The samples were then ground with a Wiley M i l l and subsequently shipped to the laboratory at U.B.C. T o t a l N was determined using the procedure s i m i l a r to that of t o t a l N i n the s o i l samples. 46 VI. RESULTS AND DISCUSSION A. Soil Characteristics The soil's physical, mechanical and chemical characteristics are listed in Tables I I , III and IV. The particle size distribution of the s o i l is shown in Figure 2 and i t indicates a clay content of the top 10 cm of around 59%. The water retention curve is shown in Figure 3 and indicates a high s o i l water content even at s o i l water tensions near 1500 kPa. B. Laboratory Studies The purpose of the laboratory studies was to determine the effect of major adverse conditions occurring on Pineview clay, such as cold temperatures and poor s o i l structures, on the emergence of barley seedlings. The physical condition of the s o i l was found to affect the rate and percentage of emergence of a barley crop (Figure 4). A physical s o i l condi-tion characterized by a lower bulk density and higher aeration porosity (Table V) resulted in substantial differences in the rate and percentage emergence of barley. The rate of seedling emergence was faster in the loose s o i l where i t took 3 days for 50% of the seedlings to emerge compared to 7 days in the compacted s o i l . The f i n a l level of emergence was also lower in the compacted s o i l . The s o i l physical conditions that were used in this experiment are quite comparable to the ones found on the Pineview clay (Table I I ) . Tillage practices that affect these physical properties can therefore also affect seedling emergence. The placement of f e r t i l i z e r with respect to the seed showed some differ-ences in the rate and level of barley emergence (Figure 5). The treatments where the f e r t i l i z e r was either mixed with s o i l or at some distance from the seed (2.5 cm below and to the side of the seed) had the highest level 47 TABLE I I P h y s i c a l p r o p e r t i e s of Pineview c l a y . Depth Aer a t i o n P o r o s i t y T o t a l P o r o s i t y Bulk Density (cm) . (%) (%) (kg/m ) 3.5-11. 0 15.4 (0.4) 64. 0 (2.0) 1002 (2) 16.5-24. 0 7.4 (0.7) 60. 2 (0.7) 1280 (14) 21.5-29.0 7.3 (2.2) 59. 3 ( l . D 1250 (57) 52.5-60.0 2.9 (0.9) 56. 3 (0.9) 1310 (57) 92.5-100 4 . 6 (4.7) 57. 1 (4.2) 1265 (7) Values i n brackets are s tandard d e v i a t i o n s obtained from 3 samples . 48 TABLE I I I Mechanical p r o p e r t i e s of Pineview c l a y , 0-10 cm. Analyses Property Value Atterberg L i m i t s P l a s t i c L i m i t (%) 38.6 (1.7) L i q u i d L i m i t (%) 57.4 (2.1) P l a s t i c i t y Index (%) 18.8 (1.8) Texture % Sand 11.3 (1.8) % S i l t 29.9 (3.4) % Clay 58.8 (2.4) P a r t i c l e Density (kg/in 3) 2220 (90) Values i n brackets are standard d e v i a t i o n s obtained from 3 samples. TABLE IV Chemical p r o p e r t i e s of Pineview c l a y , 0-10 cm. Property Value % organic matter 7.4 (0.23) pH 4.5 (0.1) N03-N (ppm) 3 . 6 (0.28) NH^-N (ppm) 20.4 (1.41) t o t a l N (%) 0.29 (.001) C/N r a t i o 14.6 (0.4) exchangeable cations (meq/100 gm) Ca 11.6 (0.30) Mg 10.0 (0.20) K 1.67 (0.55) Na 0.33 (0.10) C.E.C. (meq/100 gm) 42.5 (1.00) Base S a t u r a t i o n (%) 54. 3 (0.40) Values i n brackets are standard d e v i a t i o n s obtained from 3 samples. T~ 1 1—i 1 1 1 i T " r 3 4 5 10 20 30 40 50 100 PARTICLE DIAMETER (MICROMETERS) 5 1 o to >-Q 6 0 - , U) 100 3 0 0 5 0 0 1 0 0 0 1 5 0 0 SOIL WATER TENSION (kPa) FIGURE 3 : Soil-water r e t e n t i o n curve of Pineview clay ( 0 - 1 0 cm) 52 of emergence. Placing the f e r t i l i z e r with the seed resulted in the lowest emergence. Possibly a negative effect of f e r t i l i z e r salt on the permeability of the seedcoat could reduce emergence. However the no-fertilizer treatment showed only slightly higher levels of emergence. No replications were made, so that i t is not possible to assess a level of significance to the obtained relationships. It should be pointed out that f e r t i l i z e r placement is not likel y to affect the emergence of seedlings unless i t reduces germination by affecting seedcoat permeability or seed mortality. The seedling in i t s i n i t i a l stages 15 l i k e l y to depend primarily on the nutrients present in the seed embryo rather than those in the s o i l . The rate of seedling emergence was found to be highly dependent on temperature (Figure 6). I t took in excess of 27 days for 50% of the barley seedlings to emerge at 5°C compared to around 4 days at 20°C (Table VI!). The temperature treatments did not have a significant effect on the f i n a l level of emergence. However i t should be pointed out that the longer i t takes for a seedling to emerge, the more susceptible i t is to adverse condi-tions such as the formation of s o i l crusts and attack by s o i l fungi. In this experiment the s o i l moisture content was kept near optimum (approximately 60% of f i e l d capacity), whereas under f i e l d conditions frequent cycles of wetting and drying can enhance s o i l crust formation. Seeding is carried out after achieving a satisfactory s o i l t i l t h . If i t takes 27 days for half the seeds to emerge then i t is quite possible that by that time the s o i l t i l t h w i l l no longer be in an optimum condition for seedling emergence. This study used constant temperatures and subsequently cannot be directly compared with f i e l d conditions. The study does however indicate the importance of s o i l temperature on barley seedling emergence. Early spring s o i l temperatures 53 I O O J 2 4 6 8 10 T I M E ( D a y s ) FIGURE 4: T h e e m e r g e n c e o f b a r l e y s e e d l i n g s u n d e r r e n t s o i l p h y s i c a l c o n d i t i o n s . ( V e r t i c a l b a r s a r e s t a n d a r d e r r o r s . ) t w o d i f f e r 54 TABLE V The p h y s i c a l s o i l c o nditions of the two treatments i n the barley emergence study. Treatment T o t a l P o r o s i t y Aeration P o r o s i t y Bulk Density (%) (%) (kg/m3) Loo se 68.7 15.9 950 Compacted 62.6 7.3 1080 L.S.D. 0.05 3.3 1.7 60 Values represent averages from 3 samples. 55 100-, 8 0 J LU O LU 60. or LU LU 40J 20J 0. FERTIL IZER WITH S E E D „ FERTILIZER 2.5cm BELOW + T0 THE SIDE OF S E E D NO FERTIL IZER BROADCAST FERTILIZER 0 i 1 1 1 r~ 4 6 8 10 12 TIME (days) n 1 r-14 16 18 FIGURE 5; The emergence of barley seedlings a f f e c t e d by d i f f e r e n t methods of f e r t i l i z e r placement. 5'6 r O O C J o l O \ CM o o O o GO CD — r O — r O CVJ O ro O ^ CO c/> >» a •a zQ LU LO "-.4- LO FIGURE 6: The emergence of barley seedlings at d i f f e r e n t temperatures. ( V e r t i c a l bars are standard e r r o r s . ) 5 7 TABLE VI The emergence of barley seedlings under selected temperatures. Temperature ( C) T 50 (days) E f (%) 5.0 27.3 65.0 10.0 15.7 74.0 12.5 10.7 66.7 15.0 8.4 73.5 20.0 3.7 87 . 0 L . S . D. 0.05 1.8 not s i g n i f i c a n t T _ = time required f o r 50 % of the seedlings to emerge f = f i n a l percentage of emergence 58 i n the Pineview c l a y are q u i t e low, around 5-10 C ( A g r i c u l t u r e Canada, 1954) . Consequently management p r a c t i c e s that r e s u l t i n improving s o i l warming can thereby speed up the r a t e of s e e d l i n g emergence. In summary, the la b o r a t o r y s t u d i e s showed that the p h y s i c a l c o n d i t i o n of the Pineview c l a y had a s u b s t a n t i a l e f f e c t on the rate and l e v e l of barley emergence. Temperatures between 5 °and 10°C had a d r a s t i c e f f e c t on the r a t e of ba r l e y emergence, where i t took around seven times as long f o r h a l f the barle y to emerge at 5 C than at 20 C. Between these temperatures o the r a t e of barl e y emergence almost doubled f o r every 5 increase i n temperature. C. P r e l i m i n a r y T i l l a g e Studies Moldboard plowing at weekly i n t e r v a l s was d i f f i c u l t to evaluate i n terms of sod c o n t r o l . Use of a stubble plow to turn over an o l d sod proved to be a major problem. The' furrow s l i c e was not completely turned over, l e a v i n g a ribbon of sod at the s u r f a c e . This ribbon was the cause of much of the sod regrowth. Another f a c t o r which made t h i s study d i f f i c u l t to evaluate was that the moisture c o n d i t i o n s v a r i e d w i t h time, which had a s u b s t a n t i a l e f f e c t on the plowing o p e r a t i o n . Rotovating p r i o r to moldboard plowing r e s u l t e d i n b e t t e r sod c o n t r o l . Even i n 1978, one year a f t e r the treatments were c a r r i e d out, d i f f e r e n c e s i n sod c o n t r o l were v i s i b l e . The s o i l break-up was a l s o improved s i n c e the rot o v a t o r e f f e c t i v e l y broke up the 2-5 cm t h i c k thatch l a y e r , which r e s u l t e d i n improved s o i l f r a c t u r i n g f o l l o w i n g plowing. The cost of using the r o t o -vator p r i o r to plowing may be p r o h i b i t i v e . In t h i s study r o t o v a t i o n was c a r r i e d out twice, r e s u l t i n g i n a t o t a l treatment cost of over $100 per 59 hectare, whereas the treatment using only moldboard plowing costs $49 per hectare. In a second study various tillage systems were compared. The same stubble plow was used and the results were the same. In the treatment using rotovation prior to moldboard plowing, rotovation was carried out only once to a depth of 5 cm (2.5 cm of which was thatch). As in the f i r s t experiment, sod control and s o i l break-up were improved by using the rotovator. Disc plowing could not be carried out properly as the toughness of the sod and possibly the limited weight of the tractor caused problems in the tillage operation. Long ribbons of sod, in some cases 6-7 m long, were rolled up or thrown sideways causing mounds 70-80 cm in height. The resulting s o i l surface could only be levelled with rotovators and harrows and had to be abandoned in terms of comparisons with other tillage treatments. Chisel plowing resulted in a rough s o i l surface with chunks of sod ranging from 5-30 cm in size lying on top of the s o i l . Five passes were required to break down mounds of up to 40 cm in height which were created by the second and third pass. Sod control in the chisel plow plots was poorer than in the other plots. Applying a herbicide, Gramoxone, prior to tillage substantially reduced sod regrowth. In a l l t i l l a g e treatments s o i l break-up was characterized by a more fractured s o i l surface when Gramoxone was applied. The cost of this particular herbicide is prohibitive when using i t at 12 litres/ha, which amounts to $156/ha (Green Valley F e r t i l i z e r and Chemical Co., 1979). The minimum, maximum and mean s o i l temperatures are listed in Appendix A. The minimum temperature represents a measurement taken at 0700 P.S.T., the maximum at 1230 P.S.T. These temperatures are not true minima and maxima. 