Influence of Agricultural Systems on Soil C, N, and P Cycling Enzymes.

Activities of soil enzymes that play an integral role in biogeochemical cycling are influenced by agricultural management practices such as tillage, crop rotation, crop-livestock integration and so on. They serve as indicators of long term effects of these practices on soil structure as well as soil microbial communities and in turn help evaluate their potential to sustain soil health. Acid phosphatase, arylsulfatase, β-Glucosidase, and β-Glucosaminidase activities were determined in soils representing various management practices such as a perennial grass based crop rotation systems with and without grazing; traditional grazed pasture systems; hayed grass systems; hayed legume systems; and conventional tilled systems. A natural vegetation area representing an undisturbed site served as a control in this study.  Short-term grazing integrated into a perennial grass based crop rotation always had greater enzyme activities than non-grazed systems. Particularly significant were differences in the P cycling acid phosphatase and C and N cycling β-Glucosidase and β-Glucosaminidase activities. Acid phosphatase was significantly greater in the perennial grass based systems than all other practices as well as the control native site. Other enzyme activities were also greater in grazed pasture systems and perennial grass based crop rotation systems integrated with grazing. Conventional tilled systems had significantly lower C and N cycling enzymes as compared to the other practices. Grazed systems integrated with a sod-based crop rotation seems to have a greater potential for efficient nutrient cycling which is further supported by the greater crop yields observed in these systems.