Single superphosphate replacing agricultural gypsum: short-term effect on grain yield and soil chemical properties in subtropical soils under no-tillage

Abstract

ABSTRACT This study aimed to evaluate the short-term effect of Ca and S addition via single superphosphate (SSP) in each crop and via agricultural gypsum on soybean and wheat yield, and on soil acidity and nutrient availability in two subtropical soils (Acrisol and Ferralsol) under no-tillage. The experiments were established with the application of five rates gypsum (from 0.0 to 8.0 Mg ha−1) applied only at the beginning of the experiment combined with triple superphosphate (TSP) and another treatment without gypsum but with the application of SSP. Soil chemical properties were evaluated five months later, in the 0–5, 5–10, 10–20 and 20–40 cm layers. The application of gypsum linearly increased the available S up to 40 cm depth, and the exchangeable Ca only in the 0–5 cm layer, in both soils. Rates above 4.0 Mg ha−1 of gypsum reduced the exchangeable Mg in the Acrisol (0–10 cm) and Ferralsol (0–5 cm), and the available K in the Acrisol (0–5 cm). The use of SSP was sufficient to raise available S above critical levels in both soils. However, soybean and wheat yields were not affected by gypsum doses or P sources.