60 The damping of the d a i l y temperature wave causes the s o i l temperature at 5 cm to have minima and maxima at d i f f e r e n t times of the day than those at 10 cm and 50 cm depths. R u s s e l l (1973) reported that f o r a bare Rothamstead s o i l the maximum temperature at 5 cm depth occurred around 1300, w h i l e at 10 cm the s o i l temperature reached i t s maxima at 1600. Consequently the 0700 and 1230 temperature measurements used i n t h i s study do not i n d i c a t e true maxima and minima. They are however i n d i c a t i v e of the s o i l warming process as a f f e c t e d by the various t i l l a g e systems and give a good e s t i m a t i o n of the d a i l y average s o i l temperature. The t i l l a g e systems which d i d not leave residue on the s o i l surface (M and R + M) r e s u l t e d i n higher s o i l temperatures at both the 5 and 10 cm depths. The c h i s e l plow treatment not only had lower temperatures but a l s o had smaller d a i l y temperature f l u c t u a t i o n s around the mean temperatures (Figure 7). The sod temperatures were lowest of a l l the treatments w i t h very l i t t l e temperature f l u c t u a t i o n e s p e c i a l l y at the 10 and 50 cm depths. Temperatures i n the sod treatment can only bevcompared ap p r o x i -mately w i t h those of the other treatments s i n c e i t had a 60 cm high canopy of r a t h e r sparse v e g e t a t i o n on i t , w h i l e the surface of the other treatments was r e l a t i v e l y bare throughout the t e s t . The s o i l temperatures at the 50 cm depth are shown i n Figure 8, and i n d i c a t e d i f f e r e n c e s i n temperature only between those of the t i l l a g e treatments i n general and those of the sod p l o t s . The v a r i a t i o n of these temperatures over time i s q u i t e s i m i l a r to that at 10 cm depth. At the 10 cm depth the average d i f f e r e n c e between temperatures of the sod treatment and the t i l l e d treatments v a r i e s between 2 and 4 C. At 50 cm the d i f f e r e n c e i s reduced but i s s t i l l s u b s t a n t i a l , e s p e c i a l l y during the l a t e r p a r t of the study. The r e l a t i v e l y low temperatures of the week, J u l y 17-23 can be explained by the high r a i n f a l l previous to that week. Between J u l y 10-16 46.1 mm r a i n f a l l was recorded and 20.2 mm during J u l y 17-23 (Environment Canada, 1977) . 61 f ] M A X M E A N MIN LU £ IOOJ o g 8 0 J 1 0 - 1 6 1 7 - 2 3 2 4 - 3 0 3 1 - 6 7 - 1 3 J U L Y " — A U G U S T -FIGURE 7; S o i l temperatures of d i f f e r e n t l y t i l l e d p l o t s 1977 62 FIGURE 8; S o i l temperatures at 50 cm depth for d i f f e r e n t l y t i l l e d p l o t s . (1977) 63 In summary, the study showed that the moldboard plow used (stubble plow) was not s u i t e d f o r sod breaking o p e r a t i o n s . Rotovation p r i o r to moldboard plowing r e s u l t e d i n b e t t e r s o i l break-up and l e s s sod regrowth. C h i s e l plowing created a very rough s o i l surface and r e q u i r e d many passes. Disc plowing r e s u l t e d i n s o i l c o n d i t i o n s which could only be f u r t h e r broken down wi t h a rotovator and had to be abandoned as a treatment. The h e r b i c i d e Gramoxone p r i o r to t i l l a g e operations r e s u l t e d i n improved s o i l break-up and reduced sod regrowth. The cost of using t h i s h e r b i c i d e at $156/ha i s p r o h i b i t i v e . S o i l temperatures were higher i n the moldboard plow treatment w i t h and without p r i o r r o t o v a t i o n than i n the c h i s e l plow treatment. Lowest temperatures were found i n the sod treatment. The c h i s e l plow and sod treatments a l s o had the smallest d a i l y temperature f l u c t u a t i o n s . D. 1977-1978 T i l l a g e Study The e v a l u a t i o n of the t i l l a g e operations i s separated i n t o ( i ) p h y s i c a l s o i l p r o p e r t i e s ( i i ) n i t r o g e n transformations ( i i i ) crop y i e l d and ( i v ) economics. ( i ) P h y s i c a l S o i l P r o p e r t i e s The surface roughness measurement showed that the c h i s e l plow p l o t s (Ch) were l e f t i n a much rougher s t a t e f o l l o w i n g primary t i l l a g e than the other treatments (Table V I I ) . This surface c o n d i t i o n may be d e s i r a b l e i n areas where s o i l e r o s i o n c o n t r o l or surface mulching i s of importance. For the Pineview c l a y the rougher s o i l surface meant a greater frequency of harrowing i n order to produce an adequate seedbed. The l a r g e chunks of sod which were l e f t on the s o i l surface i n the Ch p l o t s were exposed to the d r y i n g a c t i o n of the sun during the f o l l o w i n g s p r i n g . Consequently l e s s organic matter was incorporated w i t h subsequent d i s c harrowing i n the s p r i n g , thereby reducing 64 TABLE VII P h y s i c a l p r o p e r t i e s of the s o i l s used i n the t i l l a g e experiment, 0-10 cm. Analyses T i l l a g e treatments L.S.D. M R+M Ch R+Ch 0.05 mean weight diameter,(mm) June 1 1.98 Aug 14 1.84 surface roughness;average d e v i a t i o n from datum (cm) t o t a l p o r o s i t y (%) May 11 Aug 14 aer a t i o n p o r o s i t y (%) May 11 Aug 14 3 bulk density (kg/m ) May 11 Aug 14 12.2 72.9 63. 7 20.4 22.3 897 897 1.89 1.69 1.80 1.79 1.41 1.44 10.7 22.4 12.3 71.5 64 . 9 15.6 20.7 71.8 59.4 10.0 15.0 67 . 3 61 . 4 9. 1 15.8 903 1027 • 1090 907 980 1000 0.28 * 0.28 * 4 . 7 n. s . n. s. 4.0 4.0 53 53 * s i g n i f i c a n t to the 10 % l e v e l only. 65 the b e n e f i c i a l e f f e c t of organic matter incorporation i n the s o i l such as improved s o i l aeration. The aggregate s i z e d i s t r i b u t i o n was determined and calculated i n terms of mean-weight diameter (M.W.D.), differences between treatments were com-pared using an L.S.D. value of 0.10. This l e v e l of s i g n i f i c a n c e should be considered of importance due to l i m i t a t i o n s i n the p r e c i s i o n of sample c o l l e c t i o n i n this p a r t i c u l a r a n a l y s i s . The Moldboard plow treatment (M) resulted i n higher M.W.D. than the Ch treatment. This could be mainly caused by overpulverization i n the Ch plots due to the many passes with t i l l a g e equipment. The M.W.D. values for the M and rotovation and moldboard plowing (R + M) treatments did not s i g n i f i c a n t l y change over time while for the Ch and rotovation and c h i s e l plowing (R + Ch) treatments the values decreased. The lower s t a b i l i t y of the aggregates i n the Ch and R + Ch pl o t s may be attri b u t e d to the many t i l l a g e operations. This p r a c t i c e produces a greater number of shear planes and cracks i n s o i l aggregates as compared with those produced by f r o s t action and wetting and drying cycles only, thus r e s u l t i n g i n a lower aggregate s t a b i l i t y . The t o t a l porosity values were s i m i l a r f o r a l l t i l l a g e treatments at both sampling dates (Table V I I ) . The t o t a l porosity did decrease s i g n i f i c a n t l y over time f o r a l l treatments (Appendix B). S e t t l i n g of the s o i l a f t e r t i l l a g e may be one of the causes f o r the reduction i n t o t a l p o r o s ity. The s o i l was also considerably d r i e r by the second sampling date, causing some crack formation. Sampling did not take into consideration any s o i l shrinkage. The M treatment resulted i n a s i g n i f i c a n t l y higher aeration porosity (A.P.) than the other treatments at the f i r s t sampling date (Table V I I ) . Rotovating p r i o r to moldboard plowing reduced the aeration porosity due to pul v e r i z a t i o n of large p a r t i c l e s , but the R + M treatment s t i l l had s i g n i f i -66 cantly higher aeration porosities than the Ch and R + Ch treatments. By the second sampling date the A.P. values for a l l the treatments had increased. Root channels and cracks formed due to s o i l drying could have increased the aeration (macro) porosity at the expense of the micro porosity. By the second sampling date the moldboard and chisel plow had an overriding effect on the aeration porosity regardless of rotovation. The moldboard plow over-turned the s o i l and in the process caused some s o i l shearing; however, most of the break-up of the s o i l furrow into natural s o i l aggregates was probably caused by wetting and drying and freezing and thawing cycles following plowing. The chisel plow rips the s o i l into chunks which were not previously exposed to the weathering cycles. The aggregates thus formed are then further reduced through winter action, leaving fewer large aggregates and thus fewer large pores than in the case with the moldboard plow treatment. The M and R + M treatments resulted in significantly lower bulk densities than the Ch and R + Ch treatments (Table VII). The much smaller number of passes with tillage equipment used in the two treatments using the moldboard plow resulted in less danger of s o i l compaction as compared to the other treatments. The design of the-particular chisel plow used could have resulted in excessive s o i l compaction. The angle of approach of the chisel point was roughly 20-30 degrees to the horizontal. Any resistance to the chisel point w i l l momentarily result in i t bending backwards causing the approach angle to be increased to 70-80 degrees. Consequently when the chisel tines met any resistance, they tended to ride over the s o i l rather than shearing i t thereby compacting the s o i l below the plow depth. The date of sampling did not result in any significant differences in bulk density. Soil temperatures for 1978 are listed in Appendix C. As was the case with the preliminary study, the temperature data do not present true minima 67 2 0 j I 8 J I 6 J o ixi 14. r r Z> " — < r r LU ^ 12 UJ 1 0 8 /'//» **\\ A-/7F M R + M Ch R+Ch Sod T T T 1 ~T 1 1 1 1 7 - 1 3 1 4 - 2 0 2 1 - 2 7 2 8 - 3 4 - 1 0 11-17 1 8 - 2 4 2 5 - 1 2 - 8 9 - 1 5 L M A Y " - J U N E " " J U L Y 1 FIGURE 9; Average weekly s o i l temperatures at 5 cm depth. 1978 68 and maxima, since the temperatures for a l l depths were recorded at 0730 P.S.T. and 1230 P.S.T. The average temperatures at 5 cm depth show no clear effect due to tillage (Figure 9). The temperature extremes were larger in the M and R + M plots. The bare s o i l surface following moldboard plowing allowed the s o i l surface to warm up faster but also allowed more rapid cooling at night. The Ch and R + Ch plots had surface residues which acted as a mulch layer, thereby modifying the temperature extremes. Due to the irregular sur-face conditions, especially in the Ch plots, diodes placed at a depth of 5 cm may have actually been at shallower or deeper depths. The variability of temperature readings at the 5 cm depth were substantially higher than those from the 10 and 50 cm depths. Consequently the temperature data taken from the 5 cm depth are less valuable in indicating the thermal environment of the barley seedling than those obtained at 10 cm. At 10 cm there is a definite trend in s o i l temperatures due to tillage (Figure 10). The two treatments using the moldboard plow resulted in higher temperatures (0.5 - 1.0 C) than the other treatments during the f i r s t 5 weeks of the experiment. The physical condition of the top 10 cm in the two moldboard plow treatments has a consider-' able effect on the heat flow through the s o i l . During moldboard plowing sur-face residues are buried at a depth of approximately 10 cm, whereas in the case with chisel plowing residues are mixed in with the top 10 cm of the s o i l . These residues generally retain more moisture than the surrounding s o i l and thereby act as art insulator, thus restricting heat flow beyond their depths. Moisture contents determined during the growing season are listed in Table VIII. Although no significant differences were found, there was a slight trend indicating lower s o i l water tensions for the Ch and R + Ch plots early in the growing season. The temperature in the sod plots was quite 69 2 0 J I8J I6J o o I4J U J oe Z> r -< UJ 12. Q_ UJ IOJ 8J i 1 1 1— 7-13 14-20 21-27 28-3 MAY- J L. I 4-10 -JUNE T 1 1— 1-17 18-24 25-1 T 2-8 J LJULY-9-15 FIGURE 10; Average weekly s o i l temperatures at 10 cm depth. 