Vermiculite Mining Waste Enriched with Elemental Sulfur as a Chemical Conditioner for Alkaline Saline Soils

Abstract

ABSTRACT About 60 to 80% of the material extracted in vermiculite mining consists of unused waste, composed of minerals containing plant nutrients that can chemically improve the soil. The objective was to evaluate the potential of vermiculite mining residue associated with elemental sulfur in the chemical attributes of two alkaline saline soils. Two experiments were carried out in a completely randomized design in a 6 × 2 factorial scheme with four replications. In the first experiment, six doses of vermiculite waste enriched with 5% (50 g kg−1) elemental sulfur (0, 10, 20, 30, 40 and 50 t ha−1), and two alkaline soils (sodic soil and other non-sodic) were tested. In the second experiment, six doses of elemental sulfur (0; 0.25; 0.50; 0.75; 1.0; 1.25 g dm−3) and two soils (sodic soil and other non-sodic) were tested. At 30 and 105 days after soil incubation, the hydrogenionic potential (pH) values, electrical conductivity, concentrations of available sulfate (SO4 −2), phosphorus (P), and exchangeable calcium (Ca2+), potassium (K+) and sodium (Na+) were determined. The vermiculite waste associated with elemental sulfur can be used as an alternative source of K+ and contribute to reduce the pH of the alkaline soil and adding Ca2+ and SO4 −2 to the soil. However, in soils with poor drainage, this compound should be used with caution due to the risk of soil sodification. Elemental sulfur only, reduced the pH and increased the levels of Ca2+ and SO4 −2 in both studied soils and reduced levels of Na+ in sodic soil after 105 days of incubation.