Poultry production is an important industry in the Southeastern United States, and large amounts of poultry litter are produced as a waste by-product. This litter is commonly applied to pastures to improve forage yield; however, repeated applications of litter to fields in areas of concentrated poultry production has led to both high soil phosphorus(P) levels and increases in nitrogen(N) and P in surface waters. Alternative sites for poultry litter disposal are needed to reduce pollution of water bodies by N and P. Since loblolly pine (Pinus taeda L.) plantations commonly are located near poultry production facilities, we are comparing the effects of litter application on soil processes in loblolly pine plantations and pastures to assess the relative merit of litter disposal under both types of land management. Three replicate 0.8 hectare plots were established on similar soils within both pastures and pine plantation stands. In April of 2004, half of each plot received a 9 Mg/ha litter application. The other portion of the plot had no litter application. The loblolly stands were 26 years old, and the pastures were managed for fescue and bermudagrass hay. Mineral soil samples were taken to a depth of 15 cm in January of 2005 to determine differences in the amounts of extractable-N and potential N-mineralization rates between both pasture and pine plantation soils and between litter amended and un-amended soils. Ammonium-N and nitrate-N was measured from sub-samples following extraction with 2M KCL. An additional group of sub-samples was extracted following a 28-day aerobic incubation at 25 C°. Differences between theses two extractions were used to calculate a nitrogen mineralization rate. These differences are being correlated with full soil characterization data to better understand the influence of poultry litter applications on soil and water chemistry in pastures and pine forests.
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See more of The ASA Southern Regional Branch (June 19-21, 2005)