1978 70 TABLE V I I I Percent moisture and s o i l water tensions of 4 t i l l a g e treatments during 1978 (0-10 cm depth). Sampling date M T i l l a g e R+M treatment Ch R+Ch May 17 moisture cont. (%) 40 39 42 43 standard dev. 2. 4 1 . 3 2.1 2. 6 tension (kPa) 110 140 70 55 June 7 moisture cont. (%) 34 33 33 36 standard dev. 2. 1 2.1 5.9 4. 2 tension (kPa) 390 580 580 240 J u l y 6 moisture cont. (%) 25 24 24 25 standard dev. 1 . 3 0.8 0.8 1 . 7 tension (kPa) >1500 >1500 >1500 >1500 Aug. 2 moisture cont. (%) 22 20 22 22 standard dev. 1. 7 1 . 0 1.0 1. 3 tension (kPa) >1500 >1500 >1500 >1500 Values represent averages from 3 samples. 71 s i m i l a r to that i n the Ch and R + Ch treatments during the f i r s t three weeks of the experiment. However once the s o i l warmed up the sod temperatures d i d l a g behind those of the other treatments. A s m a l l canopy together w i t h a thatch l a y e r of 2.5 cm was r e s p o n s i b l e f o r slowing down the r a t e of s o i l warming i n the sod treatment. The temperatures of a l l the treatments were q u i t e s i m i l a r at the end of the experiment, however at t h i s stage the e f f e c t of the height and d e n s i t y of the crop canopy overrode the t i l l a g e e f f e c t s . S o i l warming expressed i n degree days i s presented i n Figure 11. During the f i r s t 6 weeks a somewhat re g u l a r p a t t e r n e x i s t e d f o r the average number of degree days at 10 cm depth. The M and R + M treatments had a higher average number of degree days than the other treatments. By the 7th week of the experiment the canopies of the M and R + M treatments were s u b s t a n t i a l l y higher and denser than the other treatments and t h i s reduced s o i l warming. By t h i s time the sod treatment had the s m a l l e s t canopy and t h i s r e s u l t e d i n i t s g reatest extent of s o i l warming e s p e c i a l l y at the 5 cm depth. The temperatures at 50 cm (Figure 12) show l i t t l e d i f f e r e n c e due to t i l l a g e other than the M treatment r e s u l t i n g i n somewhat higher temperatures during a two week pe r i o d i n June. The e f f e c t of the buried residue i n the moldboard plow treatments on the heat flow through the s o i l i s p o s s i b l y o f f s e t by the higher s o i l temperatures at 10 cm f o r these treatments. In summary, the two treatments using the moldboard plow created a s u p e r i o r p h y s i c a l s o i l c o n d i t i o n compared to those using the c h i s e l plow. S o i l p h y s i c a l c o n d i t i o n s c h a r a c t e r i z e d by l a r g e r M.W.D., higher A.P., lower B.D. and s l i g h t l y warmer s o i l temperatures were the r e s u l t of using the moldboard plow as, compared to using the c h i s e l plow. The d i f f e r e n c e between these plows was r e s p o n s i b l e f o r the treatment d i f f e r e n c e s , the use of the • ( 8 Z . 6 T ) " a 0 OT P " * g jo s q a d a p s ^ o ^ d s2^iu^ j o s ^ B p a a a S a p X t ^ a a w i l l 3*111011 DEGREE DAYS PER WEEK I 1 - i 1 — ' rz — f v T " AVERAGE WEEKLY TEMPERATURE (°C) ZL 73 FIGURE 12: Average weekly s o i l temperatures at 50 cm depth. 1978 74 rotovator prior to plowing did not result in any major variations in s o i l physical properties. ( i i ) Nitrogen Transformations Total mineral N content was affected by the rate of N application and time, but not by different tillage operations (Appendix D). The organisms responsible for N mineralization are not as sensitive to low s o i l tempera-tures as those that are involved in n i t r i f i c a t i o n . N mineralization can also occur under poorly aerated conditions. Consequently differences in s o i l temperature and aeration caused by tillage may not have had a significant effect on N mineralization. F e r t i l i z e r N increments of 56 kg/ha resulted in s o i l mineral N increments of approximately 20 - 30 kg/ha (Figure 13). The levels of mineral s o i l N during the growing season are shown in Figure 14. Upon addition of the f e r t i l i z e r , there was an i n i t i a l increase in s o i l mineral N. The drastic decrease in mineral N between June and July was caused by N uptake by the barley crop since most of i t s vegetative growth took place at that time. The slight increase during the last month of the experiment can be attributed to s o i l N mineralization. The levels of NH^ -N were affected by the same factors as those of the mineral N, which were f e r t i l i z e r and time but not tillage (Appendix E). The levels of NH.-N in the s o i l followed much the same pattern as did the mineral 4 N, but were lower in value (Figure 15). For both mineral and NH^ -N maximum values were obtained in the middle of May 1978, 12 days after applying the f e r t i l i z e r . After this date n i t r i f i c a t i o n and crop uptake reduced the levels of NH.-N. 4 NO^ -N levels were affected by ti l l a g e , f e r t i l i z e r and time (Appendix F 2). The N0o-N levels were higher in the M and R+M plots than in the Ch and R + Ch 75 FIGURE 13: S o i l mineral N a f f e c t e d by selected f e r t i l i z e r N rates (0-10 cm). (Values represent average values for time and t i l l g * e . ) c n (D rt> n CD N CD 1-1 r t H CD D> r t 9 (0 3 O I o 9 M o a po-rt O 9 -< 3 ( 0 l-h i-t fD DJ a. c n 3 OQ VO ~ j 00 OQ H O t a OQ CO CD CO CO o 3 i-h O ft m ( Z 5 CD C C/) H SOIL MINERAL NITROGEN (kg/ha) 5= ^ z CZ ro H CM .o CD O J ro o 00 o J ro ro o 4 I cn — (Ti O O) ro CD 7r *r *~ ?r ( Q ( Q ( Q ( Q T T T Q Q Q Q 77 I80_ o 1 5 0 . I 2 0 _ LU O c r 9 0 . z 1 ~r •z. 6 0 . _ l o CO 3 0 J 0. i \ i' \ i 1 6 8 kg N/ha 112 kg N/ha - 5 6 kg N / ha 0 kg N /ha \ \ / \ \ \ / / / / / r \ \ \ -s— • 5 "T~ 17 M A Y -i 7 - J U N E -— i 6 J L - J U L Y -— i 2 - " A U G U S T FIGURE 15: S o i l NH^-N during the 1978 growing season for selecte d f e r t i l i z e r treatments (0-10 cm). 78 plots (Figure 16). This phenomenon can be explained by the more favourable physical conditions for n i t r i f i c a t i o n that occur in the M and R+M plots (see Table VII). These plots had substantially higher aeration porosities which favour n i t r i f i c a t i o n . They also had less organic matter incorporated in the top 10 cm (due to the plowing action), the decomposition of which could immobilize mineral N. Slightly higher s o i l temperatures in these plots (Figure 11) also would have a favourable effect on n i t r i f i c a t i o n . The rate of n i t r i f i c a t i o n shows a similar trend for a l l f e r t i l i z e r treatments (Figure 17). The highest levels of NO^ -N appeared 5 weeks after applying the N f e r t i l i z e r . This corresponds roughly with the pattern of s o i l temperature, which shows a drastic s o i l warming trend 4 weeks after f e r t i l i z a t i o n took place (Figures 11 and 12). The rapid decline of NO^ -N afterwards i s due to crop uptake, since most of the growth of the barley crop occurred in June and July. Higher rates of applied N resulted in higher s o i l NO^ -N levels. An increment in f e r t i l i z e r N of 56 kg/ha resulted roughly in an increment in s o i l NO^ -N of 6 kg/ha (averaged over the entire growing season). The ratio of NH.-N to N0„-N was affected by both f e r t i l i z e r rate and 4 3 time but not by tilla g e (Appendix G). The urea f e r t i l i z e r was rapidly ammoni-fied as shown by the high NH^ -N/NO^ -N ratios (Figure 18). N i t r i f i c a t i o n subsequently reduced the ratio to i t s lowest level 4 weeks after f e r t i l i z a t i o n . The mobility of NO^ -N plus the preferred uptake for NO^ -N by the barley crop probably increased the ratios towards the end of the experiment. Higher N rates resulted in higher NH.-N/NO -N ratios, since the f e r t i l i z e r N must f i r s t 4 3 be ammonified before n i t r i f i c a t i o n can produce nitrates. In summary, the rate of mineral N accumulation was affected by the rate of f e r t i l i z e r N and time, but i t was not affected by ti l l a g e . The rate of NH^ -N accumulation followed much the same pattern as that of the mineral N. 3 O CD o Ml O ro z H O O r t S OJ H - ^ I N ro n H (B r t ro < r - 1 C c ro ro CD CO H ro n ro co ro 3 cu CD ro o r t ro PL. a* cu < ro i cu OQ ro < cu » cw M ro c ro r t co ro H i cu O r t H g ro r t 3 H- r t S co ro SOIL N C C - N I T R O G E N ( k g / h a ) IV) CJl x\ \ \ \ \ \ \ \ \ \ \ \ \ \ \^ I ro CD J ro ro oo j ro co j O J o J L _ O VD 80 168 kg N / h a 112 kg N / h a 5 6 kg N / h a 0 kg N / h a 5 0 J i — i 1 1 r 5 17 7 6 2 •-MAY—"-JUN—"-JUL—"-AUG i — r R+ChA / \ / A \ /i \ \ it/ \ \ OfK \ \ i — i r 5 17 7 6 T 2 - M A Y — J U N — » - JUL—"-AUG FIGURE 17: S o i l N03~N for t i l l a g e / f e r t i l i z e r treatments over time. 81 \ 5.0J 4 .0J < or O 3.0J 2.0J I.OJ 0. \ \ /\ / \ / \ / \ / \ / / \ / ./ // V I I 168 kg N / h a 112 kg N/ha 56 kg N/ha 0 kg N/ha i r~ 5 17 M A Y — 7 J JUNE-(  6 -"JULY--| 2 AUGUST FIGURE 18: NH.-N/N0--N r a t i o s during 1978 a f f e c t e d by 4 J selected f e r t i l i z e r r a t e s . 