SUSTAINABLE TURKEY LITTER AMENDMENTS FOR MIXED SWARDS GRAZED BY SHEEP IN APPALACHIA: NITRATE LEACHING

Authors: Boyer, Douglas; Belesky, David; Turner, Kenneth

Submitted to: Journal of Sustainable Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2005
Publication Date: 3/21/2007
Citation: Boyer, D.G., Belesky, D.P., Turner, K.E. 2007. Sustainable Turkey Litter Amendments for Mixed Swards Grazed by Sheep in Appalachia: Nitrate Leaching. Journal of Sustainable Agriculture. 29(4):75-86.

Interpretive Summary: Increased poultry production in the Appalachian Region provides a readily available nutrient source and a means to improve soil quality. In West Virginia, the number of broilers and turkeys sold increased 50 percent from 8 million birds to 12 million birds between 1992 and 1997 with more than 75,000 MT of litter production in 1997. As with any applied source of nutrients, surface and ground water quality can be compromised if nutrient inputs exceed plant nutrient requirements. Understanding nutrient dynamics in hill-land pasture enables us to develop management practices that minimize detrimental effects on water quality and stabilize and improve the productive capacity of highly eroded soil. The objective of this research was to assess nitrate leaching under mixed swards of orchardgrass, white clover, and chicory receiving various loadings of composted turkey litter and grazed by sheep. Four treatments were studied: one with added P and K fertilizer, but no N; one with P, K, and N fertilizer; one with 3 metric tons composted turkey litter per hectare; and one with 6 metric tons of composted turkey litter per hectare. We found nitrate leaching under the treatment with 6 metric tons of composted turkey litter. Rates of composted turkey litter greater than 3 metric tons per hectare cannot be recommended from a nitrate leaching perspective.

Technical Abstract: Increased poultry production in the Appalachian Region provides a readily available nutrient source and a means to improve soil quality. In West Virginia, the number of broilers and turkeys sold increased 50 percent from 8 million birds to 12 million birds between 1992 and 1997 with more than 75,000 MT of litter production in 1997. As with any applied source of nutrients, surface and ground water quality can be compromised if nutrient inputs exceed plant nutrient requirements. Understanding nutrient dynamics in hill-land pasture enables us to develop management practices that minimize detrimental effects on water quality and stabilize and improve the productive capacity of highly eroded soil. The objective of this research was to assess nitrate leaching under mixed swards of orchardgrass, white clover, and chicory receiving various loadings of composted turkey litter and grazed by sheep. Treatments were applied in the early spring of 1997, 1999, and 2001. Treatment 1 (PK) was composed of P and no applied N. Treatment 2 (NPK) was the same as PK with additional N fertilizer. Treatment 3 (3T) was application of 3 Mg ha-1 composted turkey litter. Treatment 4 (6T) was double the litter rate of 3T or 6 Mg ha-1 composted turkey litter. Indications were that any of the treatments supplied adequate herbage to sustain rotational stocking of growing lambs, but NO3-N leaching occurred at the litter application rate of 6 Mg ha-1. Nitrate leaching also occurred when no additional N was applied as a result of an increased ratio of white clover in the sward. The ability of chicory to accumulate N in its tissues might have been instrumental in virtually eliminating NO3-N leaching in the 3T and NPK treatments. When chicory is included in the sward composition, rates of composted turkey litter application greater than 3 Mg ha-1 cannot be recommended from a NO3-N leaching perspective.