6lX UBB1S mwtmis The University of Alberta Printing Department Edmonton, Alberta SPECIAL COLLECTIONS UNIVERSITY OF ALBERTA LIBRARY REQUEST FOR DUPLICATION I wish a photocopy of the thesis by QS) a r- // (author) entitled oS>o> / The copy is for the sole purpose of private scholarly or scientific study F. 236 September 1975 THE UNIVERSITY OF ALBERTA PRODUCTION OF GATEWAY BARLEY AS INFLUENCED BY FERTILIZER, SOIL TEST LEVELS AND MOISTURE STRESS by LEONARD ANGUS HEAPY B. Sc. A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF SOIL SCIENCE EDMONTON, ALBERTA SPRING, 1971 UNIVERSITY OF ALBERTA FACULTY OF GRADUATE STUDIES The undersigned certify that they have read, and recommend to the Faculty of Graduate Studies for acceptance a thesis entitled "Production of Gateway Barley as Influenced by Fertilizer, Soil Test Levels and Moisture Stress" submitted by Leonard Angus Heapy, B.Sc., in partial fulfilment of the requirements for a degree of Doctor of Philosophy. ABSTRACT Multiple regression analysis was used to relate yield of Gateway barley, grown under dryland conditions in central Alberta, to certain controlled and uncontrolled variables. The controlled variables were rates of applied nitrogen and phosphorus fertilizers. The uncontrolled variables were soil test levels of nitrate-nitrogen and available phosphorus and moisture stress occurring prior to head¬ ing of the crop. Pooled data of 17 site-years were used to derive a barley yield equation which explained 55 per cent of yield variation occurring on three Chernozemic and three Luvisolic soils. External data were used to establish a suitable moisture stress criterion and to evaluate the effect of moisture stress on yield of barley. This analysis involved the calculation of a daily soil moisture budget for each experimental site and a count of days of moisture stress based on this budget. The growing period was divided into seven intervals, representing stages of crop development. Yield of barley was regressed on stress ratios (count of stress days/ total days in interval) occurring within the seven intervals. In this regression yield of barley was an average site yield over plots where nutrients were not limiting. This analysis carried out on external data provided a method for calculating a moisture stress index for each of the 17 site-years. The derived yield equation was used to examine several aspects of fertilizer use in cereal production. The results indicate the following. (a) The optimal inputs of nitrogen are substantially * ' lower when soil moisture conditions are poor than when they are good at time of seeding. (b) The ratio of nitrogen to phosphorus recommended at optimal input rates is unlikely to be the least-cost combination of fertilizer inputs at rates less than optimal. (c) The influence of soil nitrate-nitrogen, evaluated to a depth of 61 cm, on the nitrogen fertilizer requirement was less than the interpretation made by the provincial soil testing service. At low levels of soil nitrogen there was good agreement with the soil testing service but at moderate soil test levels the nitrogen calculated inputs were about 40 per cent higher than those presently recommended. (d) The optimal inputs of phosphorus fertilizer were about 30 per cent lower than those recom¬ mended by the soil testing service. (e) Response patterns to nitrogen and phosphorus fertilizers were similar for Chernozemic and Luvisolic soils in central Alberta, supporting the interpretation now made by the provincial soil testing service. ■ s ACKNOWLEDGEMENTS The author expresses sincere appreciation to all whose assistance and counsel contributed to the completion of this work: To Dr. G. R. Webster and Dr. J. A. Robertson, Department of Soil Science as Thesis Committee Chairman and Associate Chairman, respectively, for guidance and encouragement in all phases of the investigation. To Professor Ursula von Maydell, Department of Computing Science, who has unhesitatingly given so much of her time and attention to this study, for guidance in statistical procedures. To Dr. D. McBeath, Lacombe Research Station, Canada Depart¬ ment of Agriculture, for helpful discussions during the course of the study and to his technical staff for their co-operation. To Dr. H. C. Love, Department of Agricultural Economics for advice and constructive criticism. To Dr. N. Colotelo, Department of Plant Science, Professor R. W. Longley, Department of Geography and Mr. A. A. Kjearsgaard, Canada Department of Agriculture, for assistance and advice. To Mr. L. Merkley, Mr. D. D. Dau and Mr. C. Panter for their substantial help in programming. To Mr. H. G. Jahn, Mr. J. L. P. Konwicki, Mr. W. McKean and Mr. A. S. J. Taylor, whose co-operation was much appreciated, for help in sample collection and analysis. ' . To all rhembers of my thesis committee, whose critical review of the manuscript gave added clarity to the final results. To Mrs. Martha Laverty for typing the manuscript. To Sherritt Gordon Mines Limited, Western Co-operative Fertilizers Limited, The Alberta Agricultural Research Trust, Canada Department of Agriculture and the National Research Council of Canada for the financial assistance during the course of this study. TABLE OF CONTENTS Page INTRODUCTION . 1 REVIEW OF LITERATURE . 4 A. Fertilizer investigations in the Prairie Provinces. ... 4 B. Soil moisture conditions and crop production. 8 C. Mathematical models in agricultural research.12 MATERIALS AND METHODS.15 A. Description of the experimental area.15 B. Field techniques.18 Field investigations, 1959 - 1963. 18 Field investigations, 1964 - 1968. 20 C. Laboratory procedures . 29 Introduction . 29 Sample preparation . 29 Chemical analysis of soils . 29 Physical analysis of soils . 31 RESULTS AND DISCUSSION . 32 A. Barley response to applied nutrients.32 B. Effect of soil nutrient levels on barley response to applied nutrients . 38 C. Effects of moisture stress on yield of barley . 45 Soil moisture budget.46 Budget input data for experimental sites 1959 - 1963 . 48 - ' ' Page Budget input data for experimental sites 1964 - 1968 . 49 Moisture stress equation . 55 D. Effects of soil moisture stress and soil order on barley response to applied nutrients.68 Use of coefficients of individual site-year regression equations . 68 Comparison of regression equations involving pooled data.71 E. Applications of the barley yield equation . 74 Calculation of optimal fertilizer inputs . 75 Fertilizer inputs below optimal levels . 79 Applications of the stress index (W).83 SUMMARY AND CONCLUSIONS.87 BIBLIOGRAPHY 92 X LIST OF TABLES Table Page 1. Monthly average values of selected meteorological observations at Edmonton Industrial Airport . 17 2. Total monthly precipitation, mm, May to September inclusive, 1959-1969 at Edmonton Industrial Airport . . 17 3. Site details for field investigations 1959-1963 . 19 4. Site details for field investigations 1964-1968 . 22 5. Classification of soil series, experimental sites 1959-1968 . 23 6. Treatment numbers: rates of nitrogen, phosphorus and potassium for field experiments 1964-1968 . 24 7. Dates of certain field operations . 27 8. Soil test data: averages of initial site samples.33 9. Mechanical analysis of soils.34 10. Analyses of variance of barley yields for 10 site- years on three Chernozemic soils.36 11. Analyses of variance of barley yields for 7 site- years on three Luvisolic soils.37 12. Three regression equations for yield of barley as a function of applied N and P, showing regression coefficients, standard errors of estimate of regression coefficients and R values.. . 39 13. Three regression equations for yield of barley as a function of applied and soil N and applied and soil P, showing regression coefficients, standard errors of estimate of regression coefficients and values. . 42 14. Residual nutrient status of plots under continuous barley production to show the effect of fertilizer treatment.44 15. Site data entered in the equation for estimating a daily soil moisture budget for 27 site-years 1959-1963 . 50 16. A summary of rainfall for 27 site-years 1959-1963 .... 51 ' Table Page 17. Comparison of some estimates of potential evaporation ... 52 18. Regression of site observations (Y) on reference station observations (X) for daily wind and humidity.54 19. Site data entered in the equation for estimating a daily soil moisture budget for 17 site-years 1964-1967 . 56 20. Apparent densities and moisture characteristics of soils for experimental sites 1964-1968. 57 21. Comparison of k-coefficients used in two procedures for computing an available moisture index for stress analysis . 61 22. Yield (Y m ), total days within 7 growth intervals and two ratios M 1 and M" of stress-days/total days for 7 intervals in each of 27 site-years of barley data 1959-1963 . 63 23. Regression coefficients (b^), standard errors of estimate, partial F-values and R values of moisture stress equations for 27 site-years 1959-1963 . 65 24. Yield (Y m ), total days within 7 growth intervals, and two ratios M‘ and M" of stress-days/total days for 7 intervals in each of 17 site-years of barley data 1964-1967 . 66 25. Y m , two predictions of Y m (fand f 2 ) and index of moisture stress (W) for 17 site-years 1964-1967. 67 26. Regressions of site-year regression coefficients on soil order, T and moisture stress index, W giving r 2 and F values.70 27. Regression coefficients, F-values, squares of the multiple correlation coefficient (R^) and standard errors of estimate (Sy x ) for 5 equations involving pooled data of 17 site-years showing the effects of including soil order (T) and moisture stress (W) in the regression ... 72 28. Comparison of fertilizer recommendations by the provincial soil testing service and calculated optimal fertilizer inputs for barley production, showing the effects of soil test values and price ratios on the inputs calculated using equation (14).78 29. Effect of selected stress index (W) on optimal fertilizer input.85 ' LIST OF FIGURES Figure Page 1. Location of experimental sites.16 2. Effect of the moisture stress index (W) on barley yield for two inputs (kg/ha) of nitrogen fertilizer (N a ).76 3. Isoquant-isocline diagrams, showing optimum barley yield (Y ) for three nitrogen soil test (N ) vy IT J- O levels.80 4. Isoquant-isocline diagrams, showing optimal barley yield (Yq PT ) for three phosphorus soil test (Pg) levels.81 5. Isoquant-isocline diagrams, showing optimum barley yield (Yq PT ) at three levels of moisture stress (W) 86 ■ APPENDICES Item Page A. Yield of barley Cq/ha) for 1964 - 1967 sites. 98 B. Nitrogen, phosphorus and potassium analyses and soil moisture data of 1964 - 1967 sites.100 C. Regression equations with six variables for seventeen site-years, regression coefficients (b - •) , coeffi- cients of determination (R ) and mean yields, quintals per hectare.108 D. Regression equations with fifteen variables for seven¬ teen site-years, regression coefficients (c-^) 2 1 J coefficients of determination (R ) and mean yields, quintals per hectare.109 E. Apparent densities and moisture characteristics of soils for experimental sites 1959 - 1963 .Ill F. Notes on calculating potential evaporation by the Penman method.114 INTRODUCTION Multiple regression analysis is used to interpret the results of a field investigation into the use of fertilizers in barley pro¬ duction. Yield equations are derived, relating barley yield to: (a) rates of applied nitrogen and phosphorus fertilizers, (b) soil moisture conditions over the growing season and (c) soil test levels of nitrate-nitrogen and available phosphorus. In the semi-arid environment of the Prairie Provinces of Canada, yield and response to fertilizers of cereal crops grown under dryland condi¬ tions are largely influenced by the amount and distribution of seasonal rainfall. A soil moisture term in the yield equations is directed to the problem of collating evidence of fertilizer response obtained from sites subjected to different soil moisture regimes. The immediate application of improved soil test interpretation is evident from the call on the provincial soil testing service to provide fertilizer recommendations for the 1968 season to about 5,000 Alberta farmers. i The data for this study were obtained from an interdisciplinary research project which had the following specific objectives: (a) to derive yield equations relating yields of cereal and forage crops to a number of independent variables including available nutrients in the soil, fertilizer nutrients and certain environmental factors, (b) to determine the optimum rates of fertilization, using the derived yield equations and (c) to evaluate the effects of the variables on crop quality. 2 Field experiments were conducted at six locations in central Alberta, three within 30 kilometers of Edmonton and three within 50 kilometers of Lacombe. Sites, three on Chernozemic and three on Luvi- solic soils, were selected in consultation with personnel of the Alberta Soil Survey, a major consideration being that each site should be located upon a member of a soil grouping of significant agricultural importance. Important features of the experimental plan were: (a) A set of barley plots was laid out at each location. One crop of barley was produced annually on each set. (b) The response of barley to N, P and K fertilizers was studied. Two replications of a 5^ central composite design was used, involving 23 treatments. A fertilizer treatment, applied annually at time of seeding, was assigned to each plot. (c) In the spring and fall, prior to seeding and after harvesting, soil samples were collected from each plot for moisture analy¬ sis and soil testing. (d) Certain daily meteorological observations, including rainfall, were recorded at each site. Stages of development of the barley crop were followed by regular visits to the sites. Commenced in 1964, this phase of the barley project terminated in 1968 after twenty-six site-years had been set out. In 1969 a study commenced at all six barley sites into the residual effects of the ferti¬ lizer treatments, barley remaining as the test crop. The hazards of field experimentation took a heavy toll as nine of the twenty-six site-years had to be discarded, leaving only seventeen ' . *•/ 3 for this study. The greatest loss occurred in 1968 when all six sites had to be discarded because abundant late tillers were unable to ripen after smothering a light, earlier crop of barley. This presentation is the first formal report on results of the project. The objectives of this phase of the project were: (a) To determine the response of barley to nitrogen, phosphorus and potassium fertilizers on certain soils in central Alberta. (b) To develop a method for assessing the effect of soil moisture stress on yield and response to fertilizers of barley grown under dryland conditions. (c) To develop a methodology for determining the optimum rates of applied fertilizers for barley grown on stubble when soil test data are available. (d) To derive a generalized yield equation relating yield of barley grown on stubble to rates of applied fertilizers, soil test levels, moisture stress and soil grouping. ■ 4 REVIEW OF LITERATURE A. Fertilizer investigations in the Prairie Provinces Investigations into the response of various crops to fertilizers have long been an integral part of agricultural research in the three Prairie Provinces of Canada. Trials at the Dominion Experimental Farms, reviewed by Hopkins and Leahey (1944), failed to show appreciable yield increases until about 1928 when the practice of broadcasting the ferti¬ lizer was replaced by the combination grain and fertilizer drill. These early studies demonstrated the importance of the amount and distribution of seasonal rainfall to fertilizer response. In 1928 extensive fertilizer trials were undertaken with the aid of co-operating farmers. Trials in Alberta in 1930, summarized by Wyatt et al. (1939), demonstrated a definite response of cereals to ammonium phosphate and triple superphosphate for the Brown and Black soils. Mitchell (1932) reported some very marked responses of wheat grown on summerfallow soils in Saskatchewan to triple superhosphate and Ellis (1934) reported a response to nitrogen and phosphorus fertilizers and a general lack of response to potassium fertilizer for wheat on Manitoba soils. From the evidence of subsequent trials, a project which avoided the drier Brown soil zone, Mitchell (1946) recommended for wheat grown on summerfallow in Saskatchewan applications of 11-48-0 at rates of 20 to 40 pounds per acre. In Alberta attention was also given to the role of fertilizers in the management of Gray Wooded soils. Co-operative fertilizer trials on these soils commenced in 1929 and the Breton experimental plots were ' 5 set out in 1930. From initial observations made on the Breton plots, Newton (1936) reported sulphur deficiency of some Gray Wooded soils for legume production. Reviewing the first fifteen years of this study, Wyatt (1945) remarked that with proper management, which included the use of fertilizers, the productivity of the Gray Wooded soils compares favourably to that of the Black soils in Alberta. The Alberta Department of Agriculture (1968) published general fertilizer recommendations for crops grown in central and northern Alberta. Nitrogen and phosphorus are usually deficient for all crops. A response to potassium is noted for potatoes grown on light-textured, moderately calcareous soils. Some Dark Gray Wooded and Gray Wooded soils are sulphur deficient for legume production and the farmer is advised to set out test strips to check his fields for sulphur deficiency. Nyborg (1968) reported sulphur deficiency for oat production at four sites on different Gray Wooded soil series in the Peace River region. Campbell and Skoropad (1961) confirmed manganese deficiency as the cause of "grey speck" of oats, first observed at Edmonton in 1956. This disease of oats is sporadically distributed throughout northern Alberta, generally associated with high organic matter content of the soil, or high soil pH, or both. Foliar spraying with manganese sulphate has proven successful in treatment of the disease. The Alberta Department of Agriculture established the Alberta Soil Testing Laboratory in 1955. Some of the problems encountered by the soil testing service are pertinent to this investigation and, ex¬ cluding the interpretation of soil test data, are reviewed at this time as they relate to field investigations into the use of fertilizers. -p 6 Collection of soil samples . In Alberta the soil test sample is collected to a depth of six inches (15.2 cm) and the farmer is pro¬ vided with instructions for obtaining a representative sample (or samples) from the field. Rennie and Clayton (1960) demonstrated the variability in yield and response to phosphorus that can be expected within relatively short distances in any one field in which complexity of soil pattern occurs. Such complexity of soil would be a problem in deciding upon the appropriate fertilizer input, but the farmer can be expected to be aware of significant changes of soil pattern within a field and he has the option to select practical, but less heterogeneous, sampling units. The six-inch sampling depth, while convenient in meeting the need for a representative sample, is possibly too shallow for defining the nitrogen requirement. In Manitoba, where the nitrogen requirement is assessed by sampling to a depth of twenty-four inches, Soper and Huang (1963) found that the nitrate-N content of the soil to a depth of forty-eight inches (122 cm) gave the best correlation with yield response to nitrogen fertilizer. Nitrogen requirement . In Alberta the nitrogen requirement is based on a nitrate-N soil test, modified by crop to be grown and cropping history of the field. Perhaps the potential of the soil to mineralize organic forms of nitrogen should be considered, as shown by the studies of Synghal et_ al. (1959), Smith (1966) and Geist et al. (1970) . However the studies of Wyatt et al. (1927) indicate that this potential may not be realized under field conditions, as soil moisture conditions, the ' ' 7 growing crop, the cropping sequence, method of cultivation and soil temperature can influence the process of mineralization of organic-N. Phosphorus requirement . Most soils in the Prairie Provinces require added phosphorus for adequate crop production. Mitchell (1932) demonstrated the usefulness of a soil test method based on acid extrac¬ tion in predicting the phosphorus fertilizer requirement of Saskatchewan soils for wheat production. The provincial soil testing services in Manitoba, Saskatchewan and Alberta use different extraction procedures as a soil test for "available" soil phosphorus. The acid extraction procedure used in Alberta, described later in the text, was compared to an alkaline procedure by Robertson (1962) and both procedures yielded very similar information on 79 Alberta soils. The predictive value of the phosphorus soil test for Alberta soils is far from perfect and the empirical nature of extraction methods is a weakness in the interpretation of observed discrepancies in response to added phosphorus. Recent studies, by Nyborg and Hennig (1969) on different placements of fertilizers for several field crops, by Omanwar and Robertson (1970) on the process of P movement to roots and by Alexander (1967) on inorganic phosphorus forms in Alberta soils, contri¬ bute to an understanding of the roles of soil and applied phosphorus in crop production. The rooting habit of the plant is an important factor in the uptake of soil phosphorus; thus for important field crops, an investigation into varietal differences in phosphorus requirement seems desirable. ‘ 8 Potassium requirement . The potassium status of Alberta soils is generally sufficient for crop production. Potassium deficiencies do occur as shown by the studies of Goettel (1962) , Nelson (1964) and Tsai (1966). The Alberta soil test method for potassium (extraction by 1.0N ammonium acetate) is described later in the text. The test is not regarded as definitive, rather a test value of 250 lb/a (280 kg/ha), or less, is indicative of a possible soil potassium deficiency. B. Soil moisture conditions and crop production Soil moisture reserves and rainfall distribution during the growing season are important factors affecting cereal production in the three Prairie Provinces. Barnes (1924) used lysimeters to study soil moisture under crop and fallow conditions at Swift Current, and observed that fallow tanks were able to conserve 23 per cent of the 20 inches (50.8 cm) of precipitation received during the 12-month period prior to seeding. Hopkins (1935) found a significant correlation between yield of wheat in western Canada and the amount and distribution of sea¬ sonal rainfall; the maximum influence appeared to be exerted during the month of June. Lehane and Staple (1965), by multiple regression analysis, found that rainfall received during June and July and available soil moisture stored below the 12-inch (30.5 cm) depth were important factors influencing wheat yields in southwestern Saskatchewan. In wetter seasons, yields were higher on both clay and loam than on sandy loam. Various workers have investigated the effect of moisture stress on cereal crops. Studies in Alberta of the susceptibility of cereal , ■ ■ . 