82 The l e v e l of NO^-N was a f f e c t e d by t i l l a g e , f e r t i l i z e r N r a t e and time. This i n d i c a t e s that n i t r i f i c a t i o n i s a f f e c t e d by the changes brought about by the t i l l a g e o p e r a t i o n s , w h i l e N m i n e r a l i z a t i o n i s not. ( i i i ) Crop Growth and Development The y i e l d of b a r l e y was a f f e c t e d by t i l l a g e , f e r t i l i z e r r a t e and time (Appendix H). Moldboard plowing r e s u l t e d i n s u b s t a n t i a l l y higher y i e l d s than the other treatments i n c l u d i n g the R + M treatment (Table I X ) . Superior p h y s i c a l s o i l c o n d i t i o n s i n c l u d i n g warmer s o i l temperatures, together w i t h higher l e v e l s of s o i l NO^-N are the probable cause f o r the higher b a r l e y y i e l d s i n the M p l o t s . The y i e l d d i f f e r e n c e s were increased by the second sampling date, August 8. The r a t e of N f e r t i l i z a t i o n had a small but s i g n i -f i c a n t e f f e c t on the b a r l e y y i e l d e s p e c i a l l y i n the Ch and R + Ch treatments. The amount of N taken up by the b a r l e y crop was a f f e c t e d by t i l l a g e , f e r t i l i z e r r a t e and time (Appendix I 1). The M treatment r e s u l t e d i n substan-t i a l l y higher l e v e l s of N uptake than the other t i l l a g e treatments at both sampling dates (Table X). High l e v e l s of N uptake were found i n the M p l o t at the 0 N r a t e . This suggests that a s u b s t a n t i a l amount of N was s u p p l i e d by the s o i l organic matter. Data from the s o i l NO^-N alone cannot account f o r t h i s , s i n c e i t only represents a c o n c e n t r a t i o n of NO^-N over the top 10 cm. A more important f a c t o r i s the crop r o o t i n g depth, which was roughly twice as deep i n the M p l o t s than i n the Ch and R + Ch p l o t s . Consequently a much l a r g e r s o i l volume c o n t a i n i n g higher NO^-N l e v e l s (Figure 17) r e s u l t e d i n s u b s t a n t i a l l y more N uptake i n the M p l o t s than i n the other p l o t s . I n c r e a s i n g r a t e s of f e r t i l i z e r N d i d i n c r e as e the N uptake i n the t i l l a g e treatments. In the M treatments N r a t e s of 56, 112 and 168 kg/ha r e s u l t e d i n s i m i l a r l e v e l s of N uptake which exceeded the 0 N treatment by approximately 30 kg N per ha. Both the Ch and R + M treatments had t h e i r highest l e v e l of N uptake 83 TABLE IX Barley y i e l d as a f f e c t e d by t i l l a g e / f e r t i l i z e r treatments. T i l l a g e / f e r t i l i z e r Sampling date (kg N/ha) J u l y 7 August 8 t/ha : M 0 3.02 6.01 56 3.57 6.95 112 4.06 7.67 168 3.52 7.10 R+M 0 2.45 3.60 56 2.53 5.46 112 2.78 5.53 168 3. 07 5.53 Ch " 0 1 . 68 .3.40 56 2.17 3. 93 112 2.44 4.06 168 3.50 5.45 R+Ch 0 1 . 94 3 .68 56 2 .35 4.20 112 2 .18 4.59 168 2.51 4.33 TABLE X T o t a l N uptake by ba r l e y . T i l l a g e / f e r t i l i z e r Sampling date (kg N/ha) J u l y 7 August 8 kg/ha M 0 50.2 56.4 56 50.3 84.4 112 60.0 89.4 168 78.6 88. 3 R+M 0 19.4 29.1 56 28. 9 53.0 112 51.2 65 . 5 168 52.6 70.6 Ch 0 17 . 7 23.2 56 25.0 34.8 112 46.7 48.8 168 51 . 7 78 . 5 R+Ch 0 23.3 31.6 56 32.7 41.7 112 39.2 57.7 168 43.0 53.6 85 at 168 kg N/ha, the R + Ch treatment at 112 kg N/ha. By the second sampling date more N had been taken up. However, roughly 75% of the N had already been taken up by the f i r s t sampling date, 2 months after seeding the barley. The N content of the barley was affected by the f e r t i l i z e r N rate and time but not by tillage (Appendix J 2). Increasing rates of applied N resulted in higher N contents (Table XI). Higher concentrations of N were found at the f i r s t sampling date than at the second sampling date. The f i r s t sampling date (July 7) corresponds roughly with the start of the heading stage of the barley. Prior to the heading stage the main physiological development of the crop is to produce leafs and stalks, containing large amounts of nitrogen. During the heading stage of the crop development the barley matures and most of the growth that occurs is associated with the development of the seed with l i t t l e production of new leaf tissue. Percent f e r t i l i z e r N uptake was determined by substracting the N uptake in the non-fertilized plots from those in the f e r t i l i z e d plots and dividing the values by the amount of N applied as f e r t i l i z e r . It was found to be affected by time only (Appendix K 2). There also exist particular t i l l a g e / f e r t i l i z e r combinations that differ significantly from each other. In general the average amount of f e r t i l i z e r uptake by July 7 was 17.6%, this increased to 27.4% by August 8. The effect of t i l l a g e / f e r t i l i z e r treatment on % f e r t i l i -zer N uptake is shown in Figure 19. The M treatment had i t s highest level of N uptake at 56 kg N/ha, and the % N uptake decreased substantially with increasing rates of N f e r t i l i z e r . The Ch treatment showed a steady increase in % f e r t i l i z e r N uptake with increasing rates of f e r t i l i z e r N application. The root systems in the M treatment were considerably more extensive than those in the Ch treatments. This allowed more of the applied f e r t i l i z e r to TABLE XI Percent N of b a r l e y . 86 T i l l a g e / f e r t i l i z e r (kg N/ha) Sampling date J u l y 7 August 8 M 0 56 112 168 1. 68 1 .37 1 .40 2 .20 0.95 1 . 18 .1.17 1 .25 R+M 0 56 112 168 0.80 1.16 1 . 60 1.73 0.83 0.98 1.19 1.28 Ch 0 56 112 168 0. 98 1.13 1 .21 2 . 07 0.70 0.89 1.21 1.44 R+Ch 0 56 112 168 1.19 1.41 1 .83 1.74 0.87 1 . 00 1.25 1.26 87 v ^ j , — i r 56 112 168 FERTILIZER NITROGEN R A T E ( k g / h a ) FIGURE 19: Percent f e r t i l i z e r n i t r o g e n uptake i n A treatments a f f e c t e d by f e r t i l i z e r r a t e . t i l l a g e 88 be taken up. For the M treatment, maximum e f f i c i e n c y was achieved at a f e r t i l i z e r r a t e of 56 kg N per ha. The Ch treatment had i t s optimum e f f i c -iency at 168 kg N per ha. Both the R + M and the R + Ch treatments had maximum f e r t i l i z e r N uptake at 112 kg N per ha. In summary, the y i e l d of b a r l e y as w e l l as the t o t a l N uptake by the barley were a f f e c t e d by t i l l a g e , f e r t i l i z e r N r a t e and time. The N content of b a r l e y showed only s i g n i f i c a n t v a r i a t i o n s w i t h f e r t i l i z e r N r a t e and time. The percentage f e r t i l i z e r N uptake was only a f f e c t e d by time. ( i v ) Economic A n a l y s i s The costs i n v o l v e d i n the treatments such as t i l l a g e work, f e r t i l i z e r s and seeding equipment are l i s t e d i n Appendices L - 0. An economic assessment was c a r r i e d out comparing the t o t a l costs of the treatments w i t h the value of the s i l a g e crop produced (Table X I I ) . The M treatment r e s u l t e d i n higher y i e l d s of b a r l e y than the other treatments regardless of f e r t i l i z e r r a t e . I t a l s o had the lowest treatment c o s t s . Y i e l d / c o s t r a t i o s l i s t e d i n Table XII show the M treatment w i t h r a t i o s i n excess of 2.0, w h i l e the other t i l l a g e treatments had r a t i o s l e s s than 2.0 regardless of f e r t i l i z e r r a t e . Consequently i n terms of returns to investment ( y i e l d / c o s t r a t i o ) the M treatment was s u p e r i o r to the other treatments. There was comparatively l i t t l e d i f f e r e n c e i n y i e l d / c o s t r a t i o s amongst the other t i l l a g e treatments. I n c r e a s i n g N r a t e s decreased the y i e l d / c o s t r a t i o i n the M treatment, i n d i c a t i n g a l e s s s p e c t a c u l a r increase i n economic b e n e f i t due to N a p p l i c a -t i o n than due to the type of t i l l a g e treatment. The same phenomenon was found i n the R + Ch treatment. The other t i l l a g e treatments were more s i g n i f i c a n t l y a f f e c t e d by the f e r t i l i z e r N r a t e . The maximum p r o f i t s obtained w i t h the t i l l a g e / f e r t i l i z e r treatments are l i s t e d i n Table X I I . P r o f i t maximization occurs when the t o t a l revenue and TABLE XII Economic a n a l y s i s of t i l l a g e / f e r t i 1 i z e r treatments. T i l l a g e / f e r t i l i z e r Barley y i e l d Treatment cost P r o f i t Y i e l d / c o s t (kg N/ha) ( t / h a ) * ($/.ha)'.'.' ($/ha) ($/ha) r a t i o M 0 17 . 1 263.72 86.23 177.49 3 . 06 56 19.9 306.86 109.22 197.64 2.81 112 21 . 9 337.70 128.88 208.82 2.62 168 20.3 313.03 148.54 164.49 2.11 R+M 0 10.5 161.91 113.25 48. 66 1.43 56 15.6 240.55 136.24 104.31 1.77 112 15.6 240.55 155.90 84.65 1.54 168 15.6 240.55 175.56 64.99 1. 37 Ch 0 9.7 149.57 107.50 42.07 1.39 56 11.2 172.73 130.49 42.24 1. 32 112 11.6 178.90 150.15 28. 75 1.19 168 15.6 240.59 169.81 70.78 1.42 R+Ch 0 10.5 161.93 123.22 38.71 1.31 56 12.0 185.07 146.21 38.86 1.27 112 13. 1 202.03 165.87 37.00 1 .22 168 12.1 191.24 18 5.53 5.71 1. 03 * Y i e l d s are presented at 65 % moisture content . Market value for s i l a g e barley was es t imat ed to be $ 15. 42 per tonne ( p r i -vat e communication with J.N. T i n g l e , f i e l d crops s p e c i a l i s t B.C. M.A. P r i n c e George, B.C.) . 90 the t o t a l c o s t c u r v e s a r e f a r t h e s t a p a r t ( F i g u r e 2 0 ) . I n o r d e r t o maximize p r o f i t s , the f e r t i l i z e r r a t e s f o r each t i l l a g e t r e a t m e n t s h o u l d be; M a t 112 kg N/ha, R + M a t 56 kg N/ha, Ch a t 168 kg N/ha, and R + Ch a t 0 kg N/ha. I n summary, the economic a n a l y s i s i n d i c a t e d t h a t the M t r e a t m e n t r e s u l t e d i n s u b s t a n t i a l l y h i g h e r p r o f i t s t h a n the o t h e r t i l l a g e t r e a t m e n t s . The e f f e c t of f e r t i l i z e r N was t o d e c r e a s e the y i e l d / c o s t r a t i o i n t h e case of the M and R + Ch t r e a t m e n t s . However maximum -..yf©Td$: were o b t a i n e d w i t h i n c r e a s i n g r a t e s of f e r t i l i z e r N , e x c e p t i n the case w i t h t h e R + Ch t r e a t m e n t . Optimum t i l l a g e / f e r t i l i z e r t r e a t m e n t s were; M a t 112 kg N/ha, R + M a t 56 kg N/ha, Ch a t 168 kg N/ha, and R + Ch a t 0 kg N/ha. 91 4 0 0 - . i 1 1 1 - " - i 1 1 » 0 - L -T 1 1 1 " L i 1 1 1 0 5 6 112 168 0 5 6 112 168 FERTILIZER NITROGEN RATE (kg/ha) FIGURE 20: T o t a l revenues (TR) and t o t a l costs (TC) of t i l l a g e / f e r t i l i z e r treatments. 92 VII. CONCLUSIONS 1. In the laboratory study i t was shown that the emergence of barley 3 was faster in loose s o i l (B.D. = 950 kg/m , A.P. = 16%), where i t took 3 days for 50% germination to take place, than in compacted s o i l (B.D. = 1080 3 kg/m , A.P. = 7%), where i t took 7 days. The placement of f e r t i l i z e r 2.5 cm below and to the side of the seeds or incorporated with the s o i l resulted in the highest level of barley emergence. Placing the f e r t i l i z e r with the seed resulted in the lowest level of emergence. The rate of barley emergence was found to be highly temperature dependent. In a constant temperature growth chamber i t took 3.7 days at 20 C and 27.3 days at 5 C for half the seedlings to emerge. Between 5° and 20°C, increments of 5° resulted roughly in a doubling of the rate of barley emergence. 2. Preliminary til l a g e studies indicated that the stubble plow was inadequate as a sod breaking implement. Rotovation prior to moldboard plowing improved s o i l break-up and reduced sod regrowth. Chisel plowing was found to leave the s o i l in a rough surface condition and required many passes before secondary ti l l a g e implements could be used to complete seedbed prepara-tion. Applying the herbicide Gramoxone prior to tilla g e operations resulted in improved s o i l break-up and reduced sod regrowth. The cost of this herbi-cide ($156/ha) is prohibitive unless lower herbicide rates or cheaper alterna-tives can be used. Higher s o i l temperatures as well as greater daily s o i l temperature fluctuations were found in the plots t i l l e d with the moldboard plow, compared with those t i l l e d with the chisel plow. 3. The 1977-1978 tillage study showed that the treatments using the moldboard plow with or without prior rotovation resulted in superior s o i l physical properties with respect to those using the chisel plow. Higher values in terms of aggregate size distribution, lower bulk densities and 93 higher aeration porosities were found in the moldboard plow treatments as compared to the chisel plow treatments. At a depth of 10 cm s o i l temperatures were found to be slightly warmer in the moldboard plow treatments than in those using the chisel plow. Soil temperatures in general increased rapidly at the end of May 1978. 