The purpose of research is the development of irrigation regimes together with different agricultural practices to increase soybean yields on reclaimed land under a monsoon climate of the Amur region, the definition of the development of the root system under irrigation. The following objectives have been indicated according to the given purpose: to establish characteristics and dynamics of soybean water consumption, the formation of the water regime of soil under different irrigation regimes; to identify patterns of formation of a crop depending on the conditions of the water regime of soil and sowing time. The analysis of the calculation for the optimal water regime of the root layer of soil in the cultivation of soybeans is given. As a result, a number of studies carried out on soybean crops on the territory of the Amur region, showed that the highest yields are obtained by differential wetting of the active soil layer in plant development phases. Optimal water regime on soybean forage crops in combined seeding with Payson (80 % ÍÂ) in the active layer of soil (0–40 cm) is ensured by implementation of 4–5 vegetative irrigation in a dry year. The study carried out on experimental plots on the water regime in the active layer of the soil allowed to determine that soybean yields under irrigation over three years of research at the water regime 80 % of the HB in the layer 0.3 m changed from 1.11 to 1.71 ton per ha, in variant 80 % of HB the differentiated depth changed from 1.11 to 1.79 t/ha, in option 80 % of the HB at a depth of 0.5 m – from 1.09 to 1.68 t/ha. Optimal conditions of soil moisture of root layer for the formation of the soybean root mass are marked at antecedent threshold soil water 80 % HB, when the accumulated by roots absolutely dry organic mass was on average 1.69 t/ha for research years.
Keywords: soybean, water regime, soil, yield, irrigation rate, the active soil layer, irrigation, root system.