9 varieties to drought at different stages of development have been reported by Aamodt and Johnston (1936) for wheat and by Wells and Dubetz (1966) for barley. Chinoy (1962) studied the physiology of drought resistance in wheat. Aspinall et_ al. (1964) investigated the physiological effects on barley of repeated short cycles, single short cycles and single long cycles of moisture stress. From studies such as these, and the reviews by Henckel (1964) of the physiology of plants under drought conditions and by Slatyer (1967) of the significance of water deficits to physiological processes, certain general statements can be made of the effects of moisture stress on the growing plant: (a) The organ which is growing most rapidly at the time of a stress is the one most affected. (b) Tillering, while suppressed by stress, may be stimulated by the stress experience when the stress has been removed. (c) During the development of reproductive organs, all physio¬ logical properties change in the direction of lower resistance to moisture stress. (d) The effects of stress on yield are greater at the early boot stage than at the soft dough stage and in turn greater than at the onset of tillering or ripening. While the foregoing generalizations consider the plant in discrete stages of physiological development, doubt was expressed by Bunting and Drennan (1966) as to the reality of the concept of separate vegetative and reproductive phases for the tillering plants. Lawes and Gilbert (1880) examined the relationship between yields of wheat at Rothamsted and rainfall and commented that the effect ' 10 of a climatic event on wheat yield is influenced by the stage of growth of the plant. Numerous workers, especially in regions where the uncertainty of rainfall is a hazard to crop production, have ex¬ amined this relationship. A linear model is commonly assumed, equating yield of a particular crop to the additive effects of precipitation amounts received within chosen calendar intervals. A more realistic concept of the relationship was developed by Blumenstock (1942) and Barger and Thom (1949) who considered the effect of rainfall on avail¬ able soil moisture and the occurrence of drought. Subsequently, the "drought criterion" was proposed by van Bavel (1953) to express the physiological role of soil moisture. By this concept, a drought-day is defined as a 24-hour period in which the soil moisture stress exceeds a limit, which on the basis of experimental evidence, may be taken as a point at which the productive processes of the crop are being appreci¬ ably decreased. Parks and Rnetsch (1959) applied the drought-day concept in a study of the nitrogen fertilizer requirement for corn production of a soil in Tennessee. In this study a drought index value was obtained by inserting the count of drought-days into an externally-generated equation which weighted the relative importance of a drought condition occurring in four successive periods of corn development. Zahner and Stage (1966) also used the drought-day concept in a study of the influence of weather conditions on tree growth. An obstacle to the use of the drought-day concept in studies of crop production is the problem of assessing soil moisture conditions over the growing season. However, this obstacle is not too great as techniques have been developed to estimate a soil moisture budget by . 11 various observations on the soil-plant-atmospheric environment. In the calculation of a soil moisture budget a problem commonly encountered is a need to estimate actual upward moisture loss, or evapotranspiration. This problem is usually resolved by first estimating potential evaporation (PE), then evapotranspiration is related to PE as modified by certain soil and plant characteristics. Sellers (1965) described methods of measuring or estimating potential evaporation. Penman (1963) presented arguments for and -against some of the "drying curves" that have been proposed to describe avail¬ ability to the plant of soil water at different soil water potentials. From the work of Holmes and Robertson (1959), Baier and Robertson (1966) and Baier (1969), a soil moisture budgeting technique was evolved which considers depth of rooting, stage of plant develop¬ ment and permits the selection of a "drying curve" from several options. The methodology developed by Shaw (1963) for estimating soil moisture conditions under corn draws upon the results of prior research by Denmead and Shaw (1959, 1962) to introduce the effects of stage of development of the crop and availability of soil water to the plant. ■ > ' 12 C. Mathematical models in agricultural research In the Prairie Provinces of Canada, as in many areas of the world, fertilizers have attained much importance as an input in agri¬ cultural production. In Alberta in 1968, investment in fertilizers exceeded $30,000,000, a six-fold increase within one decade. As the nature of this increase in fertilizer usage was influenced by fertil¬ izer recommendations of an advisory service, it is desirable to examine some of the economic aspects of these recommendations. However, this appraisal is most difficult for, as commonly encountered elsewhere, much of the evidence of response to fertilizers does not exist in a mathematical form amenable to economic analysis. The input-output relationship A mathematical model is a convenient technique for expressing a concept of the relationship between two or more variables. Several workers, including Heady (1952), Munson and Doll (1959) and Tisdale and Nelson (1966) have sketched the historical development of these models in the agricultural sciences. A feature of these biological models is the need for some simplifying assumptions. Thus, a continuous causal relation between inputs (X^) and output (Y) is commonly assumed, such that the system can be described by a single equation of the form: Y = f(X x , X 2 , X 3 , ..., X n ). (1) Heady and Dillon (1961) and Smith (1969) examined various algebraic forms of this model or "yield equation", particularly with regard to the suitability of the form in describing the "law of diminishing . 13 returns". Brownlee (1965) and Draper and Smith (1967) discussed various aspects of the methodology of estimating the parameters of these models by the procedure of least squares or "regression" analysis. The mathematical analysis of a complex problem can lead logically to a system of simultaneous equations. For example, if a process occurs in discrete stages, then the resultant output can be examined as a function of the intermediate outputs in the chain. Ferrari (1965) disapproved of an unquestioning use of regression models in biological research and applied a set of simulteoieous equations to a description of relationships involved in a particular chain process. Heady and Dillon (1961) noted that "single equation estimates have generally been found to be just as logical and mean¬ ingful in an economic sense as those derived at much more expense by the use of simultaneous equation models". As understanding of plant processes broadens, more complex models will no doubt become more common in biological research. However, Grodins (1963) found system isolation and "adaptive behaviour" formidable obstacles to building realistic functional models of biological systems. Some economic considerations In fertilizer investigations, crop response to a single applied nutrient (Xj_) can be examined by a yield equation of the form Y f (X x ) . ( 2 ) , 14 For inputs of two nutrients (X-^) and (Xthe yield equation may be: Y = f(X x , X 2 ) (3) Equation (3) describes a surface in three-dimensional space, with axes X-^, X 2 and Y. In addition to factor-product relations, the three- dimensional equation implies certain factor-factor relations. Two aspects of the factor-factor relations should be noted: (a) The algebraic form of the yield equation should not constrain the model from describing the actual nature of the response surface. Heady and Dillon (1961, ch. 6) discussed the choice of the algebraic form of the yield equation and noted that a polynomial approximation usually fits the production surface adequately. (b) Usually fertilizer recommendations are made in the form of rate and formulation. The farmer may decide on a fertilizer invest¬ ment less than that implied in the recommendation and, unaware of factor-factor relations, simply reduce the rate of fertilizer applied. Heady (1952) discussed principles of resource combina¬ tion and cost minimization. Least-cost combinations of inputs on the production surface should be carefully examined and the fertilizer recommendation should reflect significant changes in fertilizer formulation (resource combination) as the capital invested in fertilizer increases. • • ✓ . 15 MATERIALS AND METHODS A. Description of the experimental area The experimental area is situated in central Alberta, between 52° and 54° N latitude and 113° and 115° W longitude, as shown in Figure 1. The elevation above sea-level increases gradually from north to south, being 670 m at the Edmonton Industrial Airport and 848 m at the Lacombe Research Station. The climate of the area is continental, with warm summers and cold winters. The prevailing winds during the summer are cool and dry with Maritime Pacific air moderating temperatures such that the highest temperature ever recorded in Edmonton is 99 F (37.2 C). The monthly average values for certain meteorological observations at the Edmonton Industrial Airport are set out in Table 1. The climate is semi- arid, with an annual average precipitation of 48 cm. While 65 per cent of the annual precipitation falls during the growing season, a moisture deficit at critical stages of crop development is usually the greatest hazard to crop production. The variability of precipitation during the summer months of May to September is indicated by data presented in Table 2. Mixed farming is general in the area, with early-ripening varieties of barley being an important cereal crop. Forage production is substantial and increasing, as a result of changing farm production patterns. The farm operator must contend with high land values and, due to social and economic pressures, increasing labour costs. To meet the problem of labour costs, there is a continuing trend to mechanization ' ■ * 16 NORTHWEST TERRITORIES Figure 1. Location of experimental sites. 17 TABLE 1. Monthly average values of selected meteorological observations at Edmonton Industrial Airport (Location: 53°35 I N,113°30 , W. Elevation: 670 m above sea-level) Observation May June July Aug. Sept. Precipitation, rum a 46 81 84 66 36 Wind, km per hour 16.9 16.1 14.3 13.7 15.4 Bright sunshine, hours a 267 251 305 268 186 Air temperatures, C Maximum 16 20 24 25 22 Minimum 5 9 12 13 9 Based on a 30-year period ending 1960. k Based on a 30-year period ending 1968. TABLE 2. Total monthly precipitation, mm, May to September inclusive. 1959-1969, at Edmonton Industrial Airport Year May June July Aug. Sept. 1959 19 68 68 98 51 1960 58 73 82 94 61 1961 22 47 95 6 25 1962 52 78 81 57 26 1963 19 55 65 28 33 1964 54 26 75 71 64 1965 72 190 54 54 23 1966 28 23 62 164 9 1967 42 43 51 74 1 1968 3 54 78 85 35 1969 33 25 84 114 80 18 as a substitute for farm labour. The size of farms varies greatly within the area, with 300 to 400 ha considered viable mixed farming units. B. Field techniques Information available from an earlier study into the response of barley to fertilizers is introduced into the analysis in the next section. As this prior study has not been reported elsewhere, field techniques are briefly presented below. Field investigations, 1959 - 1963 The objective of this previous study was to assess the pre¬ dictive value of soil test recommendations for nitrogen and phosphorus requirements of barley grown on stubble. Six of thirty-three sites were deleted from the study due to hail damage, excessive weed growth, etc. Names of co-operators, soil series and legal location of sites are presented in Table 3. Classification of the soils is set out in Table 5. At each site the experimental design was a 5 complete factorial, with six replicates. N (as ammonium nitrate) and P 2 0 5 ( as single superphosphate) were each applied in all combinations of 0, 11.2, 22.4, 44.8 and 89.6 kg/ha. Each site received a blanket application of K (aS potassium chloride) at 37.2 kg/ha prior to seeding. Plot size was 1.07 m (6 rows) by 6.10 m. Cultivation prior to seeding was done by the co-operator. The N and P fertilizers were applied at time of TABLE 3. Site details for field investigations 1959 - 1963 19 X X u CD a) X rH i—1 co CD rd Pi Pi i—i 1-1 £ £ i—i Pi Cfl 0 0 •rl £ a) O O X 0 •H O PH rd rd CD a) 2 2 o X 1 w CO CD O 0 rd 4-> 1—i tn b a a CD *rH i—i 1—1 Ph o o PM i >i >i >i PH rH a u to 0) i X CD CD CD CD Ph CD o rd rd > b to b r t! -P a PH 0 4-i a, *H i—1 rd > > PH i aj •H x b 0 •r-1 sj- 1 1 LO 1 in | in | ■ to 1 r- 1 p' 1 rH 1 rH 1 CN i ro i CO i CO 1 CO 1 to 1 -d* 1 rH 1 1—1 rd CN CN CN CN CN CN CN CN CN o i i 1 1 i 1 1 1 1 1 1 1 1 1 0 o CO CO rH rH rH r- to to to to I"" rH rH 1—t in 1 1 "d 1 1 ID 1 in 1 in tn i in tn m i in ■ in 1 LO i lO 1 1—1 1 rH 1 1—1 1 1—1 1 IT) 1 CN i CN i i"' 1 CO i o 1 r- 1 CO 1 rH 1 LO rd co CO CO rH CO | I—1 CN i—i ro i—1 to i 1 1 1 1 1 l l 1 1 i 1 1 1 CD w W w w IS H IS w IS IS W X to CO CO (/) CO § 2 CO 2 CO § 2 CO § b a) u cn CD b tn CD PH PH 4-1 PH o CD CD *r| W CD 4-> rd X >1 2 b •rH ys rd 2 ■—i 2 CD w CD PH a PH i—1 1 ■H r d X 1 rH X 0 rH Pi X N q 4-» •ro PH w CD •rH 2 0 o O 3 •H > • X CD •rH CD • o 1 2 2 CO X W C X 2 2 > 0 0 u • • • • • • • • • • • • 0 i I a) -p •rH CO ro CO ro CO CO ro to to tO to to LO in ro CO CTi o 1—1 o o o O 1—1 1—1 CN CN CN CN CN CN CN to tO to tO to LO to m r" CO O 0 to P 0 0 to td 0 p O p p s CJ < ft PQ ft P o sr ft 1 •H i i 1 i i 1 4-> LO ft CN 00 00 0 04 CN CN 1 0 •H rd 0 O e ft rd ft .— ft ft to ft ft ft ft ft ft ft to P to to 0 1 to rd to ft to P \ IS) 0 to ft aj QJ ft ft to •H 1—I ft 0 •H 0 to •H •H to i—1 > ■r4 i—1 \ to i—1 ft 1—1 e ft 44 ft i—1 .a rd ft QJ O ft tr td ft co ft •H ft ft P rd (0 QJ rd p i QJ P QJ —• >, 0 44 0 44 0 >1 ft 0 a. 0 0 P Td 0 rH 0 P to QJ 4-1 -p P ft ft ft 44 ft p ft ft ft P (d rd ft td £ ■H rd td •H td ft 1—I ■H rd rd •rl 0 O 4-1 ft CO ft to 0 ft to o in td in ft IS) Eh ft 1 1 1 1 1 1 i 1 i i 1 i 1 | Td 0 0 0 0 0 CN 00 0- in 00 'sT LO 00 UO T? m ft CO ft CO 10 10 CO cO CO CO CO CO CO CO CD 0 0 co co CO CO CO at at CO CO CO to CO o ft ft ft 1—1 1—1 i—i i—i 1—1 1—1 1—I ft ft i—i •H 0 Td 0 P e •H 0 P IS) (0 in 0 0 p i—1 •H 0 P p ft P 0 rd ft w -P P rd • Td p td ft P 0 44 0 P £ CO to •H 0 ft e td 0 < i—1 ft p to ft ft ft P p < rd to o o • ft 0 0 ft 0 0 ft p ft 0 •H ft 4-1 p o td td ft 0 in ft 0 0 0) *- t) p ft 0 0 0 0 ft 0 p •H ft p 0 in w Q 0 0 0 O 0 >i ft P < p 0 0 p Eh Td Eh p •H ft 4-) CO ft £ to (X td 0 0 44 o ft P a rd Td Td *«. 0 m •H 1 CO QJ £ (N ft ft 0 td rH 1—1 ft rH p 0 0 P ft QJ p ft P P 0 0 o QJ ft ft • 0 6 td o Pj • Ph N 0 > ft in 2 0 ft 0 o 0 2 ft Ph •H rH ft o rH O p • • td • • •H D ft > ft 0 ft ft rH p •H 0 0 ft co 0) 0 ft ft ft 00 in 1—1 00 in •H O o o CN CN CN TABLE 5. Classification of soil series, experimental sites 1959 - 1968 23 CD g g g N d> CD cd 0 N N i — 1 1 — 1 1 — 1 ft a 0 O 0 0 0 CO p G G CO co co a) p P •H rH CO ft! cd d) > > CD o X ft! P p i — 1 43 u O ft ft CJ rH o P •rH o O o o o 0 i—1 •H *H •H •H •rH 5 a > > ft) ft) g fd G p 1-1 1—1 G « X ft < c X rH rH rH rH g 0 0 cd i—1 p p ft ft -p i—1 0 0 i—1 rH CO 0 ft) ft) fd fd >i P 0 0 P P g CO 0 >1 IP o o o X! p p ft) ft) •H £ 0 CJ CJ o 0 -p i >1 >1 i—i fd o P o o p p i—i U *rH u •rH •rH u cj 0 ■H P ft ft G 4-) CD a i—1 r—1 o o tT 1 •rH £ •r| td td •H •H cd to ft p P ft ft >i co fd f? 0 ft 0 ft & >i Eh P CJ i—) o i—i •H g 0 g d) co rH g 0 CD ft! rH 0 1 CO cd >i •H O (D >1 ft! ft! fd > CO i—1 CO cj O P G CJ fd CJ ft > g ft! rH G a id O ft ft! >i ft •rH •H fd P fd £ 43 rH 43 fd P >i p fd ft a) Q CJ fd X a -p p cd U fd o o cj a cj •rH •rH •rH •H •rH .a > ft! ft! ft! ft! ■p G ft ft P ft p r—1 P P fd P o w O O Q O 0 g 1 — 1 fd G 1—1 ft! •H •H 0 ft G > ft tr> G •H 0 p i —i 43 P P ft fd •rH K -H P u 1 ft! a) (d p ft p ft G > tr> G 0 •rH 43 fd G •H r—1 CD 0 X <3 is cj ft CJ TABLE 6. Treatment numbers: rates of nitrogen, phosphorus and potassium for field experiments 1964-1968 24 r— 1 r—I i —I i—1 i—I i—1 I + I + I + rH I-I O O O O I + O CN CN CN CN CN I + + I + CN CN CN CN CN CN I + I + I I CD O o ft I—I I—1 I—I I—I I—I I I + + I HHOOOCN CN O O CN CN CN + + I + I + + CN CN CN CN CN CN I I + + I I !3 i—i i—i i—i i—i i—( I I I + + H rH O CN CN O + + I + O O O CN CN CN I i I CN CN CN CN CN CN + + + + I I ^2 CN CD CN CO CN CD i—I CO <—I CO i—I CO CN CD oT oT oT OT rH CO CN CN CN CN N 1 O CO CO O CO CN OT or or O CO O CO O O or or CTi oo CD CN CD CO CD CD CN CN CN CN rH i — 1 i — 1 i — 1 rH rd \ r* CD 4-1 cd n 2 oT CN OT CN or CN or CN CO 00 CO CO CO CD CD CD CD CD CO O CO O CO O CO O CD CD CD CD CD O co co O CO O co O co O O 1- \ oT 1-1 or i—1 or rH or CN CN CN CN CN CD in in uo in or oT CN CN or or CN CN CO 00 00 CD CO CO CD CD CD CD • • • • • • • CO CO O O co CO O O CD CD CD o CO CD CD O co CO o O CO CO o o I—1 1—1 ST or •—1 f—1 oT or CN CN CN UO CN CN uo uo uo UO CD CD CD CD CO CO CO CO CN or CN CN CN CN oT or or or ro ro ro ro o o o o o or r- r- r- o o o or or or or o o ro ro ro co o o o o CD CO CD CD CD CD CO CO CO CO 1—1 1—1 1—1 r — 1 rH i —t 1—1 rH rH ■P a u cu cd li cd P cu P H Cl CO N 1 in CO C" CO O' O H CN i—1 i—I i—I co or in cd t-' co i—I rH i—I rH rH i—I O' O H (N n cf H CN CN CN CN CN v 25 Plot size . Plot size was decided by the type of seeding equipment. In the Edmonton district plots were 244 x 610 cm, to accommodate two passes of the Allis-Chalmers drill described by Bentley (1956). This 6-row drill gave 17.8 cm spacing between rows. Plot size in the Lacombe district was 183 x 610 cm to accommodate two passes of the "Ridemaster" seeding equipment. This 4-row drill gave 23 cm spacing between rows. Seed and fertilizer . Gateway barley was the test crop, treated and sown at a rate of 91 kg/ha. N(as ammonium nitrate) and K (as potassium chloride) fertilizers were broadcast at time of seeding, whereas P (as treble superphosphate) fertilizer was drilled in with the seed. Each plot retained its treatment identity throughout the study. For example, plot number 6, site 01 annually received treatment number 5 (see Table 6). Sites were sprayed for weed control prior to heading. Harvesting . Plots were harvested at maturity, usually requiring two or more harvest dates for a site due to treatment effect. Barley straw was returned to the plot, the amount determined by weight of straw harvested from the plot sample area. Soil sampling. Soil sample cores were taken on a plot basis prior to seeding and after harvesting. Plot samples were divided into four sub-samples by depths: Code Depth, cm Depth, in. A 0.0 - 15.2 0 - 6 B 15.2 -30.5 6 - 12 C 30.5 - 61.0 12 - 24 D 61.0 - 91.4 24 - 36 - . . 26 At sites in the Edmonton district plot samples were composites of four cores; in the Lacombe district a single core was taken as the plot sample. Two sets of plot samples were required prior to seeding, one set was used for moisture determination and the other set was prepared for soil testing. In the Edmonton district soil cores were split vertically to obtain sample pairs; in the Lacombe district a second soil core was taken as the duplicate plot sample. Plot samples taken after harvest were used only for soil moisture determination. Prior to soil sampling, "fill" soil was prepared to replace the soil core removed. Dates of operations . Dates of certain field operations are set out in Table 7. Meteorological observations . A meteorological station was established at each location with daily observations made by the co- operator at 0800 hours during the growing season. Observations included precipitation, maximum and minimum air temperatures (in screen), latent evaporation (Voltz porous-disc atmometer) and soil temperature at 10 cm, under sod. During the 1967 growing season two additional instruments were installed at each site: anemometer^, 3-cup, dial type (at a height of 2 m) and hygrothermograph^, weekly chart (in screen). The atmometer, described by Carder (1960), proved unreliable as the 2 Product of Voltz Manufacturing Co., 126 Northwestern Ave., Ottawa 3. O Product of Casella, London, England. 4 Model No. 255, Science Associates Inc., Princeton, N.J., U.S.A. • * ' 27 TABLE 7. Dates of certain field operations Site- Spring Fall year sampling Seeding Harvest sampling 0164 June ! 