4. Mineral N accumulation and ammonification were found to increase with the rate of f e r t i l i z e r applied N. During the growing season mineral and NH^ -N levels i n i t i a l l y increased during the f i r s t two weeks of the experiment and decreased afterwards due to n i t r i f i c a t i o n and crop uptake. NO^ -N levels were found to be higher in treatments using the moldboard plow than those using the chisel plow. Soil NO^ -N levels increased with rates of f e r t i l i z e r applied N. Highest s o i l NO^ -N levels were found approximately one month after seeding, which corresponds well with the s o i l warming trend at that time. Crop uptake of N caused substantial reductions in the level of s o i l N03-N during June 1978. 5. Barley yields were highest in the moldboard plow treatment. The two chisel plow treatments with or without prior rotovation had the lowest yields, while rotovation and moldboard plowing resulted in intermediate yields. N f e r t i l i z a t i o n had a small but significant effect on crop yield. Highest yields were obtained at 112 kg/ha i n the moldboard plow treatment, 112 kg/ha in the rotovation and moldboard plow treatment, 168 kg/ha in the chisel plow treatment, and 112 kg/ha in the rotovation and chisel plow treatment. The amount of N taken up by the barley followed much the same pattern as that of the total yield of the crop. Roughly 75% of the N was taken up during the f i r s t two months after seeding. The percentage of N in the barley was highest two months after seeding and dropped off during 94 the third month. This reduction in the percentage of barley N was mainly due to a change in the physiological growth characteristic of the barley plant at i t s heading stage. 6. An economic analysis showed the moldboard plow treatment with the least costs and the greatest returns. This treatment had the highest yield/ cost ratios regardless of f e r t i l i z e r rate. 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Uptake o f n i t r o g e n and phosphorus i n r e l a t i o n t o s o i l s t r u c t u r e and n u t r i e n t m o b i l i t y . P l a n t and S o i l XVI No. 1:63-70. 103 Wiese, A.F. and D.W. Stanifbrth. 1973. Weed control in conservation ti l l a g e . J_n Conservation t i l l a g e . The proceedings of a national conference. Soi l Conserv. Soc. Amer. Iowa, 1973. Wilkinson, B. 1975. Field experience on heavy s o i l s . I_n Soil physical conditions and crop production. Min. Agric. Fish, and Food Tech. Bull. 29. H.M.S.O., London. Yoder, R.E. 1936. A direct method of aggregate analysis of soi l s . Journ. Amer. Soc. Agron. 28:337-351. 104 APPENDIX A l ; S o i l t e m p e r a t u r e s i n 1977. Moldboard plowed p l o t s Date 5 cm d e p t h 10 cm d e p t h min. s.d. max. s.d. mean m i n . s . d . max. s.d, 50 cm d e p t h mean min. s.d. max. s.d. J u l 11 14.0 0.1 16.5 0.1 15.3 14.3 0.8 12 12.5 0.8 20.5 1.4 16.5 13.0 0.3 13 13.5 0.1 20.5 0.8 17.0 14.0 0.6 14 13.5 0.3 22.2 0.8 16.7 13.6 0.4 15 13.0 0.7 21.0 1.0 17.0 13.0 0.3 16 14.0 0.1 14.0 1.1 14.0 14.2 0.4 17 9.7 0.1 12.5 1.1 11.1 10.4 0.5 18 8.8 0.5 12.0 0.4 10.4 9.4 0.7 19 11.2 0.5 21.0 1.5 16.1 10.8 0.6 20 11.3 0.4 23.5 2.3 17.4 11.4 0.3 21 14.0 0.3 19.0 1.5 16.5 14.0 0.4 22 11.5 0.2 21.0 2.2 16.3 11.5 0.5 25 13.5 0.4 28.0 1.6 20.8 14.2 0.6 26 16.0 0.5 28.2 2.3 22.1 16.0 0.9 27 15.6 0.1 29.5 2.0 22.6 15.8 0.8 28 16.2 0.1 21.2 2.0 18.6 17.0 0.7 Aug 2 15.2 0.3 24.5 1.4 19.9 15.2 0.7 3 15.1 0.5 23.3 1.6 18.5 14.6 0.8 4 13.5 0.2 23.5 2.3 18.1 14.2 0.8 5 13.7 0.2 23.3 1.3 19.3 13.2 0.9 8 16.4 0.2 22.2 0.8 19.2 16.4 0.5 9 13.7 0.5 22.0 1.6 18.6 16.2 0.7 10 14.2 0.3 25.5 1.0 19.7 15.0 0.8 14.2 0.6 14.3 11.0 0.4 16.9 0.9 15.0 11.1 0.4 1.9 16.1 11.5 0.5 1.1 16.5 11.7 0.3 15.4 11.7 0.5 14.4 12.1 0.4 18.2 19.3 17. 6 1 14.5 12.8 11.5 17.2 18.5 16.8 1 17.4 1 20.6 1 22.8 1 24.0 0 21.1 21.0 20.0 20.8 21.3 19.4 19.3 21.0 11.6 11.6 0.4 15. 14. 17. 19, 8 19 0.9 19 0.5 17 0.6 17 6 5 5 4 0 10.4 11 14.0 11 14.9 U 4 11 4 11 4 4 . 9 , 0 ,7 .4 1 7 0 7 0 0.4 0.3 0.3 0.4 17 . 17. 18, 17 18, 3 4 3 .4 .5 21.1 12.6 12.8 13.3 0 13.4 0 13.4 13.4 13.0 14.0 0 14.0 0 14.2 11 11. 11. 11. 12. 11. 11 . 11. 11 . 11. 11. 12. 12, 12, 13, 13 13 i 3 13 13 14 14 14 1 9 7 9 0 0 0.5 0.4 9 0 6 0 5 0 7 0.3 7 0.4 5 0.3 0.4 0.4 0.5 0.6 0 0 0 0 0 0 0 0 1 6 ,8 , 6 .4 .7 . 6 . 9 . 9 . 1 .4 6 mean 11.1 11.5 11.6 11.8 11.9 12.0 11.6 11.4 11.6 11.5 11.5 11.8 12.4 12 13 13 13 13 13 13 14.1 14.2 14.4 V a l u e s r e p r e s e n t a v e r a g e s from max.- s o i l t e m p e r a t u r e s a t 1230 3 l o c P. S a t i o n s . min.- s o i l t e m p e r a t u r e s at T. s . d . - s t a n d a r d d e v i a t i o n 0700 P.S.T. 105 APPENDIX A2; S o i l t e m p e r a t u r e s i n 1977. R o t o v a t e d and moldboard plowed p l o t s . Date J u l Aug min. 5 cm s.d. d e p t h max. s.d. mean 10 min. cm d e p t h s.d. max s.d. 50 mean cm d e p t h min. s.d. max s.d. mean 11 14. 4 0.1 17 . 4 0.4 15.9 15.2 1.0 16. 7 0.5 16. 0 10.8 0.4 11 . 4 0.4 11 . 1 12 13. 0 0.2 16. 5 1. 6 14.8 13.2 0.2 17 . 7 0.8 15. 5 10.4 0.4 10.6 0. 5 10. 5 13 13. 7 0.1 20. 4 0.9 17.2 14.1 0.5 18. 8 0.6 16. 5 10.5 0.3 10. 8 0.4 10. 7 14 13. 6 0.1 22. 5 1.9 18.1 14.0 0.2 20. 4 1. 1 17. 2 10.6 0.3 11. 1 0.4 10. 9 15 13. 3 0.3 20. 4 1.5 16.9 13.4 0.4 18. 1 0.8 15. 9 10.8 0.3 11. 1 0.4 11. 0 16 14. 2 0.1 14 . 6 0.3 14.5 14.3 0.3 14. 6 0.9 14. 5 12.0 0.3 12. 1 0.3 12. 1 17 10. 2 0.3 13. 7 0.6 12.1 10.8 0.7 13. 2 0.4 12. 0 11.7 0.3 11. 6 0.3 11. 7 18 9. 1 0.7 12. 1 0.3 10.6 9.6 1. 1 11 . 7 0.6 10. 7 11.5 0.1 11. 7 0.2 11. 6 19 11. 3 0.1 20. 9 2.1 16. 1 10.9 0.6 17 . 7 1.8 14. 8 11.6 0.1 11. 6 0.4 11. 6 20 11. 4 0.1 22. 0 1. 6 16.7 11.4 0.6 18. 9 1. 3 15. , 2 11.4 0.2 11. 9 0.2 11 . 7 21 14. , 0 0.2 18.4 0.9 16.2 14.1 0.6 17 . 0 0.4 15, , 6 11.5 0.2 11. , 6 0.3 11. 6 22 11. , 3 0.3 19.8 1. 5 15.6 11.2 0.7 17. 5 0.5 14, , 4 11.5 0.3 12 , , 1 0.3 11 , , 8 25 13, , 8 0.5 25. ,6 0.6 19.8 14.0 0.7 22. , 2 0.8 18, . 2 12.2 0.3 12, . 8 0.3 12, , 5 26 16, . 0 0.5 26, . 5 0.5 21.3 16.1 0. 9 22, , 9 0.9 19 . 5 12.6 0.3 12.8 0.3 12, . 7 27 15 . 4 0.4 28 . 4 0.4 21.8 16.0 0.9 24, , 3 1.0 20 . 1 12.8 0.3 13, . 5 0.3 13 . 2 28 16 . 4 0.9 21 . 6 0.9 19.0 17.2 0.9 21, . 1 0.9 19 . 1 13.2 0.3 13 . 4 0.3 13 . 3 2 15 . 2 0.7 23.0 1.4 19.6 15.1 0.9 21 . 2 0.9 18 . 3 13.2 0.2 13 . 8 0.2 13 . 5 3 13 . 3 0.6 22 . 1 1.2 18.6 14.9 0.9 20 .0 0.6 17 . 6 13.6 0.2 13 . 9 0.2 13 . 8 4 13 . 5 0.6 23 . 1 1. 0 18.6 14.1 0.8 20 . 0 0.6 17 . 2 13.6 0.3 14 . 6 0.2 14 . 1 5 13 . 5 0.6 25 .9 0.5 19.5 14.1 1 . 1 19 . 6 0.3 16 . 9 13.6 0.3 13 . 9 0.3 13 . 8 8 13 . 7 0.6 21 . 9 1. 0 17.8 15.9 0.7 20.4 0.4 18 . 2 13.0 1. 3 14 . 2 a. 4 13 . 6 9 16 . 0 0.7 21 . 3 1.0 18.6 16.1 0.8 19 . 9 0.3 18 . 0 14.2 0.2 14 .5 0.3 14 .4 10 14 . 2 0.5 24 . 9 1. 5 18.6 14.2 0.6 22 .4 1. 0 18 . 3 14.2 0.2 14 .8 0.3 14 . 5 V a l u e s r e p r e s e n t a v e r a g e s from 3 l o c a t i o n s , min.- s o i l t e m p e r a t u r e s max.= s o i l t e m p e r a t u r e s a t 1230 P. S . 'T. s . d . - s t a n d a r d d e v i a t i o n 106 APPENDIX A3; S o i l t e m p e r a t u r e s i n 1977. C h i s e l plowed p l o t s Date 5 cm dep t h 10 cm d e p t h 50 cm d e p t h min • s.d. max. s.d. mean min. s.d. max. s.d. mean min. s.d. max. s.d. mean J u l 11 14. 0 0.2 16.5 0.2 15.8 14.3 0.8 14 . 9 0.8 14.6 10.9 0.3 11.2 0.2 11. 1 12 13. 6 0.9 19.4 1.0 16.6 13.3 0.3 15.8 0.7 14.6 11.4 0.3 12.2 0.1 11. 8 13 13. 6 0.2 18.5 0.2 16.0 13.4 0.2 16.6 0.7 15.8 11.7 0.3 12.0 0.3 11 . 9 14 13.3 0.1 19.5 0.2 16.5 14.0 0.3 17.1 0.8 15.5 11.8 0.3 12.1 0.3 12. 0 15 13. 2 0.1 19.0 0.3 16.1 13.5 0.4 16.3 0.6 14.9 11.9 0.3 12.2 0.3 12. 1 16 13. 6 0.2 12.8 0.5 13.3 14.1 0.3 14.4 0.3 14.2 11.9 0.2 11.6 0.4 11. 8 17 9. 9 0.3 12.3 0.3 11.1 10.9 0.6 11.9 0.6 11.4 11.6 0.3 11.4 0.3 11. 6 18 8. 6 0.3 11.8 0.2 10.3 10.0 0.6 11.3 0.4 10.7 11.3 0.2 11.6 0. 2 11. 4 19 11. 5 0.6 21.3 0. 5 16.4 11.1 0.3 15.9 1.8 13.5 11.5 0.2 11.7 0.2 11. 7 20 11. 2 0.1 21.9 0.4 16.7 12.0 0.5 17.0 0.5 14.5 11.4 0.2 11.9 0.2 11. 7 21 14 . 2 0. 1 17.0 0. 1 15.7 14.3 0.4 15.6 0.2 15.0 11.6 0.2 11.6 0.2 11. 6 22 11. 4 0.1 19.2 0.1 15.4 12.4 0.5 16.1 0.5 14.3 11.6 0.3 12.2 0.3 11 9 25 13. 2 0.2 25.2 0.3 19.2 14. 1 0.3 19.3 1.0 16.7 12.2 0.3 12.6 0.4 12 4 26 16. 2 0.3 25.5 0.3 20.9 15.8 0.3 20.1 1. 5 18.5 12.6 0.3 12.8 0.5 12 6 27 15. 1 0.2 26.6 0.3 20.9 16.0 0.3 20.8 1.2 18.4 12.8 0.3 13.6 0.4 13 2 28 15. 7 0.3 18.8 0.3 17.3 16.7 0.3 18.8 1.2 17.8 13.2 0.3 13.3 0.3 13 2 Aug 2 15 1 0. 3 22.5 0.6 18.7 15.3 0.3 19.2 1. 0 17.3 13.3 0.3 13.8 0.3 13 5 3 13 2 0.2 21.2 1. 1 17.2 15.4 0.2 18.2 1.0 16.8 13.6 0.3 13.8 0.3 13 7 4 13 2 0.2 21.2 0. 7 16.7 14.6 0.2 18.0 1. 0 16.3 13.5 0.3 13.6 0.3 13 6 5 13 2 1. 1 23. 2 0.5 18 . 2 14 . 3 0.4 18.8 1. 3 16.6 13.4 0.3 13.7 0.3 13 .6 8 16 1 0.5 20.1 0.6 18.2 17.7 0.5 18.6 0.9 18.2 13.6 0.4 14.0 0. 6 13 . 8 9 15 7 0.5 21. 4 0.7 18.6 16.2 0.4 18.5 0.9 17.4 13.8 0.5 14.1 0.6 13 .9 10 14 1 0.4 24.5 1.8 19.4 15.3 0.2 19.6 2.3 17.5 13.4 0.7 14.4 0.3 13 . 9 V a l u e s r e p r e s e n t a v e r a g e s from 3 l o c a t i o n s . min.= s o i l t e m p e r a t u r e s a t 0700 P.S.T. max.- s o i l t e m p e r a t u r e s a t 1230 P.S.T. s . d . - s t a n d a r d d e v i a t i o n 107 APPENDIX A4; S o i l t e m p e r a t u r e s i n 1977. Sod p l o t s . Date 5 cm d e p t h 10 cm d e p t h 50 cm d e p t h min. s.d. max • s.d. mean min. s.d. max. s.d. mean min. s.d. max • s.d. mean J u l 11 13. 2 0.4 13. 8 0.5 13.5 12.4 0.1 12.4 0.6 12.4 11.0 0.2 11. 2 0.8 11.1 12 12. 0 0.6 15 . 8 0.9 13.9 12.4 0.3 12.9 1.0 12.7 11.4 0.0 12. 0 0. 0 11.7 13 13.0 0.7 15. 1 0.7 14.1 12.7 0.3 13.2 0.9 13.0 11.6 0.1 11 . 6 0. 1 11.6 14 13. 0 0.6 15. 6 0. 7 14.3 12.6 0.4 13.5 0.7 13.1 11.7 0.1 12. 0 0.2 11.9 15 13. 0 0.5 14 . 9 0.6 14.0 12.6 0.4 13.3 0.6 13.0 11.9 0.2 12. 1 0. 1 12.0 16 13. 5 0.5 13. 4 0.5 13.5 13.0 0.2 12.8 0.4 12.9 11.7 0.2 11. 6 0.3 11.7 17 11 . 0 0.4 12. 0 0.5 11.5 11.2 0.1 10.2 1. 6 10.7 11.5 0.1 11. 3 0.1 11.4 18 10. 2 0.3 11. 1 0.4 10.7 10.2 1.6 10.2 1. 6 10. 2 11.2 0.3 11. 4 0. 3 11.3 19 11. 2 0.4 13. 8 0.6 12.5 11.0 0.1 12.0 0.4 11.5 11.6 0.3 11 . 9 0.3 11.8 20 11. 4 0.4 15. 2 0.7 13.3 11.1 0.6 12.8 0.4 12.0 11.5 0.3 12 . 0 0.3 11.8 21 13. 5 0.6 14. 2 0.7 13.9 12.7 0.1 12.9 0.3 12.8 11.7 0.2 11. 7 0.2 11.7 22 11. 9 0.4 14. 4 0.7 13.2 11.8 0.1 12.2 1. 3 12.1 11.8 0.1 12. 1 0. 1 12.0 25 12. 7 0.3 16. 4 0.7 14.6 12.4 0.1 13.7 0.8 13.1 12.0 0.1 12. 4 0.2 12.2 26 14. 1 0.4 16. 4 0.7 15.3 12.8 0.0 13.7 0.5 13.3 12.0 0.1 12. 5 0.2 12.3 27 13. 6 0.3 17 . 1 0.8 15.4 13.2 0.0 14.6 0.6 13.9 12.1 0.1 12. 9 0.1 12.5 28 14 . 0 0.4 15 . 9 0.6 15.0 13.5 0. 1 14.2 0.5 13.9 12.4 0.1 12 . 2 0. 