SOYBEAN RESPONSES TO LIME AND GYPSUM AND ION LEACHING INTO THE SOIL-PROFILE

An experiment was carried out in order to determine soybean responses to limestone and gypsum and to evaluate ion leaching along the soil profile. A randomized complete block design was used, with four replications, in a split-plot experiment. The treatments consisted in incorporation into the plow layer of 0, 3, 6 and 9 t/ha of limestone (main plots) and of gypsum (subplots). The results showed high soybean response to lime and no response to gypsum. Liming also increased the leaf contents of N, P, and K. Liming increased the contents of Ca and Mg down to the 40-60 cm soil layer. Gypsum increased Ca and Mg leaching along the soil profile, but its effects were short-lived. Ca and S-SO4 applied after gypsum had leached beyond the 40-60 cm soil layer 18 months after application. Gypsum also increased Mg losses by leaching.