SOIL CULTIVATION METHODS’ IMPACT ON SOIL WATER-PHYSICAL PROPERTIES UNDER RAINFED CONDITIONS OF SOUTHEAST KAZAKHSTAN

Abstract

For the rational use of rainfed lands in Southeast Kazakhstan, the practical study aimed to determine the influence of different cultivation methods on the water-physical properties of the soil. The results revealed that, on average, for two years, the reserve of productive moisture in the ground during the spring with plowing at 20–22 cm was 127.8–146.4 mm, with minimal tillage at 8–10 cm (132.3–157.0 mm), and with zero tillage (122.2–140.8 mm) for all studied crops. With insufficient rainfall in summer, the moisture reserve decreased to 21.5–26.2 mm with plowing, 23.5–28.0 mm with minimal tillage, and 27.8–37.6 mm with zero tillage. In the studied crops, the soil density in the arable soil layer (0–30 cm) showed significant variations depending on the methods of soil cultivation. In spring, the soil was in a loose and weakly compacted state (1.17–1.22 g/cm3), and during harvesting, it increased and became dense (1.29–1.32 g/cm3), especially with zero tillage. Soil tillage methods provided the best structural aggregate condition (58%–71%) during the growing season of the studied crops of agronomically valuable aggregates (0.25–10 mm). However, the maximum content of structural aggregates (69%–71%) was evident with zero tillage by sowing safflower, spring barley, and Sudan grass. It indicates the excellent aggregate state of the soil under natural conditions with these crops. However, its minimum amount (58%) occurred with plowing (20–22 cm) under safflower. The water-resistant aggregate content was highest in no-tillage variants of the studied crops, varying between 17.6%–18.9%. With plowing, the water resistance of aggregates decreased to 13.1% under different crops. Over two years of research, the highest average yield of spring barley (2.42 t/ha) emerged with minimal tillage, while the lowest grain yield of Sudan grass (0.67 t/ha) came from plowing. As a result, the highest grain yields of spring barley, peas, and safflower emanated with minimal tillage, while in the Sudanese grass, with zero tillage.