Activity of Soil Enzymes In a Constructed Wetland Treated with Swine Wastewater.

Increased swine production in North Carolina has resulted in higher waste production. Continuous application of swine wastewater from lagoons to agricultural land can pose surface and ground water pollution. Constructed wetland (CW) treatment is an alternate to the lagoon spray field system that reduces the nutrients concentration through physical, chemical and biological mechanisms. One of the biological processes in CW is enzymatic activity which plays a major role in releasing nutrients from organic substances. The objectives of this research were to investigate the activity of soil enzymes at different depths of CW treated with swine wastewater and to assess the relationship between enzymes activity and nutrients concentration. One continuous marsh (CM) and one marsh-pond-marsh (MPM) wetland cells were studied, which were in operation for the last ten years treating swine wastewater. The marshes in both cells were planted with cattail and bulrushes. Soil samples from three depths in CM and pond area of MPM were collected for enzymes activities, carbon and nitrogen analysis. The activities of dehydrogenase, urease, phosphatase, arylsulfatase, and B-glucosidase were significantly higher in the soil surface layer (0-5 cm) than lower depths. Enzymes activities were higher in marsh soils of CM than pond soils of MPM. No significant relationship was found either between dehydrogenase and microbial biomass or other enzymes activity and nutrients concentration.