2 June 3 Sept. 4, 8 Sept. 17 , 18 2164 May 28, 29 June 3 Sept. 4, 11 Oct. 5 0165 May 10, 11 May 12 Aug. 16 Aug. 25 0365 May 12, 13 May 14 Aug. 13, 14 Aug. 17, 20 0565 May 18, 20 May 21 Aug. 17 Aug. 2 3 2165 June : 4 June 5 Sept. 7 Sept. 13 2365 May 19, 20 June 7 Sept. 8 Sept. 24 2565 May 21, 28 June 5 Sept. 8 Sept. 24 , 28 0166 May 18 May 19 Aug. 22 Aug. 2 3 0366 May 25, 26 May 26 Aug. 26 Sept. 6 0566 May 16, 17 May 17 Aug. 11, 12 Aug. 18, 19 2166 May 3 May 10 Aug. 12, 19 Aug. 2 3 2366 May 4 May 11 Aug. 12, 18 Aug. 24 2566 May 5 May 11 Aug. 12, 19 Aug. 24 0167 May 24 May 29 Aug. 21, 25 Aug. 2 5 0367 May 23 May 24 Aug. 28 Aug. 31 0567 May 17, 18 May 18 Aug. 15, 21 Aug. 2 2 2167 May 10 May 17 Aug. 15, 18 Aug. 18 2367 May 19 May 20 Aug. 11, 18, 29 Aug. 29 2567 May 15 May 18 Aug. 14 Aug. 2 3 0168 May 21 May 22 Aug. 29,Sept.9,12 Aug. 30, Sept.10,12 0368 May 23, 24 May 24 Oct. 8, 9 Oct. 11 0568 May 29 May 30 Sept. 9, 27 Sept. 28 2168 May 14 May 18 Oct. 21 Oct. 30 2368 May 15 May 18 Aug. 30,Sept. 24 Sept. 27 2568 May 16 May 18 Aug. 30,Sept. 24 Sept. 27 ‘ ' 28 following contributed to under- and over-estimates of evaporation: (a) sensitivity of the instrument to wind gusts, (b) improper re-assembly of the apparatus (usually a daily task) and (c) plugging of disc pores. A pair of seamless-steel access tubes for a neutron moisture meter were installed within the meteorological enclosure at each location. Inspection of sites . For the first three years of the study a technician from the Department of Soil Science, University of Alberta, visited sites at intervals of two weeks. In 1967 weekly visits commenced and were made by a senior student selected from within the Faculty of Agriculture. While costly in time and transportation, the weekly visit improved several aspects of the field investigation. The designated tasks at the time of the site visit included: (a) To record general observations on both barley and forage plots of weed growth, damage due to rodents, birds, hail, etc. and incidence of disease within the crops. (b) To record observations on stages of barley development. A code system was used, similar to the modified Feekes scale for indicating the stage of development of wheat as described by Peterson (1965). (c) To check and service meteorological instruments. (d) To take readings with the neutron moisture meter. Control over rodent damage, often a serious problem, was much improved by remedial action taken at the time of the weekly visits. ■r * 29 C. Laboratory procedures Introduction All sample preparation and much of the physical analyses of soils were shared between the laboratories at Edmonton and Lacombe. Chemical analyses of soil samples were done by the Alberta Soil and Feed Testing Laboratory (ASFTL) in Edmonton. Sample preparation Soil samples were received in the laboratory at Edmonton in tied polythene bags and at Lacombe in capped aluminum cylinders. Samples collected for moisture determination were dried to constant weight at a temperature of 105 C in a mechanical-convection oven. Samples collected for chemical analyses were dried at a temperature of 60 C, then milled to pass a 2 mm sieve opening. Barley harvested from plots, contained in cotton sacks, was air-dried in a well-ventilated loft. After drying, each sample was weighed then threshed. The threshed grain was weighed and weight of straw estimated by difference. A representative portion of the grain was cleaned of chaff, weeds and broken kernels. Chemical analysis of soils Soil reaction (pH) was determined on a saturated paste after a retention time of 30 minutes, according to a procedure described by Doughty (1941), using a glass electrode pH meter. I I , 30 Electrical conductivity (mmhos/cra) was determined on an extract from the saturation paste of the soil reaction determination. The extract was obtained after a retention time of 30 minutes and the conductivity of the filtrate measured using a Solu-bridge conductivity meter. Nitrate-nitrogen (pounds N/acre six inches) content of soil samples was determined by a method adapted from the procedures of Harper (1924) and Prince (1945). A measured volume of soil (about 5 g) and 25 ml of extracting solution (0.02N copper sulphate and 0.007N silver nitrate) were shaken in a flask for 10 minutes. Calcium hydrox¬ ide (0.2 g) was added to the flask and shaking resumed for 10 minutes. Magnesium carbonate (0.5 g) was added to the flask and shaking resumed for 2 minutes. A 10 ml portion of a filtrate (Whatman No. 30 filter paper) was taken to dryness over low heat, then cooled. The residue was dissolved in 2 ml of phenoldisulphonic acid and allowed to stand for 10 minutes before dilution with water and 20 ml of 7.5N ammonium hydroxide solution to a volume of 50 ml. The colour intensity was read on a spectrophotometer at a wavelength of 415 y, using a flow-through cuvette. Available phosphorus (pounds P/acre six inches) was extracted by the Miller and Axley (0.03 M ammonium fluoride and 0.015 M sulphuric acid) method described by Robertson (1962). The P in the extractant was determined by measuring the vanadomolybdophosphoric yellow colour by spectrophotometry. Exchangeable potassium (pounds K/acre six inches) was extracted - • , 31 by l.ON ammonium acetate. Soil (5 g) and extracting solution (25 ml) were shaken for 5 minutes. Potassium in the filtrate was determined by flame photometry. Physical analysis of soils Mechanical analysis of soil samples followed the pipette procedure described by Toogood and Peters (1953) , except that carbonates were removed by the addition of hydrochloric acid. Soil bulk density was determined by weight/volume measurements on samples obtained by a core-sampler. On two soils, a Chernozemic and a Luvisolic, this method was compared to the time-consuming method of collecting large cores (6 x 12 cm) from an exposed soil profile. Varia¬ tion in bulk density was greater between sampling points in a field than between methods. Provided a correction is applied for any observed compaction, several samples collected by a core-sampler gave a reasonable estimate of average bulk density for the area sampled. Field capacity moisture content per cent was estimated by a method using a pressure-plate apparatus at one-third atmosphere pressure, as described in U.S.D.A. Handbook 60 (1954). Moisture content was expressed on an oven dry-weight basis. Permanent wilting point (lower limit of soil moisture available to the plant) moisture content per cent was estimated by a method using a pressure-membrane apparatus (cellulose casing membrane) at 15 atmos¬ pheres pressure as described in U.S.D.A. Handbook 60 (1954). Moisture content was expressed on an oven dry-weight basis. - - Ill .< V I I 32 RESULTS AND DISCUSSION Before proceeding with the analysis of barley yield data, a brief description is presented of soil chemical and physical char¬ acteristics of the six sites. Site average soil test data of samples collected prior to the first application of fertilizers to plots are presented in Table 8. Results of mechanical analysis of these soils are listed in Table 9 and apparent densities, moisture-holding character¬ istics and moisture status at time of seeding are presented in Table 20. Certain features will be noted: (a) Soil test values indicate marked differences between sites in soil nutrient status at the start of the study. (b) Soils are medium-textured, classes include loams, clay loams and sandy loams. Site 21, a Ponoka Sandy Loam with low clay content in the upper 60 cm, has the lowest available moisture capacity. (c) Total carbon (which is mostly organic carbon) is much higher in Chernozemic than in Luvisolic soils. A. Barley response to applied nutrients In this section the relationship between barley yield and applied fertilizers is considered from the point of view of expressing yield as a function of the various nutrients applied, that is Y = f(N A , P A , K A ) , (4) where Y represents barley yield and the variables N A , P A , K A are the m ' • ■ 33 TABLE 8. Soil test data: averages of initial site samples 9 Depth Site cm Cond. Total mmhos/ Carbon^ pH cm % Available soil nutrients kg/ha n p Chernozemic soils 01 0-15 5.9 0.4 6.0 34 8 265 15-30 5.8 0.5 3.5 43 2 304 05 0-15 6.5 0.5 4.5 13 24 338 15-30 6.5 0.4 0.9 6 8 347 21 0-15 6.0 0.4 5.2 21 45 15-30 t 6.2 0.4 3.9 47 10 Luvisolic soils 03 0-15 5.5 0.3 1.3 4 7 295 15-30 4.5 0.3 0.6 2 2 416 23 0-15 6.4 0.3 1.2 3 59 334 15-30 6.0 0.3 0.4 2 18 382 25 0-15 6.5 0.5 1.6 17 112 760 15-30 6.3 0.4 0.4 6 26 344 a Initial samples are samples collected prior to the first application of f ertilizer treatments Except for carbon, there are 48 observations in each average. b Total carbon (mainly organic carbon) using Leco Induction Furnace. For this analysis only, composites of samples collected in 1968 were analyzed. \ V ■ - 34 TABLE 9. Mechanical analysis of soils per cent Depth - Site cm Sand Silt Clay Textural class 01 0-15 24 46 30 Clay Loam 15-30 24 46 30 Clay Loam 30-61 24 38 38 Clay Loam 61-91 24 37 39 Clay Loam 03 0-15 38 44 18 Loam 15-30 32 32 36 Clay Loam 30-61 32 28 40 Clay, Clay Loam 61-91 35 30 35 Clay Loam 05 0-15 38 36 26 Loam 15-30 36 34 30 Clay Loam 30-61 36 33 31 Clay Loam 61-91 36 36 28 Loam, Clay Loam 21 0-15 57 25 18 Sandy Loam 15-30 53 27 20 Sandy Loam, Sandy Clay Loam 30-61 50 28 22 Loam 61-91 12 48 40 Silty Clay, Silty Clay Loam 23 0-15 44 44 12 Loam, Sandy Loam 15-30 44 30 26 Loam 30-61 46 30 24 Loam 61-91 46 30 24 Loam 25 0-15 44 47 9 Sandy Loam 15-30 44 35 21 Loam 30-61 38 34 28 Loam, Clay Loam 61-91 38 34 28 Loam, Clay Loam 35 rates of applied nitrogen, phosphorus and potassium fertilizer, respectively. The following second order regression model was considered: Y a 0 + a l N A + a 2 P A + a 3 K A + a ll N A 2 + a 22 P A 2 + a 33 K A 2 + a l2 N A ,P A + a 13 N A ,K A + a 23 p A K A + err c> r term (e) (5) where the a^j (i,j = 1,2,3) are coefficients of the variables in the regression equation. The analysis of variance for each site-year on Chernozemic soils is set out in Table 10 and for each site-year on Luvisolic soils is set out in Table 11. The analyses indicate: (a) The N and P treatments produced significant effects on barley yields, whereas the effect of K was not significant. This evidence supported the general fertilizer recommendation for cereal crops on soils of central Alberta. (b) The lack of significant effects of applied nutrients at site 21. This result reflected the high soil nutrient status of the site. (c) Deviations from quadratic regression were generally significant. The influence of soil nutrients on treatment effects probably contributed to this lack of fit. In view of the analyses of variance, it was of interest to examine a reduced form of equation 5, eliminating K as a factor in the regression model: = b 0 + b l N A + b 2 P A + b ll N A‘ + ) 22 t A + b 12 N A* P A ( 6 ) Regression coefficients (b^ .) and the square of the correlation coefficient ' 36 03 C /) O oo u CD M O c s- CD CD CD S- -C 4 -> C o S- 03 CD >> l/) O s- o l/i "O CD >0 >> CD S~ 03 Pj CD U c 03 •r— 03 > U) 0) p rd p O' u) c 03 CD £ * * r- rH rH O o o r-* LD CP r" o *D CN ID o ID C0 O ID 00 CN O rH O o CO o o r- r- CO rH ■K * LD vD CN O rH t—1 o •— i CN 00 LD ID lD CO o CO CO LD o H* o rH • • CN CP LO rH O CO 00 CO o CN 0- r-* CN rH CN rH CO CN CN * LD LD LD CN (P LD 1—1 rH CP lD 1—1 LD CP o CO O CP CO CP CP i —1 • CN LO O o LD CP O CN LD o 00 CN CN t — 1 ID LD r- 1 — 1 O LD rH CP LD r- r- CP CO o CP CP i—1 • • CN lD o O o rH o o CP LD rH rH * * * ■K * * CO LD r- CO LD rH LD LD LD LD •—i r- LD LD LD CO O O LD • • o rH rH LD CN O rH CO CO LD rH CO CO TJ * * * * * LD LD CO CO rH r* O P CO LD *^r LD O'* o CO LD o LD LD • • O o rH LD LD O o O LD LD ID rH LD rH CN * * * ■K * * * LD LD CO CO co LD CO P 00 p LD LD O CN CP CN r- CP CN LD CO ID • O LD CN rH O co O LD LD O LD LD LD rH rH rH * * * -K ■K * -K * r- LD p- CO CO rH rH P rH CN LD LD LD CN vr O'* CO LD rH • • o r- o CN LD LD CO o rH P CN CN ID r- CN * * * * ID LD O CO CO CP CN LD co LD LD CN r- LD CN LD i—1 CN ID CO CN rH • o CN CO O CN O'* o O rH CO LD CN rH LD CN ■K * -K * * * * * CN CP O CO CN CN lD CN O LD o 00 rH O CO P LD • rH CN o 00 o rH CN rH CO co O LD o CN t—1 rH rH rH rH rH rH LH CO CO CO CO 1/3 CD i/> >> CN CN cn in cn rH ID c o o o * * * CD u rd (D u c rd o •H p •H c p •H cn 03 c «=£ CO c cn c 0 cn P C U •H G 0 0 cn cn •H P 0 •H 0) P P O •H U rH 0 04 QJ P Or H Q u P CD U p 0 Eh w Eh P o cn rH (D > CD p «d TABLE 11. Analyses of variance of barley yields for 7 site-years on three Luvisolic soils 3 - 37 - * •k •k ■k * ■K * p- ro VO ro CN i— 1 rH CT> uo ro VO o CN o i— 1 O '1 no ro CN CN LO • • CN cr» rH o VO rH o in CN VO O CO rH CN rH * * * * * * VO in CO CO CN ro CO in CO rH o VO CO O o O O CO o o 00 ro in • • CN CN VO o O CT\ VO o o CO VO CT> CO ■K -k * * * •k * in p- in in O p- CN VO rH in vo ro ro o o CT> CO O i— 1 VO CO m • « CN o\ CN o o co CN O rH O rH in o VO CN i— 1 CO ro rH Cfi CD P i—l VO VO VO P- vO co rH CN vO vo CO o ro • • CN CO p- CN O VO rH ro LO o p- VO p- ro CN vp ro O l n LO vo ro O CD O •k ■k -k -k •k -k CO O ro CO CN UO vO cn CO CN CN LO rH VO 1 — 1 CTi CO O ro i — 1 CN CN o O UO CN ro rH •k •k ■k ■k •k •k ■k -k •k * CO ro O P- vO 1 — 1 p- CN CN CN O O CN in o (T\ p^ o\ CN OA O ro UO o O rH ro P- P- or ro UO o o o 4-1 TJ CN CN m g CN CN in 0 w 4 H a U •H G cn 0 0 w W •H •P 0 i — i •rH CD ■P -P O •H CD CD -p -P G P fd fd -P > U fd fd CD fd P p Pi fd CD p •H u i (D 2 ^ T) CD 2 2 •H PI G P •H •P G fd -P > Pi rH 0 cd rH cd •H 3 G C 4 CD PI Oi H p Pi 4-1 CD P Pi 0 Eh W Eh ■k * -K CD p Id CD O c fd u •rH 4-1 •H G Cr> •H U) 4-1 O .05 38 (R ) of this equation for each of the 17 site-years are presented in Appendix C. Regression analysis, using equation (6), was also carried out for grouped site-years. The regression coefficients (b — ) and R 2 values are presented in Table 12 for three regression equations which include in regression (a) all 17 site-years (b) 10 site-years on Chernozemic soils and (c) 7 site-years on Luvisolic soils. Comparing each b^j in equation (a) with its counterparts in (b) and (c), only slight differences are found, indicating that the three equations describe similar response surfaces. However, for Luvisolic soils the response surface is poorly defined, as indicated by large standard errors of the regression coefficients for linear and quadratic P. Regression coefficients of site-year equations (Appendix C) vary both in sign and magnitude. Differences in site-year regression come from several sources which include: (a) differences in soil nutrient status over the sites, (b) residual differences (treatment effects) over the years and (c) interrelationships of weather variables with mineral nutrients. B. Effect of soil nutrient levels on barley response to applied nutrients The experimental data were examined by considering a re¬ gression equation of the form: 1 TABLE 12. Three regression equations for yield of barley as a function of applied N and P, showing regression coefficients, standard errors of estimate of regression coefficients and r 2 values 39 CO m m vO vo O O' CM in CO XX in o rH o CO CO CO o o o G CO o o o o o 0 H • • • • • *H o o o o o in o P to nj d) O CO >1 -H CM 1 iH (U 0 * * • o -P cn * * •H -H CO CO in r< CN CO CO > VO VO in 'cr VO 2 1—1 co CO o CO o r- PI •H I—1 VO r- o o o XX CO i—1 i—i o o o « . • • • • co o o o o o i—1 CO CM VO 1 CM o O' rH O CM XX CO O' O i—1 o G CO CO CN in O o o 0 «H O o O o o • • • • • years ic so o o o o o .205 i E r- VO CM P •'d’ CO i—1 o CM o o cu •H CM 00 o O o i o o o o o 1 CD -P ■H .227 CO * * * * o r~ * * * * * i— i o o o r-~ in rH CO «d< CM CO ■'d* *—i 1—1 CO o o CM o i— i •H CO 'd* CO o o o < XX 1—1 i—1 H Significance levels: ** O.Ol * 0.05 40 Y = c O + c x N a + c 2 P A + c 3 N s + c 4 P s + Cll N A 2 + c 22 P a 2 + C 33 N S 2 + C 44 P S + C 12 N A ,P A + C 13 N A* N S + C 14 N A‘ P S + c 23 P A* N S + C 24 P A* P S + c 34 N S‘ P S + e ( 7 ) where the additional variables N s and P s represent soil test values for nitrate-nitrogen and available phosphorus, respectively. At this point a decision was needed regarding depth of sampling for soil nutrients. Usually the established soil testing procedures would apply, but the 6-inch (15.2 cm) sampling depth has been questioned by several workers, particularly in assessing N s status of soils of the province. Faced with a possible change in depth of sampling, the problem was to anticipate the nature of the revised procedure. Using equation (7) four depths of sampling for Ng (0-6", 0-12", 0-24" and 0-36") and two depths of sampling for Pg (0-6" and 0-12") were compared. Regression statistics were generated for (a) individual site-years and (b) various groupings of site-years: by sites, by years, etc. The regression coefficients were tested for parallelism by a method described by Williams (1959). The predictive value of various sampling depths were compared by examining the squared correlation coefficients. These comparisons indicated: (a) The available phosphorus status of the soil could be adequately described by sampling to a depth of six inches. (b) The nitrate-nitrogen status of the soil is inadequately described by sampling to a depth of six inches. * . ' J 41 (c) The regressions were not significantly different for N s at the 12-, 24- and 36-inch depths. Anticipating an eventual change in sampling procedure for the province of Alberta, hereafter in this study the value of N s shall represent nitrate-nitrogen of the soil to a depth of 24 inches (61 cm) and P s shall represent available phosphorus to a depth of 6 inches (15.2 cm). While a 12-inch sampling depth appears adequate from the evidence examined, it is probable that the 24-inch sampling depth for Ng used in Manitoba and Saskatchewan is more appropriate for assessing the nitrate-nitrogen status of summerfallowed fields. Regression coefficients (cj_j , i,j = 1,2,3,4) and squared correlation coefficient (r 2) of equation (7) for each of 17 site-years are tabulated in Appendix D. The regression coefficients (b^) and r2 values are presented in Table 13 for three regression equations which include in regression (a) all 17 site-years (b) 10 site-years in Chernozemic soils and (c) 7 site-years on Luvisolic soils. Comparing the two regression equations having 17 site-years in the regression (Table 12, equation (a) with 5 variables and Table 13, equation (a) with 14 variables) certain features emerge: (a) Adding soil variables to the regression increased R from 0.227 to 0.386. (Elimination of some non-significant variables will be dealt with later.) (b) Setting soil test values equal to zero, both equations now describe barley yield as a function of the same five variables (applied ' . ' . , 42 TABLE 13. Three regression equations for yield of barley as a function of applied and soil N and applied and soil P, showing regression coefficients, standard errors of estimate of regression coefficients and R2 values Variable All 17 site -years 10 site-years on Chernozemic soils 7 site-years on Luvisolic soils b i s b b i s b b i s b Intercept 11.01667 10.62956 12.42906 n a 0.14415** 0.01916 0.13425** 0.02147 0.2008** 0.02970 P A 0.18279** 0.04731 0.14106** 0.05345 0.12089 0.07327 N S 0.06035** 0.01253 0.04754** 0.01337 -0.18174** 0.05132 Ps 0.05369** 0.01666 0.22297** 0.03133 0.04869* 0.02054 N A 2 -0.00073** 0.00013 -0.00066** 0.00015 -0.00086** 0.00020 P A 2 -0.00212** 0.00082 -0.00207* 0.00092 -0.00126 0.00123 N s 2 -0.00011* 0.00005 -0.00018** 0.00006 0.00167** 0.00045 Ps 2 -0.00014 0.00008 -0.00129** 0.00020 -0.00033** 0.00010 ^A* P A 0.00019 0.00020 0.00013 0.00024 0.00045 0.00031 n a -Ns -0.00041** 0.00008 -0.00017* 0.00008 -0.00152** 0.00039 n a- p s 0.00038** • 0.00010 -0.00011 0.00019 0.00043** 0.00013 V N s -0.00018 0.00019 0.00013 0.00021 -0.00125 0.00084 Pa-Ps -0.00083** 0.00025 -0.00055 0.00049 -0.00063 0.00033 N s - p S 0.00034** 0.00012 0.00024 0.00016 0.00220** 0.00037 R 2 0. 386 0.399 0 .594 Significance levels: ** 0. 01 * 0.05 - 1 . . 