PROSPECTS OF SOYBEAN GROWING IN THE WESTERN POLISSIA ZONE

Abstract

Modern climatic changes, namely significant warming in the northern Forest-Steppe and Polissia zones of Ukraine, provide opportunities for growing a number of grain and leguminous crops (maize for grain, soybeans, sunflower, and others), previously unusual for this region. Among the above-mentioned crops, soybean is a crop that can significantly improve the nitrogen balance of the soil without the use of mineral fertilizers; its cultivation to some extent can be an alternative to expensive nitrogen fertilizers because, under the condition of inoculation, soybean can leave up to 80 kg/ha of biological nitrogen, which equivalent to 300 kg of ammonium nitrate, which is enough for forming decent harvest of winter wheat or corn. The analysis of meteorological data shows that when having the current amount of heat supply during the growing season in the Western Polissia zone, it is possible to grow ultra-early and early-ripening soybean varieties with a duration of the growing season of up to 90-100 days and a required number of heat units - up to 2400-2500 CHU. It was established that the main factor limiting the cultivation of soybeans on the peat soils of the Western Polissia zone is a significantly shorter frost-free period (compared to the adjacent sod-podzolic soils on dry land). Therefore, for growing on peat soils, it is necessary to choose ultra-early varieties of soybeans with a growing season of up to 85 days and the required number of heat units - up to 2400-2500 CHU. That will allow obtaining physiologically ripe seeds before the onset of the first autumn frosts, which in some years can already occur in the first decade of September. On peat soils, the yield of the Yunka soybean variety by the variants of the experiment ranged from 15,1-24,8 t/ha, while on the adjacent sod-podzolic light loamy soils it was 30,3-46,8 t/ha. The reason for the significantly lower soybean yield on peat soils is a short frost-free period compared to sod-podzolic soils, which did not allow the studied varieties to fully realize their potential for 2 years in a row. The research has established that on sod-podzolic light loamy soils of the Western Polissia zone, under favorable conditions, the yield of such ultra-early and early-ripening soybean varieties as Yunka and Astor of the Sevita genetics selection (Canada) can be up to 45,0-46,8 t/ha. The use of Rizofix inoculant in a combination with Rice Pi phosphorus-mobilizing product allows increasing the productivity of soybeans to 6,7-7,0 t/ha. Additional profit from their use is about 8-8,3 thousand hryvnias from 1 ha.