1 12.3 Aug 2 13. 6 0. 3 16. 2 0.7 15.0 13.2 0.1 14.3 0.5 13.7 12.5 0. 1 13. 2 0.2 12.9 3 13. 4 0.3 16.3 0.7 14.9 13.0 0.0 13.4 0.2 13.2 12.5 0.1 12. 8 0.3 12.7 4 12. 9 0. 3 15. 8 0.6 14.4 13.0 0.0 13.7 0.4 13.4 12.6 0.0 12. 6 0.1 12.6 5 12. 3 0.3 15. 8 0.6 14. 1 12.6 0.3 13.7 1. 2 13.2 12.2 0.0 13. 0 0.0 12.6 8 13. 9 0.4 15. . 1 0.5 14.5 13.4 0. 2 14 . 0 0.2 13.7 12.4 0.3 12. 9 0.1 12.7 9 14. 0 0.3 14 . ,8 0.4 14.4 13.4 0.2 14 . 1 0.2 13.8 12.5 0.4 12. , 6 0. 1 12.6 10 13. , 0 0.3 17 . , 0 0.7 15.0 13.2 0.1 14.5 0.8 13.9 12.5 0.2 13. , 1 0.1 12.8 V a l u e s r e p r e s e n t a v e r a g e s from 3 l o c a t i o n s , min.- s o i l t e m p e r a t u r e a t 0700 P.S.T. max.- s o i l t e m p e r a t u r e a t 1230 P.S.T. s.d.- s t a n d a r d d e v i a t i o n 108 APPENDIX B; S o i l p h y s i c a l p r o p e r t i e s . A n a l y s i s of variance t a b l e : T o t a l p o r o s i t y . Source DF MS F-value T i l l a g e p l o t s 11 Blocks 2 10.74687 1 . 7980 T i l l a g e 3 23 . 19611 3.8808 Error (a) 6 5.97716 Time 1 434.3542 82.935 ** Time x T i l l a g e 3 12.3981 2.3673 Error (b) 16 5.2373 To t a l 23 **= S i g n i f i c a n t to the 0.01 l e v e l . A n a l y s i s of variance t a b l e : A e r a t i o n p o r o s i t y . Source DF MS F-value T i l l a g e p l o t s 11 Blocks 2 2.178 0.276 T i l l a g e 3 116.20 14.722 ** Error (a) 6 7.895 Time 1 132.20 28.050 ** Time x T i l l a g e 3 6.193 1.314 Error (b) 16 4.714 T o t a l 23 ** = S i g n i f i c a n t to the 0.01 l e v e l . 109 APPENDIX B; S o i l p h y s i c a l p r o p e r t i e s . Analys i s of variance t a b l e : Surface roughness. Source DF MS F-value T i l l a g e 3 89.6275 12.1280 ** Blocks 2 2.9034 0.3929 Error 6 7.390 To t a l 11 ** = S i g n i f i c a n t at the 0.01 l e v e l A n a l y s i s of variance t a b l e : Mean weight diameter. Source DF MS F-value T i l l a g e p l o t s 11 Blocks 2 0.05411 1.4120 T i l l a g e 3 0.17854 4.6592 0 Error (a) 6 0.03832 Time 1 0. 29840 1 .1342 Time x T i l l a g e 3 0.30085 1.1436 Error (b) 16 0.26306 T o t a l 23 °= S i g n i f i c a n t at the 0.10 l e v e l . 110 APPENDIX B; S o i l p h y s i c a l p r o p e r t i e s . A n a l y s i s of variance t a b l e : Bulk densi t y . Source DF MS F-value T i l l a g e p l o t s 11 Blocks 2 0.0013625 0 . 9800 T i l l a g e 3 0.0322280 23.181 ** Error(a) 6 0.0013903 Time 1 0.0066670 2.9199 Time x T i l l a g e 3 0.0029222 1.2799 Error (b) 16 0.0022831 Tota l 23 ** = S i g n i f i c a n t to the 0.01 l e v e l . I l l APPENDIX C l ; S o i l t e m p e r a t u r e s i n 1978. M o l d b o a r d plowed p l o t s Date 5 cm d e p t h 10 cm d e p t h min. s.d. max. s.d. mean min. s.d. max. s.d. 50 em d e p t h mean min. s.d. max. s.d. May 11 7 . 8 0.8 12. 1 0.9 10.0 8.5 0. 9 10. 3 0. 5 9.4 7 . 4 1. 4 8.0 1.7 7 . 7 12 7 . 0 0.7 1 1. 5 0.9 9.3 7 . 9 0. 9 10. 0 0. 5 8.9 7 . 5 1 . 4 8.4 1.4 8. 0 1 5 7 . 0 1 . 9 11 . 3 1 . 0 9.2 8.0 1. 7 9 . 9 0. 7 8 . 9 8. 0 0. 9 8.6 1.1 8. 3 16 7.4 1 . 3 16. 0 2.8 11.7 8.2 1 . 3 11 . 4 0. 3 9.8 7 . 9 1 . 0 9.0 1.5 8. 5 17 5.6 1 . 3 14. 1 1 . 3 9.9 8.2 1 . 1 11. 5 0. 5 9.9 7 . 9 1. 2 9.1 1.4 8 . 5 18 5.7 1. 5 17 . 5 1.8 11.6 , 7 i 6 1 . 1 12. 4 0. 8 10.0 8 . 3 1. 2 9.2 1.3 8.7 23 3. 9 0.7 12 . 0 0.9 8.0 7 . 4 1 . 9 11 . 0 0. 7 9.2 8. 7 0. 9 10.7 0.9 9.7 24 4.3 0.5 16. 5 1 . 7 10.4 7 . 0 1 . 4 12. 1 0. 5 9.6 8. 8 1. 0 10.2 1.2 9. 5 25 6.9 1. 2 15. 9 1 . 3 11.4 9.5 1. 1 13. 1 1. 1 11.3 9. 4 1. 0 10.3 1.1 9.9 26 9. 3 1. 1 19. 7 1 . 8 14 . 5 11.7 1. 1 16. 3 0. 4 14 . 0 11 . 7 1 . 2 13.2 1.2 12.5 29 8 . 5 0.6 12. 9 1. 2 10.7 10.8 1 . 5 12. 4 1. 4 11.6 12. 8 1 . 0 13.2 1.1 13.0 30 7.4 0.2 19. 8 2.2 13.6 10.2 1 . 9 15. 1 0. 5 12.6 12 . 2 1 . 1 13.0 1.1 12.6 31 10.9 0.4 24. 3 1 . 5 17.6 12.1 1 . '3 18 . 1 0. 6 15.1 12 . 3 0. 9 13.3 1.1 12.8 Jun 1 12.3 1.0 26. 4 2 . 0 19.4 13.8 1. 3 19. 7 0. 5 16.8 12. 6 0. 9 13.6 1.0 13.1 2 13.4 0.6 28. 0 0.6 20.7 15.1 1 . 5 21 . 7 0. 8 18.4 13 . 0 1. 0 14.6 1.2 13.8 5 16.5 0.7 22 . 7 0.5 19.6 18.1 1. 8 21. 2 1. 1 19.6 15. 3 1. 0 15.8 1.0 15.5 6 13.7 0.7 26. 4 1 . 1 20.1 15.8 2. 0 21 . 4 0. 9 18.6 15. 2 0. 9 16.2 1.2 15.7 7 14 . 2 0.9 26. 6 0.6 20. 5 16.5 2 . 3 21 . ,9 1. , 1 19.2 15. 7 1. , 1 16.2 1.4 16.0 8 16.1 0.7 21 . , 7 0.2 18.9 17.8 1 . , 7 20, ,5 1. , 1 19.1 16.0 1, , 0 16.3 1.1 16.2 9 11.7 1 . 1 22. , 5 0.3 17.1 15.2 1, , 4 20, .3 0, , 8 17.8 15, ,7 1 , 0 16.7 1.2 16.2 13 12.8 0. 9 17, , 2 2.3 15.0 15.0 2 , 2 16, .9 2, . 4 16.0 16, . 1 1, 2 16.8 1.6 16.4 14 11.1 0.4 14 , 4 0.8 12.7 14 . 5 2, . 3 15 .7 2 . 0 15.1 15, .7 1, . 3 16.2 1.4 16.0 15 12.9 1. 2 23, . 5 2 . 6 18.2 14 . 7 2 . 5 19.2 1 . 6 16.9 15 .8 1 . 7 16.6 1.4 16.2 16 16.3 1 . 2 26 . 0 3.2 21.2 16.9 1 . 9 20.5 1 . 9 18.7 16 . 0 1 . 1 16.1 1.1 16.1 19 14.3 2. 1 24 . 1 3 . 5 19.2 15.2 2 . 1 18 .7 2 . 2 16.9 16 . 1 1 . 2 16.7 1.2 16.4 20 15.0 0.9 21 . 1 1. 5 18.0 16.6 2 .4 19 .3 2 . 6 18.0 15.6 1 . 3 15.9 1.4 15.8 21 14 . 9 1. 0 17 . 5 0.8 16.2 16.6 1 . 9 17 .8 2 . 0 17.2 ' 13 .6 1 . 1 16.2 1.1 14.9 22 13.0 1 . 1 17 . 4 0.6 15.2 15.8 2 .4 17 . 1 1 . 8 16.4 16 . 4 1 .4 16.8 1.3 16.6 23 10.7 0.6 20 . 8 1 . 3 15.8 13.5 2 . 1 17 .9 1 . 8 15.7 15 .5 1 . 3 16.1 1.3 15.8 26 13.9 1 . 3 22 . 9 1 . 9 18.4 15.8 2 . 1 19 .3 2 . 2 17.6 15 .8 1 . 4 16.2 1.5 16.0 27 15.0 1 . 1 23 . 2 1 . 3 19.1 16.5 2 . 0 19 .5 1 . 9 18.0 16 .0 1 . 4 16.1 1.4 16.1 28 14.9 0.7 24 . 1 1 . 8 19.5 16.6 2 . 1 20 . 1 2 . 1 18.4 16 . 1 1 . 3 16.5 1.3 16.3 29 16.0 0.7 25 . 5 1. 4 20.8 17.1 2 . 0 20 .7 2 . 2 18.9 16 .3 1 . 4 16.8 1.6 16.5 J u l 6 16.2 1.0 21 . 4 0.9 18 . 8 17.5 1 .9 19 .3 1 . 9 18.4 16 .5 1 . 6 16.9 1.6 16.7 7 16.2 0.9 23 . 5 1.4 19.9 17.6 1 . 9 20 .4 2 .0 19.0 16 .7 1 . 5 14.7 1.7 16.9 10 14. 1 1. 0 18 . 5 0.5 16.3 16.3 1 .9 18 .3 1 . 7 17.2 16 .9 1 .6 17.2 1.6 17.1 11 14.9 0.8 22 . 7 0.9 18.8 16.7 1 .8 20 .0 1 . 9 18.3 16 .7 1 . 6 17.0 1.5 16.9 12 15.2 0.7 21 . 1 0.9 18.1 16.8 1 .6 19 .5 1 . 6 18.2 16 .6 1 . 5 17.0 1.5 16.8 14 14.9 1 0.8 21 .6 0.8 18.3 17.0 1 .7 18 .8 1 . 6 17.9 16 . 8 1 . 4 17.2 1.4 17.0 V a l u e s r e p r e s e n t a v e r a g e s from 3 max.- s o i l t e m p e r a t u r e a t 1230 P. l o c a t i o n s , S.T. s.d." min . - so s t a n d a r d i l t e m p e r a t u r e d e v i a t i o n at 0700 P . S . T . 112 APPENDIX C2; S o i l temperatures in 1978. Rotovated and moldboard plowed p l o t s D a t e 5 cm depth 10 cm depth 50 cm depth min. s . d . max. s . d . mean min. s . d . max. s . d . mean min. s , d . max. s . d . mean may 11 7.2 1.6 11.7 1.6 9.5 7.8 0.3 10.3 0.7 9.1 6.7 0.4 7.4 0.6 7.1 12 6.5 1.1 11.2 2.1 8.9 7.2 0.7 10.0 0.4 8.6 6.9 0.4 7.6 0.5 7.3 15 5.7 1 .1 10.7 1.5 8.2 7.0 0.4 9.7 0.4 8.A 6.6 0.5 6.6 0.5 6.6 16 6.6 1.1 13.9 2.6 10.3 7.4 0.1 11.8 1.1 9.6 6.9 0.4 7.9 0.5 7.4 17 5.3 1 .3 12.6 0.8 9.0 7.5 0.6 11.9 0.6 9.7 7.0 0.4 8.4 0.4 7.7 18 5.3 0.7 15.4 1.8 10.4 6.8 1.1 13.3 1.8 10.1 7.5 0.4 8.4 0.6 8.0 23 3.5 2.0 10.7 0.6 7.1 6.1 0.8 11.0 0.5 8.6 7.1 0.4 9.5 0.5 8.3 24 4.2 1 .8 14.6 1.6 9.4 6.5 1.0 12.8 1.0 9.7 8.0 0.6 9.3 0.6 8.7 25 6.7 1.4 14.1 0.5 10.4 8.6 0.4 13.7 0.4 11.7 8.4 0.4 9.5 0.6 9.0 26 9.0 1 .1 18.6 1.4 13.8 10.8 0.4 16.7 0.4 13.8 10.7 0.1 12.3 0.5 1 1 . 5 29 8.1 1.5 11.4 0.4 9.8 9.9 0.4 11.7 0.2 10.8 11.5 0.3 11.6 0.4 11.6 30 7.2 1.0 16.9 1.0 12.1- 8.8 0.8 15.5 0.8 12.2 10.7 0.5 11.9 0.4 11.3 31 10.2 0.2 20.7 2.5 15.5 11.1 0.3 18.9 1.8 15.0 11.0 0.3 12.3 0.4 11.7 Jun 1 11.9 0 .1 22.5 1.8 17.2 12.7 0.4 20.8 2.3 16.8 11.4 0.3 12.6 0.4 12.0 2 12.7 0.4 24.7 2.2- 18.7 13.9 0.5 22.8 2.1 18.4 11.9 0.4 13.7 0.4 12.8 5 17.0 2.2 20.6 0.8 18.8 17.2 0.1 2 1 . 1 0 . 1 19.2 14.3 0.1 1 5 . 1 0 . 6 14.7 6 13.4 0.7 23.8 1.8 18.6 14.7 0.4 22.4 1.6 18.5 14.2 0.2 15.2 0.4 14.7 7 13.6 1.0 24.2 1.7 18.9 15.6 0.6 23.0 1.6 19.3 14.3 0.1 15.5 0.4 14.9 8 15.5 0.8 19.9 0.7 17.7 19.3 0.3 20.9 0.9 20.1 15.1 0.2 15.5 0.5 15.3 9 11.8 1.4 20.5 1.4 16.2 14.1 0.9 20.7 1.3 17.4 14.7 0.3 15.7 0.4 15.2 13 11.2 2 . 0 15.8 1 .4 13.5 13.7 0.2 15.0 1.0 14.4 14.5 0.2 1 4 . 8 0 . 2 14.7 14 10.2 2.3 13.1 1.4 11.7 12.9 0.5 14.7 0.5 13.8 14.8 0.4 14.4 0.4 14.6 15 12.0 0.8 21.5 3.5 16.8 13.2 0.4 20.2 1.4 16.7 13.9 0.4 15.0 0.6 14.0 16 15.9 1.8 24.1 1.8 20.0 16.0 0.1 22.4 1.7 19.2 14.5 0.6 15.2 0.4 14.9 19 20.0 2.1 22.3 4.3 21.2 15.3 0.4 21.2 2.1 18.2 14.8 0.3 15 .2 0.3 15.0 20 14.7 1 .0 21.0 1.0 17.9 16.3 0.5 20.2 1.3 18.3 14.9 0.3 15.7 1.0 15.3 21 14.6 1.2 17.1 1.3 15.9 16.3 0.1 17.9 0.4 17.1 14.9 0.4 15.3 0.4 15.1 22 12.4 2.0 17.0 1.3 14.7 15.1 0.3 17.4 0.3 16.3 15.2 0.1 15.7 0.4 15.5 23 11.2 1.2 17.3 3.4 14.3 12.9 0.7 19.5 1.1 16.2 14.6 0.2 15.2 0.4 14.9 26 14.3 1.1 22.4 1.1 18.4 15.7 0.0 21.6 1.8 18.7 15.0 0.2 15.7 0.1 15.4 27 15.4 1.0 22.7 3.6 19.1 16.5 0.2 21.6 1.5 19.1 15.2 0.1 15.6 0.4 15.4 28 15.5 1.4 23.9 4.3 19.7 16.4 0.1 22.4 1.4 19.4 15.6 0.2 16.2 0.4 15.9 29 17.2 2.2 24.9 4.8 21.1 19.4 0.1 23.0 1.4 21.2 15.9 0.4 16.4 0.4 16.2 J u l 6 16.9 1.2 2 1 . 7 3.0 \9 .3 16.4 2.1 20.9 1.1 18.6 16.6 0.3 16.9 0.3 16.8 7 16.5 1.2 23.3 3.8 19.9 17.4 0.4 22.1 1.6 29.8 16.4 0.1 16.9 0.1 16.7 10 13.7 1.8 18.4 1.0 16.0 16.0 0;2 19.0 0.9 17.5 16.3 0.1 16.6 0.1 16.5 11 14.6 1.2 22.0 2.5 18.3 16.5 0.1 21.6 1.8 19.1 16.2 0.4 16.7 0.4 16.5 12 15.0 1.1 21.5 1.7 18.2 16.8 0.2 21.1 1.3 19.0 16.4 0.5 16.8 0.3 16;6 14 14.7 1.5 22.9 1.5 18.8 16.8 0.2 20.7 1.3 18.8 16.1 0.1 17.0 0.1 16.6 Values represent averages from 3 l o c a t i o n s , m i n . " s o i l temperature at 0700 P . S . T . max.- s o i l temperature at 1230 P . S . T . s . d . " standard d e v i a t i o n 113 APPENDIX C3; S o i l temperatures in 1978. C h i s e l plowed p l o t s Date 5 cm depth 10 cm depth 50 cm depth min • s . d . max • s . d. mean min • 8 . d. max. s . d . mean min. s . d . max • s . d. mean May 1 1 7. 6 1 . 3 10. 5 0. 9 9. 1 7 . 4 1 . 0 9.2 0.3 8 . 3 6.8 0.7 7 . 4 0. 4 7 . 1 12 7 . 1 1 . 6 9. 9 1 . 3 8. 5 6. 9 1 . 2 9.0 0.4 7 . 9 7 . 0 0. 5 7 . 8 0. 6 7 . 4 15 7 . 7 2 . 9 10. 3 1 . 8 9. 0 7. 2 2 . 2 9. 1 0.8 8.2 7 . 4 1 . 6 8 . 1 1 . 1 7 . 8 16 7. 9 2. 3 12. 8 2 . 2 10. 3 7. 6 2. 0 10.8 0.7 9.2 7 . 4 1. 2 8. 2 0. 8 7 . 8 17 7 . 4 1 . 8 12. 3 1 . 6 9. 8 7. 2 1. 6 10.6 0.2 8.9 7 . 3 0.8 8. 5 0 . 5 7 . 9 18 6. 8 1 . 8 13. 9 2. 1 10. 4 6. 9 1 . 5 11.5 0.9 9.2 7 . 8 0.8 8. 6 0. 5 8. 2 23 6. 8 3. 1 12 . 6 3. 3 9. 7 6. 8 2 . 6 10.5 1 . 0 10.1 7 . 9 1 . 7 10. 0 1. 7 9. 0 24 6. 7 2 . 3 13 . 5 1 . 8 10. 1 6. 7 1 . 8 11.3 0.7 9.0 10 .1 1 . 2 9. 6 1. 2 9 . 8 25 8. 7 1 . 8 •13. 7 1 . 8 11 . 2 9. 0 1 . 5 11.9 0.5 10.5 8.7 0. 9 9. 7 0. 8 9 . 2 26 10. 7 1 . 7 15. 4 1 . 0 13. 1 10. 6 1 . 5 15.0 0.8 12.8 11.0 0. 7 12 . 4 0. 8 1 1 . 7 29 10. 5 2. 8 13. 3 3. 5 11. 9 10. 2 2. 1 12.0 2.1 11.1 12.2 1. 6 12. 5 2 . 0 12 . 4 30 9. 6 3. 2 16. 5 3. 1 13. 1 9. 7 2. 6 14 . 3 0.8 12.0 11.6 1 . 9 12 . 2 1 . 2 1 1 . 9 31 11. 4 2. 3 20. 0 1 . 6 15. 7 11 . 1 1 . 6 17.0 1 . 2 14 . 0 11.5 1. 1 12. 6 0. 9 1 2 . 1 June 1 13. 0 2. 2 21 . 9 1 . 8 17. 4 12 . 6 1. 4 18.6 1.4 15.6 11.8 1 . 0 12. 9 1. 0 1 2 . 3 2 13. 8 2. 0 23. 7 1. 6 18. 8 13. 8 1 . 3 19.7 2.8 16.8 12.4 1. 1 13. 8 0. 6 13 . 1 5 17. 2 1. 8 21. 0 1. 6 19. 1 16. 8 1. , 1 19.5 0.4 18.2 14.5 0.7 15 . 0 0. 8 14 . 7 6 19 . 1 1 . 6 23. 4 1 . 6 21. 3 14 . 8 1 . , 6 20.4 1.4 17.6 14 . 3 0.9 15. 4 0. 7 14^  8 7 15. 4 1 . 8 23. 2 1. . 6 19. 3 15. 4 1 , , 5 20.6 1. 3 18.0 14.6 0.8 15. 4 0. , 8 15. 0 8 16. 9 1 . 8 20. 2 1 . , 8 18. 6N 18 . 