43 nutrients only). The surfaces described are very similar but on different planes with respect to the Y-axis. (c) Surface similarities decrease as Ng or Pg increase. Regression coefficients of N^.Ng and P A .Pg are negative and highly signifi¬ cant, augmenting negative curvature exerted by N^2 and P^2. The nitrogen and phosphorus treatments influenced the soil nutrient status in subsequent years. A summary over years of the residual effect of treatments on Ng and Pg is presented in Table 14. In addition to the effect of treatments on magnitude and range of Ng and Pg values the following points can be noted from the table: (a) A sufficiency of one nutrient suppresses the "build-up" of the other nutrient in the soil because plant growth is not restricted. (b) A deficiency of one nutrient can result in the "build-up" of the other nutrient at higher treatment levels. (c) The Ng status of all plots at site 03 increased sharply after the first season of cropping. This site had been in pasture for many years and apparently the potential was high for mineralization of organic forms of nitrogen. It is seen that less than 40 per cent of the variability in barley yield between 816 plots in the study can be explained as effects of fertilizer treatments or soil nutrient status. It is evident that equation (7) does not consider other variables known to influence yield, such as certain physical properties of the soil environment and com¬ ponents of weather influencing the atmospheric environment. The variation due to these other factors is lumped into the error (residual) variation in the regression analysis. « 44 TABLE 14. Residual nutrient status of plots under continuous barley production to show the effect of fertilizer treatment 3 Soil test values (kg/ha) averaged over plots Nitrate-nitrogen (N s ) depth of 61 cm to Available phosphorus (P g ) to depth of 15 cm Nitrogen treatment, kg/ha Phosphorus treatment. kg/ha Site-year 0 34 67 101 134 0 13 27 40 54 Chernozemic soils 01 1964 102 118 108 108 111 8 9 9 8 7 1965 57 90 96 144 157 20 21 27 27 34 1966 34 36 47 60 86 10 16 19 24 29 1967 20 18 34 52 94 9 13 20 25 32 1968 16 17 21 27 78 10 13 15 34 38 05 1965 27 27 22 24 26 24 22 22 26 25 1966 20 19 24 24 28 16 18 20 25 36 ‘ 1967 31 36 36 44 58 20 25 28 47 49 1968 7 10 15 13 46 13 22 20 24 34 21 1964 195 156 183 177 197 46 46 43 45 52 1965 109 144 127 153 168 49 53 53 67 66 1966 74 81 100 116 159 41 53 82 78 99 1967 50 69 63 73 153 52 57 93 97 125 1968 46 59 108 150 227 31 49 83 96 139 Luvisolic soils 03 1965 10 9 12 10 15 6 9 6 7 7 1966 43 44 41 45 55 17 17 20 27 30 1967 43 46 58 67 101 12 13 19 38 29 1968 31 45 63 81 119 9 11 20 25 31 23 1965 9 10 9 10 10 62 59 63 58 58 1966 29 32 31 34 40 53 54 81 63 68 1967 31 31 34 34 45 62 75 103 96 110 1968 22 30 44 73 113 47 71 97 119 172 25 1965 24 29 28 37 24 111 114 120 116 100 1966 17 18 22 31 34 96 103 106 106 109 1967 31 37 31 49 53 102 109 141 143 164 1968 34 40 63 105 146 91 123 156 172 186 a Number of plots in , averaged values are : 12, 8, o 1—1 8 and 10 i, in order of increasing treatment level. Interaction ef fects , if present, are con- founded by this one-way summary. k . .. * 45 At this time prior knowledge directs attention to the role of soil moisture conditions in the growth and development of cereal crops. The need arises for some measure or index of the soil moisture regime, such that a soil moisture variable of some predictive value can be introduced into the yield equation. C. Effects of moisture stress on yield of barley The analysis presented here is based on data obtained in a prior study (1959 - 1963) that measured the response of Gateway barley to applied fertilizers. Field techniques and site locations of this prior study were described earlier in the text. Aspects of the method¬ ology used in the analysis of the relationships between soil moisture- stress and yield of barley are outlined briefly: (a) Moisture-holding properties were determined on soil samples collected from the 27 experimental sites. (b) A site daily soil moisture budget was computed using a technique described by Baier and Robertson (1966) for which potential evaporation was estimated by a modified Penman equation. (c) Stages of barley development were divided into seven intervals: (1) planting - emergence (2) onset of tillering (3) jointing (4) heading (5) milk (6) soft-dough and (7) hard-dough stage. (d) The drought-day criterion described by Van Bavel (1953) was used to identify moisture-stress days. Severity of drought within an interval was described as: drought-days/total-days in interval. (e) The effect of moisture-stress on yield was studied by using a J 46 linear model with yield regressed on seven (interval) drought ratios. Site yield was described by using at least 10 per cent of the 150 plots, those for which nutrients were not limit¬ ing. Soil moisture budget The soil moisture budget equation advanced by Baier and Robertson (1966) and a modification described by Baier (1969) were studied. The budgeting technique makes use of the concept of potential evaporation (PE) as an indicator of the possible maximum loss of water from the soil. It is convenient to present the equation used in the original model for estimating daily actual evapotranspiration (AE): AE i n Z j=l PE. e -“ (PE i - PE) ( 8 ) where AE actual evapotranspiration for day i ending at the morning observation of day i + 1. n E = summation carried out from zone j = 1 to zone j = n. j=l k. D coefficient accounting for soil and plant characteris¬ tics in the jth zone. S j (i 1 ) available moisture in the jth zone at the end of day i - 1, that is, at the morning observation of day i. S. 1 capacity for available water in the jth zone. Z. J adjustment factor for different types of soil dryness curves. PE. l potential evapotranspiration for day i. . ■ Q 1 *;> •»' • ■ ’ 47 to = adjustment factor accounting for effects of varying PE rates on AE/PE ratio. PE = average PE for month or season. A feature of the model is that the total available water in the soil is divided into several zones of varying capacities. Simulation of actual moisture loss from the soil, by evaporation and by transpiration, is obtained by progressive withdrawal of moisture from different depths in relation to the rate of PE and the available moisture in each zone and root development. The growing period is divided into intervals (growth stages). Within each interval k-coefficients are assigned in accord with an assumed water extraction pattern of the crop (Table 21). For this study a rooting depth for barley was assumed, defined by that depth of soil with a capacity of 4.00 inches (10 cm) available soil moisture. By this assumption rooting depth varied from 62 cm at site 03 (a Cooking Lake Loam) to 89 cm at site 21 (a Ponoka Sandy Loam). From curves depicted by Baier and Robertson (1966, p. 304) a type "E" drying-curve was chosen to describe the potential gradient developed during drying of the medium-textured soils used in this investigation. The budgeting equation requires input of daily PE and a slightly modified Penman equation was used to estimate this site variable. Several problems were encountered in using the Penman equation, such as printing errors in the Smithsonian Meteorological Tables, List (1949) of two ancillary equations, one of which has been corrected by List (1968). While detailed notes are presented in Appendix F on the variables enter¬ ing the Penman equation, certain variables to be discussed in this section are defined: r is the albedo or reflection coefficient, that portion of incident solar radiation that is reflected from the surface. 48 is the saturation vapour pressure (nun Hg) of the atmosphere, is the actual (observed) vapour pressure of the atmosphere, e^-e^ is the vapour pressure deficit of the atmosphere, u is the wind (miles per day) observed at a height of 200 cm. Budget input data for experimental sites 1959 - 1963 It was decided to estimate the relationship between moisture stress and yield of barley from observations external to the 1964 - 1968 study. Data obtained from field experiments 1959 - 1963 were selected for this purpose. This source was selected because: (a) Field moisture conditions had been determined prior to seeding. (b) Samples could be collected from the sites for determination of moisture-holding characteristics for these soils. (c) Field notes were sufficient to define stages of crop growth. (d) Variation in yield of barley due to nutrient effects could be eliminated by using only data from high-yielding treatments. (e) Site daily PE could be estimated from meteorological observations at Edmonton Industrial Airport. (f) Site rainfall had been recorded, though only at the irregular intervals of site visits. Site soil moisture contents at 1/3 and 15 atm pressure were determined and the difference in moisture contents at the two pressures is taken as the available moisture capacity. Site data are set out in Appendix E, showing moisture characteristics, soil densities and avail¬ able moisture contents. ' 49 Input data (excluding daily rainfall and PE) for the soil moisture budget equation for the 27 experimental sites are recorded in Table 15. The problem that rainfall observations of sites were periodic rather than daily was not too serious, because days of rainfall are usually regional in pattern. Site rainfall data were distributed over days after rainfall records of adjacent stations reporting daily rain¬ fall had been examined. A summary of site rainfall is presented in Table 16. Daily potential evaporation (PE) for the soil moisture budget equation was calculated by the Penman equation, using meteorological observations at Edmonton Industrial Airport. Differences in site albedos (see Appendix F) were considered in calculating PE: estimated initial albedos are listed in Table 15 and an albedo of 0.18 was assumed appropriate for a complete barley cover. From the meagre data available, estimates of PE for central Alberta as determined by four methods are compared in Table 17. The need for consistency of method in estimating PE is indicated by the marked differences between the results obtained by the four methods. Budget input data for experimental sites 1964 - 1968 The planned collection of site data was sufficient to meet the needs of the budget equation. Failure of the porous-disc atmometer to supply a reliable estimate of site PE posed a difficult problem, because in some cases elements of the site environment influenced un¬ measured meteorological variables used in computing a Penman estimate ' TABLE 15. Site data entered in the equation for estimating a daily soil moisture budget for 27 site-years 1959 - 1963 - 50 - o rH CO o o O O CM O O in m uo o UO o o o o o r- o uo O o o UO CN o CN vD o o O rH CM UO co CM CO vD uo o uo o VD rH CN rH CN CO rH o o rH 1—1 rH O O o O O o O o o o rH o rH o O o o O o o O O c •H rtf CD rH rH z XI rtf O rtf NT CO o o o r- UO r- UO CM o rH o O r- o o o o uo CO CO CN vD P CO rH CN rH CO co ro r-H (N CN 1—1 rH CM CN co CN co CO CM co co CN CO CN rH rH rH rH CN o H o rtf o O o o O o O o o o O o o O o o O o o o o O o o O O O > < o vD co o o O rH 00 o CO in 00 o o o co o o CO o co O CM CN CO r- CN rH rH CM CM CN rH rH r-H rH o rH rH CN rH CM CN rH CM CM rH CN rH rH rH rH o rH O O o o O O O o o o o O o O o o O o o o o O O o o O o o rH 0) nd 4n ■H CO cn VD UO co CM CM o co CM CO VD co co UO CO r* UO UO UO UO VD co vD uo 0 s in in m uo UO VD vD vD vD VD in LO uo uo UO UO uo in uo UO uo in UO uo UO uo uo •p Q) 9 01 c X in ID CM vO O ao r- o 00 uo CO UO UO CN rH UO CN CN CN CM CO U0 CO CN 0 uo sr KT vr p tp a •H a m vD rH in CO co uo CO r- CN CN rH rH rH CM co rH CM CN co rH <1> ro co ro ro CO ro co ro co CO co ro CO CO ro CO CO co CO CO CO co CO CO CO ro CO w e o w CO rH o CM rH CN i—i rH O rH CN O CO rH CO CT> rH rH o rH CN rH CN o W 1—1 rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rtf a >. >1 >1 >< >. > >< >i >. >. c c >. C c >1 >. >, >i > >. >1 >1 c a) rtf rtf rtf rtf rtf rtf rtf rtf rtf rtf rtf rtf rtf rtf p 3 rtf P p rtf rtf rtf rtf rtf rtf rtf rtf w 2 r. 2 £ 2 2 2 s 2 2 2 2 2 2 ►o >0) 2 n 2 2 2 2 2 2 2 2 0 Ttf CN CN CO CM CM CM UO CN CO CO CO rH CO UO UO CO rH CO uo CO CO CO r-H rH CO UO CO •H 0) rH rH rH rH rH rH rH rH rH rH rH CN rH rH rH rH CN rH rH rH rH rH CM CN rH rH rH O CO -Q rH o O o o o o o o O o o O o o o o o o o O o o O o o O o rtf 1 0) u O rH >i o o o O O o O O O O o o O rH o o O O rH rH rH O o O O rH rH Development stages: emergence, jointing, heading, milk, soft dough, hard dough. ■ - t 51 TABLE 16. A summary of rainfall 9 for 27 site-years 1959 - 1963 Inches rainfall for eight intervals after date seeded Site- year Date seeded 10-day interval number 1 2 3 4 5 6 7 8 0259 May 27 0.06 1.34 1.52 0.19 0.49 0.47 1.72 1.61 0359 May 2 6 0.06 1.34 1.00 0.19 0.49 0.47 1.46 1.14 0160 May 31 0.34 0.50 1.41 0.15 0.43 0.52 3.82 0.43 0260 May 30 0.34 0.30 1.91 0.17 0.43 0.52 4.18 0.35 0360 May 30 0.34 0.30 1.91 0.17 0.43 0.52 4.18 0.35 0460 May 25 0.01 0.33 1.01 1.55 0.37 0.43 1.02 0.82 0560 May 25 0.01 0.33 1.01 1.00 0.37 0.43 1.02 1.32 0361 May 25 0.30 0.10 0.50 0.50 0.25 2.15 0.25 0.05 0561 May 18 0.30 0.00 0.45 0.60 0.75 0.90 5.40 0.55 0661 May 19 0.30 0.00 0.45 0.60 1.25 1.00 1.75 0.50 0761 May 23 0.42 0.20 1.48 1.40 0.00 0.50 0.50 0.20 0861 May 26 0.42 0.78 1.20 0.50 0.50 1.60 0.58 0.20 0961 May 23 0.42 0.20 1.18 1.30 0.00 1.05 1.75 0.20 1061 May 24 0.42 0.68 0.72 1.58 0.00 1.65 1.35 0.18 0562 June 19 0.26 1.12 0.86 0.87 1.83 0.00 0.55 0.55 0762 June 8 1.80 0.15 0.65 1.17 0.50 2.43 0.29 0.11 0862 May 31 0.60 1.20 0.80 1.24 1.46 0.20 1.50 0.00 0962 June 8 1.80 0.15 0.35 1.17 0.49 1.44 0.29 0.19 1062 June 7 1.30 0.15 0.40 1.22 0.38 2.55 0.00 0.64 1162 May 24 1.41 2.48 0.65 0.99 0.67 0.85 0.32 1.73 1262 May 31 1.94 2.39 0.70 0.30 0.97 0.61 1.38 0.00 0563 May 27 0.60 1.50 0.40 1.20 0.80 0.40 0.05 0.45 0763 May 30 0.05 0.25 0.05 0.95 1.20 0.21 0.05 0.24 0863 May 28 0.05 0.45 0.10 0.25 0.75 0.40 0.10 0.40 0963 May 30 0.05 0.25 0.05 0.60 0.55 0.41 0.05 0.24 1063 May 29 0.00 0.20 0.05 0.75 1.20 0.26 0.10 0.54 1163 May 27 0.40 1.05 0.35 1.20 0.80 0.40 0.05 0.25 Summarized from an estimated distribution of rainfall (see text) recorded. ■ . . ✓ : 52 TABLE 17. Comparison of some estimates of potential evaporation Monthly total evaporation, inches water May June July August September Penman estimate, data Edmonton Industrial Airport 1959 4.78 4.74 5.94 3.57 2.45 1960 4.74 5.00 5.93 3.95 2.80 1961 5.02 6.18 5.34 4.58 2.49 1962 4.15 5.27 4.75 4.01 2.62 1963 4.64 6.26 6.72 5.25 3.48 1964 5.15 6.09 6.52 4.81 2.65 1965 5.26 5.41 6.05 4.75 2.31 1966 6.00 5.60 5.68 4.03 3.18 1967 4.75 5.31 5.36 4.95 3.99 1968 5.34 5.02 5.27 3.63 2.18 Average 4.98 5.49 5.76 4.36 2.82 Sunken-tank evaporimeter a , Lacombe Research Station, Can. Dept. Agr. 1959 3.93 5.09 2.86 1960 4.54 5.09 3.86 Long-term average 3.25 3.48 4.17 3.44 2.06 b Estimate , data Edmonton Industrial Airport Long-term average 3.5 3.9 4.6 3.5 1.8 Class "A" open-pan evaporimeter, Edmonton International Airport 1967 6.91 6.82 1968 8.80 7.47 7.62 4.81 3.31 1969 7.16 8.77 8.17 7.65 3.89 a Robertson, Geo. W. 1964. Evaporation measurements. Publ. 1210, Agrometeorological Section, Plant Research Institute/ Research Branch, Can. Dept. Agr. Coligado, M. C., W. Baier and W. K. Sly. 1968. Risk analyses of weekly climatic data for agricultural and irrigation planning. Tech. Bull. 45, Agrometeorological Section, Plant Research Institute, Research Branch, Can. Dept. Agr. ' 53 of PE. Degree of exposure, with its consequent effects on humidity and wind speed, was the one site characteristic of special concern: site 05 was highly exposed. Situated on a prominent ridge, the winds were relatively high. site 23 was protected from prevailing winds, within the shelter of a crescent of trees. sites 01 and 25 were partially protected from prevailing winds by surrounding vegetation. To measure site wind and humidity relationships, an anemometer and a thermohygrograph were set out at each site late in the 1967 season. In order to estimate the missing wind and humidity observa¬ tions for some of the 17 site-years the following linear regressions for known observations were used: Y = b rt + b X 0 1 where values of Y are site observations of humidity (or wind) and values of X are corresponding observations at a reference station. The coefficients of these regressions are given in Table 18. Edmonton Industrial Airport (E Ind A) and Lacombe Research Station (Lac CDA) were used as reference stations. There were some differences in the nature of the observations: wind observations were at different heights above ground level: sites at 2.0 m, E Ind A at 17.4 m and Lac CDA at 12.2 m. Reference station wind observations were reduced to equivalent winds at a height of 2.0 m using the empirical power law (see Appendix F). 54 TABLE 18. Regression 9 of site observations (Y) on reference station observations (X) for daily wind and humidity Reference station Site b 0 b l X Y n b R SEE c Wind (u) relationships E Ind A 01 -3 0.868 149 127 232 0.82 31 E Ind A 03 14 0.847 148 140 229 0.82 30 E Ind A 05 13 1.080 148 173 230 0.82 39 Lac CDA 21 9 1.100 101 121 189 0.89 22 Lac CDA 23 27 0.657 102 94 224 0.58 38 Lac CDA 25 14 1.080 101 122 222 0.86 26 Vapour pressure of air (e d relationships E Ind A 01 2.3 0.958 6.7 8.7 232 0.83 1.3 E Ind A 03 4.0 0.764 6.8 9.2 229 0.66 1.7 E Ind A 05 3.0 0.883 6.7 8.9 230 0.77 1.4 Lac CDA 21 2.2 0.872 7.3 8.5 189 0.81 1.2 Lac CDA 23 2.2 0.965 7.2 9.2 224 0.79 1.4 Lac CDA 25 2.4 0.801 7.3 8.3 222 0.74 1.3 Vapour pressure deficit (e a - e d ) relationships E Ind A 01 -0.63 0.604 6.7 3.4 232 0.89 0.9 E Ind A 03 i o • 0.512 6.6 2.8 229 0.76 1.4 E Ind A 05 -0.61 0.603 6.7 3.4 230 0.84 1.2 Lac CDA 21 -0.47 0.629 6.0 3.3 189 0.89 1.0 Lac CDA 23 -0.34 0.626 5.9 3.3 224 0.82 1.3 Lac CDA 25 0.05 0.604 5.9 3.6 222 0.81 1.4 Equations used to estimate missing site values. Where (n) is number of observations. Q Reference station wind (mpd) reduced to equivalent wind at height of 2 m before linear relationships estimated. ^ Units are mm Hg pressure for all humidity observations. * - s. 55 site humidity calculations were based on abstracts from charts for 0500, 1100, 1700 and 2300 hours. Four e a and four e^ values were calculated then averaged. Observations of wet- and dry- bulb temperatures at reference stations at 0800 and 1700 hours were used to calculate e^ and e^j values. a. Q. 5 Input data (excluding daily rainfall and PE) for the soil moisture budget equation are presented in Table 19. Moisture charac¬ teristics, soil densities and available water contents of the soils are recorded in Table 20. Moisture stress equation In a previous section yield equations were presented des¬ cribing the relationship between yield of barley and levels of nitrogen (N a , Ng) and phosphorus (P A , Pg) available to the crop. Here a pro¬ cedure will be described for obtaining a site index (W) of moisture stress. The index will later be incorporated into a yield equation of the form: Y = f(N A , N s , P A , P s , W) (9) The general procedure, showing relationships between the soil moisture budget equation, the Penman equation and a moisture stress equation, 5 Available from the Department of Soil Science, University of Alberta. * TABLE 19. Site data entered in the equation for estimating a daily soil moisture budget for 17 site-years 1964 - 1967 - 56 - o 00 o CN o r** ID ID LD o O CN ID 01 CO CO o rH CN CN CN ID o CN ID 4 z Q) G O c ro CT» r-* vD CN LD LD O o o o ro r- D VO -P o 0 vO LD LD LD vD O o o o cn (71 w • N *H f—1 o o o o O o O O rH o o o o O 0 4-1 e 0 CD CD «—1 z H XI o 3 ro CO vo o CO LD r- O o o o CN o o O rtf LD -P CN ro ro CN rH ro ro ro ID LD ID LD LD i—1 • cn •H O •H O O O o o O O O o O O O o O o o O 03 O > £ 03 CD •— 1 z r—1 03 O P CN CN CN CO co rH CN CN O o o LD o O -P ro 03 rH CN CN 1 — 1 CD CN CN CN CN CO ro ro CN CN ro CN ro 0 • i—l H O •H 03 O o O o O O O O O O O O o O O O O J> < o Oi LD CO vD LD LD LD o O O D r- o D O CN O rH rH o O rH >—i rH rH CN CN CN rH rH CN rH CN o o o O o O O o O O O O O o O O O O rtf <1) rtf +J U ) Q X H CN ^ 00 VD oi 01 r* CO CO r- ^ ^ h ^ CO CO CO 01 01 01 CO vd ^ vd n CO or Or CO ^ CO lO <0 ["- vo r- r- in n h r"* co cn r- r» r- r- co rH co co h n co r- r' co h- (U > 0) T3 4-1 -H O £ co co LD VO LD o r- vD vD co oi h o ro r* r* i/i m cO cO cO cO r- vd vQ vO ro vD vO v£> vO vD ro O no cO CO ^ ld ^ ^ vD or ^ 01 m 01 ^ ^ ld ro vd ld ^ 01 H CO ^ m sr tj* £ •H T3 0) QJ W CN 01 rH lO CD n n rn m ro n m m n co cn m ro no ro ro ro ^ ro CN in ro co o sr ro ro U 4-1 w >1 rtf Q W o o O (N ^ sf ^ |—I T3 ro CN 01 i — l r- CO ro LD O r" rH o LD rH GO 1 >i >1 >. >1 >1 G G >1 >1 >i G >1 >■ Q Q3 3 rtf rtf rtf rtf rtf rtf rtf G G rtf rtf rtf rtf G rtf rtf W H) £ £ £ £ £ £ £ h) •d £ £ £ £ H) £ £ TJ . >i >1 >i >i >1 >1 >i G >. >1 >1 >i >1 >1 Q rtf G rtf rtf rtf rtf rtf rtf rtf rtf G rtf rtf rtf it) rtf rtf rtf W P) £ £ 2 £ £ £ £ £ h) £ £ £ 2 £ £ £ o rH T5 CN rH CN CN rH rH •H 0) rH CN rH rH CN CN 0 A • • * • • • CO rH o o o O o O rd i QJ u LD r- ID r- ID D r- LD D r- D r- ID vD r- -P rtf D O D vD vD D D vD D O vD vD VD D vD vD vD •H i o O O O O O O O CN CN CN CN CN CN CN CN CN Development stages: emergence, jointing, heading, milk, soft-dough and hard-dough. ' TABLE 20. Apparent densities and moisture characteristics of soils for experimental sites 1964 - 1968 - 57 - 00 O X3 ro ro in CN CO in rH o in O CN CP o rH CO 00 o UO 40 40 CN CN 00 rH O' o •^r ro ro CN rH o UO r- ro ro o ro ro in 40 in CP rH o O o o O o rH rH o o O o o o o o o O o o O o O O CP r- CP 40 rH rH CP r- CN 00 r- r- rH CP 40 o o uo o 40 in ro r- CN 0) G 40 40 in 40 O' CN 40 ro in r- 40 CN r" CP o CO CP 40 o CO X) O x: T3 rH o’ o o o O o rH rH o o rH o o o o o o o o o rH o rH rH c 0) •H U) 40 40 CO CN CN CN CO X3 o o o CN fTl CN ro CP ro CO * 4-1 40 r- CN p" in in r- CP o CO ro CO 40 CP u 0 (P t • • • 0) rH o o o rH o o o o o o o o o o O o o o O o ■P a) E s •H 4-> in CN CO CN ro i — 1 CO CP CP in 40 o CN CP o O UO ro CP O'* CD 40 40 LO LO in in r-* rH ro CP r-H CP 40 CO rH o CO 40 40 i —1 -p CP XI < rH o o O o o o o o o o o o o o o o o o O o rH o rH o i — 1 •H rtf ro CN 40 r- o CN > X5 CO in CP ro < CP • • • • • • rH o o o o o o o O ro E X) o X) CP rH ro o rH CO CP CN CP CP 40 C CP rH 40 r** CO rH [">- 40 CO X) ro o r* r- r- 40 r- U0 rH UO 40 •H rH CO CN rH rH r-H rH rH rH CN 1—1 rH rH ro CN rH rH 1—1 rH •—i r-H CN r-H •—i rH T1 CD ID o o o CM rH CT* o o o ro o o o o o o o ro o oo o o o o o o o o o o o o o o o O o o o o o o o o rH o o 1 —1 o *—i rd r- ro ro CM CM CM CM CM ro ro ro CM CM CM CM ro CM CM ro ro ro ro ro ro ro ro ro ro > u rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH i—1 rH rH rH 1—1 I—1 1 rd rH rH rH rH rH rH rH rH rH rH rH rH rH i—1 rH rH rH rH rH •—l rH rH rH rH rH rH rH TJ ro O o rH O'! rH CM CM CM rH O rH o o O rH o O OO o OO OO o OO OO OO 4-1 0 rH rH rH rH rH rH i — 1 rH rH rH rH rH rH rH rH rH rH i—1 rH rH u CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM Q) q rH 1—1 rH rH rH i—1 rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH rH 1 rH1 ro rH o CM rH CM rH rH O rH CM O Oo rH 00 00 rH rH O rH CM i—1 CM O rH rH iH rH rH rH rH rH rH rH rH i — 1 rH rH rH rH rH rH rH rH rH rH rH rH rd CM in rH ro rH r- CM rH o CO rH CM rH in O'- C" 00 r- CO oo ro C" CM r- U0 CO ro £ x: >H > CM ro O'* CM CM CO r- rH r- o CM ro VD CO r* uo ro ro in CM C" r" UO rH rH ro CM rH CM CM rH rH rH rH rH CM ro ro CM CM CM ro ro CM CM ro rH rH CM 1 Q) g Or 00 o O o o o rH i — 1 '—1 rH rH rH rH CM CM CM CM CM CM CM ro ro ro ro ro ro 4J aj m in ID ID vO ID ID ID ID ID ID ID ID ID vD ID iD ID vD ID vD vD ID vD vD vD vD •H CM ro rH CM ro UO ro in vD r- 00 CO O UO r" 00 oo O rH CM UO r- CO oo o rH CO >1 O O o O o o O O o O o O O rH O o o O rH rH rH O o O o rH rH £ rd and M" are the ratios obtained by procedures (1) and (2), respectively, described in the text (p. 62). • , 64 Y m = 34.7 - 4.7M , 1 - 9.6M' 2 - 15.7M‘ 4 (11) and Y m = 31.4 - 5.4M" 1 - 7. 