Management of nitrogen and composted biosolids to cycle nutrients and enhance environmental quality during production and after transplanting turfgrass sod

Land application of large, volume-based rates of municipal biosolids (MB) enhances soil physical properties and provides an alternative to disposal in landfills. Yet, topdressing or incorporation of the volume-based rates can increase non-point source losses of sediment and nutrients from excavated soils to surface waters. Research objectives were developed to evaluate the options for cycling of MB through turfgrass sod during production and after transplanting. The first objective was to compare the production of Tifway bermudagrass sod between fields grown with and without MB under increasing rates of supplemental fertilizer N. The second objective was to compare runoff losses between soils constructed with and without MB before planting to sprigs or sod transplanted from turfgrass grown in soil with and without incorporation of MB. Incorporation of 25% by volume of MB in soil enhanced (p < 0.001) turfgrass coverage of the soil surface compared to soil without MB. In addition, amending soil with MB reduced wet and dry sod weights (p < 0.001) and increased soil water content (p < 0.001) at harvest compared to sod without MB. Runoff concentrations and mass loss of total dissolved P (TDP) were significantly greater (P=0.001) for MB-amended compared to un-amended sod. In addition, a linear relationship (R2 = 0.94) was observed between water extractable soil P within the 0- to 2-cm depth and concentrations and mass loss of TDP in runoff. Similarly, runoff loss of NO3-N was greater (P = 0.05) for soil mixed with 25% by volume of MB than soil alone and variation of NO3-N loss among treatments was directly related to soil NO3-N concentration within the 0- to 5-cm depth. In contrast, runoff concentrations of NH4-N were directly related to inputs of N from turf clippings returned to soil rather than soil NH4-N concentrations. Total Kjeldahl N (TKN) concentration in runoff was unrelated to soil N concentrations, but was linearly related to mass loss of sediment in runoff. Transplanted sod reduced sediment loss compared to sprigged soil during turfgrass establishment and MB-amended soil reduced sediment loss compared to soil without MB. In addition, the MB imported in sod or incorporated in soil before sprigging increased soil organic carbon and mean soil water content compared to sod or soil without MB over a 92 day period. Incorporation of MB within soil prior to planting fertilizer grown turfgrass sod enhanced water conservation and reduced nutrient loss compared to planting MB-grown sod on un-amended soils.