The authors present the results of investigations based on field experiments and laboratory investigations conducted in 1976-1980 on typical brown soils formed on loess. The investigations comparised the effect of selected crop rotations on the dynamics of microbiological activity of soils together with an evaluation of their effect on biological productivity of ecosystems. Among the specialized crop rotations the following crop plants were considered: A - maize, sugar beets, spring barley, clover, and rape, and B - winter wheat, winter wheat, maize, winter wheat, and sugar beets. The obtained results indicate that the applied agrotechnical measures in the investigated specialized crop rotations contributed to acquire comparatively high yields - without affecting the ecological stability of the investigated biocenoses

In the northern part of the North American Great Plains the level of cultivar winterhardiness required for winter cereal production is extremely high. Therefore, for successful production in this area close attention must be paid to all factors that influence a plant's ability to attain maximum winterhardiness. In this study, the influence of date of seeding on fall growth and winter survival of winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) was assessed in seven trials grown on udic and typic boroll soils in the northcentral part of the agricultural area of Saskatchewan. In these trials, four wheat and two rye cultivars were seeded at 2 week intervals between 1 August and 15 October in each of 3 years. During this period, rye accumulated shoot dry matter at twice the rate of wheat. However, as expected, a decrease in shoot dry weight of both wheat and rye occurred with each succeeding delay in seeding date. The only meaningful winter damage that was observed in the rye was for the last two seeding dates with ‘Cougar’. The effect of date of seeding on survival of wheat was not consistent among trials. However, average survival was highest for the 15 August and 1 September seeding dates. This was 4 to 6 weeks prior to the onset of fall conditions favorable for cold acclimation. Differences in survival among wheat cultivars were not influenced by seeding date. This allowed for utilization of the Field Survival Index to evaluate the relative effects of suboptimal seeding dates on winter survival potential of cultivars. These results demonstrate that the Field Survival Index can be used to evaluate the effects of certain management practices in addition to inherent cultivar potential on winter survival.

Conservation bench terraces were cropped to winter wheat (Triticum aestivum L.) in both annual and summer fallow cropping systems. Leveled benches did not support annual cropping of winter wheat. In 2 of 4 years, available water in the surface 30 cm of soil at planting time had to average at least 3.3 cm for successful wheat establishment, and yields were 21% less than the fallowed contributing areas. Summer fallowing benches increased the amount of available soil water 1.7 times at planting and resulted in 18% greater wheat grain yields compared to yields on the fallowed contributing areas. Leveling, with or without runoff contribution, significantly increased available soil water and winter wheat yields. Lengths of contributing area did not significantly influence depth of runoff in the benches. During the course of this study, there was never enough runoff to completely inundate the leveled benches. Regression analysis of grain yield and water data predicted a maximum yield of 2,800 kg/ha with 69 cm of available water. This amount was available in only one year of the study with summer fallow and zero years with continuous cropping. Since the level benches were never inundated and the water supply for maximum yield was seldom attained, conservation bench terraces with ratios of contributing area to level-bench area of 3:1 were effective for controlling erosion in the semiarid region of the west-central Great Plains.