Soil chemical attributes and soybean performance as a function of acidity management and cover crops

Agricultural soil acidity reduces soybean yield significantly, requiring correction, especially in current systems involving no-tillage (NT) and precision agriculture. The objective of this study was to evaluate the soil chemical attributes and soybean performance after cover crops and acidity management with liming by Ca and Mg saturation in the effective cation exchange capacity (ECEC) and gypsum application at variable rates to increase subsurface Ca saturation. The experiment was carried out in Guarapuava, PR, Brazil in an Oxisol, assessing two factors, (1) cover crops: fallow, oat + turnip and polyculture; and (2) acidity management: without correction and areas with lime (calcitic + dolomitic) or lime + gypsum. The soil chemical attributes were evaluated: pHCaCl2; exchangeable Al; H+Al; Ca; Mg; S; V%; Ca/ECEC and Mg/ECEC. The chlorophyll index and soybean performance were evaluated through yield components. The liming recommendation for saturation of Ca/ECEC and Mg/ECEC increases pH, base saturation, and exchangeable Ca and Mg contents and decreased potential and exchangeable acidity in the 0-0.1 m layer, independently of the addition of gypsum. Oat + forage turnip accumulate more Mg and increase base saturation in the 0-0.1 m layer compared to fallow and polyculture. Gypsum application effective in increasing Ca contents in the 0.1-0.2 m layer, after five months. The lime mixture, associated or not with gypsum increased the soybean yield.