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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION SYSTEMS RESEARCH FOR IMPROVING ENVIRONMENTAL QUALITY AND PRODUCER PROFITABILITY Title: Nitrogen Fertilizer: Timing, Source, and Rate for a Winter Cereal Cover Crop

Authors
item Balkcom, Kipling
item Arriaga, Francisco
item Mitchell, Charles - AUBURN UNIVERSITY
item Delaney, Dennis - AUBURN UNIVERSITY
item Bergtold, Jason - KANSAS STATE UNIVERSITY

Submitted to: Annual Southern Conservation Tillage Conference for Sustainable Agriculture
Publication Type: Proceedings
Publication Acceptance Date: July 15, 2008
Publication Date: July 31, 2008
Citation: Balkcom, K.S., Arriaga, F.J., Mitchell, C.C., Delaney, D.P., Bergtold, J.S. 2008. Nitrogen fertilizer: Timing, source, and rate for a winter cereal cover crop. In: Endale, D.M., editor. Proceedings of the 30th Southern Conservation Agricultural Systems Conference and 8th Annual Georgia Conservation Production Systems Training Conference, July 29-31, 2008, Tifton, GA. Available at: http://www.ag.auburn.edu/auxiliary/nsdl/scasc/.

Interpretive Summary: The expected benefits associated with any type of conservation system require the use of a winter annual cover crop in the Southeast, usually a winter cereal. A winter cover crop can be used to supplement previous crop residues to maximize the amount of residue left on the soil surface, which protects the soil from erosion during the winter and early spring months. However, in order to maximize the benefits of a conservation system, supplemental N should be applied to enhance biomass production. An alternative to commercial N applied to the cover crop is poultry litter. The organic N fraction of poultry litter is not readily available, but will supply N over a longer time-frame as the litter is decomposed by soil microorganisms. Scientists with USDA-ARS located at the National Soil Dynamics Laboratory in Auburn, AL in cooperation with scientist from Auburn Univ. initiated a study to determine optimal rates and times of application to maximize cover crop biomass production. Poultry litter appears comparable to fertilizer as a source of N for a rye cover crop. An application of 30 lb N ac-1 produced sufficient biomass to meet a minimum biomass threshold, and a fall application of N was more beneficial during two out of three years. These results represent only one location over a 3-year period; therefore, these findings can not be expected to represent the entire Southeast. However, these results can be expected to provide general information related to N fertilizer and biomass production in the Southeast.

Technical Abstract: The expected benefits associated with any type of conservation system require the use of a winter annual cover crop in the Southeast, usually a winter cereal. A winter cover crop can be used to supplement previous crop residues to maximize the amount of residue left on the soil surface, which protects the soil from erosion during the winter and early spring months. However, in order to maximize the benefits of a conservation system, supplemental N should be applied to enhance biomass production. An alternative to commercial N applied to the cover crop is poultry litter. The organic N fraction of poultry litter is not readily available, but will supply N over a longer time-frame as the litter is decomposed by soil microorganisms. No information exists on the optimal rates or time of application to maximize cover crop biomass production. Poultry litter appears comparable to fertilizer as a source of N for a rye cover crop. An application of 30 lb N ac-1 produced sufficient biomass to meet a minimum biomass threshold, and a fall application of N was more beneficial during two out of three years. These results represent only one location over a 3-year period; therefore, these findings can not be expected to represent the entire Southeast. However, these results can be expected to provide general information related to N fertilizer and biomass production in the Southeast.

Last Modified: 10/22/2014