Availability of carbon-bonded sulfur for mineralization in forest soils

Abstract

The capacities of soil from hardwood, clear-cut, and pine forests of the Coweeta basin to mineralize, adsorb; and incorporate into Organic matter carbon-bonded sulfur in the form of L-methionine was investigated. These soils adsorbed and incorporated between 40 and 66% of this amino acid within a 0.5-h incubation period, but much of the immobilized sulfur was mineralized after 48 h incubation. Ah additional hardwood forest (watershed 18) was chosen for further study of the incorporation process in both litter and mineral horizons. The O2 forest floor layer exhibited the highest levels of activity in samples taken along a transect of this watershed. Incorporation of methionine into the organic matter of these samples was complete within about 12 h of incubation and was inhibited by pretreatment of the samples with sodium azide; a general inhibitor of cell respiration. The capacities for methionine incorporation determined invitro complement observations of the high levels of carbon bonded sulfur found insitu in forest litter and soil.