Sulfur Dynamics and Activities of Sulfur-Transforming Enzymes in Prairie Soils.

Maintaining ecosystem health and function are essential for sustaining agricultural production. Understanding sulfur (S) cycling in the soil environment is important in assessing ecosystem functions that may be directly linked to land use and management practices. Thus, the main objective was to evaluate the impacts of grazing and cultivation on soil S content and activities of S- transforming enzymes. Soils from five different management systems, including undisturbed, set-aside from cultivation (was cultivated but returned to grassland >30 yr ago), moderately grazed, heavily grazed, and cultivated with continuous winter wheat (Triticum aestivum L.) were evaluated. Total S, available S, and activities of arylsulfatase and rhodanese were determined. Similar trends were observed for total S content and arylsulfatase activities. Of the soil ecosystems evaluated, the undisturbed system had the highest while the cultivated ones had the lowest total S and arylsulfatase activity. However, the cultivated soils had the highest available S. Rhodanese activity was highest in the moderately grazed system. The set-aside from cultivation system had the lowest rhodanese activity, and a lower arylsulfatase activity of the uncultivated systems evaluated. Grazing, in general, enhanced or maintains activities of arylsulfatase and rhodanese and the capacity of soil to cycle S nutrient.