Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 7, 2011
Publication Date: N/A
Technical Abstract: Poultry litter provides a rich nutrient source for crops, but the usual practice of surface-broadcasting litter can degrade water quality by allowing storm runoff to transport nutrients into streams and lakes, while much of the ammonia-N escapes into the atmosphere. We developed and tested a knifing technique to decrease nutrient losses while increasing soil productivity by directly applying dry poultry litter beneath the surface of pastures and other no-till systems. Results showed that subsurface application of litter decreased ammonia-N volatilization and nutrient losses in runoff more than 90% (compared to surface-applied litter), to levels statistically as low as those from control (no litter) plots. Given this success, two advanced tractor-drawn prototypes were developed to subsurface apply poultry litter in field research, and have been tested in pasture and/or no-till experiments. When compared to surface-applied litter, both prototype subsurface applicators were effective for improving nutrient-use efficiency, increasing crop yields (possibly by retaining more nitrogen in the soil), and decreasing nutrient losses to near background (control plot) levels. In a paired- watershed study, cumulative phosphorus losses in runoff from continuously-grazed perennial pastures were decreased by 55% over a three-year period if the annual poultry litter applications were subsurface applied rather than surface broadcast.