| Turfgrass soils encompass a large area of the United States and are capable of storing large quantities of C and N. Making more refined fertilizer recommendations would reduce the potential for N-leaching, which has environmental and human health effects. We need background data on the quantities of soil organic C (SOC) and N (SON), best simulation practices for DAYCENT (potential tool to make fertilizer recommendations), and an understanding of the mechanisms for C and N storage in turfgrass soils.;Chapter 2 quantified SOC and SON across a variety of ages, soil types, and management of turfgrass areas. Soil organic C and N increased at slow, linear rates that were markedly lower relative to other studies. At the individual soil series level, accumulation rates may match the literature values for SOC accumulation. This suggests that making broad-scale estimates of C accumulation from turfgrass based on studies using a single value of a few soil series may result in overestimation of potential C storage.;In Chapter 3, best simulation practices for DAYCENT use in turfgrass were explored. Web Soil Survey based soil properties could be used in place of or in combination with measured soil properties without sacrificing model accuracy. Specific land use history generally improved estimates of SOC and SON compared to using a simple, universal land use history. Simulations of N-leaching in chemically fertilized cropped sites showed threshold levels of N-leaching may be reached earlier than expected. This implies that these sites should have reductions in fertilizer much earlier than current UW-Extension guidelines recommend.;Fractionation of SOC and SON into pools allows for determination of SOC and SON saturation and further detail on SOC and SON accumulation. Our C and N saturation ratios showed predominantly undersaturated clay minerals and aggregate stability did not change with time, both of which support the hypothesis of an effective stabilization capacity in our turfgrass soils. Turfgrass soils of Wisconsin we studied do accumulate SOC and SON and appear to reach stabilization quickly, which could mean losses of N; however, DAYCENT represents a potential tool to reduce leaching through making better fertilizer recommendations. |
