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Title: Influence of aeration implements, phosphorus amendment and soil taxa on phosphorus losses from grasslands

Author
item Franklin, Dorcas
item Butler, David
item CABRERA, M - University Of Georgia
item CALVERT, V - University Of Georgia
item WEST, L - Natural Resources Conservation Service (NRCS, USDA)
item REMA, J - University Of Georgia

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2010
Publication Date: 3/1/2011
Citation: Franklin, D.H., Butler, D.M., Cabrera, M.L., Calvert, V., West, L.T., Rema, J.A. 2011. Influence of Aeration Implements, Phosphorus Amendment and Soil Taxa on Phosphorus Losses from Grasslands. Journal of Environmental Quality. 40(2):312-319.

Interpretive Summary: Mechanical aeration has largely been promoted to alleviate soil compaction, increase rainfall infiltration, and to improve the health of turf grasses and the productivity of forage grasses. There is also the potential for aeration to reduce P losses in runoff from grasslands with applied P amendments through increased rainfall infiltration, partial incorporation of applied manures, binding of P with soil minerals, and slowing of runoff flow through increased roughness of the soil surface. Studies have been conducted to explore the viability of aeration to provide environmental and agronomic benefits, however, research results have been variable. Scientists from USDA ARS J. Phil Campbell Sr., Natural Research Conservation Center, USDA ARS U.S. Horticultural Research Laboratory, The University of Georgia, and the USDA NRCS conducted two small-plot aeration studies and one field-scale paired watershed study, which are reviewed in this manuscript. The overall objective of these studies was to determine the impact of aeration on runoff volume and P losses in runoff from mixed tall fescue-bermudagrass grasslands fertilized with P amendments. Small-scale rainfall simulations were done on two soil taxa using three types of aeration implements. The-field scale study was conducted in six 0.7–ha (1.7-acre) bermed field-scale watersheds with varied soil taxa and drainage classes. Small plot studies showed that core aeration reduced total P (46 %) and dissolved reactive P (62%; DRP) losses from plots fertilized with broiler litter. In the field-scale study, aeration reduced DRP losses by 35% in fields with well-drained soils, but not in poorly-drained soils Small plot studies showed that core aeration reduced total P (46 %) and dissolved reactive P (62%; DRP) losses from plots fertilized with broiler litter. In the field-scale study, aeration reduced DRP losses by 35% in fields with well-drained soils, but not in poorly-drained soils. In summary, soil characteristics such as internal drainage, depth of the BC horizon, position of shallow BC horizons, compaction, aeration implement, and type of manure applied on the grassland surface are likely to interact to determine the overall effectiveness of aeration on runoff volume and P losses.

Technical Abstract: Attenuation of rainfall within the solum may help to enhance forage productivity during droughty periods, retard flooding during periods of heavy rainfall, and move nutrients and contaminants into the soil to be better utilized, transformed, or sequestered. Application of broiler litter to grasslands may lead to elevated concentrations of phosphorus (P) in surface runoff, which has potential to cause eutrophication of surface waters. Thus, management practices are currently needed to reduce the amount of P loss in runoff from fertilized grasslands. Studies have been conducted to explore the viability of aeration to provide environmental and agronomic benefits, however, research results have been variable. Here, results from two small-plot aeration studies and one field-scale paired watershed study are presented. The overall objective of these studies was to determine the impact of aeration on runoff volume and P losses in runoff from mixed tall fescue Lolium arundinaceum (Schreb.) Darbysh.]-bermudagrass (Cynodon dactylon L.)] grasslands fertilized with P amendments. Small-scale rainfall simulations were done on two soil taxa using three types of aeration implements. The-field scale study was conducted varied soil taxa and drainage classes. Small plot studies showed that core aeration reduced total P (46 %) and dissolved reactive P (62%; DRP) losses from plots fertilized with broiler litter. In the field-scale study, aeration reduced DRP losses by 35% in fields with well-drained soils, but not in poorly-drained soils. In summary, soil characteristics such as internal drainage, depth and position of the BC horizon, compaction, aeration implement, and type of manure applied on the grassland surface are likely to interact to determine the overall effectiveness of aeration on runoff volume and P losses.