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United States Department of Agriculture

Agricultural Research Service

Title: Narrow Grass Hedge Effects on Phosphorus and Nitrogen in Runoff Following Manure and Fertilizer Application

Authors
item Eghball, Bahman
item Gilley, John
item Kramer, Larry
item Moorman, Thomas

Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 2000
Publication Date: N/A

Interpretive Summary: Effects of narrow switchgrass hedges on runoff losses of N and P were determined on tilled and no-till soils receiving manure and inorganic fertilizer. The objective of this study was to evaluate the effects of narrow switchgrass hedges (~ 3 ft wide) on the transport of P and N from a field receiving beef cattle feedlot manure in tilled and no-till conditions. This study was conducted on a steep (12 % average slope) Monona silt loam soil near Treynor, Iowa. The experiment was a split-plot with no-till and disked systems as main plots and subplots of manure, fertilizer and check with or without a grass hedge. A rainfall simulator was used and runoff was collected from both the initial and the following wet simulations. Only 38% of the no-till plots and 63% of disked plots had any runoff during the initial 2.5 in hr-1 water application. A single narrow grass hedge reduced runoff concentrations of dissolved P (DP) by 47%, bioavailable P (BAP) by 48%, particulate P (PP) by 38%, total P (TP) by 40%, and NH4-N by 60% during the wet simulation on the no-till plots receiving manure, compared with similar plots with no hedges. The corresponding reductions in concentrations as a result of a grass hedge for DP, BAP, PP, TP, and NH4-N on the disked plots were 21, 29, 43, 38, and 52%, respectively. Grass hedges also reduced total quantities of DP, BAP, TP, and NH4-N during the wet simulation. The TP loss was 3.3% of applied P fertilizer and was 0.3% of applied manure P. Narrow grass hedges were effective in reducing P and N losses in runoff from both manure or fertilizer application.

Technical Abstract: Runoff losses of N and P from field-applied manure can contribute to surface water pollution. Grass hedges may reduce runoff losses of nutrients and sediment. The objective of this study was to evaluate the effects of narrow switchgrass (Panicum virgatum L.) hedges (~ 0.75 m wide) on the transport of P and N from a field receiving beef cattle feedlot manure in tilled and no-till conditions. This study was conducted on a steep (12 % average slope) Monona silt loam (fine-silty, mixed, superactive, mesic Typic Hapludolls) soil near Treynor, Iowa. The experiment was a split-plot with no-till and disked systems as main plots and subplots of manure, fertilizer and check with or without a grass hedge. A rainfall simulator was used and runoff was collected from both the initial and the following wet simulations. A single narrow grass hedge reduced runoff concentrations of dissolved P (DP) by 47%, bioavailable P (BAP) by 48%, particulate P (PP) by 38%, total P (TP) by 40%, and NH4-N by 60% during the wet simulation on the no-till plots receiving manure, compared with similar plots with no hedges. The corresponding reductions in concentrations as a result of a grass hedge for DP, BAP, PP, TP, and NH4-N on the disked plots were 21, 29, 43, 38, and 52%, respectively. Runoff NH4-N concentration from fertilizer applied to the disked plots was reduced by 61%, NO3-N by 21%, and total N (TN) by 27% during the wet simulation when grass hedges were used. The TP loss was 3.3% of applied P fertilizer and was 0.3% of applied manure P. Narrow grass hedges were effective in reducing P and N losses in runoff from both manure or fertilizer application.

Last Modified: 7/25/2014
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