Phosphorus forms in biosolids-amended soils and losses in runoff: effects of wastewater treatment process.
Continuous addition of municipal biosolids to soils based on plant nitrogen (N) requirements can cause buildup of soil phosphorus (P) in excess of crop requirements; runoff from these soils can potentially contribute to nonpoint P pollution of surface waters. However, because biosolids are often produced using lime and/or metal salts, the potential for biosolids P to cause runoff P losses can vary with wastewater treatment plant (WWTP) process. This study was conducted to determine the effect of wastewater treatment process on the forms and amounts of P in biosolids, biosolids-amended soils, and in runoff from biosolids-amended soils. We amended two soil types with eight biosolids and a poultry litter (PL) at equal rates of total P (200 kg ha(-1); unamended soils were used as controls. All biosolids and amended soils were analyzed for various types of extractable P, inorganic P fractions, and the degree of P saturation (acid ammonium oxalate method). Amended soils were placed under a simulated rainfall and all runoff was collected and analyzed for dissolved reactive phosphorus (DRP), iron-oxide-coated filter paper strip-extractable phosphorus (FeO-P), and total phosphorus (EPA3050 P). Results showed that biosolids produced with a biological nutrient removal (BNR) process caused the highest increases in extractable soil P and runoff DRP. Alternatively, biosolids produced with iron only consistently had the lowest extractable P and caused the lowest increases in extractable soil P and runoff DRP when added to soils. Differences in soil and biosolids extractable P levels as well as P runoff losses were related to the inorganic P forms of the biosolids.
Penn
Chad J
CJ
Department of Plant and Soil Sci, Univ of Delaware, Newark 19717-1303, USA. chpenn@vt.edu
Sims
J Thomas
JT
D000383:Agriculture; D000818:Animals; D001682:Biological Availability; D008372:Manure; D010316:Particle Size; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D011200:Poultry; D011891:Rain; D012987:Soil; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements
D008372:Manure; D012987:Soil; D010758:Phosphorus