USE OF SYNTHETIC GYPSUM (FDG) IN AGRICULTURE AS AN AMENDMENT OF SOILS WITH SALINITY PROBLEMS

Abstract

Salinity and sodicity of soils are problems that cause a decrease in crop yield potential and an imbalance in the soil matrix. The aim of this study was to evaluate the use of synthetic gypsum (FDG) derived from coal-fired power plants, and compare its performance against naturally mined gypsum
in a Sodic Haploxerert. The experimental design was completely randomized factorial arrangement of three treatments with three replicates (3 x 4). The treatments were: T0: control; T1: natural gypsum (1.9 t ha-1); T2: synthetic gypsum (1.9 t ha-1). Four irrigation applications of 150 mm each were used
per treatment until reaching 600 mm. The soil analysis showed high levels of electrical conductivity (EC = 2.5 dS m-1) and sodium (Na+ = 14 meq L-1), and a slightly alkaline pH value (pH = 8.6). The sodium adsorption ratio (RAS) was medium (RAS = 4.26); synthetic gypsum did no show significant differences (p < 0.05) in terms of sodium removal compared to natural gypsum, reaching EC and Na+ values that were higher than those recorded in the control. The best results regarding sodium removal were obtained after the first irrigation application (150 mm). This indicates that, given the test conditions, natural gypsum can be replaced by synthetic gypsum, resulting in water savings in the proposed soil remediation.