Submitted to: Sustainable Land Application Conference
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2003
Publication Date: 1/1/2004
Citation: Delaune, P.B., Daniel, T.C., Moore Jr, P.A., Lemunyon, J. 2004. Effect of composting broiler litter on nitrogen: Phosphorus ratios and phosphorus runoff [abstract]. Sustainable Land Application Conference. p. 114.
Technical Abstract: Due to nitrogen (N) losses, mass and volume reduction, and retention of non-volatile phosphorus (P) during composting of broiler litter, N:P ratios decrease; thereby, increasing the risk of P runoff. The objectives of this study were to evaluate the effect of chemical and microbial amendments to composting broiler litter on: 1) N:P ratios of composted litter; and 2) P runoff. Composting studies were conducted two different years at a commercial composting operation. At the beginning of each study, compost was treated with 1) aluminum sulfate, 2) phosphoric acid, 3) a microbial mixture, and 4) an untreated control. After the compost process was complete, compost and fresh broiler litter was applied to small runoff plots cropped to tall fescue and rainfall simulators were used to provide a 5 cm hr-1 storm event. Nitrogen: Phosphorus ratios of composted litter were reduced by as much as 51% compared to initial N:P ratios. All compost treatments had lower N:P ratios than fresh broiler litter. Soluble reactive P (SRP) concentrations were also greatly affected. Phosphoric acid additions to compost resulted in the lowest N:P and N:SRP ratios among all treatments. Alum-treated compost greatly increased N:SRP ratios compared to all other treatments, including fresh broiler litter. Alum-treated compost reduced SRP concentrations in runoff by as much as 84%. In year 2, all compost treatments not treated with alum resulted in higher P concentrations in runoff than fresh broiler litter. Adding amendments to composting manure that reduce SRP concentrations may be necessary to increase N:P ratios and decrease P runoff.