DIFFERENT TILLAGE REGIMES' EFFECT ON SOIL-WATER PHYSICAL AND AGROCHEMICAL PROPERTIES UNDER THE ENVIRONMENTAL CONDITIONS OF SOUTHEAST KAZAKHSTAN.

For improvement and rational use of rainfed lands, a study on the influence of different tillage methods proceeded on the soil-water physical relationship and soil agrochemical properties in Southeast Kazakhstan. In the arable soil layer (0-30 cm), the soil density during the studied crop's life from sowing to harvesting, enhanced to a medium compacted state with the traditional method of tillage (1.28-1.29 g/cm3), slightly higher with the minimum tillage (1.30-1.31 g/cm3), and the highest with zero tillage (1.32-1.33 g/cm3). Tillage with better crumbling, dissolution, and superior ingestion of plant vestiges in the cultivated soil layer contributed to a slight decrease in soil density, both with traditional and minimum tillage regimes. Given the least rainfall in summer, there was a decline in the productive moisture reserves in the soil with customary tillage (15.9-34.5 mm). However, the soil moisture enhanced gradually with reduced tillage, i.e., minimal tillage (20.7-36.7 mm) and zero tillage (29.8-54.8 mm). The nitrate nitrogen content in the soil also decreased from the initial state to the cultivated crops' harvest, and a significant decrease emerged with zero tillage. The prolonged rainless period, accompanied by a decline in relative air humidity, soil moisture, and temperature increases, affected plants' physiological processes and, eventually, the studied crops' yield. In the studied crops, on average, acquiring the highest yield of 1.76 t/ha was with minimal tillage. Based on two-way analysis of variance (ANOVA), the contributed share of the crops in the grain yield formation was according to crop season, ranging from 0.73% to 2.89%, and the soil cultivation methods' share was 83.3%-93.8%. The grain yield formation has a greater dependence on the tillage regimes, although that reliance might vary in association with weather conditions during the crop life. In rainfed conditions of Southeast Kazakhstan, zero tillage results in a significant reduction in nitrate nitrogen compared with conventional and minimum tillage. Therefore, with no tillage, more nitrogen fertilizer is necessary than usual plowing and the application of potash fertilizers, regardless of tillage methods. [ABSTRACT FROM AUTHOR]