Nutrient and Trace Metals Exports In Surface Runoff from Plots Receiving Pelletized Broiler Litter.

The use of pelletized broiler litter (PBL) as a substitute for inorganic fertilizers is increasingly being encouraged, especially, in states like Delaware which have a large poultry industry and considerable surplus of litter.  The use of PBL is potentially promising since it reduces the input of the expensive inorganic fertilizers and also simultaneously solves the problem of disposing waste from animal operations.  However, very little is known about how PBL applications on agricultural lands may impact runoff water quality.  We explored the exports of nutrients (nitrogen and phosphorus) and selected trace metals (Al, Cu, and Zn) in surface runoff from experimental plots receiving PBL and Urea.  The study was conducted in an agricultural farm in Middletown, Delaware. PBL and urea were applied at the rate of 252 kg N/ha in early spring 2007 to plots in conventional (CT) and no tillage (NT) treatments. Corn was used at the cover crop. Concentrations and mass exports of nutrients and trace metals were studied for twelve natural storm events during June-August 2007. Exports of NH₄–N and NO₃–N were highest from plots in CT receiving PBL (0.83 g/ha and 0.49 g/ha, respectively).  Concentrations of NH₄–N and NO₃–N in surface runoff were also greater for plots receiving PBL versus those with urea. Concentrations and exports of total phosphorus were maximum for no-till plots receiving PBL application.  Mass exports of Al (0.07 to 0.56 g/ha) were again highest for the conventionally-tilled plots with PBL. The mass exports of Cu and Zn were less than 0.001 g/ha and concentrations were below 10 ppb. These results suggest that PBL applications on agricultural fields may have the potential to increase the exports nutrients and trace metals in surface runoff.