The influence of main soil treatment and green manure on the formation of soil moisture reserves and water consumption of soybean

Abstract

The results of research on the formation of a favorable water regime during the growing season as one of the most important conditions for realizing the existing potential of soil fertility and obtaining stable crop yields under irrigation conditions are presented. It was established that the early spring moisture reserves in the 0–100 cm soil layer during 2021–2022 were quite high in all variants of the main cultivation and amounted to 166–177 mm. Under the conditions of post-harvest sowing of green manure, the moisture reserves were greater by 4.0–6.0 mm for zero tillage in the first year and by 2.0–2.8 mm for long-term sowing in untreated soil. When plowing to a depth of 28–30 cm, more intense evaporation of water from the surface of the soil not covered with mulch occurred, which led to a loss of 10.0% of moisture, while the losses were 8.0 and 6.4% under the zero tillage options studied. The use of post-harvest green manure, compared to no green manure background, provides greater reserves of productive moisture in the soil in the pre-sowing period: with plowing — by 2.0–5.4%, with zero tillage in the first year and long-term use — up to 8.5% and 6.0%, respectively. With zero tillage and a fertilization system with the use of green manure, the share of used soil moisture in the total water consumption by soybeans increased to 5.7%. However, due to the greater density of the dark chestnut soil, which was observed in the no-till options, the efficiency of moisture use was lower than in the plowed options, which in turn led to a decrease in crop yield. It has been proven that the most efficient use of moisture for the formation of one ton of soybean crop during plowing, while the water consumption coefficient was 1280 m3/t. With zero tillage, water consumption was higher and reached 17%. However, the use of post-harvest buckwheat and phacelia crops increases the efficiency of water use under zero tillage by 5.0–10.0% and 3.0–17.0%, respectively.