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1015. Bowren, K.E. (ed.).. 1986. Soil improvement with legumes.. Saskatchewan Agriculture, Soils and Crops Branch.
This excellent publication summarizes research over the past 40 years pertaining to the use of legumes for soil improvement in Saskatchewan. The role of legumes in maintaining soil nitrogen was crucial prior to available fertilizer. But their value extends beyond their nitrogen contribution to the improvement of soil physical properties. One study found the tillage draft requirement to be up to one-third lower where legumes had been a regular part of the rotation. The positive effects of alfalfa were measured for over ten years in a series of wheat crops compared to plots with no alfalfa. Over 17 years, the average grain yield from a wheat-wheat/clover-clover green manure rotation with no fertilizer were 30% higher that a wheat-wheat-fallow rotation with fertilizer. Moisture depletion by legumes is the biggest hurdle to their use in very dry areas. Adequate fertility for the legumes is necessary to maximize their benefit. Use of selected Rhizobium strains can improve nitrogen fixation, especially on acid soils. Several varieties of sweetclover are mentioned with adaptation to forage or green manure use. The booklet has numerous color photos and many data tables and figures.
1165. Campbell, C.A., D.W.L. Read, R.P. Zentner, A.J. Leyshon, and W.S. Fer. 1983. First 12 years of a long-term crop rotation study in southwestern Saskatchewan.. Can. J. Plant Sci., 63:91-108.
On a crop-year basis, continuous wheat yields averaged 75% of fallow yields when recommended rates on N and P fertilizers were applied. Yield variability was lower for rotations that included high proportions of fallow than for continuous-type rotations. Fertilizer N applied at recommended rates increased yields of wheat grown on fallow by an average 5% and wheat grown on stubble by an average 7%. Application of P fertilizer at recommended rates increased yields of wheat grown on fallow and stubble by an average 12%. Total wheat production (kg/ha/yr) was inversely related to the frequency of fallow in the rotation. Continuous wheat (N and P applied) outproduced wheat grown on fallow in the 2-yr rotation by 53% over the 12-yr period.
1180. Campbell, C.A., R.P. Zentner and P.J. Johnson. 1988. Effect of crop rotation and fertilization on the quantitative relationship between spring wheat yields, available soil moisture, and precipitation.. Canadian J. Soil Sci., 68(1):1-16.
The effects of crop rotation and fertilization on the quantitative relationship between spring wheat yields, available soil moisture, and growing season precipitation were determined. Stubble-seeded wheat required 68 mm of moisture to produce the first kilogram per hectare of grain; fallow-seeded wheat required about 46mm. The lower threshold level of MU for grain production decreased from about 140mm to the values cited above; this has resulted in substantially greater moisture use efficiency in recent years likely due to better, more timely crop mangement and the improved cereal varieties.
1396. Cook, F.D., F.G. Warder, and J.L. Doughty. 1957. Relationship of nitrate accumulation to yield response of wheat in some Saskatchewan soils.. Canadian J. Soil Sci. 37:84-88.
Good correlation between wheat yields and soil nitrate levels. Estimated that a significant yield increase from N fertilizers can be expected when the nitrate accumulation value is below 50 ppm N in soil from stubble fields or 40 ppm N in fallowed soils.
1657. Doughty, J.L., F.D. Cook, and F.G. Warder. 1954. Effect of cultivation on the organic matter and nitrogen of brown soils.. Canadian J. Agr. Sci. 34:406-411.
Over 14 yr of cropping, soils lost 26% of OM and 33% of total N. Only part of the N loss is accounted for by crop removal. Some N is lost by leaching, also some gaseous loss of N other than as ammonia.
2043. Fowler, D.B. and J. Brydon. 1989. No-till winter wheat production on the Canadian prairies: placement of urea and ammonium nitrate fertilizers.. Agron. J. 81:518-524.
A practical snow management system, which utilizes no-till seeding into standing stubble immediately after harvest, has permitted expansion of winter wheat production in western Canada. This study examined grain responses to urea and ammonium nitrate fertilizer banded and broadcast at seeding, or broadcast in the late fall or early spring. A moisture shortage biased the results. Fall banding prior to seeding helped reduce volatilization losses of urea (which were as much as 50%), but presented other problems and did not outperform broadcast ammonium nitrate.
2809. Hume, L.. 1982. The long-term effects of fertilizer application and three rotations on weed communities in wheat.. Can. J. Plant Sci., 62:741-750.
The effect of fertilizer application and three rotations (continuous cropping, fallow-wheat, and fallow-wheat-wheat rotations)on the species composition of the weed community was examined using rotations that had been running for 21-22 yrs. Fertilizer application tended to reduce community differences between continuous cropping and short-term wheat-fallow rotations. With the use of 2- or 3-yr wheat-fallow rotations and herbicide application, weed problems can be minimized in southeastern Saskatchewan.
7761. Zentner, R.P., E.D. Spratt, H. Reisdorf and C.A. Campbell. 1987. Effect of crop rotation and N and P fertilizer on yields of spring wheat grown on a black chernozemic clay.. Can. J. Plant Sci., 67:965-982.
Including grass-legume forage, or legume green manure crops in the rotation increased yields of wheat grown on the unfertilized partial fallow by 15-24% and on unfertilized stubble by 33-71%; the yields were similar and sometimes higher than those obtained on fallow in the well-fertilized monoculture wheat rotations. Yields of fallow- and stubble-wheat were generally maintained over time with the application of recommended rates of N and P fertilizers, or by inclusion of legume-forage crops in the rotation, but yields of unfertilized stubble-wheat declined with time possibly reflecting declining soil fertility.
7770. Zentner, R.P., M.A. Stumborg, and C.A. Campbell. 1989. Effect of crop rotations and fertilization on energy balance in typical production systems on the Canadian prairies.. Agric., Ecosys., Environ. 25:217-232.
Non-renewable energy inputs, metabolizable energy output, and the energy efficiency of 10 spring wheat rotations were examined over 18 yr. Conventional tillage was used. Results showed total energy input per unit of land was lowest for the traditional wheat-fallow rotation (3482 MJ/ha), intermediate for N and P fertilized fallow-wheat-wheat (4470 MJ/ha), and highest for fertilized continuous wheat (7100 MJ/ha). Fuel accounted for 30-50% of the energy inputs, and fertilizer accounted for 15-49%. Pesticides were only 4-11%. Energy output to input ratios and the quantity of wheat per unit of energy decreased with cropping intensity. The average energy O/I was: F-W 3.6, F-W-W 3.3, cont. W 2.6. Rotations that included flax or cereal forage crops had the lowest energy efficiency.
9698. Nuttal, W.F., H.G. Zandstra and K.E. Bowren. 1970. Exchangeable ammonium- and nitrate-nitrogen related to yields of Conquest barely grown as second or third crop after fallow in NE Saskatchewan.. Can. J. Soil Science 51:371-377..
Exchangeable ammonium- plus nitrate-nitrogen measured to depth of 60 cm in 18 stubble fields during 1967, 1968 and 1969 in Black, Dark Gray and Gray Wooded soils of northeastern Saskatchewan was inversely related by regression analyses to yield increases of Conquest barely. The mean protein content of the grain was significantly related by regression to nitrogen soil tests. Increased yield from nitrogen fertilization resulted in a decrease in phosphorus content of the grain.