0M" 2 - 13.8M" 4 (12) where M'^ and M"j_ refer to the stress-ratios for the ith growth interval and the superscripts (') and (") refer to procedures (1) and (2), respectively. Addition of one or more ratios of the remaining four intervals to the equation made no significant difference to the re¬ gression, where the sequential F-test was used as test criterion. Statistics of the regression by procedures (1) and (2) before elimination (see equation (10)) and for equations (11) and (12) are presented in Table 23. As stated earlier in this section, these stress equations were developed in order to obtain a site index (W) of moisture stress. The validity of equations (11) and (12) were examined as predictors of yield for the 1964 - 1967 field experiments. Site yields Y m , duration (days) of intervals of crop development and ratios M* (obtained by procedure 1) and M" (obtained by procedure 2) are presented in Table 24 for the 17 site years 1964 - 1967. Predictions of Y m are compared in Table 25. For pro¬ cedures (1) and (2) the simple correlation coefficients between Y m and A Y m (prediction of Y m ) were 0.600 and 0.736, respectively. Procedure (2) was selected over procedure (1) on the basis of the higher correlation obtained in the prediction of Y m . Values of W, calculated by the equation W = 5.4M X + 7.0M 2 + 13.8M 4 (13) are included in the data presented in Table 25. .. . i 65 TABLE 23. Regression coefficients (b-j), standard errors of estimate, partial F-values and R2 values of moisture stress equations 3 for 27 site-years 1959 - 1963 Variable b i S . E . E. of b^ Partial F-values^ 3 S.E.E. Overall F-value R 2 Equation (10) procedure (1) M' x -5.75427 3.32173 3.001 M' 2 -8.57919 3.16723 7.34* “*3 6.89168 3.98306 2.99 M*4 -20.10815 4.95710 16.45** M's -1.19888 3.77192 0.10 6 2.78420 6.79639 0.17 m' 7 -5.00389 4.65650 1.15 Intercept 34.01930 4.139 15.07 0.847 Equation (10) procedure (2) M'V -8.51430 4.36465 3.8lt m" 2 -6.39033 3.71268 2.96 m" 3 9.22146 6.77465 1.85 M "4 -22.08078 8.29361 7.09* m" 5 0.79660 4.29577 0.03 M'V 6 4.70644 8.63829 0.30 m" 7 -3.28964 5.30372 0.38 Intercept 30.16960 Equation (11) 4.727 10.92 0.801 M' -4.65574 2.80198 2.76 m ' 2 -9.62282 2.69855 12.72** m' 4 -15.73995 2.90466 29.36** Intercept 34.73161 Equation (12) 4.220 32.25 0.808 M'V -5.41335 2.98418 3.29t m" 2 -7.04115 2.91279 5.84* m" 3 -13.75858 2.91788 22.23** Intercept 31.38275 4.541 26.82 0.778 M' and M" are the ratios obtained by procedures (1) and (2), respectively, described in the text (p. 62). Levels of significance are: ** 0.01 * 0.05 t 0.10 „ * ■ - 66 - vO VO o p o p o o CO O O O o in O O O p CD o in O VO o o vO O O o o m o o O r—1 CN o CO O 00 o o CO O O o o O' o o VO O o o o O o o o o o o O o o o o O O o o o O O’ o o o o o O o vO o o o vO o o o o o rH o o o o o O o CO o o o o o o o o CN o o o o o o o CN o o o o o o o o O o o o o o o o O o o o o o o o o' O p H o o o H o O o o VO o o o o p O p H o o o H o O o o in lO o o o o O’ o o »H o o o vO o CN o o o rH o o o o o o o o o o O o O o o o in o ro o CO o 01 CO m o CO CO rH H o CN ro _ in o CO o 00 o O O’ O' o r- O' cn cn o 00 O’ s o* O’ o CO o in o cn VO in o CN H o o o rH H o o o o o o o O o o o O o o o o o in o’ o rH o p co o o o o ro o o o o o in m o ai o p CO o o n o CO o o o o o o co o’ i —i o o CO o in o o o o o o o o o o o o o o o o o o o o o o o o o o o to >> i—i o o o CN ro o o H o in O’ in O’ o CN o 01 o o o CO CO o o o H O’ CO H o VO o CN O o o o rH o o o o o VO O’ co CN o O’ m rO +-> o o o o o o o o o o O o O O o o o O o o o p p o o o o o o o O’ o o CO o to o o o vO vO o o o o o o o H o o CO o i—H o o o VO VO o o o CN o o o r* o o in o ra -a rH o o o O o o o o o o o o o o o o 00 00 CD vO vO o p o p o o CO o o o o in o o o 00 p CO o in o VO o o vo o o o o in o o o p i—i CN o CO o CO o o CO o o o o O' o CJ vo N— o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o VD o o o o o o o o rH o o o o o o o CO o o o “O vO o o o o o CN o o o o o o o CN o o o c ra o o o o o O o o o o o o o O o o o o o o o O’ o p I—1 o o o H o O o o VO *— o o o o p o p H o o o H o O o o 1/1 ra LD o o o o O’ o o H o o o vO o CN o o o oo O rH o o o o o o o o o o o o O o o o •r* vo ra cr> o' o ro CN CO o CT> vO CTi o vO vo in O’ o in r- 1 vO o CO CO 00 o o CO o o CO CO m VO o O’ in i s o’ ro o in rH in o ai p cn o vO CN O’ CO o m co o o o o O o o o o o o o o o o o o o +-> oo cn in CN ro O’ o ro CO o o o r- r- o o o o m vO p vO o P ro o m o vO v0 vO o o CJ o ra ra ro o’ o CN ro O CN in o CN o o H o o o o o +-> o o O O O O O o O o o o o o o o o oo “a ra >i s- o o o O O o o o o o o o o O o o o c -Q ,r “ o o o p p o o o o o o o O’ O o CO o ° o o o VO vO o o o o o o o •—i O o ro CJ +-> rH o o o VO vO o o o CN o o CJ r- o o in o £ OO S- 1—1 o o o o o o o o o o o o o o o o i- ra cn CD >, r^. 1 CD 1 — 1 rd > r- p o’ CO O o m o p- cn vo m o in H vo in o rH iH rH rH r—i H H H H H H H H H H -C to CD -P vO vO o CO O 01 •O’ ■O’ o P" in in r- O’ r- LO in r- •H •—1 rH rH H H H rH H H H H H to 4- per m in o in o ai •O’ CO CO vO O’ O’ CO O' o O’ in CO <—i rH iH rH rH H H H H H H rH H CN rH rH H *o _C CJ w rH CN rH CN H H O’ H H H O' H H t—1 H O’ ra -H o CD C > rd TJ m rH i—1 rH ro rH rH i—1 rH rH o H H H ro rH o H CN rH O’ <—1 m H CN H in H O H O’ r—1 O’ H H 4_J 4-) rH rH rH rH rH H H H H H 1 — 1 H H H 1 — 1 H H ** to 0 ' — u CN rH CN o CN rH CN CN o H CN ro cn CO O’ ro CO O - P- p CO ai vO p CO O’ o in CN in O’ CO in co vO O’ fcs >< o \ ai p CN LO ■O’ CO ai CN CO o o* r- r- r- CN o tr rH CN CN CN rH CN H CN CN CN co CN H CN ro CN CO C\J LU a) p o 1 in p m p in vO O’ m vO r- vO r- in vO p* < 4-> rd vO vO vo vo vo vO vO vD VO vo vO vo vO vO VO vO VD Cl) rH co ro in in in H H H H co co in i/1 in co >i o o o o O o O o CN CN CN CN CN CN CN CN CN and M" are the ratios obtained by procedures (1) and (2), respectively, described in the text (p. 62). 67 TABLE 25. Y m , tv/o predictions of Y m (f-j and f£) a and index of moisture stress (W)^ for 17 site-years 1964 - 1967 Site- year Y m f l f 2 W 0164 19.7 23.4 19.1 12.3 0165 27.'8 34.7 31.4 0.0 0167 22.9 25.5 26.8 4.6 0365 25.6 28.7 27.8 3.6 0367 14.7 20.7 18.5 12.9 0565 28.8 33.9 30.8 0.6 0566 19.4 20.4 18.9 12.5 0567 27.0 22.3 22.6 8.8 2164 22.5 18.6 22.2 9.2 2165 28.2 34.7 31.4 0.0 2166 30.5 18.8 23.3 8.1 2167 24.4 25.9 26.3 5.1 2366 17.8 20.5 23.6 7.8 2367 27.5 26.9 28.6 2.8 2565 37.3 34.7 31.4 0.0 2566 22.6 19.2 22.7 8.7 2567 30.4 24.3 25.9 5.5 a Prediction obtained using equation (ID , f 2 obtained using equation (12) . b Calculation of index (W) by equation (13). 68 D. Effects of soil moisture stress and soil order on barley response to available nutrients In the last section evidence was presented that, with nutrients non-limiting, more than 50 per cent of the variation in barley yield was accounted for by moisture stress occurring prior to heading of the crop. Earlier, using equation (7) stated on p. 40, an 2 R value of 0.386 was obtained (see Table 13) in a regression of barley yield on available nutrients (N^, P A , N g , Pg) involving pooled data of the 17 site-years 1964 - 1967. The poor correlation obtained for this regression was not unexpected, since variation in soil moisture con¬ ditions for different site-years had not been considered. With the objective of obtaining a barley yield equation of some value in predicting nitrogen and phosphorus fertilizer requirements for barley, interrelations were examined between variables of equation (7) and two selected site variables: soil order and soil moisture condi¬ tions. The dummy variable (T) was used to identify Chernozemic (T = 0) and Luvisolic (T = 1) soils and the site index (W) was used as a measure of moisture stress over the growing season. Use of coefficients of individual site-year regression equations The coefficients (b^) of 17 individual site-year regression equations involving terms N , P , N and P are presented in Appendix D. The effects of the independent variables T and W on regression co¬ efficients were examined in a series of 15 regression equations: ■ - 69 (a) bg Zq + z'qT + z "qW, (b) b 1 = z ± + z'-jT + z'^W, (c) b 9 = z 2 + z' 9 T + z" 9 W, (n) b 24 = Z 24 + z '24 T + z" 24 (o) b 34 = Z 34 + z '34 T + z" Z 34 The results of this analysis, presented in Table 26, indicate an influence of T or W on certain variables in equation (7): (a) Variation in the intercepts (see b^ in Appendix D) can partly be explained in terms of soil order (T), whereas soil moisture conditions (W) do not contribute significantly to the variability in the b^'s. (b) Variation in the N coefficients (b,) and in the N 2 co - 1 n efficients (b.^) as P ar tly due to moisture stress (W) . In 2 . . both cases the magnitude of the N and N coefficient is reduced by the moisture stress factor. (c) The variation in the coefficients (see b 24 in Appendix D) of the interaction of applied and soil phosphorus (P^-Pg) is partly due to having some sites on Chernozemic and other sites on Luvisolic soils. The interrelations as determined above were considered in the sub¬ sequent analyses of the data. ' ■ ■ 70 TABLE 26. Regressions of site-year regression coefficients on soil order, T, and moisture stress index, W, giving R 2 and F values Variable Regressions of on T and W R 2 F value 3 Intercept ii o A 17.5 - 7.5T 0.187 3.46t n a ii i —i n 0.264 - 0.016W 0.265 5.43* n a 2 b ll = -(0.00111 - 0.00006W) 0.274 5.65* p *p ii CN XI 0.00424 - 0.00450T 0.304 6.55* * : t: with 1, 15 degrees of freedom a Levels of significance are: 0.05 0.10 . 71 For completeness it should be pointed out at this stage that in a similar study, Eck and Tucker (1968) compared standard partial regression coefficients (b 1 ^) rather than the (partial) regression coefficients (b^), where b * . = b. s i 1 i— ' s y with s^ and s the standard deviations of the ith independent variable and the dependent variable y, respectively. Voss and Pesek (1965), in a greenhouse experiment, compared interrelations between b^ for applied nutrients and soil test values by examining the correlation coefficient matrix adjusted for intercorrelation between soil test values. Comparison of regression equations involving pooled data Statistics for five regression equations are presented in Table 27, each equation involving pooled data of the 17 site-years 1964 - 1967. Equations I (see equation (6) and Table 12) and II (see equation (7) and Table 13) were discussed previously. Equation III 2 was obtained by elimination of the non-significant variables P g , N .P and P .N from equation II, reducing the number of independent variables in regression from 14 to 11. Evidence was presented (see Table 26) of interrelations of soil order and soil moisture stress with certain variables which are present in Equation II. To examine this evidence further, barley ■ TABLE 27. Regression coefficients, F-values, squares of the multiple correlation coefficient (R2) and standard errors of estimate (sy.x) f° r five equations involving pooled data of 17 site-years showing the effects of including soil order (T) and moisture stress (W) in the regression 72 4c * * 4c * * 4c 4c 4c 4c * -K * 4c * * 4c ro CO rH CM o rH ro P o X> CM p CO p X> CO uo oo OO P X) 4C > X) CM CM p o CM O o o ro O ro 4C rr p o O O o o r- p X) uo rH rH o o o O O o o CM uo o UO uo o O o o o o O o o ro o UO ro o 1 1 1 1 1 rH 00 4C 4C * 4C * 4C * 4C 4c 4c 4C 4c 4C * 4c 4C 4C * 4c 4c 4c 4c 4c CO OO P UO UO o ro UO p X> P to CO ro o ro 1—1 ro CO o X) P 4c > CO CM p p 1—1 CM O O o 00 O CM ro 4c oo w X) CO ro uo o O O O o O ro CM ro CM rH o o o O o O o o o CO rH U0 uo rH O o o o o O o O o o o ro ro rH o U0 1 1 1 i 1 1 rH CO * * ■K * * * 4c 4c 4c 4c * * 4C * 4C * * 4C 4c 4c 4c p uo CM rH ro CM p ro CO p ro H CO oo oo CO ro rH oo ro ro 4c M 00 X) CM O CM o o O O O P 4c ro H CD uo ro O O o o o o O rH ro CO CO rH iH o O O O o o o o O CM ro ro ro o O o O o O o o o o O O uo O uo 1 1 1 1 rH 4c 4c 4C * 4C * 4c 4C 4c 4< -K * 4C * * 4c * 4c 4c 4C 4C ID oo uo 00 ro CM rH OO rH CO CO ro P t—1 p ro X) p rH rH rH rH ro .H CO ro X) 4c M 'tr CM O ro o CM o O O o O O O O X) 4c X) H CO X> UO o O o O o o O o O o rH o CO P rH rH O O o O o o o o O o O o o o ro oo o o O O o O o o o o O o O o rH X) O uo i 1 1 1 i 1 1 rH ro 4C 4C * * ■K 4C * * * o o p UO rH o CM p oo ro 4C ro O o CM o rH 4c P H CO o o o CO p CM X) rH rH o O o rH 'TT CM X) O o o O o X) p o X) 1 1 rH 4-1 c G 0 • ITJ 2 2 2 cu 2 2 2 M 1 CM >< > tu X w Levels of significance: **: O.Ol *: 0.05 73 yield (pooled data) was regressed on 18 independent variables, the 14 variables in equation II (applied and soil nutrient terms) and the variables T, N^.W, N^2.w and P^.Pg.T. Eliminating terms with non-significant coefficients from the 18-variable regression equation, equation IV was obtained. From Table 27 it is seen that about 55 per cent of the variation in yield (pooled data) was explained by 12 variables in equation IV. Equation IV is reasonable in an agronomic sense, although from the processes involved in phosphorus uptake by the plant, an interaction between moisture stress and available phosphorus could be expected. Other features of equation IV, including the absence of the linear variable W, suggested the need for further examination of influences of T and W on the regression. Yield of barley (pooled data) was regressed on 14 variables (applied and soil nutrient terms) and the two linear variables T and W. Equation V was obtained after variables with non-significant co¬ efficients had been eliminated. With 11 variables (including T and W) in the regression, again about 55 per cent of the variation in yield was explained by the regression equation. From Table 27 it is seen that equations IV and V explain the same percentage of the variation in barley yield for the pooled data of 17 site-years. Equation IV was taken as the final yield equation for the purpose of examining economic aspects of the influence of environmental factors on the response of barley to nitrogen and phosphorus fertilizers. . 74 E. Applications of the barley yield equation The barley yield equation (Table 27, equation IV) selected in the last section was used to examine several aspects of the econ¬ omics of fertilizer use in barley production. The main objective in the analyses was to appraise the usefulness of the equation as a predictive model. The equation is presented again for convenience: Y = 13.12 - 3.83T + 0.03737N g + 0.05705P S + 0.26868N A - 0.00043N a .N s + 0.00035N a .P s - 0.01906N A .W + 0.18289P A - 0.00087P a .P s - 0.00135N a 2 + 0.0001lN A 2.W - 0.00210P A 2 (14) It was necessary to first select unit prices for barley (p Y ) and fertilizers (p N , p p ). The 5-year average price of barley to 1969 was considered relevant: 84C/bu (= 1.75C/lb). This price is subject to fluctuations in response to foreign as well as domestic market situ¬ ations. Selected fertilizer costs were: lOC/lb for nitrogen and 18C/lb for phosphorus (8C/lb p 2 0 5^ * The following price ratios were calculated Py/P N = 17.50 kg/q, P Y /P P = 9.72 kg/q and Pp/Pfj = 1.80. To examine the effect of changing price ratios on optimal fertilizer inputs, other prices were considered. The price ratios: p Y /p N = 15.75 kg/q and Py/Pp 8.75 kg/q . r r v . 75 are 10 per cent lower than the price ratios calculated above and represent either (a) an increase in the price of barley or (b) a decrease in the cost of fertilizer. Equation (14) describes the influence of moisture stress (W) on the response of barley to applied nitrogen (N A ). The nature of this interrelation is illustrated in Figure 2 for two levels of N A as W increases from 0 to 20. It was convenient to postpone until later a more detailed examination and discussion of the moisture stress index. To examine other variables in the yield equation isolated from varia¬ tions in W, a value of 5.0 was assigned to the index. This value of W is considered appropriate to the situation where soil moisture conditions are good at seeding, followed by average amounts of rainfall normally distributed. Calculation of optimal fertilizer inputs The effects of soil test values and input - output prices on optimal fertilizer inputs were determined by calculations based on equation (14). The marginal products (MP) per unit of N A and P A were obtained as the first derivatives of equation (14), thus: MP = 0.26868 - 0.00270th - 0.00043N o + 0.00035P_ n a ASS - 0.01906W + 0.00022N a .W (15) and 0.18289 - 0.00087P S - 0.00420P a . (16) YIELD Q/Hfl .00 10.00 20.00 30.00 40.00 76 MOISTURE STRESS INDEX Effect of the moisture stress index (W) on barley yield for two inputs (kg/ha) of nitrogen fertilizer (N a ). A Figure 2. 77 Assuming a stress index (W) of 5.0, equation (15) reduced to: MP 0.17338 + 0.00035P - 0.00043N - 0.00160N a . O O ( 17 ) P N /Py 0.17338 + 0.00035P S - 0.00043N S - 0.00160N A (18) Pp /Py 0.18289 - 0.00087P S 0.00420P A* (19) Equations (18) and (19) were used to calculate optimal inputs of N and P at different price ratios and soil test values. Calculated optimal inputs were compared to recommendations of the provincial soil testing service. The data presented in Table 28 indicate: (a) At low N s levels, calculated optimal inputs of N A compare favour¬ ably to inputs recommended by the soil testing service. At a Ng level of 28 kg/ha (an average situation) calculated optimal input is approximately 44 per cent higher than that presently recommended by the soil testing service. (b) Calculated optimal inputs of P A are about 30 per cent lower than recommendations of the soil testing service. (c) As inputs become 10 per cent cheaper relative to output, optimal in¬ puts increase but the ratio of fertilizers is changed. For certain situations the optimal inputs compare poorly to recommenda¬ tions of the soil testing service. Hov/ever, the opinion is held by some that recommendations of the soil testing service underestimate the nitrogen requirement and overestimate the phosphorus requirement. The calculated data lend qualified support for this body of opinion ' I \ TABLE 28. 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The observed effects of changes in price ratios on fertilizer inputs appear reasonable. Fertilizer inputs below optimal levels Farm credit facilities in the Province of Alberta are such that the situation of limited capital for resource allocation is seldom a problem influencing input of fertilizers for cereal production. However, it is not an uncommon practice for fertilizers to be used at levels below that which is recommended. This practice is based on the uncertainty of product price and the risk of drought. Also, it is supported by some workers on the premise that marginal products are much higher at lower input levels. It was decided to test the barley yield equation by an examination of this aspect of fertilizer use. The isocline equation or least-cost expansion path was calculated by setting MP ratios equal to their inverse price ratios, thus from equations (18) and ( 19 ): % P P 0.17338 + 0.00035P S - 0.00043Ng - 0.00160N A 0.18289 - 0.00087P - 0.00420P„ S A ( 20 ) In Figures 3 and 4 isoquants and isoclines are presented for several soil test (N s , Pg) situations, where W, p N and p p were held constant at 5.0, 10£/lb and 18C/lb, respectively. Equation (14) was used to calculate the isoquants and equation ( 20 ) was used to calculate the isoclines. To indicate the region of economic interest, yield (Yqpt^ at optimal inputs of N A and P A is shown on each diagram, calculated * 80 o cc o a: o a: o Isoquant-isocline diagrams, showing optimum barley yield ( Y opT ) for three nitrogen soil test (N s ) levels. Variables held constant: W = 5.0, P s = 30, py = 175, p N = 10 and p p = 18. Figure 3. PHOSPHORUS APPLIED, KG/HA PHOSPHORUS APPLIED, KG/HA PHOSPHORUS APPLIED, KG/HA 0.00 25.00 50.00 JO. 00 25.00 50.00 JO.00 25.00 50.00 81 Isoquant-isocline diagrams, showing optimal barley yield (Y opT ) for three phosphorus soil test (P s ) levels. Variables held constant: W = 5.0, N s = 25, p Y = 175, p N = 10 and p p = 18. Figure 4. 82 by equations (14), (18) and (19) where p Y was held constant at In the three diagrams of Figure 3, Pg was assigned the value of 30 and three levels of N g were compared: (a) 0, (b) 25 and (c) 100 kg/ha. In the three diagrams of Figure 4, Ng was assigned the value of 25 and three levels of Pg were compared: (a) 0, (b) 30 and (c) 100 kg/ha. The isoquant and isocline diagrams of Figures 3 and 4 illustrate cer¬ tain features of equation (14) including the following: (a) At certain levels of output, isoquants may intersect one or both of the axes. This is a feature of the quadratic form. (b) Soil test values influence the geometry of the isoquants. Figure 3 indicates that, with P A at 0 and P g held at 30, a barley yield of 22 q/ha can be attained at N g values of 0, 25 and 100 by inputs of at 47, 43 and 27 kg/ha, respectively. (c) Isoclines in each situation intersect the N^-axis. This feature is of considerable economic importance because the proportions of and P A recommended at the optimal level of fertilizer use do not represent least-cost combinations for levels below the optimal. The relationships implied by the isoquants and isoclines of Figures 3 and 4 are based on equation (14) and relevant price data. These relationships appear reasonable. If desired, the isocline equation (20) could be used to provide fertilizer recommendations for inputs below the optimal level of fertilizer use. * ' ' k ■ 83 Applications of the stress index (W) The bulletin containing general fertilizer recommendations for soils of central and northern Alberta, published by the Alberta Department of Agriculture (1968) remarks on the influence of soil moisture conditions on the economics of fertilizer use: "... The amount of soil moisture at seeding, the amount and distribution of rainfall during the growing season, growing season temperatures, availability of other soil nutrients and previous crop and soil management will, to a great extent, affect the economy of fertilizer use. . ." The moisture stress index can be used to modify optimal fertilizer recommendations to account for soil moisture conditions prior to seeding. In selecting a value of W relevant to moisture conditions in the spring, the evidence examined in calculating the moisture stress equation provided useful guidelines: (a) Amounts and distribution of average rainfall and evaporative demand are such that short periods of moisture stress will normally be encountered from planting to heading, even under the situation of good spring moisture conditions. (b) Soil moisture conditions at seeding were observed to influence the incidence of moisture stress in the "critical" stage from jointing to heading of the crop. The values assigned to W were 5.0 for good spring moisture conditions and 10.0 for poor spring moisture conditions assuming in each case a normal seasonal rainfall pattern. A refinement in the prediction of W should involve an analysis of the risk of drought, a study beyond the scope of this investigation. ■ . I 84 The effect of a selected value of W on the optimal fertilizer input is shown in Table 29. The value of W influences the recommended input of nitrogen fertilizer, but not of phos¬ phorus fertilizer. Given the situation of poor soil moisture conditions at time of seeding, the nitrogen recommendation is reduced about 45 per cent from that recommended when soil moisture conditions are good. The isoquant-isocline diagrams presented in Figure 5 further illustrate these relationships. As W increases, the distance between isoquant lines also increase and curvature of the isoquants change such that, at higher predictions of W, larger fertilizer inputs are required to attain a specified yield. A comparison of isoclines of the three diagrams (where the variables N s and P g are held constant) indicates an influence of W on the least-cost combinations of nitrogen and phosphorus inputs. The remarks quoted above from the bulletin on general fertilizer recommendations regarding the influence of soil moisture conditions on the economy of fertilizer use are supported by the foregoing discussion. * ' * 85 TABLE 29. Effect of selected stress index (W) on optimal fertilizer input a Assigned moisture stress index Optimal fertilizer input (kg/ha) Nitrogen Phosphorus 0.0 78 13 1.0 78 13 2.0 77 13 3.0 76 13 4.0 74 13 5.0 72 13 6.0 70 13 7.0 67 13 o • 00 63 13 9.0 55 13 10.0 41 13 11.0 6 13 a Calculations based on equation (14), variables held constant: N g = 25, P g = 30, p Y = 175, P N = 10 and p p = 18. * 86 o ac o a: o ac o Figure 5. Isoquant-isocline diagrams, showing optimum barley yield (Yq PT ) at three levels of moisture stress (W). Variables held constant: N s = 25, P s = 30, p y = 175, p N = 10 and p p = 18. 