Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 4, 2002
Publication Date: June 20, 2003
Citation: KLEINMAN, P.J., SHARPLEY, A.N. EFFECT OF BROADCAST MANURE ON RUNOFF PHOSPHORUS CONCENTRATIONS OVER SUCCESSIVE RAINFALL EVENTS. JOURNAL OF ENVIRONMENTAL QUALITY. 2003. V. 32. P. 1072-1081. Interpretive Summary: The management of manure to protect water quality is a priority in many agricultural watersheds across the US. In this study, the effects of manure management factors on phosphorus loss in runoff were quantified using a rainfall simulator. Manure application rate, timing of application and source of manure all significantly affected runoff phosphorus. Results from the study can be used to calibrate site assessment indices, such as the Phosphorus Index, to reduce the impact of land applied manure on water quality.
Technical Abstract: Concern over eutrophication has directed attention to manure management impacts on P loss in runoff. This study sought to quantify the effects of manure application rate, timing and type on runoff P losses from agricultural soils common to Pennsylvania and New York. Two simulated rainfall-runoff experiments were conducted. In one experiment, Buchanan and Lewbeach soils were packed into 100 x 20 x 5 cm runoff boxes and three manures (dairy, layer poultry and swine slurry) broadcast at rates of total P (TP) addition ranging from 0-150 kg ha-1. Simulated rainfall was applied at 7.0 cm hr-1 until 30 min of runoff was collected 3-, 10- and 24-d after manure application. In the second experiment, runoff boxes packed with Buchanan soil were broadcast with dairy, layer poultry and swine manures at 100 kg TP ha-1 and subjected to rainfall 3-, 4-, 5-, 10-, 11- and 12-d following application. Results revealed significant interactions between application rate, timing of event and type of manure on runoff P. Application rate was positively related to runoff P concentration, with regression slopes for poultry and swine manure significantly higher than dairy manure for the first runoff event, but eventually converging with dairy manure with subsequent events. Runoff P concentrations declined in a logarithmic fashion with successive runoff events, likely due to depletion of P from the soil surface. Differences in runoff P losses among manure types were associated with the water extractable P concentration of the individual manures. Differences in runoff TP concentrations between soils indicate that soil properties should not be discounted in evaluating causes of P loss from recently manured soils.