Soil Organic Carbon and Microbial Dynamics in Turfgrass Systems: Impacts of Management Intensities.

Turfgrass systems represent a significant proportion of intensively managed ecosystems. In these systems, human management practices such as irrigation and fertilization critically influence carbon inputs to soil, soil microbial processes, and soil C and N turnover and long-term C balance. We investigated the effects of management duration and intensities on soil moisture, soil extractable C and N, microbial biomass, and microbial activities (respiration and N mineralization) on two golf courses dominated by Bermudagrass. On the Hope Valley course (Durham, NC), we compared the impact of the long-term (80 years) and the short-term (10 years) on an array of soil and microbial parameters. Soil moisture, soil extractable C and N, microbial biomass N, and heterotrophic microbial respiration were higher in the 80- than the 10- year managed areas, but microbial biomass C, net N mineralization was the opposite. On the Treyburn Golf course (Durham, NC), we examined how different management intensities (intensive in the fairway versus less intensive in the rough) affect these soil and microbial parameters. Soil moisture, microbial biomass N were consistently higher in the fairway than in the rough. However, extractable C and N, microbial biomass C, microbial respiration and net N mineralization were lower in the fairways than in the roughs. The impact of management intensities on soil C and N turnover is being analyzed through examining the changes in the natural ¹³C and ¹⁵N abundance over the time. Our results suggest that water and fertilizer inputs have significant impacts on soil microbial biomass and activities, and likely play a dominant role in determining the long-term C balance in these systems.