0 1 , , 0 18.9 0.5 18.5 15.0 0.8 15. 5 0. , 7 15. , 3 9 14. 0 1. 8 20. 6 2. , 0 17 . 3 14 . , 1 1 , , 6 18.9 0.7 16.5 14.8 0.9 15. 8 0, , 7 15. , 3 13 14 . 6 3. , 3 17 . 8 4 , 1 16. , 2 14 . , 4 2, .4 16.4 2.4 15.4 13.6 1 . 2 16. 1 2 , 3 14 , 8 14 14 . 0 3, ,4 16 . 0 3, , 4 15. , 0 13, , 7 2 , . 3 15.2 2.4 14.5 15.0 1 . 9 15. , 6 1 , . 9 15, , 3 15 16. 0 3, , 8 21 . 2 -.3 , 3 18, , 6 14 , 2 2 . 9 18.7 2.9 16.5 15.1 2.5 15, , 7 1 , , 7 15 . 4 1 6 16. 7 2 , 4 22 , , 7 2 , . 6 19. , 7 16, , 5 1 .6 20 .1 1 . 6 18.3 15 .2 1 . 4 1 5 , , 4 0 . 8 15 , 3 19 15. , 0 1 , , 5 21 . ,5 1, . 5 18, , 2 14 , 5 1 . 3 18.8 2 . 0 16.6 15.3 1 . 5 15, , 1 1 .4 15 . 2 20 16. , 2 1 , . 9 20, , 0 1, . 5 18, , 1 16 , . 6 1 . 0 18.4 0.6 17.5 15.3 1 . 3 16, , 0 0 . 8 15 . 7 21 16, , 2 2, . 1 18, , 3 2 . 8 17, , 3 15, . 8 1 . 0 17.1 1. 0 16.5 15.2 1 . 1 15 . 6 1 . 2 15 . 4 22 15, , 5 2, . 7 18, . 6 3 . 5 17 , . 1 15, . 3 2 . 0 16.9 1 . 5 16.1 15.4 1.5 16 a 1 . 5 1 5 . 8 23 13.3 2, . 4 20, . 3 2 . 6 16, . 8 13, . 1 2 . 0 18.0 1. 3 15.6 15.8 1. 3 15 . 4 1 . 3 15 . 6 26 15 , 8 1 . 6 22.0 2 . 1 18, . 9 15 . 3 1 . 2 19.3 1. 0 17.3 15.1 1 . 0 15 . 5 0 . 8 15 . 3 27 16, . 5 1/5 22, . 2 1 . 5 19, . 3 15 . 9 1 . 0 19. S 1.0 17.7 15.4 0. 9 15 . 7 0 . 9 15 . 5 28 19 . 3 1 . 6 23 . 0 1 . 6 21 . 2 16 . 5 0 . 6 20.3 1 . 3 18.4 15.5 0. 9 16 . 1 0 . 9 15 .8 29 21 . 2 1 . 6 23 . 8 2 . 6 22 . 5 18 .4 0.9 20.8 1.4 19.6 15.9 0.9 16 . 7 0 . 2 16 . 3 J u l 6 17 . 3 0 . 2 21 . 1 1 . 6 19 . 2 17 . 1 0.8 19.3 0.8 18 . 2 16.4 0.8 16 . 6 0.7 16 . 5 7 17 . 8 1 . 9 23 . 1 1 . 9 20.5 17 . 2 1 . 2 20.4 0.9 18.8 16.4 0.8 16 . 7 0 . 6 16 . 6 10 16 . 2 2 . 3 19 .6 2 . 6 17 . 9 16 . 1 1 . 7 18.0 1 . 7 17.1 16.8 1. 6 17 . 0 1 . 4 16 . 9 11 17 . 9 2 . 3 22.7 2 . 3 20 . 3 17 . 1 1 .6 20.1 1. 6 18.6 16.6 1.4 16 . 7 0 . 8 16 . 6 12 16 . 8 1 . 7 21 . 5 1 .7 19 .2 16 . 1 1 .4 19.9 1.4 18.0 16.4 1. 0 16 . 7 0 . 6 16 . 6 14 19 . 2 1 .6 21 . 7 1 . 6 20.5 18 . 0 2 .6 19.9 2.6 18.9 16.4 0.7 16 . 8 0 . 6 16 . 6 Values represent averages from 3 l o c a t i o n s . mia.= s o i l temperature at 0700 P . S . T . max.- s o i l temparature at 1230 P . S . T . s . d . - standard d e v i a t i o n 114 APPENDIX C4; S o i l t e m p e r a t u r e s i n 1978, R o t o v a t e d and c h i s e l plowed p l o t s Date 5 cm d e p t h 10 cm d e p t h 50 cm d e p t h min. s.d. max. s.d. mean min. s.d. max. s.d. mean min. s.d. max. s.d. May 11 12 15 16 17 18 23 24 Jun J u l 25 26 29 30 31 1 2 5 6 7 8 9 13 14 15 16 19 20 21 22 23 26 27 28 29 6 7 10 11 12 14 8. 7 . 7 . 8. 7, 7 , 6, 6 9 1 1 10 9 4 0 9 5 3 8 1 3 , 3 3 11.8 13.4 14.5 17.8 15.4 15.8 17.5 14 . 5 14.1 13.3 14.0 17.8 16.5 16.8 16.9 15.1 13.2 16.6 17.4 20.8 0.6 0. 5 0. 5 0.4 0.2 0. 1 0.2 0.4 0.4 0.0 0.4 0.0 0.3 0. 5 0.0 1 . 1 0. 7 18. 19, 18, 16, 17 17 17 0.6 0.7 0.4 0.5 0.6 0.4 0.6 0.4 0.5 0.4 11.8 1. 1 10.0 8.1 0.8 11.0 1.7 9. 6 6.7 1.3 7.3 1. 2 7 . 0 11.2 0. 8 9.5 7.6 1.1 10.7 1.2 9. 1 6.8 1.2 7 . 8 1 . 2 7 . 3 11.0 1 . 1 9.2 7.2 1.3 10.5 1.2 8. 8 6.9 1.2 8.2 1. 3 7 . 3 13.4 1. 2 10.7 7.8 1.0 12.5 2.2 10. 1 7.0 1.3 8.2 1 . 5 7 . 6 13.0 1. 1 10.5 8.4 0.8 12.5 1.6 10.5 7.6 1.2 8.5 1 . 2 8.1 15.0 1. 4 11.3 7.5 1.1 13.1 2.1 10. 3 7.7 1.3 8.6 1 . 3 8. 1 12.1 0. 2 9.2 6.4 1.6 11.4 0.9 8. 9 7.2 1.1 9.6 1 . 3 8.4 14.2 1. 5 10.5 6.8 1.3 13.7 3.1 10. 3 8.4 1.2 9.5 1 . 2 9.0 14.4 1. 2 11.7 9.1 0.9 11.0 2.0 10. 1 8.6 1.2 9.7 1 . 2 9. 1 18.6 0. 9 15.0 11.2 1.3 17.3 1.3 14. 2 9.1 2.2 12.8 1 . 5 11.0 12.8 0. 9 11.5 10.3 1.1 12.3 1.1 11 . 3 11.0 1.7 12.4 1 . 7 11.7 16.8 1. 8 13.1 9.4 1.4 11.3 1.4 10. 3 11.7 1.8 12.5 1.8 12.1 20.5 2. 1 16.1 11.9 0.5 19.2 3.9 15 . 6 11.7 1.8 12.9 1.8 12.3 22.7 2. 1 18.1 13.3 0.4 20.8 4.5 17 . 0 12.0 1.8 13.1 1.8 12.6 24 . 6 2. 4 19.6 14.4 0.6 22.5 4.4 18. 5 13.1 1.8 14 . 0 1 . 7 13.6 21.6 1 . 0 19.7 17.3 0.6 20.7 1.3 19. 0 13.6 1.9 15.0 2 . 0 14.3 24 . 1 1 . 6 19.8 15.2 1.0 21.9 3.5 18. 6 14.3 1.9 15.4 1 . 9 14.9 24 . 5 1 . , 3 20.2 15.6 1.0 2 2.4 3.5 19. 0 14.4 1.8 15.6 1. 8 15.0 21.0 1. , 0 19.3 14. 1 4.7 20.1 1.4 17 . , 1 15.2 2.0 15.5 1 . 9 15.4 21.6 1 ,  1 18.0 14.4 1.3 20.1 1.9 17 , , 2 14.9 2.0 16.0 2 . 0 15.4 17.1 0, , 3 15.6 14.0 1.3 16.2 0.1 15, , 1 15.0 1.9 15.5 1 . 9 15.3 15.3 0, , 1 14.3 13.3 1.4 15.0 1.4 14, , 1 14.7 1.9 15.2 1 . 7 15.0 21.6 1, . 8 17.8 13.7 0.9 19.7 2.6 16 . 7 14.7 2.0 15.7 2.0 15.2 24.3 2 . 0 21.0 16.4 0.0 21.7 3.7 19 . 1 15.2 1.9 15.7 1 . 9 15.5 23 . 9 2 . 1 20.2 15.3 0.2 20.4 4.2 17 .8 15.7 2.1 15.3 1 . 9 15.5 21.9 2 . 3 19.4 16.6 0.4 20.2 2.9 18 .4 15.3 2.1 15.7 1.8 15.5 19.0 1 . 1 18.0 16.4 0.1 17.8 0.6 17 . 1 15.4 2.1 15.7 2.0 15.6 18.7 1 . 6 16.9 15.2 1.1 17.4 1.1 16.3 15.6 1.8 16.2 1.8 15.9 21.5 2 . 2 17.3 13.3 1.3 19.5 2.6 16 .4 15.9 1.7 16.0 1. 8 16.0 23.7 2 . 1 20.2 15.9 0.1 20.9 3.3 18 .4 15.6 1.8 16.3 1 . 9 15.9 24.1 2 . 0 20.8 16.9 0.4 21.2 0.4 19 . 0 15.9 2.2 16.2 2 . 1 16.1 25.2 0 . 4 23.0 16.8 0.0 21.9 3.5 19 . 3 16.1 2.2 16.7 2 . 2 16.4 26.2 1 . 8 22.3 17.8 0.4 20.1 3.4 19 . 0 16.4 2.2 16.9 2.3 16.7 23.3 1 . 5 21 . 1 18.2 0.3 21.0 2.4 19 .6 17.2 2.2 17.4 2 . 3 17.3 24.6 1 . 1 21.5 18.0 0.1 22.0 2.6 20 . 0 17.1 2.1 17.5 2. 1 17.3 20.5 1 .4 18.5 16.3 0.8 19.2 1.5 17 .7 17.1 2.2 17.5 2.2 17.3 23.9 1 .4 20.6 16.7 0.4 21.6 2.7 19 . 2 17.0 2.2 17.5 2.2 17.3 22.9 1 . 7 20.2 17.2 0.6 21.3 2.6 19.3 17.1 2.2 17.6 2 . 0 17.4 23.7 1 . 5 20.6 17.2 0.6 21.7 3.5 19 .4 17.2 2.1 17.7 2 . 2 17.5 V a l u e s max. " r e p r e s e n t a v e r a g e s from 3 l o c a t i o n s , s o i l t e m p e r a t u r e a t 1230 P.S.T. s.d.' mi n . - s o i l t e m p e r a t u r e s t a n d a r d d e v i a t i o n a t 0700 P.S.T. 115 APPENDIX C5; S o i l temperatues i n 1978. Sod p l o t s Date 5 cm depth 10 cm min. s . d . max. s . d . mean min. s . d . depth 50 cm depth max. s . d . mean min. s . d . max. s . d . mean May 11 12 15 16 17 18 23 24 Jun J u l 25 26 29 30 31 1 2 5 6 7 8 9 13 14 15 16 19 20 21 22 23 26 27 28 29 6 7 10 11 12 14 7.8 0.9 9.8 1.1 7.3 0.6 8.3 0.8 11.9 0.8 11.5 1.1 2 2 11 . 14. 0.8 0.8 0. 3 0.5 7 0.7 11.1 0.8 10.9 0.8 9 11 12 13 15 13 13 15 12 1,2 2. 1 0.7 0.6 0.6 0.9 0 13.1 0 12.8 0 13.7 0.4 17.1 0.6 14.5 15.0 6 3 6 5 2 3 15. 14 . 12. 15. 16. 19. 0.7 0.6 0.6 0.6 0.9 0.7 0.8 0.6 0.4 13.4 14 . 6 0.3 11 . 14 , 13.8 18 . 4 13.1 16.0 0 18 19 22 7 7 7 18.5 0 0 0.4 1 . 1 3.0 3 3 3 21.1 21.8 0, 18.2 0.6 18.7 0.1 16.1 0.4 14.4 0.1 20.5 0.2 21.8 0.0 20.4 0.0 18.9 0.5 17.4 0.8 0.7 0.2 0.3 0.1 16.9 0.6 18.0 0.8 17.7 0.6 16.0 0.4 17.1 0.6 17.3 0.6 17.5 0.6 17.1 19.6 21.7 22.3 23.1 0.3 24.3 0.1 22.7 0.4 24.3 0.9 19.9 0.2 23.7 0.0 2 2.4 0.1 23.3 0.3 9.8 10.7 9.2 11.2 10.7 11.1 8.9 10.7 11.3 14.8 12.0 12.7 15.1 16.4 18.2 16.9 17.3 17.7 16.8 15.6 14 . 6 13.7 17.1 19.0 17.5 17.0 16.5 15.7 16.1 18 . 6 19.3 21.1 20.6 20.4 21 18 20 19 20 7, 7 7 7 8 7 6 7 8 10 10 10.1 11.0 11 12 14 13 13.3 14 . 5 12.9 13.1 12.9 13.4 15.0 14 14 14 14 12 14 15 15 15 0.5 0.4 0.4 0.5 0.4 0.4 0.5 0.4 0. 5 0.4 0.2 0.2 0. 1 0.3 0.4 16.8 16.5 16.1 16.5 17.1 17.4 0.3 0.3 0.4 0.4 0.3 0.4 0.4 0.4 0.3 0.4 0.5 0.4 8.5 0.6 7.9 7.6 0.3 7.8 0.3 7 . 7 8.6 0.4 7.8 7.5 0.3 8.4 0.3 8.0 8.7 0.9 7 . 9 7.6 0.2 8.6 0.4 8 . 1 10.1 0.2 8.9 7.8 0.3 9.0 0.3 8.4 10.0 0.1 9.3 8.1 0.2 9'. 1 0.3 8.6 9.7 0.2 10.4 8.4 0.3. 9.2 0.3 8.8 9.4 0.2 8.0 7.7 0.4 9.9 0.3 8 . 8 10.2 0.3 8.6 8.8 0.5 10.1 0.2 9.4 10.3 0.3 9.4 9.1 0.1 9.6 0.6 9 . 4 14.0 0.4 12.5 11.6 0.4 13.5 0.3 12.6 11.4 0.3 11.1 12.0 0.4 12.3 0.3 12.2 13.5 0.4 11.8 11.6 0.4 12.6 0.4 12.1 14.3 0.5 12.7 12.0 0.3 13.0 0.3 12.5 15.1 0.4 13.5 12.7 0.4 13.6 0.2 13.2 16.0 0.3 14.2 12.8 0.4 14.1 0.4 13'. 5 15.8 0.7 15.2 13.6 0.1 13.9 0.1 13.8 16.4 0.3 14.8 13.4 0.1 14.4 0.1 13.9 16.6 0.4 15.0. 13.4 0.2 14.5 0.0 13.9 16.7 0.4 15.6 14.1 0.1 14.1 0.0 14.1 15.6 0.4 14.3 13.7 0.2 14.5 0.1 14.1 14.4 0.3 13.8 13.7 0.2 14.5 0.2 14.1 13.6 0.3 13.3 13.5 0.1 14.0 0.2 13.7 16.2 0.5 14.8 13.8 0.2 14.8 0.2 14.3 17.2 0.5 16.1 14.4 0.2 15.0 0.2 14.7 16.8 0.4 15.8 15.0 0.2 15.1 0.9 15.1 16.7 0.1 15.5 14.3 0.0 15.1 0.9 •14.7 15.3 0.2 15.0 14.5 0.1 14.7 0.1 14.6 15.0 0.1 14.7 14.7 0.1. 14.8 0.1 14.8 15.7 0.4 14 . 2 14.0 0.1 14.9 0.1 14.5 17.1 0.4 16.0 14.9 0.1 15.4 0.1 15.2 17 i-5 0.5 16.4 15.1 0.0 15.5 0.1 15.3 17.8 0.4 16.7 15.4 0.1 15.7 0.1 15.6 18.5 0.5 17.2 15.7 0.1 16.0 0.1 15.9 18.3 0.5 17.6 16.2 0.1 16.5 0.1 16.3 18.9 0.6 17.7 15.9 0.0 16.4 0.1 16.2 17.6 0.5 16.9 16.3 0.2 16.6 0.1 16.4 19.4 0.4 18.0 16.'3 0.2 16.7 0.1 16.5 19.0 0.5 18.1 16.5 0.0 16.9 0.1 16.7 19.1 0.4 18.3 16.8 0.1 17.4 0.2 17.1 Values max. = represent averages from 3 l o c a t i o n s s o i l temperature at 1230 P . S . T . s . d . . m i n . " so • standard i l temperature dev iat ion at 0700 P.S.T. 116 APPENDIX D l ; Mineral s o i l nitrogen, ppm NO^ -N + NH.-N i n 4 s o i l samples (0-10 cm) N rat e Sampling T i l l a g e treatments (kg/ha) date M R+M Ch R+Ch 0 M a y 5 29.1 25.0 21.8 21.7 M a y 17 44 . 9 51.3 41.2 49.3 Jun 7 60.7 46.1 34.7 41.2 Jul 6 17.7 16.7 20.9 16.7 Aug 2 17.9 30.1 17.5 26.2 56 M a y 5 2 9.1 25.0 21.8 21.7 M a y 17 98.2 63.2 75.0 98.3 J un 7 112.2 86. 1 72.6 99.4 J u l 6 22.5 26.0 34. 9 25.1 Aug 2 30.8 57 . 6 37 . 8 44.5 112 M a y 5 29.1 25.0 21.8 21 . 7 M a y 17 142.5 13 7.1 119.5 130.9 Jun 7 153.5 156.5 100. 7 112.2 Jul 6 52.5 54.4 60.6 37.4 Aug 2 89.6 108 . 1 90.9 75.7 168 M a y 5 29. 1 25.0 21.8 21.7 M a y 17 235 .6 259.2 193. 5 194.5 Jun 7 196.0 2 6 5 .7 113.0 155.3 J u l 6 56.2 61. 6 125.6 73.8 Aug 2 71.5 122.2 80.5 77 . 6 APPENDIX D2; Mineral s o i l n i t r o g e n . A n a l y s i s of variance table Sourc e DF MS F-value Subplots 59 Main p l o t s 11 Blocks 2 335 .73 0.20 T i l l a g e 3 3650 .11 2.12 Error (a) 6 1719 .10 F e r t i l i z e r 3 87631 .22 118.71 ** F e r t i l i z e r x T i l l a g e 9 1384 . 01 1. 87 Error (b) 36 738 .21 Time 4 86476 .66 21.72 ** Time x T i l l a g e 1 2 2431 . 93 0.61 Time x F e r t i l i z e r 12 10974 . 90 2.76 ** Time x T i l l , x F e r t . 36 771 . 93 0.19 Error (c) 117 3 981 .01 To t a l 239 ** = S i g n i f i c a n t to the 0.01 l e v e l 118 APPENDIX D2; Mineral s o i l n i t r o g e n . Table of means F e r t i l i z e r rate (kg/ha) 0 56 11 2 168 31 . 5 54 . 0 86.0 119.2 Mean separation 0 56 112 168 L.S.D. 0.05 = 10.1 Time (sampling date) May 5 = 24.4 May 17 = 120.7 Jun 7 = 112.9 J u l 6 = 43.9 Aug 8 = 61.4 Mean separation May 5 J u l 6 Aug 8 Jun 7 May 17 L.S.D. 0.05 = 25.5 F e r t i l i z e r x Time (kg/ha) May 5 May 17 Jun 7 J u l 6 Aug 8 0 24.4 46.7 56 24.4 82.9 112 24.4 132.5 168 24.4 220.9 L.S.D. 0.05 45.7 18.0 22.9 92.6 27.1 42.8 130.7 51.2 91.1 182.5 79.3 88.8 = 94.5 119 APPENDIX E l ; S o i l NH.-N (0-10 cm depth). ppm NH.-N F e r t i l i z e r Sampling T i l l a g e treatments (kg N/ha) date M R+M Ch R+Ch 0 May 5 8.1 8.9 8.9 7.2 May 17 16.8 12.0 12.5 15.7 Jun 7 13.5 14.7 17.7 10.6 J u l 6 9.9 9.6 10.0 12.1 Aug 2 13.6 11.9 22.6 11.8 56 May 5 8.1 8.9 8.9 7.2 May 17 53.9 54.2 29.8 34.7 Jun 7 48.3 48 . 2 42.4 2 7.2 J u l 6 15.2 16.8 19.2 23.4 Aug 2 32.8 22.5 42.6 26.7 112 May 5 8.1 8.9 8.9 7.2 May 17 97 . 5 99.6 89.2 80.3 Jun 7 59.8 84.6 87 . 7 44.2 J u l 6 25.7 36.0 46.0 46.3 Aug 2 51.1 64.6 81 . 9 7 0.3 168 May 5 8. 1 8.9 8.9 7.2 May 17 153.1 188.4 230.0 148.8 J un 7 83.2 121.7 168.0 45.2 J u l 6 51. 0 33.4 44. 9 96.4 Aug 2 53.8 46.5 82. 5 58.8 120 APPENDIX E2; S o i l NH.-N (0-10 cm depth). A n a l y s i s of variance table Source DF MS F-value Subplot s 59 Main p l o t s 11 Blocks 2 109.32 0,07 T i l l a g e 3 2407.51 1. 