Organic and Inorganic Sulfur Constituents of a Forest Soil and Their Relationship to Microbial Activity

Organic and Inorganic Sulfur Constituents of a Forest Soil and Their Relationship to Microbial Activity

1982

Sulfur (S) constituents, microbial biomass, and sulfohydrolase activity were determined for each soil horizon at both hardwood and conifer sites in a Becket soil (Adirondack Mountains, New York). Drying of soil before analysis altered the S constituents. There was a threefold increase (p < 0.05) in sulfate in the organic horizons. Total S was greatest in the O horizons with 2,010 and 1,690 µg S/g in conifer and hardwood solums, respectively. Mineral soil had a maximum S concentration in the B21h horizon. Sulfate concentrations were a small proportion (<15%) of total S in B horizons. Organic S was dominant (93% of total S) in all horizons. Carbon-bonded S and ester sulfate were 74 and 18% of total S, respectively. Microbial biomass was greatest in the 01 horizon of both hardwood and conifer solums (59 and 70 mg biomass C · 100 g⁻¹ dry mass, respectively). The B21h horizon contained the greatest biomass in the mineral soil. Sulfohydrolase activity exhibited the same distribution. Total S, carbon-bonded S, and ester sulfate were all positively correlated (p < 0.05) to percent organic matter in the soil horizons. Correlations between microbial biomass and sulfohydrolase activity with organic S indicate the potential for microbial S transformations. Sulfate formation by mineralization may be more important than exogenous inputs. This has major implications for assessing the impact of atmospheric S deposition on soils.

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