Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2002
Publication Date: 8/20/2002
Citation: CALLAHAN, M.P., KLEINMAN, P.J., SHARPLEY, A.N., STOUT, W.L. ASSESSING THE EFFICACY OF ALTERNATIVE PHOSPHORUS SORBING SOIL AMENDMENTS. SOIL SCIENCE. 2002. V. 167. P. 539-547. Interpretive Summary: Concern over the contribution of agricultural phosphorus (P) to fresh water eutrophication has focused attention on practices that decrease P loss from agricultural soils. At present, few management options exist for soils with P levels in excess of crop P requirements other than restricting P applications. In this study, the authors evaluate the ability of various compounds, from industrial by-products to readily available minerals, to reduce the availability of soil P to runoff water. Notably, gypsum, already in use as an agricultural soil amendment, shows promise in reducing the availability of P to runoff water without adversely affecting the availability of that P to crops.
Technical Abstract: Concern over the contribution of agricultural phosphorus (P) to fresh water eutrophication has focused attention on practices that decrease P losses from agricultural soils. At present, few management options exist for soils with P levels in excess of crop P requirements other than restricting P applications. This study assesses various readily available materials as possible P Sorbing Soil Amendments (PSSAs) by comparing their near- and long-term effects on soil P solubility and potential availability to runoff, with their impact on plant available P. Specifically, anthracite refuse ash, bituminous refuse ash, by-product gypsum (CaSO4), siderite (FeCO3), steel processing sludge, water treatment residual and wollastonite (CaSiO3) were incubated in three acidic and one neutral loam soils for 21- and 120-d to compare starting and ending water extractable soil P (WEP) and Mehlich-3 P concentrations. Across all soils, by-product gypsum and bituminous refuse ash consistently reduced WEP at the lowest rates of application without lowering Mehlich-3 P below crop requirements. In addition, for by-product gypsum no significant difference in WEP and Mehlich-3 P was observed between the 21-d and 120-d incubation periods, indicating that sorption reactions induced by this material are both rapid and stable with time. Water treatment residual exhibited intermediate degrees of efficacy in reducing WEP, while anthracite refuse ash, siderite, steel processing sludge and wollastonite were ineffective at reducing WEP in soil at practical application rates. Results support the use of by- product gypsum and water treatment residual on acidic and neutral soils representing critical source areas.