Evaluation of Nutrient and Pathogen Losses From Various Poultry Litter Storage Methods
Considerable concern has developed over the possible pollution from poultry litter storage methods. This study was conducted to evaluate three different storage scenarios; covered stockpiles, uncovered stockpiles, and litter sheds. The stockpiles were monitored over two rainfall simulation events, in both the Ridge and Valley and the Piedmont physiographic provinces, with both surface and subsurface flows analyzed. An observational study, where subsurface water was sampled for a nine-month period was conducted using six litter sheds, three in each of the above provinces. Samples were analyzed for nutrients, fecal coliforms, and solids.
Concentrations of NHx, TKN, OP, TP, VSS, and FC in surface runoff from uncovered litter piles were all statistically higher than that from covered piles, with NO3 being the exception. However, increased runoff volumes originating from the covered litter piles caused mass loadings from both covered and uncovered piles to be similar enough that statistical significance was not obtained, except in the case of FC.
Soil water samples from litter stockpiles did not show a statistically significant treatment effect for concentration data, but uncovered piles did exhibit higher nitrogen concentration estimates than the covered piles. Sample collection frequency showed a statistically significant increase in the number of samples that could be obtained from the edge lysimeter under uncovered litter piles from the Piedmont experimental site. This result indicates uncovered piles are releasing the precipitation absorbed during the rainfall simulation into the sub-surface environment.
In the storage shed study, a greater number of samples were collected per attempt at the Piedmont sheds compared to those at the Ridge and Valley site. While both areas were undergoing a significant drought, Piedmont porous-cup lysimeters yielded samples 63% of the time, compared to 10% for Ridge and Valley lysimeters. Lysimeters located near the edge of the shed were also more likely to yield a sample than those in the center or a background location. Unknown interferences within the litter shed samples prevented three laboratories from obtaining valid nutrient concentrations.