Sowing Date and Fertilization Level Are Effective Elements Increasing Soybean Productivity in Rainfall Deficit Conditions in Central Europe

Soybean yield is the result of the interaction of environmental factors and agricultural practices. Agricultural practices developed for soybean assume optimal cultivation conditions. Aberrant rainfall distribution during the growing season reduces the productivity of the plants and the efficiency of N uptake, which is reflected in the seed yield and quality. Few studies in the literature focus on this question. Therefore, the purpose of this assessment was to compare yield, yield quality of two soybean cultivars (Augusta and Mavka) with two nitrogen application rate (basic and increased) and two date of sowing (early and late), in two-year field experiments under temperate zone conditions in central Europe. Results show that early sowing in combination with higher nitrogen application substantially improves crop productivity and the efficiency of nitrogen binding, especially in drought years. In contrast, delaying sowing by two weeks reduced the productivity of the plants, which was not compensated for by a higher level of mineral nitrogen application. Early sowing of the Mavka cultivar was more productive and more efficient in nitrogen accumulation in the seed yield in comparison to the Augusta cultivar. Under water deficit conditions a higher level of urea application and earlier sowing are recommended.