Municipal biosolid waste can be recycled to soils in the urban landscape to improve soil physical and chemical characteristics. Municipalities are encouraging large, volume-based rates of composted municipal biosolids (CMB) for poor quality urban soils without constraints on concentration or rate of nutrient in compost or amended soil. The high nutrient rates applied in CMB, including P, can increase soil concentrations above plant requirements and increase potential loss in runoff during storm events or irrigation. The objectives of this study were to: 1.) Quantify P export in a turfgrass sod crop grown with volume-based CMB rates (0.6 and 1.25-cm surface layer) and 2.) Compare soil P loads and loss in water runoff between soil mixed with a volume-based CMB rate (25% compost/75% soil) and sod imported with a 1.2-cm depth of CMB. The volume-based CMB rates recommended by municipalities provided up to 719 kg P ha-1 in transplanted sod and 747 kg P ha-1 in a 5-cm depth of amended soil. Initially, greater total P loss (dissolved plus sediment-bound P) was observed in runoff water from transplanted CMB-grown sod than from soils mixed with CMB prior to sprigging. In contrast, total P concentrations in runoff water were similar among treatments in subsequent runoff events. The total P concentrations in runoff water from the amended soils exceeded clean water standards during each runoff event during the study. Municipal programs intended to promote CMB use on urban soils can lead to P enrichment in soil and increased total P loss in runoff water.
See more of Soils Posters/Reception
See more of The ASA Southern Regional Branch (June 19-21, 2005)