EFFECT OF POULTRY DIET ON PHOSPHORUS LOSS IN RUNOFF FROM SOILS AMENDED WITHPOULTRY MANURE AND COMPOST

Authors: Vadas, Peter; Meisinger, John; Sikora, Lawrence; McMurtry, John

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2004
Publication Date: 9/1/2004
Citation: Vadas, P.A., Meisinger, J.J., Sikora, L.J., Mcmurtry, J.P. 2004. Effect of poultry diet on phosphorus loss in runoff from soils amended withpoultry manure and compost. Journal of Environmental Quality. 33(5):1845-1854.

Interpretive Summary: Use of phytase in poultry diets may be able to decrease the phosphorus (P) content of poultry manure and thus decrease P in runoff from fields where manure is applied. We investigated the effect of adding phytase and reducing supplemental P in poultry diets and composting manure with and without Fe and Al amendments on P loss in runoff. Adding phytase and decreasing P in diets reduced total P but increased soluble P content in manure compared to the normal diet. Composting reduced both total and soluble P content compared to manures, but adding Fe and Al to composts had no consistent effect on compost P content. For manures, adding phytase and decreasing P in diets increased soluble P loss but had not effect on total P loss in runoff. Composting greatly reduced both total and soluble P loss in runoff, but adding Fe and Al to compost had an inconsistent effect on P loss. Use of phytase in poultry diets may not be a management practice that will consistently decrease P loss in runoff from manured fields, but composting manures may achieve this goal.

Technical Abstract: Loss of phosphorus (P) in runoff from agricultural fields to which poultry litter has been applied is an environmental concern. We investigated the effect of adding phytase, reducing supplemental P in poultry diets, and composting poultry manure with and without Fe and Al amendments on P loss in runoff. Six week feeding trials were conducted with four different diets: a normal diet, normal diet + phytase, normal diet + phytase - 0.1% P, and normal diet + phytase - 0.2% P. Manure and composted manure were analyzed for soluble and total P. Adding phytase and decreasing P in diets reduced total P but increased soluble P in manure compared to the normal diet. Composting reduced both total and soluble P compared to manures, but adding Fe and Al to composts had no consistent effect on compost P. Manures and composts were surface applied to soil boxes and subjected to simulated rainfall. Runoff was collected every five minutes for 30 minutes and analyzed for volume, sediment content, and soluble, total dissolved, and total P. Runoff volumes increased with time and were similar for all experiments. Sediment content in runoff decreased with time and was greatest for boxes treated with manure, least for background boxes, and intermediate for boxes treated with compost. Phosphorus concentrations in runoff behaved the same as sediment concentrations. For the manures, adding phytase and decreasing P in diets increased soluble P loss but had no effect on total P loss in runoff. Composting greatly reduced both total and soluble P loss in runoff, and adding Fe and Al to compost had no effect on soluble P loss but significantly reduced total P loss. Overall, adding phytase and decreasing supplemental P in poultry diets can decrease total P in manure, but will likely increase soluble P in manure, thus increasing soluble P loss in runoff once the manure is surface applied to soils. Composting is an effective means to reduce total and soluble P contents of manure and thus P loss in runoff.