58 Error (a) 6 1520.34 F e r t i l i z e r 3 55652.67 109.64 ** T i l l a g e x F e r t i l i z e r 9 992.22 1.95 Error (b) 36 507.59 Time 4 36872.62 43.44 ** . Time x T i l l a g e 12 1453. 15 1.71 Time x F e r t i l i z e r 12 9401.24 11.08 ** Time x T i l l . x F e r t . ' 36 653.56 0.77 Error (c) 117 848.83 T o t a l 239 ** = S i g n i f i c a n t to the 0.01 l e v e l 121 APPENDIX F l ; S o i l NO^-N (0-10 cm depth), ppm N0_-N F e r t i l i z e r Sampling T i l l a g e treatments (kg N/ha) date M R+M Ch R+Ch 0 May 5 20.2 15.5 14.6 13.6 May 17 32.9 38 . 9 25.4 35.8 Jun 7 46.0 28.4 24. 1 27 . 7 J u l 6 4.8 6.7 8.7 6.8 Aug 2 6.0 7.5 5.7 9.3 56 May 5 20.2 15.5 14 . 6 13.6 May 17 39.6 33 . 4 40.3 41.1 Jun 7 56.7 43.7 45.4 51.1 J u l 6 4.8 6.8 11.5 9.9 Aug 2 7.7 15.1 11.0 12.7 112 May 5 20. 2 15.5 14.6 13.6 May 17 42.9 47 . 9 39.2 33.4 Jun 7 68. 9 68.8 56.5 52.4 J u l 6 16.6 8.4 14.3 11.7 Aug 2 25.0 26 . 2 20.6 24. 6 168 May 5 20.2 15.5 14.6 13.6 May 17 47 . 2 29.5 44.7 41.7 Jun 7 74.4 97.7 68.7 72.0 J u l 6 22.8 16.7 29.2 22. 9 Aug 2 25.0 39.7 25. 1 23.8 122 APPENDIX F2; S o i l NO_-N (0-10 cm depth). A n a l y s i s of variance table Source DF MS F-value Subplo t s 59 Main p l o t s 11 Blocks 2 799.085 50.393 ** T i l l a g e 3 196.880 12.416 ** Error (a) 6 15.857 F e r t i l i z e r 3 3743.250 50.834 ** T i l l a g e x F e r t i l i z e r 9 63.423 0.861 Error (b) 36 73.637 Time 4 15918.000 165.570 ** Time x T i l l a g e 12 155.030 1.610 Time x F e r t i l i z e r 12 722.251 7.509 ** Time x T i l l , x F e r t . 36 87.411 0.910 Error (c) 117 96.172 T o t a l 239 ** = S i g n i f i c a n t to the 0.01 l e v e l 123 APPENDIX F2; S o i l NO-^ -N (0-10 cm depth). Table of means (ppm) Blocks A = 3A.7A Mean separation: B = 28.27 A B C C = 2A.69 L.S.D. 0.05=1.5A T i l l a g e M = R+M = Ch = R+Ch = 30. 11 28.86 26.39 26.57 Mean separation: Ch R+Ch R+M M L.S.D. 0.05 = 1.78 Fert i l i z e r (kg N/ha) 0 56 112 168 18.93 2A . 73 31 . 07 37.21 Mean separation: 0 56 112 168 L.S.D. 0.05 = 3.18 T ime May 5 = May 17 = Jun 7 = J u l 6 = Aug 2 = 15.96 38. 38 55.11 12. 67 17.81 Mean separation: J u l 6 May 5 Aug 2 May 17 L.S.D. 0.05 = 3.96 Jun 7 F e r t i l i z e r x Time (kg N/ha) May 5 May 17 Jun 7 J u l 6 Aug 2 0 56 112 168 15.96 33.27 31.54 6.76 7.11 15.96 38.60 A9.23 8.25 11.63 15.96 AO. 86 61 . 66 12 . 76 2A. 10 15.96 40.79 77.99 22.90 28.39 L.S.D. 0.05 .= 7.83 124 APPENDIX G l ; S o i l NH.-N/NO--N r a t i o s (0-10 cm depth) NH.-N/N0--N r a t i o s 4 i F e r t i l i z e r Sampling T i l l a g e treatments (kg N/ha) date M R+M Ch R+Ch 0 May 5 0.42 0.63 0.52 0.62 May 17 0.39 0.29 0.66 0.58 Jun 7 0.31 0.62 0.48 0.53 J u l 6 2.19 1. 58 1 . 39 1 .52 Aug 2 2. 02 3. 68 2.01 1 .79 56 May 5 0.42 0.63 0.52 0.62 May 17 1 .49 0.96 0.91 1 . 32 Jun 7 0.77 0.97 0.64 0. 98 J u l 6 3.15 2 . 68 2.54 1 . 53 Aug 2 2.69 2.86 3.32 2.50 112 May 5 0.42 0.63 0.52 0.62 May 17 2.46 1.85 2.03 2. 98 Jun 7 1.31 1 .32 0.70 1.16 J u l 6 2.58 11. 68 3.35 2. 38 Aug 2 2.61 3. 08 3.35 2.15 168 May 5 0.42 0.63 0.52 0.62 May 17 3,91 9.13 3.45 3.73 Jun 7 1. 92 1. 67 0.71 1.19 J u l 6 1.52 2.69 3. 34 2.50 Aug 2 2. 05 2. 05 2.33 3. 68 125 APPENDIX G2; S o i l NH.-N/NO.-N 4 3 r a t i o s CO-10 cm depth). A n a l y s i s of variance table Source DF MS F-value Subplo t s 59 Main p l o t s 11 Blocks 2 11.83 2.14 T i l l a g e 3 10.26 1.86 Error (a) 6 5.53 F e r t i l i z e r 3 23.72 7. 68 F e r t i l i z e r x T i l l a g e 9 2.57 0.83 Error (b) 36 3.09 T ime 4 52.91 12.57 * * Time x T i l l a g e 12 3.03 0.72 Time x F e r t i l i z e r 12 13. 07 3.10 ** Time x T i l l , x F e r t . 36 5.29 1 .26 Error (c) 117 4.21 To t a l 239 ** = S i g n i f i c a n t to the 0.01 l e v e l 126 APPENDIX G2; S o i l NH4~N/N03-N r a t i o s (0-10 cm depth). Table of means F e r t i l i z e r (kg N/ha) 0 56 11 2 168 Time May 5 May 17 Jun 7 J u l 6 Aug 2 F e r t i l i z e r x Time (kg N/ha) May 5 May 17 Jun 0 0. 55 0.48 0.49 1. 67 2. 37 56 0. 55 1.17 0.84 2. 47 2. 84 112 0. 55 2.33 1. 13 5 . 00 2. 80 168 0. 55 5.06 1.37 2. 52 2. 53 L.S. D. 0.05 = 3. 26 1.11 Mean separation: 1 , 5 8 0 56 112 168 2.36 2.40 = 2.92 = 2. 64 L.S.D. 0.05 = 0.65 0.55 Mean separation: 2 , 2 6 May Jun May Aug J u l 0. 96 5 7 17 2 6 L.S.D. 0.05 = 0.83 127 APPENDIX HI; Barley y i e l d . A n a l y s i s of variance t a b l e Source DF MS F-value Subplot s 47 Main p l o t s 11 Blocks 2 5 . 8282 3.4567 T i l l a g e 3 21 6900 12.8680 ** Error (a) 6 1 . 6856 F e r t i l i z e r 3 5.1900 3.9480 * T i l l a g e x F e r t i l i z e r 9 0.4156 0.3160 Error (b) 24 1.3146 Time 1 140.4301 234.520 ** Time x T i l l a g e 3 2.993 4.998 * Time x F e r t i l i z e r 3 0.7300 1.219 Time x T i l l a g e x F e r t . 9 0.2320 0. 387 Error (c) 32 0.5988 To t a l 95 ** = S i g n i f i c a n t to the 0.01 l e v e l , * = S i g n i f i c a n t to the 0.05 l e v e l 128 APPENDIX H2; Barley y i e l d . Table of means (t/ha) T i l l a g e M = R+M = Ch = R+Ch = 5. 24 3.88 3.22 3.22 Mean separation: Ch R+Ch R+M M L.S.D. 0.05 = 0.92 F e r t i l i z e r (kg N/ha) 0 56 112 168 3, 3 , 4, 4 23 90 17 26 Mean separation: 0 56 112 168 L.S.D. 0.05 = 0.68 Time J u l 7 Aug 8 2 5 68 10 L.S.D. 0.05 = 0.32 T i l l a g e x Time T i l l . J u l 7 Aug 8 Mean separation: M 3.54 6.93 2.71 5. 05 J u l 7 Ch R+Ch R+M M R+M Ch 2.22 4.2-1 Aug 8 R+Ch Ch R+M M R+Ch 2 . 25 4.20 L.S.D. 0.05 = 1. 02 129 APPENDIX I I ; T o t a l nitrogen uptake by barley. A n a l y s i s of variance t a b l e Source DF MS F-value Subplot s 47 Main p l o t s 11 Blocks 2 1306.9 1.999 T i l l a g e 3 4613.2 7.057 * Error (a) 6 653.7 Fert i l i z e r 3 5 217.6 46.289 ** F e r t i l i z e r x T i l l a g e 9 173.1 1 . 536 Error (b) 24 112.7 Time 1 5221.5 28.231 ** Time x T i l l a g e 3 101.6 0.549 Time x F e r t i l i z e r 3 150.6 0.814 Time x T i l l , x F e r t . 9 131.0 0. 708 EfcEor (c) 32 184.9 T o t a l 95 ** = S i g n i f i c a n t to the 0.01 l e v e l , * = S i g n i f i c a n t to the 0.05 l e v e l 130 APPENDIX 12; To t a l nitrogen uptake by barley. Table of means (kg/ha) T i l l a g e M = 69.6 Mean separation: R+M = A6. 3 R+Ch Ch R+M M Ch = 40.7 R+Ch = 40.3 L.S.D. 0.05 = 18.1 Fer t i l i z e r (kg N/ha) 0 31.3 Mean separation: 56 = 43.8 0 56 112 168 112 = 57 . 3 168 = 64. 6 L.S.D. 0.05 = 6.3 Time J u l 7 Aug 8 41.9 • 56.6 L.S.D. 0.05 = 5.7 131 APPENDIX J ; Nitrogen content of barley (%) . A n a l y s i s of variance t a b l e Source DF MS F-value Subplots 47 Main p l o t s 11 Blocks 2 0.02 0.13 T i l l a g e 3 0.17 1.06 Error (a) 6 0.16 F e r t i l i z e r 3 1.88 23.50 F e r t i l i z e r x T i l l a g e 9 0.14 1.75 Error (b) 24 0.08 Time 1 4.14 51.75 Time x T i l l a g e 3 0 . 08 1 . 00 Time x F e r t i l i z e r 3 0.16 2. 00 Time x T i l l , x F e r t . 9 0.07 0.88 Error (c) 32 0.08 T o t a l 95 ** = S i g n i f i c a n t to the 0.01 l e v e l Table of means (%) F e r t i l i z e r (kg N/ha) 0 = 1. 00 Mean separation: 56 = 1. 14 0 56 112 168 112 = 1.43 168 = 1.62 L.S.D. 0.05 = 0. 12 T ime J u l 7 = 1.51 Aug 8 = 1.09 L.S.D. 0.05 = 0. 12 132 APPENDIX K l ; Percent f e r t i l i z e r n i t r o g e n uptake. % N uptake T i l l a g e Sampling date F e r t i l i z e r 56 r a t e 112 (kg N/ha) 168 M J u l 7 13.9 15.0 16.9 Aug 8 49. A 29.3 19.0 R+M J u l 7 15.5 26.9 19.3 Aug 8 42.7 32. 5 24.7 Ch J u l 7 13.7 26.2 20.5 Aug 8 20.7 22.8 32. 9 R+Ch J u l 7 16.9 14.2 11 . I Aug 8 18.6 23.3 13.1 133 APPENDIX K2; Percent f e r t i l i z e r n i trogen uptake. A n a l y s i s of variance t a b l e Source DF MS F-value Subplots 35 Main p l o t s 11 Blocks 2 671.38 1 .65 T i l l a g e 3 362.58 0.89 Error (a) 6 406.75 F e r t i l i z e r 2 133.26 3.56 T i l l a g e x F e r t i l i z e r 6 163.92 4. 38 Error (b) 16 37.46 Time 1 1750.35 7.79 Time x T i l l a g e 3 177.18 0.79 Time x F e r t i l i z e r 2 287.76 1. 28 Time x T i l l , x F e r t . 6 167.08 0.74 Error (c) 24 224.82 T o t a l 71 * = S i g n i f i c a n t to the 0.05 l e v e l Table of means (%) Time J u l Aug 7 = 17.6 8 = 27.4 L. S .D. 0. 05 = 7 F e r t i l i z e r x T i l l a g e (kg N/ha) M R+M Ch R+Ch 56 31. 7 29.1 17.2 17.7 112 22.2 29.7 24.5 18.7 168 18.0 22.0 26.7 12.4 . 29 L.S.D. 0.05 = 13.4 APPENDIX L l ; T i l l a g e c o s t s . Moldboard plowing (3 x 16 i n . ) Machinery $ 7.98/hr * Labour $ 5.00/hr P r o f i t $ 3. 30/hr ** T o t a l 16.28/hr Cost per ha @ 0.8 ha/hr ..$ 20.35 C h i s e l plowing Machinery $ 7.25/hr (14 ' HD c u l t i v a t o r ) Labour $ 5.00/hr P r o f i t $ 3. 58/hr T o t a l 15.83/hr Cost per ha @ 2.8 ha/hr...$ 5.65 Rotovating Machinery $ 9.73/hr (5' r o t o r ) Labour $ 5.00/hr P r o f i t $ 1 . 48/hr T o t a l 16.21/hr Cost per ha @ 0.6 ha/hr...$ 27.02 Disc harrowing Machinery $ 19.22/hr (16') Labour $ 5.00/hr P r o f i t $ 4 . 30/hr T o t a l 28.52/hr Cost per ha @ 3.0 ha/hr...$ 9.51 * See A l b e r t a A g r i c u l t u r e Farm Machinery Guide. ** A l l costs are based on custom operator b a s i s . APPENDIX L2; T i l l a g e c o s t s ; t i l l a g e systems. M Moldboard plowing Disc harrowing R+M Rotovating Moldboard plowing Disc harrowing Ch C h i s e l plowing Disc harrowing R+Ch Rotovating C h i s e l plowing Disc harrowing 1 x $ 20.35 = $ 20.35 3 x $ 9.51 = $ 28.53 To t a l = $ 48.88 1 x $ 27.02 = $27.02 1 x $ 20.35 = $ 20.35 3 x $ 9.51 = $ 28.53 T o t a l = $ 75.90 4 x $ 5.65 = $ 22.60 5 x $ 9.51 = $ 47.55 To t a l = $ 70.15 1 x $ 27.02 = $ 27.02 2 x $ 5.65 = $ 11.30 5 x $ 9.51 = $ 47.55 T o t a l = $ 85.87 Summary, t i l l a g e system cost per hectare: M = $ 48.88 R+M = $ 7 5.90 Ch = $ 70.15 R+Ch = $ 8 5.87 136 APPENDIX M; F e r t i l i z e r c o s t s . Banded f e r t i l i z e r 70 kg/ha of 11-55-0 @ $ 231.33/t * = $ 16.20 Broadcast f e r t i l i z e r 56 kg/ha of N as 46-0-0 @ $ 161.50/t * - $ 19.66 112 kg/ha of N as 46r0-0 @ $ 161.50/t = $ 39.22 168 kg/ha of N as 46-0-0 @ $ 161.50/t = $ 58.98 F e r t i l i z e r treatment costs Broadcast ni t r o g e n Banded nit r o g e n T o t a l cost (kg/ha) ($/ha) (kg/ha) ($/ha) ($/ha) 0 0 70 16.20 16.20 56 19.66 70 16.20 35.86 112 39.22 70 16.20 55.52 168 58. 98 70 16.20 75.18 * Cominco L t d . , Vancouver, B.C. (ffeb 1979) stat e that these f e r t i l i z e r s w i l l be d e l i v e r e d to anywhere i n B.C. at these p r i c e s . 137 APPENDIX N; Miscellaneous c o s t s . $ 8.72/ha Seed 112 kg/ha of barley seed (Gait) . . .$ 12.43/ha . . .$ 3.33/ha . . .$ 24.48/ha * P r i c e l i s t e d by B u c k e r f i e l d ' s L t d . , Surrey, B.C. (Feb 1979). 138 APPENDIX 0; Treatment costs.($/ha). T i l l a g e / f e r t i l i z e r T i l l a g e F e r t i l i z e r M i s c e l l . T o t a l (Kg N/ha) £6 sf cost cost cost M 0 48.88 16.20 21.15 86.23 56 48.88 35. 86 24.48 109.22 112 48.88 55. 52 24.48 128.88 168 48.88 75.18 24.48 148.54 R+M 0 75.90 16.20 21.15 113.25 56 75.90 35.86 24.48 136.24 112 75.90 55.52 24.48 155.90 168 75.90 75.18 24.48 175.56 Ch 0 70.15 16.20 21.15 107.50 56 70.15 35.86 24.48 130.49 112 70.15 55.52 24.48 150.15 168 70.15 75. 18 24.48 169.81 R+Ch 0 85.87 16.20 21.15 123.22 56 85.87 35.86 24.48 146.21 112 85.87 55.52 24.48 165.87 168 85.87 75. 18 24.48 185.53 

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