Factors involved in potential sulfur accumulation in litter and soil from a coastal pine forest

Abstract

Samples of 01/02, Al, E2 and Bh horizons collected from a coastal pine forest were assayed for the potential capacity to adsorb and to form organic sulfur from added sulfate. The subsequent mobilization (mineralization) of organic S was also assayed to determine potential capacities of the samples for organic S accumulation. Organic and inorganic forms of S were quantified, as were total carbon and nitrogen levels. Relationships between these parameters and the above S processing capacities for each sample were examined, and fluctuations were statistically analyzed. Of the organic S present, sulfonate-S (non-Raney Ni-reducible S) was found to be the major component irrespective of horizon. Adsorbed and soluble S were found to be low, suggesting that loss by leaching may be an important fate of incoming sulfate at this site. Results from this study were compared with those obtained for two additional sites, which have been examined in detail and documented previously to be S accumulating. Soils from the pine forest site adsorbed substantially less sulfate than those from the other two sites. The organic S accumulation capacity was relatively low for the pine site, averaging less than one third of the potential established for the other two sites.

Soil Chemistry in a Loblolly/Longleaf Pine Forest with Interval Burning

“…The total S content of the Oe+Oa in burned plots ranged from 2.0 to 5.3 g/m 2 lower than in the controls. The S constituents were consistent with previous studies on forest soils in the United States (Bartel-Ortiz and David 1988, Watwood et al 1988, Autry et al 1990, David et al 1990). Because organicS constituents were the dominant fractions of total S, both C-bonded S and ester sulfate concentrations and content decrease in the Oe+Oa with decreasing fire interval.…”

“…The concentrations of theseS forms were low, and only small, negligible differences resulted from prescribed burning. The S constituents were consistent with previous studies on forest soils in the United States (Bartel-Ortiz and David 1988, Watwood et al 1988, Autry et al 1990, David et al 1990). OrganicS dominated totalS in all horizons, and ranged from 97 to 98% of totalS in the Oe+Oa, and 70-95% oftotal S in mineral soil.…”

Sulfur cycling, retention, and mobility in soils: A review

“…Immobilization, or the assimilation of S into microbial cells (Randlett et al 1992), depends completely on microbial metabolism (Fitzgerald et al 1983). Both aerobic and anaerobic microorganisms take part in organic S formation (Watwood et al 1988b), though only 1 to 3 percent of microbial biomass is composed of S (Saggar et al 1981a;Strick and Nakas 1984;Chapman 1987). The short life cycles of microorganisms, however, result in rapid turnover and S recycling (Smith and Paul 1990;McLaren et al 1985).…”

“…Immobilization occurs in organic and mineral soil layers (Fitzgerald et al 1983), and immobilized S usually is incorporated into organic matter by covalent bonding (Strickland et al 1987;Watwood et al 1988b). Sulfate added to soil can be adsorbed quickly or transformed to low molecular weight organic S compounds, especially ester sulfates as fulvic acids (Saggar et al 1981b), thereby resulting in rapid retention.…”

“…Depolymerization results in the solubilization of previously insoluble S matrices. Mobilization occurs even when excess SO 2-4 is available from precipitation (Strickland et al 1986b), and very rapid mobilization has been documented (Watwood et al 1988b). Two possible mechanisms offered for rapid mobilization are direct oxidation of C-S linkages, and conversion of C-S linkages to ester sulfate linkages.…”