Sulfur transformations in forest soils collected along an elevational gradient

Abstract

15S-labeled inorganic sulfate was incorporated into organic matter from A-horizon soils collected along an elevational gradient. These samples formed between 0.7 and 1.7 nmol S (as organic S) g −1 dry wt. Soils with high moisture (65%) and high carbon content (8.4%) exhibited higher rates of organic S formation. Of the organic S generated. 33–44% was mineralized (mobilized) during 24 h. Samples containing high concentrations of indigenous sulfate exhibited lower rates of mobilization and vice versa. Assays of samples collected over the gradient demonstrated that pH decreased as carbon content and sulfate adsorption (salt extractable S) increased. Total S, ester sulfate and inorganic sulfate content increased with increasing elevation.