Aiming to evaluate the effect of gypsum on the modification of chemical properties of saline-sodic soils collected in the Irrigated Perimeter of Ibimirim-PE, an experiment was carried out in soil columns installed at the Soil Mechanics and Residue Recovery Laboratoy at the Universidade Federal Rural de Pernambuco. The treatments were arranged in a completely randomized design with factorial arrangement of two soils (S1 and S2) and seven levels of gypsum requirement (50, 75, 100, 125, 150, 175 and 200%) determined by the Laboratory Method Schoonover-M1. The gypsum was incorporated in to the soils, in three replications, totaling 42 experimental units. The parameters evaluated were: electrical conductivity (EC), soluble cations and sodium adsorption ratio (SAR) in the saturation extract of soil. The level of the 100% of gypsum requirement caused decreased in sodicity values of SAR under 13 (mmol L-1)½, presenting itself as an effective method in reducing the levels of sodium in areas affected by salt. The water depth equivalent to three times of the volume of pores (3VP) decreased the EC of saturation extract to values < 4 dS m-1, being so indicated for soil salinity correction.
sodium adsorption ratio; water depht; gypsum requirement
