Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/18/2002
Publication Date: 11/20/2002
Citation: KLEINMAN, P.J., SHARPLEY, A.N., MOYER, B.G., ELWINGER, G. EFFECT OF MINERAL AND MANURE PHOSPHORUS SOURCES ON RUNOFF PHOSPHORUS LOSSES. JOURNAL OF ENVIRONMENTAL QUALITY. 2002. V. 31. P. 2026-2033. Interpretive Summary: The loss of phosphorus from agricultural lands in runoff has become a major water quality concern due to the widespread problem of eutrophication in many agricultural watersheds. In this study, the authors examine the role of alternative sources of land-applied phosphorus on phosphorus loss in runoff to determine if certain sources of phosphorus are more prone to runoff losses than others. Results show that the water soluble phosphorus content of a manure is a key factor affecting the loss of dissolved phosphorus in runoff. Furthermore, the method by which a phosphorus source is applied to soil greatly influences phosphorus losses in runoff, with significantly higher losses from surface applied phosphorus sources than incorporated phosphorus sources. This study provides the basis to differentiate between various phosphorus sources from a water quality standpoint.
Technical Abstract: Concern over non-point source phosphorus (P) losses from agricultural lands to surface waters has resulted in scrutiny of factors affecting P loss potential. An indoor rainfall simulation study was conducted to quantify the effects of alternative P sources (dairy manure, poultry manure, swine slurry, diammonium phosphate), application methods, and initial soil P concentrations on runoff P losses from three acidic soils (Buchanan- Hartleton, Hagerstown, and Lewbeach). Low P (12-26 mg kg-1 Mehlich-3 P) and high P (396-415 mg kg-1 Mehlich-3 P) members of each soil were amended with 100 kg total P ha-1 from each of the four P sources either by surface application or mixing. Treated soils were subjected to simulated rainfall (7 cm hr-1 for 30 min). Following surface application, P losses differed significantly by source, with dissolved reactive P (DRP) accounting for 64% of total P (TP) (versus 9% for the unamended controls), such that for the high P Hagerstown soil, for example, surface runoff TP was 20.40 mg L-1 fo diammonium phosphate, 3.54 mg L-1 for dairy manure, 21.26 mg L-1 for poultr manure, and 18.97 mg L-1 for swine slurry. For manure amended soils, these losses were linearly correlated with the water soluble P concentration of the manure (r > 0.90). When P sources were mixed with soil, losses were not significantly different than from the control. Furthermore, TP losses were related to erosion, with DRP representing 9% of TP. In all soils, mixing significantly decreased P losses relative to surface P application; and, P losses from the Lewbeach soil following mixing were not significantly different than those from the unamended control. Results of this study can also be applied to site assessment indices to quantify the potential for P loss from recently manured soils.