Activity of soil enzymes in constructed wetlands treated with swine wastewater

Continuous application of swine wastewater from lagoons to agricultural land can pose surface and groundwater pollution. Constructed wetland (CW) is an alternate to the lagoon spray field system that reduces the nutrients concentration. 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 in CW treated with swine wastewater and to assess the relationship between the enzyme activity and nutrients concentration. One continuous marsh (CM) and one marsh-pond-marsh (MPM) wetland cells were investigated for enzymatic activity. The activities of dehydrogenase, urease, phosphatase, and β-glucosidase were significantly higher at 0−3 cm than 6−12 cm depth. Enzyme activities were higher in marsh soils of CM than pond soils of MPM. There was no significant difference in enzyme activity between inlet and outlet of CM and pond area of MPM. No significant relationship was found between the enzyme activity and nutrient concentration. Urease, phosphatase, and arylsulfatase activity were correlated with soil C and N, whereas, β-glucosidase activity was correlated with soil C. The results suggest that enzyme activity has aided in detritus decomposition and thus, decreased enzymatic activities may decrease nutrients availability.