87 SUMMARY AND CONCLUSIONS Fertilizers have recently attained considerable importance in crop production in the province of Alberta. In 1968, investment in fertilizers exceeded $30,000,000, a six-fold increase within one decade. In the same year about 5,000 Alberta farmers obtained fertil¬ izer recommendations from the provincial soil testing service. General fertilizer recommendations for soils of the province are based on more than 40 years of research into fertilizer use, com¬ bining field and laboratory studies. The Alberta Department of Agriculture established a provincial soil testing service in 1955. Emphasis in fertilizer research was then directed to the many problems related to fertilizer recommendations based on soil test evaluation. The importance of amount and distribution of seasonal rainfall to fertilizer response was the major problem encountered in collating evidence over sites and seasons of crop responses to fertilizers. In 1964 an interdisciplinary research project was undertaken to study the response patterns and economics of fertilizer use in cereal and forage production as influenced by available nutrients in the soil and certain environmental factors. Field experiments were conducted in central Alberta at three locations on Chernozemic soils and at three locations on Luvisolic soils. The results reported here are for Gateway barley, the selected cereal crop. The main objectives of this examination were: (a) to develop a method for assessing the effect of soil moisture stress on yield and response to fertilizers of barley grown under dryland conditions and . 88 (b) to derive a generalized yield equation relating yield of barley grown on stubble to rates of applied fertilizers, soil test levels, moisture stress and soil grouping and to examine the economic implications. To study the response of barley to three fertilizer nutrients, nitrogen, phosphorus and potassium, each at five levels, a central composite design was used with 23 treatment combinations in each of two replicates. A fertilizer treatment, applied annually at time of seeding, was assigned to each plot. Prior to seeding and after harvesting, soil samples were collected from each plot for moisture analysis and soil testing. Certain daily meteorological observations were recorded at each site. Sites were visited at regular intervals and stages of crop development were recorded. Analyses of variance on data of 17 individual site-years indicated the N and P treatments produced significant effects on barley yields, whereas the effect of K was not significant. The lack of significant effects of applied nutrients at site 21 could be attributed to the high soil nutrient status of this one Chernozemic soil. Regression analyses were carried out on the relationship of yield of barley (Y) to applied nitrogen (N^) and phosphorus (P^) using a second-order polynomial model. For the regression involving pooled data of the 17 site-years, regression coefficients of linear and quadratic terms were significant at the 1 per cent level and the regression coefficient of the interaction N .P was significant at the ' > ... - , 89 5 per cent level. The square of the multiple correlation coefficient (r 2) for this regression was 0.227. Using the second-order polynomial model, regression analyses were carried out on the relationship: Y = f(N A , P A , N s , P s ), where the additional terms Ng and Pg represent soil test values for nitrate-nitrogen and available phosphorus, respectively. The value of Ng represents nitrate-nitrogen of the soil to a depth of 24 inches (61 cm) and the value of Pg represents available phosphorus to a depth of 6 inches (15.2 cm). A regression equation was obtained involving pooled data of the 17 site-years where the non-significant variables Pg , N A .P A and P A .Ng were eliminated by a forward selection procedure. With eleven variables retained in the regression, the value was 0.383. Data external to this investigation were used to derive an equation relating yield of barley to moisture stress occurring within three stages of crop development: (1) planting to emergence, (2) emer¬ gence to onset of tillering and (3) jointing to heading. Moisture stress analysis was based on a computed daily soil moisture budget for each site. The moisture stress equation was used to calculate a moisture stress index (W) for each of the 17 site-years. For pooled data of the 17 site-years a yield equation was obtained relating yield to applied and soil nutrients (N A , P A ' N S' P S>' the stress index (W) and soil order (T). The term W was introduced ' . ■ 90 into regression as an interaction with applied nitrogen (N .W, N A 2 .W), whereas T was introduced as a linear variable. With 12 variables in the regression, the R 2 value was 0.549. This yield equation was applied to an examination of several aspects of the economics of fertilizer use. The following conclusions can be drawn from the evidence presented: (a) The prediction of nitrogen fertilizer requirement is significantly improved by evaluation of nitrate-nitrogen in the soil to a depth of 12 or 24 inches over evaluation to a depth of 6 inches (15.2 cm). (b) With nutrients non-limiting, about 55 per cent of the variation in yield of barley observed in central Alberta can be explained by moisture stress occurring prior to heading of the crop. (c) The response surface of nitrogen and phosphorus fertilizers applied to barley for the three Luvisolic soils was very similar to that of the three Chernozemic soils. This evidence supports procedures of the soil testing service in evaluating fertilizer requirements of these soils in central Alberta. (d) A favourable change in product price increases optimal inputs, but the optimal fertilizer combination is changed. (e) At low soil test values of N the calculated optimal input of fertilizer N agrees closely with recommendations of the soil testing service. At a soil test value of 25 kg/ha the calculated optimal input is 44 per cent higher than that recommended. ' 91 (f) Calculated optimal inputs of fertilizer P are about 30 per cent lower than recommendations of the soil testing service. (g) The ratio of N to P recommended at the optimal level of fertilizer input is often not the least-cost combination of N and P for fertilizer inputs below the optimal level. (h) Based on predicted values of W, given the situation of poor soil moisture conditions at time of seeding the calculated optimal input of fertilizer N is reduced about 40 per cent from that calculated for good soil moisture conditions. This evidence supports general fertilizer recommendations for cereal crops in central Alberta. Further examination of the data is recommended with reference to interactions of W and T with other variables in regression and also the usefulness of a linear W variable in the regression. The usefulness of the moisture stress index (W) in predicting fertilizer requirements could be much improved by related drought risk analyses for selected soil moisture conditions at time of seeding. Gateway barley was selected as the test variety for this project mainly upon the characteristic of early-ripening. 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Nutrition of the Irish potato with reference to potassium. M. Sc. Thesis, University of Alberta, Edmonton. U. S. Department of Agriculture. 1954. Diagnosis and improvement of saline and alkali soils. Agr. Handb. 60. U. S. Govt. Printing Office, Washington, D. C. 160 p. Van Bavel, C. H. M. 1953. A drought criterion and its application in evaluating drought incidence and hazard. Agron. J. 45: 167-172. Voss, R. and Pesek, J. 1965. Geometric determination of uncontrolled- controlled factor relationships affecting corn yield. Agron. J. 57: 460-463. Wells, S. A. and Dubetz, S. 1966. Reaction of barley varieties to soil water stress. Can. J. Plant Sci. 46: 507-512. Wijk, W. R. van. 1966. Physics of plant environment. 2nd ed. North Holland Publishing Co., Amsterdam. 382 p. Williams, E. J. 1959. Regression analysis. John Wiley and Sons, New York. 214 p. ■ ■ 97 Wyatt, F. A. 1945. Fifteen years experiments on the Gray Wooded soils of Alberta. Sci. Agr. 25: 626-635. Wyatt, F. A., Newton, J. D. and Ignatieff, V. 1939. The use of fertilizers in Alberta. Circ. No. 23, Coll. Agr., University of Alberta, Edmonton. Wyatt, F. A., Ward, A. S. and Newton, J. D. 1927. Nitrate pro¬ duction under field conditions in soils of central Alberta. Sci. Agr. 7: 377-384. Zahner, R. and Stage, A. R. 1966. A procedure for calculating daily soil moisture stress and its utility in regressions of tree growth on weather. Ecology 47: 64-74. APPENDIX A. YIELD OF BARLEY (q/ha) FOR 1964-1967 SITES - 98 - CN o’ ID ro rH ro CN CN VD ro in 00 uo o O’ P** CD CN O' VO P* ro CN ro o- ro O p* 00 in O CT* uo Or rH o UO UO ro VD UO CN O^ CN o UO ro p* CN CN CN CN CN CN CN ro CN CN CN ro CN CN (N CN ro ro vD in o O' in O ro ro o' rH O’ P' 00 in rH O' vD VD CO 00 CO r» O O rH oo OO rH o' CN O' in CO a* rH VD CT* CN O' P> uo CO P- O' CO CN P' CO CO uo O' CN CN CN CN CN CN CN ro CN rH ro CN CN CN CN rH rH rH CN CN CN CN r—i rH ID p* ro CN CO P- CN p* in o' uo ro CO ro O' O o ro CN ro ro •— 1 ro ro CN vD CT» O'* ID CN i — 1 in CN VD CN CT* CO rH uo CN o o CN O uo O CN i —i P- vD rH rH ■—i i — 1 CN CN rH CN rH CN CN CN CN VD in o o' Or rH ro rH ao CO O CN UO in in CO P» CT* O' CN uo O p- CO P' CO ro rH CO D p- rH CN cr» o' ro UO CN CT* vD ro p- CN 1—1 CN i—1 VD CN rH o CN rH rH rH CN CN rH CN CN CN rH rH rH rH rH rH rH rH rH rH rH CN CN rH rH O' in rH VD CN O' CT* o’ VD m CN CT* rH CN O O' oo vO CO rH UO rH VO O' CN ro ro CN rH ro CN ro rH in rH CO O' CN VD CN ro O CO CN P- O ro O in CN CN CN CN ro ro ro ro CN rH CN CN ro CN CN i—1 rH rH CN r—i rH ro i—1 i—1 vD in o in VO ro rH i—1 P- *D O ro UO i—1 *D p" r—1 in rH CN O' i—1 i—1 O CN vD vD i—1 o' ro r" CO O CN ro *D P- CT* CN O' CN uo ro O' UO CO o r—i in rH ro vD CN CN CN CN ro ro ro CN CN rH ro CN ro CN ro i—1 rH rH ro ro CN (N rH rH or o’ ro CO CN P- C0 O i—1 o’ in CN O CO vD uo O' O’ vD vD oo CT* VO CN CN ro o' O CO CN in in vD P- CN p* VD UO UO vD CO CN ro CO ro UO CO rH r** rH rH rH 1 — 1 ■— 1 i — i rH rH rH i — i rH rH rH i — 1 rH rH rH i — 1 rH vD ro O ro o CO VD o o o ro o’ CT* CN D CO CT* CO ro 00 OO in CN in in CN VD i — 1 CO in p" p* o rH p- CO CO CN O' VD O’ CN P- OO in uo oo VD VD i—1 OO rH rH 1—1 rH rH rH rH rH i — i rH rH rH rH rH rH rH rH rH rH V o o' CN o' CT* P* >—1 CN o or CO P- CN P" CT* p- P- P" p' oo ro O' ro O' -p CN 03 p* CN O' O' ao CN CT* m ID ro in O' O P* O' o* CN O' O' ro uo O ro vO in u •— i CN CN CN i — i CN CN CN CN ■—I CN rH ro CN CN i—i t —1 rH rH i—l CN ro rH rH vD •H ro i-H o a p- CT* vD CN or P- CT* o o’ CO CT* CN CN P* O uo P- o CN Oo CN rH O' UO Q) i — 1 U o r- O' o P' O CN p* rH p' UO p- i — 1 ro uo UO O' O' P** oo O’ ro UO CN rH CN CN rH CN ro CN CN rH CN 1—1 CN CN CN rH rH 1—1 rH rH CN CN rH i—1 in D vD in o 00 O' 1—1 VD vD vD o CN CO vD UO CO CN o 00 VD OO rH CO CN o CN i — 1 o CN CT* O' CO O' rH r- CO CO i — 1 P- rH O P- CO O O' ro ro CN O o’ O CO CO o p- m CN D O' O’ CO oo D O' CO O' CO VD i—1 O’ O’ VD CN CN CN i — i rH CN CN CN CN rH CN rH 1—1 rH CN rH rH rH r-H rH i — 1 ro rH rH vD O in <— 1 P- vD r- i — 1 CT* CN P* O' O’ vD rH CT* vD (N o i—1 ro CO CO CN O' vD i — 1 CO ID rH p* CN o’ O’ CD CD in O rH D D ro UO uo OO O' UY VD rH rH CN ro CN ro CN CN O' ro ro CN CN O' CN ro rH rH CN rH rH ro ro rH CN o* VO ro CN p» ro P* D CN O' *D O CT* P* a* 00 CO O’ VD o CN rH OO O’ CN vD CO o CT* ro 00 CO P" CN CT* CO D r-H o rH OO UO VD CO VD P- m CN ro CN CN ro CN CN CN CN rH CN CN CN CN CN CN CN CN rH CN CN CN rH rH vD 1 —i o CN O' CT* CN CO m O CN vD UO in ro CO rH CN P- O P- O’ O O'* UO CN i —1 o r> ro ro o CN CN I—( O O'* CT* i —l CT* OO oo oo P" vD 00 U) VD CD ro O ro CN ro ro ro ro ro ro ro CN CN CN CN CN CN rH rH CN r-H CN CN CN CN CN rH o' ro CT* O O *D ro ro ro P" rH vD OO O CO OO O O' rH VD CN CN rH CN ro CN CO O in in i—1 o o' 00 P> ro rH CO P* rH CD P- o rH O'* CN OO rH o' rH i —1 rH CN r—i rH CN CN rH 1—1 rH rH CN rH i — 1 rH CN rH rH rH rH CN r-H vd o ro VO CT* CO in O CO CN CN O UO o CO ro rH P" CO OO CD CN ro CN CN rH CN CN i — 1 rH rH CN rH CN CN CN rH CN i — 1 CN rH CN rH rH CN CN rH i-H Eh o H o CN ro o’ uo D p* CO CT* o <—1 CN ro O’ UO vD P' CO OO O rH CN ro O' >: 2 rH rH i —1 rH rH 1 — 1 rH rH rH rH CN CN CN CN CN •• . . . ' APPENDIX A. (continued) - 99 - CM r- rH rH o co CO CO rH VD r-* in VO VO in VD r- ro in O’ VD vD CM O’ CO pH VD CO CO CO CM rH C" CM o CM vD in o VD P" in ro rH O’ 00 r- r-* co PO PO CM OP CM CO CO CO CM ro ro PO ro ro CM PO ro ro PO VD in CM rH vD vD CO O'* in CO O' in CM r- CM r- 00 O’ •H ro o’ CT 00 O CO ro CT o* CT CO o in rH vD in O’ CM vD o- O in O O’ o VD CM CO vD o rH CT CO CM CM CO CO CO CM CO CO rH ro ro CO ro ro rH rH CM CM CM ro CM cr CO o’ cr rH rH rH CM rH VO cr VD CM CT ro 00 ro 00 PO r- in O ro CM rH O ro CO o’ CO 0“ CM PO o- in CT* in VD ro o* r- 00 CM rH CM in ro ro ID rH CM CM rH CM CM rH CM CM ■ — i CM CM CM CM CM CM CM CM vD in CM rH rH i — i CO rH VD in CM in O CM cr ro CM CT r- co vD ro CM ro O’ CM r- m CO in CO rH CT CM ro 00 in r- O’ O' (T ro in CT O’ O’ CM O' VD CT rH rH rH rH rH CM CM CM CM CM rH CM CM rH rH CM CM CM CM i — 1 rH O CM in r- CT VD CM I"" CM CO CM CM CM r- O rH o’ o CO CO 00 co in rH in rH rH 1 — 1 CM rH rH rH CM rH rH rH 1 — 1 rH rH CM rH rH rH rH vO m CM rH VD o vd pH o O’ 00 vD c- r- in o’ o PO 00 CO r- ro ro CT in CT in ro r- vD o in VD (T CO O O' CT* ID CM O’ ro 00 CM r- ro PO in O’ CO CT O rH rH CM rH »H rH i — 1 CM rH rH rH CM CM CM rH rH rH pH CM rH rH CO 00 O’ o o' CM in VD CM CT* CM CM O’ CM in pH o rH CM o C' rH CO ro CM CO rH VD o’ CM in CT* pH r- ro CM CO ID ro pH VD 00 ro O’ ro a* rH r- rH r- CM CM CM CM CM CM CM CM CM CM CM CM CM CM ro rH rH CM CM CM rH CM rH CM vD i—i CM rH pH (T> ao rH CO VD co r* CM CM ro O O’ vD rH VD (T CM VD CT in O’ ro CM r- in in CO VD VD in ro ro VD 00 in VD CO CO CM rH r- O'* vD O'* ro CM CM CM CM CM CM CM CM CM CM CM CM CM CM rH 1—1 rH CM CM rH rH CM rH CM O’ m CT in ro C- o vD CO CO in vD CO CM ro VD in ro pH rH CT O’ rH rH CM o* c- CT CO r- in CT o* cr in vD CO o CO rH CT (T 00 in PO O rH 00 O CM CM r-* r- m CO rH vo ro CM in pH CT ro in CT O PO rH o in 00 O’ CT r- O’ CM CM CM CM rH CM CM CM CM CM CM pH CM CM CM CM CM CM CM CM rH CM pH CM vD CM O' o’ VD VD O’ CO CM CO VD r- O’ -12" 12- 24" 24- 36" 0365 1 3 3 2 0 4 0 2 2 6 6 6 1 386 248 306 380 12 5 12 3 15 1 15 8 12 9 13 1 12 0 11 7 2 3 5 0 1 10 2 0 2 6 8 4 0 252 200 240 304 12 5 11 5 14 1 16 1 14 6 12 8 12 9 12 2 3 2 4 1 2 4 2 4 4 6 12 0 3 198 206 404 306 12 8 11 8 18 2 14 8 15 5 14 1 13 2 12 4 4 3 2 3 1 6 4 10 2 3 8 0 6 312 230 440 356 15 2 13 9 17 2 18 2 12 7 13 3 12 9 10 5 5 5 2 4 1 10 4 10 4 3 15 0 3 308 308 368 392 14 2 13 4 17 7 16 2 13 6 13 1 11 9 12 8 6 3 3 1 1 10 4 16 4 14 8 6 9 172 354 318 476 11 1 15 3 14 9 16 5 13 9 12 8 13 6 11 1 7 3 2 2 2 4 0 8 2 9 3 0 0 262 204 386 440 14 0 12 3 17 0 17 7 14 9 14 8 13 7 13 2 8 3 2 0 2 2 2 4 4 9 0 3 0 294 330 400 408 13 5 15 7 14 9 21 8 12 9 15 2 12 3 12 2 9 2 2 2 1 2 2 2 2 6 9 3 0 336 300 354 352 12 8 14 6 16 1 14 3 13 3 13 0 12 8 11 0 10 5 4 10 2 6 2 8 4 6 6 0 0 268 186 384 354 14 3 10 7 19 0 16 3 13 4 14 0 12 0 11 7 11 2 4 1 1 2 2 4 2 6 0 0 0 304 230 330 478 9 1 13 9 13 7 16 3 13 6 13 2 12 1 13 1 12 3 1 4 1 8 2 22 2 0 0 0 2 324 348 436 400 14 8 15 1 17 9 17 0 14 2 13 5 12 7 12 8 13 5 3 4 2 8 2 8 2 13 9 3 0 198 174 428 330 12 7 12 2 17 7 17 4 15 3 14 4 13 2 12 7 14 5 6 3 4 8 2 8 4 0 4 1 3 324 324 432 386 14 2 11 8 17 3 15 0 13 5 14 1 11 7 12 7 15 3 2 13 1 4 0 6 2 11 5 3 0 384 204 440 360 11 0 12 0 14 5 15 5 13 9 15 8 12 3 14 2 16 9 2 2 0 2 0 0 0 6 9 10 3 200 280 404 372 12 1 13 6 15 4 16 1 13 5 14 3 12 0 13 4 17 2 2 2 2 10 4 8 4 9 4 1 4 224 342 368 348 13 3 13 2 15 4 17 5 16 5 14 0 14 2 12 5 18 2 11 1 3 4 2 2 2 5 3 3 4 276 322 404 436 12 8 15 3 14 3 17 3 12 2 14 3 11 4 12 0 19 15 5 6 9 8 6 10 2 6 4 4 0 290 240 428 224 12 7 12 6 15 3 13 5 14 3 14 9 12 6 13 8 20 4 2 3 3 4 4 2 2 6 8 0 0 230 236 342 372 14 4 10 9 15 8 15 4 14 0 15 8 13 5 13 8 21 2 2 1 2 4 4 0 4 3 5 1 1 204 182 416 392 12 0 12 9 17 4 18 0 14 4 13 3 13 1 10 8 22 5 2 3 1 8 2 6 4 3 9 0 2 304 182 388 244 14 0 11 9 16 7 14 4 12 6 14 1 12 2 13 3 23 1 2 2 1 0 0 4 2 0 4 0 0 300 260 438 424 13 6 13 1 17 9 17 0 13 8 15 3 12 3 13 4 24 2 3 1 1 2 4 4 0 6 10 0 0 180 188 404 448 12 3 11 5 14 7 14 5 13 4 13 2 12 4 12 4 0366 1 20 32 3 3 2 0 2 2 14 10 4 4 268 204 456 400 13 1 13 1 18 6 14 4 19 0 17 3 18 0 16 4 2 39 53 5 5 0 2 2 6 20 13 8 4 232 264 312 380 12 8 11 4 13 2 16 9 18 9 17 4 16 7 17 9 3 31 53 5 10 0 8 0 4 22 26 6 4 192 166 224 282 12 4 11 1 13 9 16 7 20 5 19 3 17 6 17 6 4 15 22 0 3 0 0 0 0 29 22 8 6 244 268 522 374 13 5 11 7 19 4 19 4 18 0 18 7 17 5 15 6 5 19 17 3 4 4 4 4 6 9 9 6 3 308 268 460 428 13 6 13 2 20 4 18 7 18 2 18 0 16 0 16 1 6 43 26 5 4 0 4 0 2 28 19 14 17 208 268 312 496 11 8 15 4 14 5 19 2 19 4 17 8 17 4 15 6 7 29 41 5 16 8 4 4 2 35 17 9 9 216 188 388 288 13 5 11 9 15 1 15 1 20 2 19 8 18 1 18 1 8 13 47 1 9 6 8 2 4 16 25 9 4 318 250 452 392 13 0 12 4 18 1 21 0 18 1 19 9 16 2 16 9 9 33 25 4 5 2 4 2 4 18 16 8 6 240 268 418 354 13 2 13 1 16 6 16 5 17 0 18 0 15 6 16 8 10 12 25 0 5 0 0 0 0 14 16 6 4 262 218 416 146 12 2 10 7 18 3 16 0 18 8 19 5 16 5 17 4 11 22 20 8 5 0 10 0 4 14 8 6 6 172 372 332 454 11 8 14 6 16 7 19 3 19 8 18 4 17 5 18 0 12 9 28 0 3 0 4 0 4 14 8 6 6 342 312 528 448 13 6 13 2 19 7 19 8 18 6 17 5 16 9 16 4 13 34 32 7 7 2 4 2 4 47 20 9 4 212 250 388 356 11 8 12 9 17 9 18 7 20 6 18 7 18 5 16 6 14 24 26 2 9 2 6 2 10 14 21 4 3 282 260 420 322 13 9 12 7 20 4 16 6 19 0 19 4 16 4 17 0 15 40 40 7 7 2 4 2 4 32 26 9 10 236 192 488 256 12 4 12 6 15 5 14 5 19 3 19 5 17 8 17 6 16 33 42 2 4 4 0 0 2 14 19 4 9 206 282 454 362 12 7 11 9 17 8 15 8 18 5 18 7 17 0 18 4 17 53 25 8 4 2 6 0 8 42 17 9 9 224 312 440 392 12 6 14 9 14 6 19 3 20 8 17 6 17 7 15 8 18 34 22 1 8 0 6 6 6 21 23 3 6 262 220 460 336 12 2 11 2 17 8 19 7 18 2 19 8 16 4 17 0 19 46 56 8 17 10 16 6 8 25 20 9 8 204 224 386 378 11 9 11 8 17 3 12 6 20 1 18 0 17 8 17 2 20 37 49 6 14 4 6 4 10 16 14 6 6 252 216 362 282 12 9 11 1 17 1 16 1 19 1 19 7 17 8 16 4 21 41 16 9 4 6 4 2 4 32 16 3 6 206 264 354 368 12 0 12 5 15 0 20 5 19 8 18 1 17 3 15 6 22 26 35 3 9 2 4 4 4 32 20 9 6 306 218 476 274 11 2 11 9 18 9 14 9 19 0 18 9 17 5 16 5 23 27 18 4 2 0 2 2 2 15 9 4 4 212 290 362 460 12 0 12 6 17 7 18 8 18 6 19 4 17 7 19 6 24 46 40 11 7 0 4 0 2 13 18 4 9 208 224 366 366 12 1 12 1 14 4 15 8 17 6 17 7 16 5 16 7 0367 1 23 27 9 11 2 16 2 8 12 15 2 2 280 206 306 296 11 4 11 2 18 8 16 7 15 8 17 8 16 9 16 6 2 37 30 31 22 6 2 2 2 17 12 2 2 212 212 262 236 11 1 11 3 14 6 15 0 17 8 17 0 17 2 16 9 3 23 26 15 9 2 2 2 2 50 19 2 5 196 186 200 180 11 1 10 6 15 8 16 1 18 8 19 2 16 0 16 9 4 9 15 2 6 2 4 2 2 19 19 2 2 250 228 262 228 11 1 11 7 18 3 18 7 16 5 18 0 16 8 15 8 5 23 42 9 28 2 8 2 8 7 7 2 5 252 238 316 308 10 9 12 2 18 4 19 0 15 6 16 7 14 1 16 8 6 25 38 37 25 14 10 6 6 19 10 5 2 224 252 256 294 12 2 11 6 16 8 17 4 19 5 16 8 17 8 14 8 7 16 36 33 11 12 4 2 2 59 22 5 5 218 198 288 280 13 9 11 9 16 5 18 3 18 5 18 1 16 8 17 0 8 40 46 25 13 2 6 0 2 33 55 0 2 232 238 340 280 10 2 10 9 16 6 19 9 15 2 17 2 14 2 17 0 9 15 18 12 10 2 2 2 4 12 15 2 5 238 240 250 264 12 1 11 9 16 3 17 6 15 8 16 3 16 0 15 4 10 9 40 1 7 2 2 2 2 7 19 2 2 268 218 294 312 13 2 10 2 18 5 19 5 16 5 17 8 16 4 17 2 11 46 35 39 11 8 4 8 2 15 7 2 2 186 248 244 274 10 7 12 8 16 0 17 9 17 6 16 3 16 4 17 3 12 42 51 18 14 4 2 4 4 10 5 2 5 274 276 328 286 12 3 11 7 18 8 18 0 16 5 16 6 16 2 16 7 13 24 29 23 19 10 4 8 4 26 26 5 2 236 208 368 294 11 7 10 9 20 0 18 6 20 3 19 0 17 4 17 0 14 13 52 1 25 0 8 0 8 17 19 5 2 276 220 324 324 13 4 10 2 16 8 16 0 15 6 16 7 14 6 16 7 15 20 39 16 31 6 8 2 2 15 41 5 2 294 232 238 268 12 6 11 4 17 5 14 2 19 5 19 2 17 7 17 9 16 27 26 10 17 2 16 0 2 10 15 1 5 218 262 312 268 9 4 10 7 15 8 16 0 16 8 18 8 16 1 18 3. 17 18 11 12 1 2 2 2 2 24 24 5 5 212 272 244 272 12 5 13 2 15 0 17 0 18 9 16 2 16 9 15 8 18 6 12 1 4 0 4 0 6 15 17 2 1 224 224 306 276 10 6 12 7 18 4 21 0 16 0 18 6 14 8 16 4 19 51 71 38 61 4 20 6 12 10 12 2 5 268 200 318 206 11 2 10 1 18 2 13 6 18 6 18 8 16 8 16 8 20 39 46 51 16 26 22 12 14 10 15 2 5 238 188 296 186 12 2 10 8 17 3 15 6 18 4 18 8 17 0 16 8 21 30 39 13 15 2 6 2 6 15 22 1 2 188 230 318 290 11 1 11 9 19 0 17 8 17 7 16 5 17 2 15 3 22 63 51 18 33 16 18 6 8 59 29 2 0 250 238 324 276 10 7 11 1 18 0 15 5 17 0 18 0 16 5 16 5 23 29 30 21 14 2 4 2 6 12 12 2 4 230 248 290 248 11 8 10 6 18 7 17 9 19 2 18 9 17 5 19 2 24 47 36 19 10 2 6 2 2 8 12 1 4 212 228 322 252 10 4 12 1 16 7 17 0 17 1 16 7 15 8 17 2 & MT. NO. '565 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 )56 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 )56~ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 - 103 - B. (continued) nitrate -N available-P exchangeable- K soil moisture per cent (oven-dry basis! (lb/a) (lb/a) (Ib/a) 0- 6" 6- 12" 12- 24" 24- 36" 0- 6" 6- 12" 0- 6" 6- 12" 0-6 ■ 6-12" 12- 24" 24-36" 22 2 11 7 6 0 8 6 7 11 10 4 244 306 330 330 29.8 20.1 17.8 13.9 13.2 9.7 13.1 11.3 13 10 5 2 12 4 6 4 24 24 11 9 336 360 282 368 28.5 22.3 15.3 15.4 10.9 9.6 11.2 11.8 14 14 6 6 4 10 4 6 28 25 11 6 380 308 396 336 30.9 27.7 17.7 16.5 13.8 11.1 12.5 10.1 10 11 7 2 4 4 4 4 38 23 16 0 318 174 288 328 31.5 24.3 21.6 15.2 12.6 10.1 11.4 11.1 15 11 6 2 4 2 4 4 25 22 13 6 300 300 296 372 29.2 25.9 16.0 16.9 11.2 11.0 10.1 11.1 18 17 4 6 4 4 4 8 28 20 7 3 400 272 268 324 25.9 24.3 15.4 17.3 11.8 9.5 11.4 11.0 12 12 5 5 4 4 4 4 27 18 6 6 436 360 444 362 27.3 23.2 15.2 13.4 11.8 11.5 10.9 14.4 10 12 4 2 4 4 8 6 9 19 6 4 332 328 322 360 21.7 23.2 15.5 15.7 9.5 10.2 11.2 11.3 17 6 6 1 4 4 4 4 26 19 9 9 332 296 386 324 31.2 21.0 19.9 16.4 16.7 12.6 15.0 13.8 18 10 12 6 6 4 14 8 26 16 11 2 294 178 304 250 26.5 23.2 17.8 13.9 10.6 9.7 9.8 10.4 10 6 2 3 4 4 4 6 16 16 3 6 276 294 384 286 22.8 21.2 15.9 13.1 13.8 9.1 13.4 10.2 11 10 2 4 4 4 4 4 28 23 19 . 