Effect of Added Elemental Sulfur on Soil pH and Phosphorus Availability in Sandy Soils

Abstract

Phosphorus precipitates out of soil solution and becomes unavailable for plant uptake as soil pH and Ca content increases. The reduced P plant availability in soils with pH >7.0 and Ca concentrations >1000 mg·L–1 renders soil tests using Mehlich 1 extractant ineffective because the acids that make up this extractant can dissolve precipitated P and reflect soil P concentrations not available to plants. The effect of lowering soil pH with S to increase plant availability of fertilizer P is of interest to growers, environmentalists, regulators, and the general public because of improved P availability to crop plants and possible impact of increased S concentrations on the environment. The objective of this field study was to determine the length of time soil pH was reduced by application of S in polyethylene-mulched beds and the subsequent affect on growth and productivity of tomato (Solanum lycopersicum L.). Sulfur was applied to two selected fields at two rates in combination with four P rates. It was determined that the soil pH reduction from the initial S applications rates equivalent to 280 and 560 kg of S per hectare applied only in the planted row lasted less than 60 days and had minimum effect on P availability during the entire crop growing season.