ARS | Publication request: Developing Technology for Applying Poultry Litter below the Surface of Perennial Pastures

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: March 18, 2009
Publication Date: N/A

Technical Abstract: Poultry litter provides a rich nutrient source for crops, but the usual practice of surface-applying litter on pastures can degrade water quality by allowing nutrients to be transported from fields in surface runoff, while much of the ammonia-N escapes into the atmosphere. Our goal is to develop improved management options that allow producers to decrease nutrient losses from poultry litter, thus protecting water quality while increasing soil productivity. We established field plots to test the hypothesis that nutrient losses could be decreased by using a knifing technique to apply dry poultry litter beneath the surface of perennial grassland. Results showed that subsurface litter application decreased nutrient losses in runoff more than 90 percent compared to those from surface-applied litter, and prevented the volatilization of ammonia-N. In fact, nutrient losses from subsurface litter were statistically as low as those from plots receiving no litter. Furthermore, subsurface-applied litter produced greater forage yields than surface-applied litter, possibly by retaining more N in the soil. However, subsurface litter application will not become a practical management option for producers until the technique is fully mechanized. We initially tested single-shank and four-shank prototypes that successfully placed dry poultry litter under the surface of rocky perennial pasture, but these have limited capacity and litter distribution capabilities. Therefore, we have constructed a larger (eight shank) tractor-drawn prototype that can transport five tons of dry untreated litter directly from the poultry house and rapidly apply it under the surface of perennial grassland at the desired rate. Initial field testing indicates the eight-shank prototype decreases nutrient losses (including ammonia-N) by more than 90 percent compared to surface-applied litter.