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Integrating Phosphorus Source and Soil Properties into Risk Assessments for Phosphorus Loss
Author(s) -
Shober Amy L.,
Sims J. Thomas
Publication year - 2007
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2006.0253
Subject(s) - biosolids , soil water , phosphorus , zoology , poultry litter , chemistry , environmental chemistry , saturation (graph theory) , litter , nutrient , agronomy , environmental science , environmental engineering , soil science , mathematics , biology , organic chemistry , combinatorics
Differences in P solubility of biosolids and manures, as a result of chemical treatment or other factors, have prompted states to incorporate weighting factors, sometimes called phosphorus source coefficients (PSCs), into P risk assessment tools. The value of PSCs in risk assessment has been demonstrated when organic P sources are surface‐applied, but not when P sources are incorporated into soils. Ten organic P sources were incorporated into eight Mid‐Atlantic soils (0–5 cm) at 135 kg total P ha −1 and incubated for 2, 30, and 180 d. Samples were analyzed for Mehlich 3 phosphorus (M3‐P), M3‐P saturation ratio (M3‐PSR), and water‐soluble phosphorus (WSP). Average increases in M3‐P (26 mg kg −1 ) and M3‐PSR (0.03) for all soils were similar for untreated manures and inorganic P compared to alum‐treated poultry litter (APL) and biosolids (24 mg kg −1 , 0.03). In contrast, average concentrations of soil WSP (2 d) were highest following incorporation of untreated manures and inorganic P (5.2–8.0 mg kg −1 ), followed by biosolids or APL (2.9–3.4 mg kg −1 ) and unamended soils (2.7 mg kg −1 ) with similar trends at 30 and 180 d. Source effects were most pronounced for soils with higher M3‐PSR. Regression equations using soil M3‐PSR and default PSCs could predict soil WSP at 2, 30, and 180 d (r 2 = 0.67, 0.69, 0.60, all significant at P = 0.001). Based on our results, we developed a new weighting factor (using M3‐PSR and default PSCs) for risk assessment tools that will better predict the potential for P loss when biosolids or manures are incorporated into Mid‐Atlantic soils.