Sulfate retention and release in soils at Panola Mountain, Georgia

Inorganic sulfate pools, sulfate sorption characteristics, and Fe and Al fractions were determined on soils at Panola Mountain, a 41-ha forested watershed in the Georgia Piedmont. Sulfate sorption properties of these soils fall along a continuum between two end members. The "low-adsorbing' end member comprises shallow soils (0-10 cm), with high water-soluble sulfate (Sw), low phosphate-extractable sulfate (Sp-w), high organic matter, low sulfate retention ability, and high sulfate adsorption reversibility. The "high-adsorbing' end member comprises deeper soils (>10 cm), with higher total native sulfate (mostly as Sp-w), low organic matter, high sulfate retention ability, and low sulfate adsorption reversibility. Sulfate retention was only weakly related to Fe and Al fractions, possibly because of inhibition of adsorption by organic matter. Sulfate concentrations in surface waters reflect the spatial distribution of soil sulfate retention properties. -from Author