Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/11/2003
Publication Date: 12/1/2003
Citation: Pote, D.H., Kingery, W.L., Aiken, G.E., Han, F.X., Moore Jr, P.A., Buddington, K.K. 2003. Water-quality effects of incorporating poultry litter into perennial grassland soils. Journal of Environmental Quality. 32(6):2392-2398. Interpretive Summary: Poultry manure is a rich source of plant nutrients that is most commonly used as a fertilizer on the surface of hay fields and permanent pastures. The practice of surface spreading manure allows runoff from heavy rains to carry some of it into nearby streams and lakes. Poultry producers need better options for applying manure to make the valuable nutrients more available to crops while protecting the quality of water supplies. In this study, the effects of a knifing method to incorporate poultry manure into the soil below the pasture surface was investigated. This incorporation method decreased losses of most manure components in runoff water by more than 80%, and tended to increase hay production. This information is of value to poultry-beef producers in the southeast United States and agricultural professionals like NRCS and extension agents who advise landowners. More research will be needed for the knifing method to be mechanized and fully tested as a practical management option for producers.
Technical Abstract: Poultry litter provides a rich source of nutrients for perennial forages, but the usual practice of surface-applying litter to pastures can degrade water quality by allowing nutrients to be transported from fields in surface runoff, while much of the NH4-N volatilizes. Incorporating litter into the soil can minimize such problems in tilled systems, but has not been used for perennial forage systems. In this study, we minimized disturbance of the crop, thatch, and soil structure by using a knifing technique to move litter into the root zone. Our objective was to determine effects of poultry litter incorporation on quantity and quality of runoff water. Field plots were constructed on a silt loam soil with well-established bermuda grass (Cynodon dactylon L.) and mixed grass forage. Each plot had 8-10% slopes, borders to isolate runoff, and a downslope trough with sampling pit. Poultry litter was applied (5.6 Mg ha-1) by one of three methods: surface-applied, incorporated, or surface-applied on soil-aeration cuts. There were six treatment replications and three controls (no litter). Nutrient concentrations and mass losses in runoff from incorporated litter were significantly lower (generally 80-95% less) than in runoff from surface-applied litter. By the second year of treatment, litter-incorporated soils had greater rain infiltration rates, water-holding capacities, and sediment retention than soils receiving surface-applied litter. Litter incorporation also showed a strong tendency to increase forage yield.