Comparison of the efficiency of soybean microirrigation under extreme conditions on rice soils

The purpose of the article is to experimentally compare the effectiveness of drip and subsurface drip irrigation when growing soybeans in extreme conditions in the absence of precipitation and the presence of high daily air temperatures on rice soils in crop rotation stubble crops. Материалы и методы. Comparative experimental studies of drip and subsurface drip irrigation were carried out, in which the moisture content of rice soil was maintained within 80–90% HB in a soil layer of 0.5 m, in lysimeters 1.25 ? 2.7 ? 0.7 m in size, which were Botanical garden of Kuban State Agrarian University. Sowing of soybeans on rice soils in a lysimeter was carried out in 2 rows with a distance between rows of 0.5 m to a depth of 0.05 m from the soil surface in 2 variants and 2 repetitions. The germination of soybean seeds in soil from a rice field stubble under extreme conditions with subsurface drip irrigation (SDI) is 1.28 times higher compared to drip irrigation (DI). With SDI, the duration of the growing season of soybeans is reduced by 12-13 days in comparison with DI. In the phases of branching, flowering and maturation, the height of soybeans at SDI was 3.6, 4.1 and 5.9 cm higher, respectively, compared to DI. The number and mass of beans, with SDI is more by 24.2 and 24.1%, respectively, in comparison with DI. The average soybean yield, for the same irrigation rate of 3325 m3/ha, with DI and SDI is 2.77 and 3.42 t/ha, respectively, that is, the yield of soybean with SDI increases by 23.5% compared with DI. The total water consumption was 4875 m3/ha, with an average water consumption coefficient of 1761 and 1426 m3/t for DI and SDI, respectively. Thus, for the same irrigation rate, the average water consumption coefficient decreases with SDI by 19.0% compared with DI. The reason for the difference in results between DI and SDI is the high air temperature and evaporation from the soil surface. With DI, irrigation water does not have time to fully reach the root system of plants.