Influence of Poultry Litter Application Methods on the Longevity of Nutrient and E. coli in Runoff from Tall Fescue Pasture

Significant quantities of the broiler chicken (Gallus gallus domesticus) litter produced in the USA are being applied to pasture lands. The traditional surface- broadcast application of animal manure onto permanent pasture, however, may lead to high concentration of nutrients and pathogenic microorganisms near the soil surface that could be transported off site by runoff water. Subsurface banding of poultry litter has the potential to reduce nutrient and pathogen losses through runoff. However, this has not been thoroughly investigated. In this study, we used rainfall simulations to examine the effect of broiler litter application methods on the longevity of nutrient and Escherichia coli losses in runoff by successive runoff events. Runoff plots were constructed on Hartsells fine sandy loam (Typic Hapludults) soil with permanent Kentucky 31 tall fescue (Festuca arundinacea) pasture in Crossville, AL. Treatments included two methods of litter application (surface broadcast and subsurface banding), commercial fertilizer, and control (no litter or fertilizer applied). To evaluate the longevity of nutrient losses, simulated rainfall (110 mm h⁻¹) was applied to each plot on days 1, 7, and 14 following litter and fertilizer applications. Total P (TP), inorganic N, and E. coli concentrations were all significantly greater in runoff from broadcast litter application than the subsurface litter banding treatments. The TP losses from broadcast litter applications averaged 6.5 times those from subsurface litter applications. About 81% of the runoff TP concentration was in the form of dissolved reactive phosphorus for both litter application methods. The average losses of NO₃-N and total suspended solids from subsurface litter banding plots were 358 g ha⁻¹ and 68 kg ha⁻¹ compared to 462 and 60 kg ha⁻¹ for the broadcast method, respectively. This study shows that subsurface banding of broiler litter into perennial grassland can substantially reduce nutrient and pathogen losses in runoff compared to the traditional surface-broadcast practice.