STRUCTURAL-AGGREGATE COMPOSITION AND SOIL WATER RESISTANCE BASED ON TILLAGE REGIMES IN SOUTHEAST KAZAKHSTAN

The promotion and rational development of drylands employed two tillage regimes (plowing to 20–22 cm and no-till) during the spring wheat and barley cultivation in Southeast Kazakhstan. The results established that the no-till scheme contributed to forming an excellent aggregate state of the arable soil layer for spring wheat and barley (65%–69%). The water-resistant aggregates were the highest with no-tillage (19.3%–21.8%), indicating the unsatisfactory water resistance of the soil structure. Enhancing the water-resistant aggregates requires using organic fertilizers to improve the establishment of perennial grasses, green manuring, and cover crops. No-till system inclined to boost the optimal soil density from a loose and slightly compact state of 1.19–1.23 g/cm3 to a dense 1.32–1.39 g/cm3. According to crop cultivar and tillage methods, the spring wheat and barley grain yield varied between 2.84 and 3.89 t/ha. High grain yield came from the spring barley cultivar Symbat. Spring showed promising performance when the plowing level was 20–22 cm and inferior only by 0.25 and 0.15 t/ha with no-till. Based on the two-factor analysis of variance, the cultivar contribution to the spring wheat and barley grain yield buildup depended on the shares of crop season of the research (year – environment) (40.9%–62.2%) and the tillage regimes (22.4%–32.2%). The grain yield formation was more dependent on the studied crops and their cultivars, and the dependence increased over the crop seasons due to weather conditions during the crop period.