|Allen, A -|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 10, 2010
Publication Date: January 24, 2011
Citation: Pote, D.H., Way, T.R., Kleinman, P.J., Moore Jr, P.A., Meisinger, J.J., Sistani, K.R., Saporito, L.S., Allen, A.L., Feyereisen, G.W. 2011. Subsurface application of poultry litter in pasture and no-till soils. Journal of Environmental Quality. 40:402-411. Interpretive Summary: Poultry litter is a rich nutrient source for crops, but the usual practice of broadcasting litter on the field surface allows valuable nutrients to evaporate or be carried by storm runoff water into nearby streams and lakes. Research has shown that applying dry litter in shallow trenches (bands) below the soil surface can prevent most nutrient losses with very little disturbance of the soil structure or plant roots; so two advanced tractor-drawn prototypes have been developed to mechanize the subsurface-application technique, and are being field tested in pasture and no-till systems. When compared to litter broadcast on the surface, these prototype subsurface applicators increased crop yields while decreasing short-term nutrient losses by more than 90% and long-term (3-year) phosphorus losses at the watershed scale by 55%. The study is of interest to scientists, extension personnel, agricultural producers, and the general public because these prototypes can help make subsurface application of poultry litter a practical management option for producers, and could potentially lead to more efficient nutrient use on millions of acres while improving air and water quality.
Technical Abstract: Poultry litter provides a rich nutrient source for crops, but the usual practice of surface-applying litter 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 was to improve upon conventional litter application methods to decrease associated nutrient losses to air and water while increasing soil productivity. We developed and tested a knifing technique to directly apply dry poultry litter beneath the surface of pastures. Results showed that subsurface litter application 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. The two prototypes have been tested in pasture and/or no-till experiments, and are both effective in improving nutrient-use efficiency compared to surface-applied litter, increasing crop yields (possibly by retaining more nitrogen in the soil), and decreasing nutrient losses, often to near background (control plot) levels. A paired-watershed study showed that 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. Results highlight opportunities and challenges for commercial adoption of subsurface poultry litter application in pasture and no-till systems.