6 308 312 238 198 27.3 23.7 18.6 15.9 11.9 11.5 10.7 12.5 13 2 7 6 8 8 6 12 19 24 11 7 306 288 290 262 27.1 23.1 18.4 16.5 12.1 9.6 11.3 9.9 10 9 3 4 12 6 10 4 16 19 9 5 312 294 304 286 23.4 22.8 14.3 17.3 9.1 10.8 11.1 9.9 • 17 10 4 8 0 14 4 12 22 23 9 6 296 240 218 282 22.8 21.6 14.9 13.7 11.7 9.0 11.6 10.5 10 10 3 6 4 8 2 6 16 22 5 4 256 268 378 324 24.2 22.3 18.0 14.1 12.6 8.7 13.9 10.6 13 6 2 2 4 4 4 8 26 17 7 4 206 352 354 306 22.1 21.1 15.1 15.6 11.2 9.3 12.8 9.9 21 20 10 6 8 8 6 6 31 24 6 9 392 322 288 294 28.1 24.4 16.6 19.2 10.3 10.8 10.0 9.8 14 11 2 6 6 4 10 4 20 25 0 9 264 312 268 290 26.4 22.7 10.5 14.8 10.2 10.8 13.1 10.1 12 15 6 5 12 4 12 6 15 26 8 8 300 206 306 158 25.8 28.5 20.3 14.4 11.1 9.7 12.9 10.4 15 10 8 7 12 6 10 4 23 19 4 8 166 290 208 294 25.6 25.0 17.4 19.5 10.6 10.3 10.4 9.6 14 8 9 2 4 4 4 4 26 16 18 4 196 274 288 360 25.8 21.1 13.0 13.9 10.6 10.1 11.1 11.4 14 4 3 12 4 2 8 4 9 23 7 11 374 336 404 308 25.3 30.5 15.7 15.7 13.6 11.5 14.0 9.9 16 10 6 4 4 4 8 4 25 16 9 4 264 344 312 316 28.7 20.1 16.5 13.0 11.7 8.0 10.3 9.5 16 6 5 1 8 2 4 0 26 17 7 9 336 354 386 342 27.9 19.8 18.0 17.3 13.4 14.4 13.9 12.9 14 5 4 1 6 2 8 4 11 11 5 0 352 352 360 408 26.6 21.4 16.1 15.9 11.2 11.7 11.7 13.4 16 8 3 3 8 0 10 2 32 19 4 3 340 294 460 308 29.6 25.9 20.6 15.7 17.6 12.3 13.7 11.6 8 10 3 2 6 4 8 4 18 21 6 9 328 366 404 432 29.0 21.3 18.4 17.7 14.6 12.4 12.0 13.6 25 10 7 1 4 2 4 4 16 14 3 13 416 328 328 360 26.9 21.9 18.4 15.8 11.9 12.5 10.5 13.1 9 11 14 3 2 4 2 10 21 9 4 3 360 328 400 366 26.2 22.0 17.6 15.6 12.6 10.5 12.5 13.0 19 8 2 2 0 4 4 B 26 28 3 4 352 344 478 368 24.4 22.9 18.7 14.7 14.8 12.8 15.0 14.8 10 12 5 2 14 2 4 8 13 22 9 6 380 386 354 420 H O' 21.6 16.3 17.1 10.9 12.8 14.5 13.1 17 9 8 4 10 2 12 0 27 16 3 6 366 340 304 418 31.8 21.9 22.5 19.1 20.6 14.4 16.8 15.0 14 9 2 1 4 8 0 12 20 21 5 5 322 316 400 344 26.4 21.6 17.5 16.0 13.8 13.0 11.4 11.7 17 5 5 2 6 2 4 4 13 18 0 9 342 322 416 352 22.6 21.7 18.7 15.1 14.5 10.1 15.4 12.3 11 13 3 3 10 2 8 8 12 14 10 4 342 352 360 404 24.1 20.6 15.7 15.7 12.4 12.6 13.8 14.2 11 18 4 3 6 4 12 2 17 20 7 0 340 300 332 282 25.1 24.2 18.6 18.2 12.2 12.7 10.8 11.6 13 14 5 2 4 0 8 2 21 17 8 9 340 316 342 348 22.3 23.5 18.1 17.2 12.8 11.7 14.0 11.8 10 11 0 4 0 6 0 10 32 14 7 7 476 294 416 330 21.6 24.1 17.0 15.4 12.7 10.9 13.2 10.5 10 8 3 2 0 0 8 2 10 11 7 13 322 330 396 344 25.9 21.2 19.0 16.7 15.7 14.4 17.6 13.6 15 7 1 2 0 6 4 2 92 23 3 6 392 356 440 324 24.3 21.9 17.8 17.2 14.0 13.7 13.8 13.5 17 10 2 1 4 4 10 2 23 39 5 8 342 344 348 354 25.0 24.2 16.9 18.0 12.2 12.7 13.5 12.5 10 16 2 6 2 2 10 6 15 14 3 9 360 316 438 316 23.1 22.5 16.6 16.1 12.3 12.2 12.6 11.9 15 17 3 7 2 10 2 8 9 12 4 8 372 318 374 280 24.2 25.0 15.9 20.7 11.0 11.9 13.6 13.2 20 18 5 5 2 0 0 0 28 20 9 5 354 322 316 296 26.9 23.8 19.6 17.4 12.8 11.9 11.8 10.4 41 14 11 3 0 2 0 2 33 20 8 2 396 332 282 342 26.7 21.0 17.2 14.6 13.5 10.3 14.2 11.6 11 12 0 2 2 6 6 2 18 19 7 5 324 312 306 360 26.1 24.1 17.2 16.0 16.9 12.9 15.7 12.5 25 8 7 1 14 2 6 4 15 15 7 4 404 362 352 348 25.7 19.5 17.7 16.9 12.5 13.6 11.8 13.2 27 15 5 2 4 4 2 2 24 15 10 4 348 328 322 274 30.3 18.7 18.7 17.5 16.1 16.3 13.2 15.3 24 24 4 5 4 6 4 4 24 19 7 7 444 378 288 362 30.7 23.8 21.1 17.6 16.3 14.8 13.0 11.9 20 20 7 5 4 8 2 8 48 26 10 7 384 282 372 312 30.6 22.2 22.4 16.5 19.8 14.8 14.6 11.0 30 19 6 3 6 4 2 4 57 50 10 5 362 372 288 348 30.3 21.9 20.0 18.0 16.4 17.0 12.2 15.7 27 28 8 11 8 8 0 8 24 26 10 7 360 372 274 272 31.6 24.2 19.9 18.8 16. 3 15.1 11.4 12.7 23 19 25 3 8 4 0 8 26 19 10 4 388 342 316 316 29.7 20.6 20.2 18.3 17.5 16.6 12.4 13.7 25 16 6 7 6 8 4 4 36 22 5 5 362 360 380 288 24.1 24.0 18.3 19.1 18.1 16.5 14.8 15.8 19 20 7 4 12 8 4 2 53 48 7 4 324 312 262 324 20.5 21.7 17.0 18.4 14.9 15.9 11.6 11.9 20 15 11 6 4 6 4 8 36 29 12 7 400 328 316 290 31.6 22.2 24.9 18.5 20.7 18.5 16.1 14.3 25 25 6 4 4 6 4 8 33 22 15 5 332 322 262 262 27.1 21.0 18.8 18.9 18.4 16.7 14.2 14.1 19 19 5 3 4 8 8 4 19 26 5 5 330 316 276 290 25.6 20.9 12.2 17.9 17.4 16.2 12.1 11.9 22 14 7 4 8 4 6 2 19 17 5 5 362 300 250 290 26.2 21.4 19.3 18.2 16.5 16.6 12.1 12.0 19 23 7 7 10 10 8 10 29 36 7 7 372 288 280 240 18.8 25.0 20.3 17.6 17.6 15.2 17.1 11.0 16 19 3 4 4 8 4 2 22 15 7 2 342 238 248 272 22.0 23.0 16.7 18.0 14.8 16.0 12.4 12.7 15 24 6 5 8 8 4 8 29 22 7 5 336 294 342 264 25.2 24.7 19.7 17.7 16.8 14.8 12.6 10.5 19 23 3 3 2 8 2 8 15 19 5 5 340 340 296 282 23.2 21.6 19.5 18.1 18.6 15.7 16.0 14.4 24 15 4 2 4 2 6 2 83 50 6 7 384 304 356 262 25.5 20.1 19.7 17.1 19.9 16.5 17.4 14.1 11 13 1 6 0 4 0 4 41 17 7 19 400 282 288 236 31.2 24.6 19.4 19.4 16.5 17.5 13.6 14.6 25 28 16 13 30 22 8 10 19 15 5 6 288 280 312 228 25.0 22.0 18.8 16.2 15.7 14.9 11.7 13.1 19 25 22 19 26 40 8 8 17 19 7 10 328 304 256 240 22.3 23.8 19.0 16.8 16.3 16.4 14.1 12.7 22 25 5 11 8 12 4 4 22 43 6 10 306 316 296 238 24.6 24.7 19.2 19.2 16.8 16.2 14.3 11.4 26 23 7 9 8 18 4 12 69 50 10 5 448 354 268 312 27.1 22.6 16.9 17.8 16.5 16.6 14.4 13.6 19 31 4 5 2 8 0 6 22 22 7 10 318 318 318 312 27.4 25.4 20.4 17.0 18.8 16.8 16.3 12.0 29 12 4 2 2 4 2 2 19 17 7 7 348 324 264 268 29.7 19.9 21.4 16.2 16.5 16.0 11.5 14.6 ' • - 104 - APPENDIX B. (continued) SITE- YEAR & TMT. NO. nitrate-N (lb/a) available-P (lb/a) exchangeable- (lb/a) K soil moisture per cent oven-dry basis) 0- 6" 6- 12" 12- 24" 24-36" 0- 6" 6- 12" 0- 6" 6- 12" 0-6 6-12" 12- 24" 24- 36" 2164 1 20 18 43 29 158 54 44 42 9 6 25 8 23 2 17 0 24 5 17 9 15 8 20 6 15 8 2 19 18 27 31 80 90 42 35 8 3 25 6 22 9 25 2 24 5 13 2 17 8 23 1 18 1 3 20 16 50 20 58 40 46 29 8 6 26 3 24 5 27 5 25 1 13 2 11 4 18 1 12 8 4 19 18 40 38 94 112 55 61 9 19 24 8 21 8 26 9 27 9 14 9 19 7 17 7 20 8 5 22 16 52 25 112 90 46 42 11 4 25 0 23 2 24 8 22 9 15 7 9 8 25 4 17 8 6 31 36 56 27 90 90 44 35 10 1 25 8 25 1 26 1 25 2 14 0 16 6 23 8 17 3 7 22 36 29 45 104 112 12 41 36 3 26 2 22 4 26 8 24 6 16 4 18 5 21 4 16 0 8 16 27 40 31 94 58 35 44 0 11 27 2 25 2 28 9 26 1 17 7 14 8 21 5 19 1 9 20 18 45 40 126 104 39 60 11 11 27 5 24 4 29 2 24 8 18 3 15 1 18 6 21 5 10 31 22 52 47 112 100 53 35 9 6 25 5 26 3 24 9 26 7 15 1 14 6 16 5 13 6 11 18 43 63 50 134 80 35 47 8 6 26 9 25 9 27 8 28 0 17 9 16 5 18 2 19 7 12 18 18 47 40 54 90 50 58 9 14 25 3 27 2 27 2 25 5 19 0 12 9 23 2 17 4 13 22 16 45 18 112 126 55 41 13 9 24 2 24 5 27 4 24 4 17 2 13 9 25 4 18 8 14 20 20 19 27 108 54 3 29 35 0 25 4 25 6 28 4 25 3 21 7 15 8 15 7 22 4 15 19 16 50 38 158 134 51 30 14 3 30 9 22 6 28 9 23 8 18 5 18 9 21 4 12 8 16 36 18 63 22 94 80 51 37 9 9 25 8 25 1 28 7 25 4 17 5 13 0 22 0 21 0 17 18 22 47 54 108 108 47 47 7 4 25 0 24 7 23 1 27 0 14 5 18 2 22 2 21 2 18 22 18 52 45 134 90 22 54 13 10 25 6 24 3 26 1 25 4 19 0 14 1 21 3 20 9 19 47 18 54 50 86 94 23 37 11 4 26 2 25 0 27 4 26 7 18 2 13 1 22 6 18 5 20 27 18 47 29 134 94 35 21 3 0 27 5 22 8 27 8 25 3 18 9 19 7 21 2 12 7 21 20 20 67 22 104 36 52 48 11 8 22 3 24 5 27 2 23 3 17 2 9 7 21 9 19 0 22 22 31 50 50 134 126 58 39 12 4 25 9 23 1 26 6 22 2 17 2 14 3 29 8 21 8 23 29 18 52 18 112 44 38 48 11 12 25 7 25 3 26 0 23 6 15 8 11 4 20 4 21 6 24 18 38 67 47 158 94 52 38 22 6 24 6 23 2 27 2 23 8 14 2 19 4 17 9 23 3 2165 1 15 8 46 12 174 56 56 35 21 9 800 588 308 220 36 2 33 7 33 9 32 0 24 3 33 2 20 2 20 0 2 28 15 22 16 84 60 41 41 7 7 558 636 212 290 39 9 31 1 33 4 30 6 20 4 25 0 18 4 20 0 3 10 7 14 9 70 34 41 46 6 16 418 476 180 272 38 3 35 0 31 0 30 6 20 7 16 2 20 8 19 9 4 9 12 25 22 158 126 45 82 6 11 428 516 162 168 38 6 36 6 32 5 42 7 20 3 24 6 19 6 17 7 5 11 9 22 21 108 58 47 42 22 6 688 500 300 230 36 6 35 7 34 6 30 9 25 3 16 3 19 6 16 2 6 19 21 27 29 110 90 45 69 4 11 600 684 250 272 41 2 36 5 34 1 31 0 21 8 25 0 19 3 20 0 7 14 11 15 33 154 106 61 44 7 3 562 472 262 220 40 4 34 4 35 7 29 8 22 8 24 6 17 6 21 6 8 69 17 18 36 56 44 70 95 3 3 498 504 218 232 39 8 36 3 34 5 31 8 22 4 19 8 17 6 16 6 9 14 12 23 27 80 100 57 78 12 13 632 600 268 178 38 7 38 6 33 2 33 4 19 1 24 4 20 8 18 7 10 5 15 18 16 118 32 49 57 14 3 380 600 204 238 38 8 36 2 32 1 33 9 22 6 24 3 21 7 20 2 11 10 13 15 20 32 90 31 57 0 20 476 756 228 324 40 0 37 3 35 8 36 4 22 8 25 0 18 9 20 0 12 13 8 14 15 50 82 51 54 28 6 956 424 452 162 37 1 36 8 36 3 42 1 25 0 20 0 20 0 19 1 13 20 6 11 18 100 64 61 54 30 11 1132 572 440 262 37 6 28 1 35 3 33 0 25 0 20 1 20 0 14 9 14 10 6 20 11 60 28 33 21 6 0 522 368 268 218 40 3 38 6 34 5 36 1 20 8 21 5 21 2 20 9 15 9 10 26 23 194 74 61 28 14 3 512 368 186 224 38 7 33 8 38 1 29 9 27 2 21 5 17 8 15 6 16 15 15 28 21 40 52 84 38 26 6 960 704 368 232 37 6 37 0 37 7 34 4 25 0 18 4 20 0 16 7 17 16 11 22 18 52 78 73 66 7 14 480 556 172 188 38 4 37 5 15 2 37 7 20 8 25 6 15 3 19 9 18 15 11 21 20 60 82 57 98 17 28 836 584 384 304 37 6 39 0 37 1 30 7 25 0 20 9 20 0 15 9 19 16 14 31 36 90 102 59 35 23 4 608 536 612 244 36 6 35 2 38 8 33 8 25 0 23 2 20 0 16 6 20 18 10 38 16 114 44 28 20 2 6 552 524 250 200 39 5 33 9 33 3 33 6 23 3 23 3 17 4 20 0 21 37 11 52 26 110 94 5 37 7 7 204 388 300 188 39 2 35 3 36 8 22 6 25 0 16 3 20 0 15 2 22 22 7 63 26 210 130 66 77 13 18 556 792 212 352 40 7 35 0 37 0 33 4 26 3 25 0 19 9 20 0 23 16 14 19 16 56 56 32 39 8 9 484 428 230 180 40 6 35 5 32 8 28 1 21 2 17 3 17 1 19 8 24 12 13 18 18 102 40 47 41 8 6 374 572 146 252 37 7 33 1 33 9 28 7 20 7 25 7 19 8 15 2 • . 105 APPENDIX B. (continued) SITE- nitrate-N available-P exchangeable-K YEAR & (lb/a) tlb/a) (lb/a) TMT. NO. 0-6" 6-12" 12-24" 24-36" 0-6" 6-12" 0-6" 6-12" 2166 1 29 23 26 28 16 18 40 36 8 9 672 460 238 224 2 16 34 22 13 16 58 36 38 6 8 524 558 182 224 3 26 23 18 17 24 12 39 73 8 16 400 472 308 218 4 14 12 24 17 30 56 67 85 14 11 504 522 204 178 5 27 27 41 39 24 40 53 69 11 16 576 552 300 220 6 29 25 43 41 64 32 58 47 10 9 556 600 238 248 7 25 29 45 34 36 46 82 73 27 3 600 528 272 216 8 18 30 30 29 26 50 48 92 4 9 464 588 230 228 9 26 11 30 35 36 40 77 76 8 10 500 552 228 162 10 10 28 23 13 18 12 91 45 23 7 912 468 212 196 11 15 17 35 49 50 60 47 87 8 7 556 424 260 198 12 17 24 11 35 18 64 35 60 3 28 584 712 294 180 13 29 27 34 12 50 38 77 127 14 17 656 558 264 262 14 26 25 40 24 18 14 66 70 8 10 562 380 276 264 15 11 29 24 33 62 46 114 54 19 2 408 600 192 218 16 30 25 25 16 16 18 44 32 7 9 594 684 186 264 17 19 37 11 23 20 24 109 71 7 4 480 424 188 200 18 27 15 19 15 16 18 98 98 14 11 616 600 224 196 19 19 16 52 39 98 36 44 29 9 4 472 460 186 206 20 35 25 43 26 114 52 30 8 6 9 454 262 218 308 21 33 25 52 35 114 60 96 73 6 16 524 444 192 208 22 22 17 51 31 142 64 73 63 9 9 444 478 204 212 23 30 35 25 29 14 24 32 58 9 17 562 600 224 182 24 16 22 17 33 48 26 56 14 19 15 562 356 172 342 2167 1 10 7 21 19 18 0 70 6 50 38 10 5 784 520 256 204 2 9 11 16 15 22 18 22 8 64 55 10 7 548 540 204 220 3 6 7 40 5 46 0 20 0 90 57 7 10 492 460 198 240 4 8 18 33 26 76 58 98 72 78 120 15 31 500 644 198 238 5 6 6 57 15 46 0 96 14 50 50 7 15 566 522 260 232 6 4 7 38 37 90 34 6 26 55 45 10 15 484 464 240 238 7 4 9 7 0 54 2 102 34 83 76 24 10 476 576 230 224 8 5 10 6 7 46 34 44 48 76 116 10 48 556 664 228 360 9 8 9 9 13 22 10 52 6 64 114 7 15 478 504 236 182 10 6 13 12 9 6 2 12 2 93 41 19 5 732 440 180 296 11 8 8 15 23 74 68 126 44 64 114 7 19 456 796 204 232 12 4 11 25 21 36 28 36 22 48 62 17 15 836 608 268 204 13 6 7 7 17 32 26 68 30 121 107 12 10 1032 492 262 236 14 4 15 22 25 36 10 70 2 64 45 5 5 496 366 244 208 15 5 3 15 20 92 26 112 20 114 116 17 10 472 712 178 232 16 7 8 9 19 38 8 14 6 43 31 19 12 696 548 212 250 17 7 11 4 9 20 20 12 4 93 121 17 15 424 500 166 196 18 7 8 18 11 30 12 34 2 114 109 15 7 784 566 182 156 19 7 39 65 34 122 66 90 78 41 17 15 17 498 344 196 316 20 7 5 26 52 136 50 88 66 36 17 7 7 600 420 206 198 21 14 1 65 34 122 8 84 78 86 109 10 12 412 416 198 180 22 28 11 80 20 150 34 144 38 144 112 12 10 496 600 188 220 23 9 10 12 10 30 66 60 72 33 144 15 15 600 456 228 200 24 12 12 17 28 22 18 70 24 48 33 17 5 420 592 152 235 soil moisture per cent (oven-dry basis) 0-6" 6-12" 12-24" 24-36" 25.4 32.6 27.1 28.1 31.3 29.0 27.8 24.0 28.6 29.7 26.6 24.0 31.3 30.3 29.6 26.6 25.5 33.0 27.8 29.3 32.2 30.6 26.0 24.3 29.3 31.7 29.9 28.8 31.9 32.4 28.1 26.8 28.5 27.2 26.3 30.4 27.4 30.2 32.3 28.4 28.4 29.0 30.0 30.3 29.3 28.4 27.3 26.3 30.3 32.3 30.1 29.9 32.2 29.3 30.5 24.6 31.0 26.4 30.2 24.0 30.5 30.0 28.5 28.9 29.1 28.6 31.6 26.1 28.9 30.9 26.2 26.8 32.1 33.2 26.3 29.3 29.9 18.1 29.2 24.0 31.6 27.9 28.8 23.0 28.6 30.4 24.8 30.6 29.9 32.3 29.7 27.7 29.3 31.4 30.9 38.8 21.6 19.4 17.4 15.4 18.7 19.5 17.7 23.2 13.4 10.7 16.1 16.3 18.3 19.9 20.6 22.8 13.9 21.2 16.3 17.2 13.6 13.7 19.8 16.8 13.8 15.4 17.6 17.4 17.1 17.8 16.9 16.2 14.2 19.9 14.8 17.1 14.4 14.7 17.1 19.2 16.8 17.1 17.9 19.6 23.0 13.0 12.9 18.2 21.6 17.7 18.8 18.8 20.7 13.3 15.6 10.9 19.4 21.4 18.3 13.7 17.9 15.5 19.7 17.8 14.5 15.9 16.5 18.0 14.0 16.0 17.3 19.1 17.0 16.9 20.5 16.0 21.6 19.3 16.8 13.4 13.4 10.7 20.2 14.7 10.3 19.6 20.4 20.4 20.9 16.2 16.2 20.7 19.4 21.2 13.6 18.7 32.7 28.5 33.0 24.5 30.8 28.7 29.9 25.0 30.9 29.2 32.1 24.5 31.4 28.8 29.5 27.6 31.2 29.4 24.3 24.0 32.2 30.8 30.5 25.8 32.4 28.8 28.9 27.4 34.9 31.4 32.1 30.8 34.1 28.8 31.8 24.2 29.6 31.0 29.3 21.5 34.0 30.0 30.9 32.5 27.7 31.1 28.2 17.8 32.7 30.9 30.7 24.1 25.2 31.3 30.2 24.8 31.1 28.9 30.7 27.9 28.9 29.9 30.3 26.5 33.3 29.3 30.6 30.5 31.2 30.0 27.8 28.1 30.2 31.0 31.2 29.6 35.8 29.2 31.1 26.4 31.7 29.3 28.2 24.8 28.4 29.2 26.3 26.6 33.6 29.7 31.1 24.3 30.7 29.2 23.8 27.1 15.0 8.8 17.4 18.2 15.1 16.8 17.5 17.5 12.9 9.8 17.4 8.4 15.5 17.7 15.9 17.1 14.1 11.4 14.8 15.6 14.5 25.3 17.8 19.4 20.0 22.9 14.4 13.8 19.7 26.6 19.0 16.9 19.4 14.1 13.1 20.1 17.7 14.7 15.3 19.7 20.7 17.6 17.1 18.4 30.3 12.8 19.3 22.1 20.4 13.6 18.7 16.5 16.6 13.8 18.1 16.5 20.4 23.9 17.8 14.0 20.1 13.7 20.7 15.5 13.7 16.3 12.5 17.8 13.6 14.1 18.1 17.8 20.4 16.8 31.2 15.2 20.9 21.7 19.7 19.2 17.3 12.3 19.6 12.1 15.1 16. 3 15.8 13.9 17.5 11.6 18.6 13.8 16.5 20.1 20.8 19.8 ■ * , - 106 - APPENDIX B. (continued) SITE- YEAR & nitrate (lb/a) -N available-P (lb/a) exchangeable- (lb/a) K soil moisture per cent (oven-dry basis) TOT. NO. 0 -6" 6- 12” 12- 24" 24- 36" 0 -6” 6- 12” 0- 6" 6- 12" 0-6 • 6-12" 12- 24" 24- 36" 1 3 1 1 1 2 2 54 49 16 14 306 304 300 400 23.1 21.8 17.0 18.1 17.6 10.3 12.6 11.6 2 2 2 2 1 4 2 51 42 21 11 208 260 276 332 20.4 23.5 15.7 15.2 17.3 12.8 13.6 13.6 3 5 1 2 4 8 2 47 54 19 20 316 412 416 294 21.4 20.6 19.5 14.9 15.0 16.1 9.9 12.7 4 3 10 3 2 6 4 38 63 11 16 380 286 360 304 21.7 21.3 19.2 18.7 18.6 17.4 11.0 15.0 5 5 2 0 2 2 2 56 58 25 13 216 328 344 374 21.1 20.7 17.9 16.7 17.6 15.7 12.0 19.9 6 2 5 2 1 4 4 55 59 23 16 264 294 342 366 22.9 23.2 18.2 15.2 17.3 12.8 12.9 13.6 7 6 1 3 1 8 0 58 51 35 9 340 348 356 380 21.0 23.4 16.2 18.2 14.8 16.2 13.6 11.5 8 3 2 2 1 4 4 55 47 11 6 282 374 344 354 21.3 20.2 14.6 18.5 17.1 16.5 12.3 14.5 9 3 2 2 2 6 4 51 72 13 22 288 304 384 322 19.1 21.6 17.4 16.1 16.8 17.8 10.6 15.8 10 3 0 4 2 6 4 58 51 16 11 236 260 332 340 22.4 23.6 19.0 18.1 17.9 16.8 12.3 11.9 11 4 3 1 1 2 2 54 58 9 15 260 280 316 408 22.1 18.9 15.0 18.7 17.5 18.2 13.6 12.0 12 4 1 3 1 4 2 65 50 16 12 256 368 304 342 22.0 20.9 15.0 18.4 16.3 17.5 13.1 16.3 13 5 0 2 1 4 2 52 60 9 15 252 286 296 374 19.3 21.8 16.9 17.8 17.2 16.9 12.3 11.4 14 4 4 1 1 2 0 59 55 30 14 288 282 352 342 22.2 20.8 16.1 17.2 17.9 17.3 11.7 12.9 15 2 3 2 1 4 2 46 55 9 17 496 288 278 352 22.7 22.8 19.4 18.6 17.6 17.8 13.8 13.6 16 5 3 3 1 4 2 54 52 13 13 280 276 340 392 21.4 27.6 18.3 18.0 16.5 18.6 11.6 15.5 17 2 2 3 2 6 6 55 55 14 16 204 280 330 288 23.6 21.8 17.8 17.6 17.2 17.2 13.4 13.7 18 2 3 3 3 4 0 45 60 3 20 328 248 238 330 22.1 21.1 18.3 17.3 17.0 17.7 12.9 15.3 19 6 4 0 2 10 2 55 46 20 8 260 322 354 396 22.2 22.7 18.3 22.0 18.0 17.9 11.8 11.9 20 5 13 1 0 0 6 56 53 12 16 262 312 286 464 22.5 22.7 18.2 20.4 18.1 16.8 13.1 11.6 21 3 1 2 1 4 2 49 47 22 19 392 276 296 348 23.1 20.3 15.4 17.8 16.3 18.0 14.7 17.2 22 3 2 4 1 8 2 48 47 13 6 378 300 432 348 19.4 22.4 21.2 20.0 18.0 17.5 15.9 12.8 23 4 0 2 1 6 2 56 55 22 23 294 296 256 300 21.1 21.2 16.1 17.3 17.4 16.6 14.5 12.3 24 2 1 4 1 6 2 61 54 30 8 296 236 308 356 22.3 21.6 17.6 18.6 17.5 16.2 13.0 13.1 2366 1 18 12 5 6 6 2 22 59 9 13 280 276 464 404 21.0 15.4 18.0 15.2 14.1 15.3 13.9 15.3 2 25 19 6 3 8 2 59 47 19 6 296 268 306 448 18.0 13.2 15.5 15.9 17.2 14.3 14.9 15.1 3 16 14 2 4 4 12 46 49 6 11 306 240 440 354 15.9 15.9 16.8 15.8 16.8 11.8 16.0 12.2 4 17 29 4 3 4 8 47 70 11 13 354 352 362 356 16.1 16.6 13.8 15.3 17.1 14.8 13.7 15.6 5 17 20 5 7 8 8 42 54 12 11 250 272 384 342 17.5 16.8 11.9 15.8 14.4 16.3 13.7 15.3 6 27 17 6 6 6 6 51 52 11 9 290 294 398 472 18.4 16.7 16.9 18.5 12.0 18.1 13.2 15.8 7 19 9 5 4 8 2 72 70 16 4 328 374 496 552 15.9 15.5 15.8 18.4 11.8 12.5 12.2 15.8 8 19 9 8 3 6 12 59 38 8 1 264 352 392 468 16.5 14.0 16.0 17.5 13.8 15.4 13.8 14.0 9 24 13 3 5 6 4 63 49 17 7 336 244 420 374 15.2 18.9 15.2 15.0 13.2 13.0 15.1 14.7 10 35 13 6 4 10 6 66 58 13 9 360 280 412 400 19.1 15.1 15.1 17.6 15.0 16.4 15.6 16.5 11 20 17 8 9 8 20 67 120 9 3 262 352 396 412 19.2 17.0 15.1 16.7 15.0 14.7 13.6 15.6 12 19 10 8 3 10 4 46 38 14 10 294 296 240 356 16.5 17.0 11.8 17.0 11.2 17.6 13.4 13.9 13 15 19 5 2 6 10 35 98 14 16 250 280 240 356 17.1 14.9 15.4 13.4 13.6 13.3 12.9 14.3 14 15 23 6 4 10 6 81 58 20 6 340 264 456 398 12.5 16.2 16.3 15.7 16.6 12.6 14.5 13.2 15 13 14 5 5 8 4 67 90 6 6 360 318 468 464 16.4 14.5 17.0 16.7 16.3 13.5 13.4 12.4 16 13 12 4 5 6 6 51 57 23 4 418 256 294 416 16.6 15.5 13.4 14.3 15.4 14.0 18.1 13.7 17 14 11 5 3 4 6 59 82 17 6 290 220 374 356 18.0 17.4 17.5 15.5 15.9 15.6 14.6 14.9 18 13 17 4 6 6 8 63 61 4 11 276 238 418 378 15.0 17.1 16.5 14.9 10.7 16.3 14.3 15.1 19 9 26 7 8 12 4 51 54 7 17 240 380 436 360 15.1 14.4 17.6 14.9 18.4 15.9 19.3 16.0 20 28 26 6 12 8 18 47 41 12 3 324 322 500 454 17.0 14.3 16.9 16.6 15.5 11.3 14.1 10.8 21 12 11 5 3 6 8 53 63 17 17 304 262 368 300 17.8 16.4 15.9 16.1 17.5 18.1 14.8 17.6 22 14 29 4 5 4 14 53 47 4 9 380 290 444 384 15.9 16.1 18.9 16.3 14.9 17.2 12.5 15.8 23 20 6 4 3 4 4 53 35 20 14 256 324 280 384 15.9 15.8 14.2 17.8 13.6 18.4 13.2 15.3 24 25 8 4 2 6 8 47 39 11 6 316 240 436 380 16.0 19.2 15.7 15.3 14.7 15.2 16.5 16.1 2367 1 19 14 14 14 8 12 4 4 78 69 12 19 324 318 378 288 16.6 18.9 18.9 13.5 17.5 19.9 16.1 18.1 2 14 7 4 6 6 6 2 0 69 72 12 15 306 276 308 362 19.0 13.6 17.6 18.0 18.0 17.8 13.9 14.1 3 8 2 7 12 14 16 4 14 86 86 22 24 316 330 252 238 17.2 20.4 12.3 15.5 17.8 15.6 15.0 16.2 4 7 11 3 10 2 8 4 6 78 90 12 15 378 290 352 316 16.3 16.6 16.5 17.0 17.6 16.3 12.8 17.2 5 10 1 8 15 12 20 6 10 50 57 15 12 230 274 294 332 15.6 19.6 16.6 16.1 17.4 18.2 14.3 17.2 6 18 8 11 2 14 12 6 6 86 52 29 10 356 372 250 368 18.6 15.7 16.0 15.9 16.4 16.8 14.2 17.4 7 11 7 11 4 10 10 4 10 83 95 22 10 300 340 374 420 16.9 15.0 16.9 16.5 17.7 17.9 13.7 17.8 8 18 2 18 2 14 8 6 4 86 88 7 7 308 330 360 362 18.1 15.7 15.0 18.2 16.2 18.8 16.1 15.0 9 17 22 14 18 16 14 6 6 83 78 17 12 340 264 330 236 15.8 22.6 14.5 16.1 15.6 17.6 13.0 17.0 10 15 8 15 8 10 8 6 2 93 86 17 12 318 328 294 308 19.3 16.9 16.0 16.2 17.0 16.8 14.7 16.5 11 18 5 9 7 22 10 4 8 95 90 24 17 322 340 228 282 19.1 16.7 14.5 15.8 16.9 18.8 13.5 15.9 12 13 8 13 10 14 6 4 2 57 36 17 7 274 288 250 344 15.9 15.2 *14.1 18.3 13.2 18.1 13.3 14.7 13 12 8 8 7 12 2 6 2 120 105 12 15 290 294 296 322 17.4 16.3 16.0 16.2 17.1 17.1 16.7 14.1 14 11 9 7 9 10 4 6 0 90 105 24 10 282 264 332 340 16.7 14.5 18.7 16.9 18.1 17.3 13.9 15.4 15 10 12 7 5 2 2 8 6 97 100 12 15 438 356 318 336 18.4 13.5 10.1 18.7 17.2 18.1 16.1 15.7 16 8 12 7 14 6 10 4 0 59 62 19 15 272 374 288 312 17.0 17.9 17.0 16.2 17.7 17.9 14.7 17.1 17 14 15 12 15 4 8 4 4 93 100 19 12 248 288 348 244 15.8 20.4 18.3 13.2 17.9 17.6 14.1 18.3 18 13 11 8 11 6 10 4 4 102 120 10 17 282 286 290 262 16.1 17.0 10.5 15.1 17.1 17.1 15.0 17.5 19 11 8 9 5 20 24 14 14 55 55 12 10 268 354 342 384 16.5 14.4 17.4 14.5 17.5 18.4 14.7 17.5 20 7 15 15 9 32 24 18 16 55 55 19 7 342 360 272 432 17.2 14.8 15.5 20.8 16.2 19.6 14.8 17.4 21 12 14 12 11 12 14 10 14 76 93 17 17 268 276 332 296 17.4 18.2 17.3 14.4 16.7 17.6 14.1 16.9 22 8 12 12 12 14 22 6 10 88 86 7 15 408 296 362 276 15.8 15.6 18.6 16.4 17.2 17.1 20.8 15.6 23 12 8 11 7 4 6 2 0 67 55 22 22 260 260 238 340 19.5 16.6 13.7 16.0 17.7 16.9 19.1 16.5 24 7 8 8 6 8 2 4 0 52 57 15 15 328 288 336 312 18.4 13.2 16.7 17.3 17.7 18.5 17.2 17.6 ■ . • ' » . •$ • ' * - - 107 - APPENDIX B. (continued) SITE- YEAR & nitrate-N (lb/a) available-P (lb/a) exchangeable-K (lb/a) soil moisture per cent (oven-dry basis) TMT. NO. 0-6” 6-12" 12-24" 24-36" 0-6" 6-12" 0-6" 6-12" 0-6" 6-12" 12-24" 24-36" 2565 1 14 14 3 6 4 12 101 153 19 20 684 999 332 428 23 6 17 6 17 9 17 4 18 3 15 3 13 5 9 7 2 9 5 3 3 4 2 59 105 11 28 432 548 206 282 24 4 26 7 17 5 17 9 16 1 18 1 13 9 16 6 3 12 14 5 8 6 16 73 125 25 35 544 876 280 432 22 1 21 7 18 7 18 1 16 1 17 5 12 2 12 1 4 9 24 9 7 8 6 85 120 79 23 616 999 684 230 22 9 24 0 16 6 15 9 15 9 15 9 11 1 12 4 5 8 14 4 4 4 6 77 114 23 26 312 296 306 256 22 0 24 2 17 6 16 2 17 9 14 9 15 6 11 6 6 15 12 9 6 6 2 101 108 17 13 792 896 240 290 25 0 24 1 16 0 18 2 17 0 14 9 15 2 14 5 7 43 24 16 12 6 4 68 164 20 42 532 999 332 324 23 7 25 5 18 6 16 4 17 0 14 4 13 1 10 7 8 20 19 5 7 18 6 114 84 14 12 772 732 224 318 25 1 20 6 17 9 18 6 16 2 17 5 11 8 14 4 9 16 22 7 5 6 2 80 104 16 25 660 848 352 206 20 0 23 8 17 3 18 1 17 4 15 3 12 5 14 1 10 11 32 3 5 4 6 79 146 20 13 562 572 230 244 24 0 24 6 17 2 18 3 16 7 15 6 13 7 11 6 11 21 16 4 7 2 2 104 110 18 28 744 984 244 260 24 4 25 0 18 5 15 3 14 9 17 2 12 5 17 3 12 8 16 2 3 2 2 85 79 16 32 660 600 348 280 17 6 21 4 16 7 15 1 17 4 14 2 13 1 12 9 13 8 28 2 10 2 6 80 149 20 35 656 584 354 432 21 7 24 2 18 1 16 3 17 5 16 1 12 1 11 6 14 13 38 5 5 2 4 80 177 20 19 624 999 304 388 22 6 23 6 17 0 16 9 16 