Soil water balance and soybean productivity cultivated under different water deficit levels in South Brazil

Abstract

The water balance of soil has been studied for several years, due to the detailed information generated and that help in understanding the availability of water in soil to the plants, in the development of agricultural crops and, consequently, in their productivity. The main objective of this work was to evaluate the dynamics of the water balance for the soybean crop [Glycine max (L.) Merrill.] submitted to different levels of water deficit and its impact on crop productivity. The experiment was conducted inside a mobile cover (Rainout shelter) in the period 2014/2015 and 2016, where four treatments with different levels of water deficit were tested: T1 (no water deficit), T2 (light water deficit), T3 moderate water deficit) and T4 (severe water deficit). The experimental design was completely randomized, with three replicates. Water balance variables such as crop evapotranspiration (ETc), irrigation, precipitation, runoff and soil water variation (ΔASW) were monitored daily. The results show an influence of the different levels of deficit irrigation and the meteorological conditions on the components of the water balance, the crop cycle, morphological characteristics and, yield components. A grains yield reduction was observed with the increase in soil water deficit, for treatments without deficit to severe deficit, from 42 to 11,5%, respectively, for year 1 and year 2, respectively