Application of calcium sulfate to a soil with a high concentration of sodium of natural origin

Abstract

Soils with excess sodium of natural origin increase the concentration of exchangeable Na with depth. These soils are unproductive due loss of macroporosity and the negative effect on plant metabolism. Gypsum improves the properties by displacing excess Na by Ca. To evaluate the effect of gypsum on a soil with excess Na of natural origin and implanted pasture (Festuca arundinacea), was installed two contiguous experiments of plots arranged at random: Experiment 1, four doses (1, 2, 3, 0 Mg ha^-1) of two gypsums; and Experiment 2, three doses (0, 0.6 Mg ha^-1 of sulfur, 3 Mg ha^-1 of three gypsums). After 420 days, in the plots of Experiment 1 where the amendment was applied, the exchangeable Na was reduced by 22% with a parallel increase of 10% of exchangeable Ca, presenting greater penetrability and soil moisture and around 50% higher yield from the pasture. Meanwhile, in Experiment 2 there were similar yields for the amendments, although the absorption of sulfur was 5 % higher by the pastures with gypsum. Concluded that agricultural gypsum is effective for reducing exchangeable Na in studied soil depth, an increasing yield and improving pasture quality. Due natural source of Na cannot be isolated, the effectiveness of the doses and sources of gypsum should be studied a long term.