Sulfur transformations in forest litter and soil: Results of laboratory and field incubations

Field incubations of litter (01 and 02 layers) and A horizon soil utilizing S-labeled inorganic sulfate were conducted during July 1985 in an eastern white pine and a hardwood forest. Samples were assayed for the capacity to form S-labeled organic S, and in most cases these capacities were very similar to those determined in corresponding laboratory incubations. The A horizon soils from both water sheds formed approximately 3.0 nmol of organic S g^-1 dry weight of sample during 2-d field or laboratory incubations. No substantial increase in this amount was observed after 7-d field incubations. Intrinsic S fractions of samples were quantified prior to and following field incubations, and organic S represented the majority of the total S in all cases. Sulfonate S and nonphosphate extractable ester sulfate were the largest organic S pools. Additional study results are discussed.