0 16 1 13 8 11 5 15 9 14 3 9 0 6 61 131 20 15 468 816 260 280 23 5 23 3 17 0 16 6 17 0 17 3 13 5 14 4 16 9 16 3 4 4 4 82 93 14 12 608 796 280 344 21 1 22 9 17 0 17 5 17 1 16 5 13 8 12 1 17 3 14 3 4 4 4 26 82 14 15 264 596 250 206 24 9 22 7 17 3 16 1 15 1 16 0 14 2 13 0 18 9 20 4 5 4 2 82 101 55 9 632 744 250 218 21 4 23 6 13 5 17 2 15 9 16 1 13 9 12 6 19 7 12 5 12 2 10 82 130 33 16 600 536 268 352 21 2 25 0 15 8 16 8 18 1 17 0 14 8 14 8 20 20 17 5 1 2 2 104 163 13 9 748 999 424 544 25 5 24 5 16 5 17 7 19 0 15 9 13 3 16 4 21 9 14 5 1 4 2 85 90 9 39 612 720 280 272 22 4 25 5 16 3 15 8 18 6 15 7 12 4 12 5 22 5 9 0 7 0 6 71 124 26 26 456 776 206 244 21 2 25 0 16 9 15 3 16 2 17 2 10 5 17 3 23 20 9 7 2 4 0 85 89 20 28 748 584 296 238 25 7 24 5 18 4 15 6 17 2 14 0 12 6 13 6 24 14 3 3 8 4 2 90 108 28 34 584 772 208 318 22 4 25 2 15 2 18 2 16 6 16 0 14 9 13 7 2566 1 10 18 3 4 4 4 55 178 5 33 576 960 440 572 15 3 16 8 14 1 14 1 14 9 12 2 12 4 9 2 2 12 7 2 2 0 2 63 176 9 17 484 576 252 356 14 0 17 9 10 1 12 2 12 7 11 2 13 4 13 3 3 9 15 1 5 0 2 63 139 9 26 408 908 360 400 14 0 14 5 15 5 13 5 10 6 12 6 8 9 10 6 4 6 10 4 3 2 2 76 99 11 21 540 684 340 282 16 1 15 1 13 2 10 4 14 1 11 0 13 1 13 4 5 18 11 7 5 2 8 84 117 9 25 592 572 362 282 16 3 15 9 13 9 13 9 10 8 15 1 11 5 12 2 6 25 24 4 8 2 2 73 92 6 20 516 836 276 304 15 4 15 9 13 3 11 6 13 3 8 4 14 3 11 6 7 14 18 6 3 2 2 80 149 6 25 576 880 354 444 16 4 17 1 14 4 13 3 11 6 12 2 13 9 12 3 8 18 27 16 8 2 0 63 89 4 14 600 712 330 418 14 1 17 2 13 1 20 4 12 0 12 4 13 8 15 2 9 10 10 4 4 2 4 6 89 2 14 460 584 416 228 12 5 16 4 14 5 12 0 12 4 13 9 11 8 14 3 10 6 20 0 4 0 4 79 117 9 13 516 816 272 432 13 6 15 4 11 2 15 4 13 3 13 2 13 8 13 0 11 19 27 7 13 4 8 115 112 11 38 720 984 274 520 16 7 16 2 12 8 12 3 11 1 10 9 11 7 11 1 12 15 14 4 4 2 4 55 66 11 25 556 468 374 288 15 8 16 6 12 4 11 5 12 3 15 8 12 2 10 6 13 10 13 1 4 2 4 80 120 14 11 512 999 386 520 13 8 15 6 15 1 15 6 13 4 14 4 11 3 12 8 14 17 8 5 4 0 16 96 141 13 9 648 944 348 380 14 3 15 3 15 5 18 1 15 3 12 5 11 4 11 7 15 6 15 6 1 2 0 65 131 9 9 472 688 220 512 15 1 16 6 12 6 14 7 9 6 13 1 12 0 10 6 16 12 10 2 5 2 4 57 92 9 16 416 920 300 492 12 2 13 9 12 1 14 2 14 6 15 0 14 2 12 5 17 5 8 1 4 2 2 59 79 4 8 436 460 260 294 16 1 14 7 11 8 11 4 12 9 14 1 13 8 13 5 18 6 10 1 3 0 2 95 103 41 19 600 600 272 296 12 3 12 5 9 2 13 4 12 1 14 2 10 0 12 5 19 9 32 8 11 8 4 60 82 32 16 388 784 218 418 13 9 16 2 10 9 15 2 13 0 13 4 12 9 12 0 20 16 18 7 9 6 2 79 149 6 9 672 776 264 684 16 4 17 0 13 0 15 1 14 5 12 2 13 9 10 6 21 20 16 3 8 2 6 77 125 51 26 520 448 386 206 15 5 17 1 12 3 13 0 14 4 12 0 12 4 9 9 22 13 10 4 2 8 2 93 143 14 20 564 520 244 262 14 7 18 6 13 2 13 2 11 4 15 7 13 6 11 4 23 20 8 4 2 2 4 95 143 15 26 768 708 366 312 15 3 16 3 12 9 10 3 13 3 14 5 11 2 13 6 24 6 17 2 2 0 2 60 92 13 21 508 632 294 378 16 0 17 6 9 9 11 3 13 5 12 8 13 9 14 2 2567 1 11 19 12 22 8 10 2 6 67 202 10 29 492 968 342 460 20 5 20 2 16 0 14 0 16 5 16 4 15 2 12 0 2 6 12 7 5 4 2 0 4 81 83 10 36 460 796 208 324 25 5 24 9 13 6 17 2 15 3 16 3 15 3 18 2 3 4 21 8 18 2 20 2 26 95 160 19 17 600 1040 276 600 22 0 18 6 16 7 17 1 15 1 16 2 13 7 12 6 4 5 28 6 15 4 10 0 8 97 95 24 22 392 840 218 240 25 6 20 0 14 6 11 9 14 9 17 9 17 7 15 1 5 13 21 12 17 10 18 12 42 78 105 7 12 588 696 324 404 22 9 21 0 14 5 16 2 17 2 17 2 14 0 16 2 6 22 19 18 16 6 16 4 8 74 88 12 12 600 772 262 360 22 1 20 0 14 1 16 9 17 5 13 6 15 1 14 6 7 7 17 9 15 6 16 2 6 114 212 15 81 572 1000 384 384 21 7 22 3 17 5 13 3 17 0 16 1 12 5 13 2 8 8 26 22 18 6 10 4 10 100 150 15 15 744 896 264 444 24 0 23 1 14 0 16 8 16 5 16 7 14 9 15 5 9 5 15 12 13 4 6 2 4 83 95 5 15 672 584 468 220 20 4 21 3 21 2 16 7 15 9 10 9 13 6 15 1 10 6 31 4 21 2 14 2 8 83 170 19 19 572 1968 250 984 23 4 22 3 15 8 13 3 16 0 16 1 16 0 13 2 11 16 23 17 16 10 10 4 8 102 129 19 22 572 920 240 280 21 7 21 7 16 1 15 6 17 8 15 2 16 0 14 8 12 12 14 13 10 6 6 2 6 50 78 10 17 558 600 372 296 21 5 24 1 15 2 13 5 17 2 18 8 13 2 17 5 13 5 14 6 11 4 8 2 8 102 184 19 7 552 796 344 398 20 6 20 7 15 6 18 2 16 4 17 6 14 9 15 9 14 12 17 19 12 8 8 4 8 114 202 19 15 644 872 282 438 24 1 24 2 16 6 17 1 15 8 15 2 13 4 15 7 15 10 11 9 7 2 2 0 2 144 134 22 12 772 800 260 342 22 4 21 2 16 1 14 5 17 0 16 3 14 1 15 4 16 10 16 4 14 6 8 2 12 69 100 29 12 660 952 114 556 15 8 20 6 16 7 14 9 16 9 20 2 16 0 16 1 17 9 13 7 10 2 4 0 4 129 105 15 5 504 512 212 290 23 7 19 3 15 5 13 0 15 8 16 5 17 0 16 9 18 7 8 6 11 4 2 0 4 160 202 31 10 724 772 324 264 17 8 19 3 13 9 15 8 17 2 21 5 17 8 14 2 19 13 25 10 22 18 22 8 18 74 90 36 10 522 840 162 448 20 5 22 8 11 5 15 2 14 8 18 1 15 4 16 8 20 9 11 17 18 32 18 8 8 105 194 15 31 756 984 344 396 26 3 22 9 15 7 13 2 14 9 15 9 9 0 10 9 21 8 13 12 16 28 18 12 12 116 170 15 36 592 548 332 256 22 7 23 2 15 1 13 2 16 7 18 0 15 5 14 9 22 6 15 11 15 8 14 6 4 124 170 19 50 498 800 248 294 19 3 25 9 14 8 19 5 15 6 16 4 15 2 13 5 23 12 10 14 14 4 16 0 6 64 76 12 22 600 544 324 220 22 5 22 6 17 1 14 3 18 2 14 5 15 1 14 9 24 10 6 12 3 4 2 2 0 105 83 26 45 600 800 172 374 21 1 22 3 8 5 11 4 15 7 15 4 16 8 16 3 1 ■ , S APPENDIX C. REGRESSION EQUATIONS WITH SIX VARIABLES FOR SEVENTEEN SITE-YEARS, REGRESSION COEFFICIENTS (b..)*, COEFFICIENTS OF DETERMINATION (R 2 ) AND MEAN YIELDS, QUINTALS PER HECTARE - 108 - TJ a h dj «j a ) s: 0) -h \ s >1 t? in cm co coin o o co co co h o x> o o co -^i^ro rH CM CM CM rH CM rH CM CM r- rH CO ^ CD CM CM CO CM rH CM r- cp co CM fH CM CM -P c 0) •rH u •rH Ip 4H CD o u a o •H U) W CD •K * * -p * * * * * * * rtf in O rH CO O in CO O CM o r- ro ro CO CM U rH O in in CM in O

ro in P- CM rH rH o o CM o O rH CO in o CM o ro o CM < CU 2 CM rH XI CM < Oa CM CM XI CM < 2 < CM 0. XI < 2 r- CP CO CM CO co in 00 CM ro cp CM CP in CM (P CO CM CP in o p- CO ro cp CM CP rH X) co X) r- CO X> p* r- co CM ro X) X) 00 p- o o o o o o o o O o O o o o o o o I I I I I * He He He He He in (P in r* CO ro CP CM CM X) X) CM ro o CM o in co in CP CM O i—1 rH ro CP 00 p- o o o i—i o o O o o rH O o O o o o o o o o o o o O o o O o CO o o o o o o o o o o o O o o o o o o o o o o o o o o o o o o o o 1 o o 1 o 1 o o o o * * * He ■K * * * -K He He He He He X) CP r- rH X) CO X) X) o CM CM ro X) CM 1 —1 X) ro rH ro 1—1 rH CP rH o r- ro CO CO ro X) in ro in CM ro CM CM ro 1—1 CM X) O o o o o O o O O o o O O o o o O o o o o o O o O O o O O O o o o O o o o o o o o O O o O O o o o o O o o I I I I I I I I I I I I He He He He He He He He He He He He He He He He H< He He CP 00 X) CO ro in X) in CM 00 uo CO CP O'* CP rH CM o CO r* (p o X) CO ro in r* o rH 'TT CP CP CO o o o o o rH o o O o o rH o o o o 1—1 o o o o o o o o O o o O O o o o o o o o o o O o o O o o O O o o o o o o o o o O o o O o o O O o o o o till He He He He He He He He He He He He He He O X) O X) X) KT o r-H ro X) ro CP P* uo CM UO CP X) CM i—1 O r- p* r* CP CP p* o UO CM CP CO CM CM O X) X) 00 co U0 ro CM m ro o uo CP CO CP o in co X) in ro ro X) CP o • — i p- ro ro ro CM ro rH rH rH rH ro ro o rH ro o o rH o o O O o o o o o O O o o O o o o I I •K He He He He He •K He He He He He He He He He He He HC He He He He ro r- o UO o O X) rr p- CP co CM CP r- ro ro X) CP CM o rH rH 0" uo •—i O CP ro X) co X) CP CP p* CP CM X) X) X) X) X) X) X) M W rH rH rH ro ro uo uo in rH rH rH rH ro ro uo uo L/T o o o O O o o o CM CM CM CM CM CM CM CM CM CD u TJ c rd CD H A rd •H U fd > * LD o o co p LD CO p CD 00 CO P P P "M LD ID rH LD LD rH LD CD CM CM CM LD LD LD m O rH o LD CM CO o CM ■—i o o O O o o a* u rH i-H O CM o rH O o o o o o o O O o o O O O o o o O O o o o o o O O o o o 1 O 1 o 1 O o o 1 o O 1 o 1 o o 1 o o O I o 1 o 1 o * * ID p CM o o rH p CD LD LD p CM rH CD CM o P LD p CO CM LD o CD o o LD p CO CD CO CO CO LD o O co o LD p rH rH o CM P LD CD CD LD 2 V o 00 rH i—1 LD CM CM 1—1 o CM CO O'* CM rH o o o o o rH CO rH o o o o rH co CM rH o o o i o o o o 1 o i O o o 1 o i o O o o 1 O 1 * -K * * * * O'* LD ■—i rH rH CD o CO o CO co CM 1—1 CO LD CO LD o CO o O'! p lD CO CO LD LD CD CM CD CM CO CO < CM p CO CO LD LD CO LD o CM LD CO rH KT p LD a* o CM CD p CD CD CD CD CM LD LD CD p O LD •— 1 CO LD CM co i — 1 CO rH rH o rH CO rH o CM LD O o co o O o o o O o o O O o o O O O o o 1 rH O o * * * * * * * .. * -K * * * * * * * LD p CO CD LD CM CM CD 00 LD o O CM LD LD O * CM i— i 00 LD rH CM LD CO p rH LD p O'* P CM ID LD < r—1 o o LD CO LD LD p CM LD CO CO LD CD P CM 2 o i — i CD LD o rH CO CO CO CO LD p rH CD LO CD CO rH p O p LD CM U3 4J G 1 — 1 CO LD rH CO LD rH LD CO CM o CO 00 CM 4H H CM rH rH rH rH CM rH CO CM CM rH rH 1 CO 0 03 rH 03 > 1 <13 w Pi ID P LD p LD LD p LD LD p LD P LD LD P < LD lD LD LD lD LD LD lD LD LD LD lD lD LD LD LD LD H w 1 — 1 rH rH co CO LD LD LD rH rH rH rH co CO LD LD LD rd CO O o O o O O O o CM CM CM CM CM CM CM CM CM rQ Units are kilogram/hectare for soil and applied nutrient levels. variable and regression coefficient^ - 110 - TJ c rH fd in (N m CO in o o 03 o r- 00 CO CO rH o fd CD ■C r- vD o o co r- co CN rH co CD r- 03 CO >i »—i CN CN CN CN rH CN CN CN CO CN rH CN CN rH CN CO co o rH CO CO 03 O'* ro r- rH r- o VD vO r-H 'X o cr> i—1 co VO i —i CN o 03 m CO O CO CO r- CO 00 r" CO r- 03 VO in r- CO CO CO o o o o o o o o o o o o o o o o o * •K * * CD * •K * * * * •P in CO CN VO CN CN o 03 CN CO CO O CO CO in vo 03 rd co 03 CN CO CO in CN CO VO o VO CO in ^r vo 03 o in in O'* o VO o CO or CO vo r- vo O CN •H u vo vO in 03 in GO o> VO rH in m cr> co in CO rH r- CO in in CO co O'* o vo o CO vo vo co in ft 4) CN o • — i o o CN o rH rH or 1/3 o CN rH CN o CN & 1 i i 1 1 1 1 1 I 1 i CO VO CN 03 00 or vO CN co co 03 CO in in rH vO or 0* or 03 rH vo vo or 03 vO r-H CO in CN CO CO or o rH • CO r- o rH r- 1—1 or or rH o o ■—i o o in CN CN rH CO O o o o o o o rH o o o o o o o o o O 2 o o o o o o O O o o o o o o o o O o o o o o o o o o o o o o o o o o I I C/3 • CN < o a* in or vO o CO OT co o 03 CO in 03 CO CN or CN vo rH CO in CN rH CN rH or CO •— i VO CO V0 CN rH in CO CO in rH co vO m or o or o CN rH rH O o o o o o o rH O o o o o o o o o O o o o o o O O O o o o o o o o o o o o o o o o O o o o o o o o o o o o co 2 co • CN c o cj < CD < 2 in CO CO r- CO CO CN 00 r- rH rH rH or CN in or CN CO CO rH in rH rH r- rH o v0 rH r- o co r- vo o rH o o rH i — 1 O rH o rH rH rH o rH rH o o 1 — 1 o o o o o O o O o o o o o o o o o o o o o o o O O o o o o o o o o o o o o o o O o o o o o o o o o o o o x >—• o Q_ Cl. C I w CD or in in in v0 C" or in vD r- v0 r- in vO Eh vD vO vO vo vD v0 VO VO v0 to vO vo vD vo vO vO vo H s r-H rH rH co CO in in in rH i—* rH i —i CO CO in in in CO o o o o O o o o CN CN CN CN CN CN CN M CN Ill APPENDIX E. APPARENT DENSITIES AND MOISTURE CHARACTERISTICS OF SOILS FOR EXPERIMENTAL SITES 1959 - 1963 available SITE- YEAR hor¬ izon depth a in. d g/cm^ moisture per cent water, in. when sown 1/3 atm 15 atm 1/3 atm when sown 0160 Ap 0- 7 1.32 22.0 15.8 7.5 0.77 1.34 B 7-21 1.58 18.0 14.9 8.7 1.37 2.06 C 21-36 1.54 12.0 11.4 7.2 0.97 1.11 0259 Ap 0- 5 1.20 32.0 37.9 19.2 1.12 0.77 B 5-19 1.52 22.0 32.9 18.1 3.15 0.83 C 19-36 1.56 28.0 32.6 13.6 5.04 3.82 0260 Ap 0- 4 1.20 43.0 35.9 19.0 0.81 1.15 B 4-19 1.54 26.0 31.6 15.6 3.70 2.40 C 19-36 1.42 30.0 38.0 14.3 5.72 3.79 0359 Ap, Ae 0- 8 1.25 23.0 30.4 14.0 1.64 0.90 Bg 8-22 1.64 18.0 22.0 11.6 2.39 1.47 Cg 22-36 1.78 17.0 22.6 11.6 2.74 1.37 0360 Ap, AB 0-11 1.40 29.0 23.7 10.4 2.05 4.40 B 11-22 1.66 19.0 21.8 11.2 1.94 1.42 C 22-36 1.80 17.0 23.1 11.5 2.92 1.39 0361 Ap 0- 7 1.26 25.6 27.0 12.3 1.30 1.25 AB, B 7-19 1.74 17.0 25.1 12.4 2.65 0.96 C 19-36 1.64 18.8 21.8 10.6 3.12 2.29 0460 Ah 0- 9 1.13 25.4 32.5 16.2 1.66 0.94 Bg 9-24 1.46 13.8 26.7 12.9 3.02 0.20 Ckg 24-36 1.45 19.9 33.4 15.4 3.13 0.78 0560 A 0- 6 1.18 26.0 28.6 12.1 1.17 0.98 AB 6-18 1.28 14.0 26.2 10.6 2.40 0.52 B 18-36 1.36 20.0 33.3 14.0 4.72 1.47 0561 A 0-10 1.32 16.7 27.8 10.8 2.24 0.78 B 10-30 1.51 16.7 28.7 13.2 4.68 1.06 C 30-36 1.39 16.2 33.7 12.4 1.78 0.32 0562 A 0-10 1.24 25.7 25.8 10.8 1.86 1.85 AB, B 10-22 1.46 21.2 25.4 10.9 2.54 1.80 B 22-36 1.46 17.4 29.8 12.7 3.50 0.96 a Observations not converted to metric equivalents as required in scale shown for input in soil moisture budget equation. " . ■ « V . ' > 112 APPENDIX E. (continued) SITE- YEAR hor¬ izon depth a in. d g/cm3 0563 A 0- 7 1.41 B 7-23 1.56 C 23-36 1.28 0661 Ap, Ae 0- 9 1.26 B 9-31 1.49 C 31-36 1.39 0761 A 0- 9 1.38 B 9-22 1.54 C 22-36 1.53 0762 A 0-8 1.41 B 8-24 1.66 C 24-36 1.54 0763 A 0- 8 1.39 B 8-24 1.77 C 24-36 1.80 0861 A 0-12 1.26 B 12-24 1.40 C 24-36 1.47 0862 A 0-10 1.26 B 10-21 1.48 C 21-36 1.48 0863 A 0-10 1.26 B 10-19 1.38 C 19-36 1.52 0961 A 0-12 1.28 B 12-29 1.51 C 29-36 1.41 0962 A 0-13 1.38 B 13-25 1.60 C 25-36 1.63 available moisture per cent water, in. when 1/3 15 1/3 when sown atm atm atm sown 21.1 27.0 10.2 1.66 1.08 16.6 31.5 14.9 3.72 0.42 15.6 34.7 11.6 3.84 0.67 20.4 32.7 10.3 2.54 1.15 18.3 33.9 14.5 6.36 1.25 17.0 39.0 14.2 1.72 0.19 17.8 20.9 8.0 1.60 1.22 15.0 18.9 9.2 1.94 0.72 9.4 14.4 6.1 1.78 0.71 26.2 19.4 7.8 1.31 2.08 14.0 13.9 7.3 1.75 1.78 9.2 17.1 7.0 1.87 0.41 12.0 18.3 6.1 1.36 0.66 11.0 18.4 9.4 3.19 0.57 11.0 19.4 9.5 1.43 0.22 22.9 24.3 9.8 2.19 1.98 18.8 24.6 8.6 2.69 1.71 18.4 27.2 9.8 3.07 1.52 20.6 22.2 7.6 1.84 1.64 15.7 24.0 9.4 2.38 1.03 14.9 25.6 9.9 3.49 1.11 17.8 23.0 9.3 1.70 1.07 13.8 22.0 9.1 1.60 0.58 11.2 26.1 9.9 4.19 0.34 27.5 27.2 12.8 2.21 2.24 20.6 27.8 16.2 2.75 1.04 18.9 28.4 12.5 1.57 0.63 30.9 22.5 13.0 1.80 3.21 17.4 20.8 10.2 2.04 1.38 20.0 25.3 11.7 2.44 1.49 1 \ .113 APPENDIX E. (continued) available moistu re per cent water , in. SITE- hor- depth a d when 1/3 15 1/3 when YEAR izon in. g/cm^ sown atm atm atm sown 0963 A 0-10 1.31 18.4 23.2 9.7 1.77 1.14 B 10-26 1.61 15.0 20.9 11.3 2.47 0.95 C 26-36 1.63 13.4 24.0 11.6 2.02 0.29 1061 A 0-12 1.25 27.6 32.7 14.2 2.78 2.01 B 12-31 1.37 21.8 31.6 15.6 4.16 2.21 C 31-36 1.46 23.0 35.6 13.7 1.60 0.68 1062 A 0-12 1.22 33.5 32.4 16.0 2.40 2.56 B 12-30 1.44 21.7 30.8 15.3 4.02 1.66 C 30-36 1.40 23.4 34.2 13.2 1.76 0.86 1063 A 0-12 1.18 25.0 36.0 16.4 2.78 1.22 B 12-29 1.48 22.3 31.6 15.0 4.18 1.03 C 29-36 1.46 26.4 37.1 13.9 2.37 1.28 1162 Ap 0- 5 1.38 22.9 24.6 9.8 1.02 0.90 B 5-20 1.52 19.0 28.6 14.2 3.28 1.09 B 20-36 1.56 18.8 31.0 15.5 3.87 0.82 1163 Ap, Ae 0- 8 1.34 20.1 22.0 8.4 1.46 1.25 B 8-19 1.49 15.5 15.8 7.6 1.34 1.29 B 19-32 1.38 20.4 33.6 14.1 3.50 1.13 1262 Ap, Ae 0-12 1.39 24.3 23.2 8.0 2.54 2.72 B 12-28 1.55 20.0 29.1 14.6 3.60 1.34 C 28-36 1.51 18.8 29.7 12.2 2.11 0.80 - 114 APPENDIX F NOTES ON CALCULATING POTENTIAL EVAPORATION BY THE PENMAN EQUATION Introduction A large number of rather complex computations are encountered in using the Penman equation to estimate daily potential evaporation. A computer programme^ written in FORTRAN IVH was devised for these computations and used on an IBM 360/67. These notes describe methods used to compute the terms in the general Penman equation. The programme uses basic equations to calculate vapour pressure relationships from psychrometric observations. There are two restrictions to the direct application of the computer programme: (a) Calculations are limited to 153 days of the year. May 1 to September 30, inclusive. (b) A listing of maximum hours of bright sunshine is used which i is appropriate to latitude 54. Penman equation The Penman equation and modifications to meet particular situations of the evaporation surface were reviewed by Penman (1963). 6 Available from the Department of Soil Science, University of Alberta. *s . - 115 - The general equation is of the form: E fa + E a 1 where E is potential evaporation, H is the heat budget, E a is an expression for the "drying-power" of the atmosphere and the ratio is a weighting factor. Each of these terms will be discussed, but it is convenient to first describe calculations of vapour pressure relationships. Psychrometric computations Psychrometric observations are used to determine saturation (e a ) and actual (e^j) vapour pressures (mm Hg) of the atmosphere. The programme accepts sets of observations recorded in one of three forms: (a) dry- and wet-bulb temperatures (2 sets daily), (b) dry-bulb and dew-point temperatures (2 sets daily) or (c) air temperature and relative humidity (4 sets daily). Saturation vapour pressure of the atmosphere The equations of Goff and Gratch (1946) are used to compute e a . These equations are stated and discussed by List (1968) in the Smithson¬ ian Meteorological Tables (p. 350) . It is noted that: (a) Two equations are presented, describing the condition over water (e w ) and over ice (ej_) , expressed in mb. •s' - 116 - (b) The equation for e^ is called in the programme only when dry- bulb temperature is less than 32 F. (c) Two errors in stating the equation for e w were corrected in the 1968 reprint of the Smithsonian Meteorological Tables. (d) A linear correction is applied for actual air pressure. As discussed by Harrison (1965a), moist air does not exactly ful¬ fill relationships that express the ideal gas law. However, at an air pressure of 935 mb (Edmonton average pressure) the assumption of ideality results in an error of less than 0.4 per cent in computing e . Actual vapour pressure of the atmosphere The method for computing e^ depends on the form in which the psychrometric data has been recorded: (a) Dry- and wet-bulb temperatures require the psychrometric equations presented by List (1968, p. 366) to calculate e^. (b) Dew-point temperature, T^, of moist air at temperature T, is the temperature to which the air must be cooled in order that it shall be saturated with respect to water. Thus, e^ is calculated as e a at temperature T^, using equations presented by List (1968, p. 350). (c) Air temperature and relative humidity (RH) require the calculation of e a , then e^ can be calculated: e d = e a x RH/100 - ’ . - 117 - Delta (A) The A term in the Penman equation is the slope of the saturation vapour pressure curve at temperature T. A printing error occurs in the formula presented by List (1968, p. 372) for calculating A: 174209 x 10 - 1302.88 should read: 174209 x 10 ~ 13 ° 3 /gg- . T T Psychrometric constant (Y) A value of 0.65 mb/°C is assumed for the so-called psychrometric constant. Calculations based on data presented by List (1968, p. 365) and Harrison (1965b) reveal that this assumed value of Y is without error at a wet-bulb temperature of 45 F and the actual error would seldom exceed 1 per cent. t Heat budget (H) The heat budget can be divided into its component parts by the relationship: H = (1-r) R x - Rg where r is the albedo (reflection coefficient), Rj is incoming short¬ wave radiation and R B is net outward long-wave radiation. This relation¬ ship neglects horizontal gradients of temperature and humidity, an *■ * -113 - ideal situation where the site of meteorological observations is indistinguishable from the surrounding macroenvironment (this larger area being of the order of 1C)5 m2) . a more complete treatment of aspects of the heat budget has been given by Penman (1963), Sellers (1965) and Slatyer (1967). Albedo (r) Surface albedo, the portion of incident solar radiation that is reflected from the ground, is principally a function of the angle of incidence of the solar radiation and the nature and condition of the reflecting surface. Since Rg is not a negligible quantity relative to Rj, the estimation of H is rather sensitive to the value assigned r. In estimating the heat budget over annual crops the problem arises that the albedo of the bare soil may differ markedly from that when a complete ground cover is achieved. An option is provided in the computer programme permitting an initial albedo to be assigned relevant to the colour and condition of the soil surface after seeding of the crop. This option requires that the date of crop emergence be designated. The initial albedo is used in calculations of the daily heat budget until crop emergence, thereafter the albedo changes slowly until the albedo is appropriate to a complete ground cover. The albedos used to estimate potential evaporation in this study were not obtained by direct observation, but were estimates based on data presented by Bowers and Hanks (1965), van Wijk (1966) and Ioffe and Revut (1959). ' •V - 119 - Incoming short-wave radiation (Rj) In this study, observations of made with an Eppley pyrheliometer at Stony Plain (near Edmonton) were used in calculating daily heat budgets for all experimental sites. Penman (1963, p. 41) presented .a formula for estimating R , R I = R a ( 0.18 + 0.55 n/N), where R A is the theoretical maximum solar radiation that could reach the site in the absence of the earth's atmosphere and n/N is the ratio of actual to possible hours of bright sunshine. This formula takes into account the amount of cloud cover, but not the type of cloudiness. Net outward long-wave radiation (R B ) In the computer programme a formula presented by Penman (1963, p. 41) is used to estimate daily R B , r b = OT 4 (0.56 - 0.09 e d *2) (0.10 + 0.90 n/N), where e d is actual vapour pressure of the air, n/N is the ratio of actual to possible hours of bright sunshine, T is mean air temperature (°K) and a is the Stefan-Boltzmann constant (= 1.98 x 10 - ^ mm f^O/cm^/ day/ ° K 4 ) . It is noted that regional observations of R^ were available but, since instruments for long-wave radiometry are generally unreliable, it was decided that a calculated value of R would be more suitable for B estimating the heat budget. ■ ' - 120 - Drying-power of the atmosphere (E a ) The equation of the drying-power of the atmosphere, appropriate to a crop surface, was presented by Penman (1963, p. 42): E a = 0.35(1 - u/100)(e a - e^), where u is wind speed (miles/day) at a height of 200 cm. The terms e a and e^ have been described. A sub-routine in the computer programme permits estimation of u from wind observations are made at heights other than 200 cm. The relationship expressed by the power law is used: u l /u 2 = < z l/ z 2 >P ' where u-^ is wind speed at height z-^, U 2 is wind speed at height Z 2 and p is a variable depending upon the stability of the air layer. Based on evidence presented by Sutton (1960) and Sellers (1965) , a value of 0.20 was chosen for this exponent. It is noted that while values of p given in the literature range from near zero to 0.85, the value 0.20 is compatible with evidence obtained at heights from 2 to 15 meters at wind speeds in the moderate range. / - .