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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF MODELS AND CONSERVATION PRACTICES FOR WATER QUALITY MANAGEMENT AND RESOURCE ASSESSMENTS Title: Nitrogen and Phosphorus Runoff from Cropland and Pasture Fields Fertilized with Poultry Litter

Authors
item Harmel, Daren
item Smith, Douglas
item Haney, Richard
item Dozier, Monty - TEXAS AGRILIFE EXTENSION

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 17, 2009
Publication Date: November 1, 2009
Repository URL: http://hdl.handle.net/10113/37922
Citation: Harmel, R.D., Smith, D.R., Haney, R.L., Dozier, M.C. 2009. Nitrogen and Phosphorus Runoff from Cropland and Pasture Fields Fertilized with Poultry Litter. Journal of Soil and Water Conservation. 64(6):400-412.

Interpretive Summary: The recent expansion of land applying litter and other organic by-products offsite of animal production facilities has created both environmental concerns and agro-economic opportunities, but limited long-term, field-scale data are available to guide management decisions. Thus, the objective of this study was to determine the water quality effects of repeated annual poultry litter application. Eight years of data collected on ten field-scale watersheds indicated several significant water quality differences based on litter rate (0.0-13.4 Mg/ha). Increasing litter rates (with corresponding decreases in inorganic N) increased P concentrations in runoff but reduced extreme high N concentrations on cultivated site. Runoff N concentrations were much lower on cultivated sites, but P concentrations were similar between land uses. Runoff N and P concentrations generally decreased as time since fertilizer application increased, but few long-term trends in N and P runoff occurred due to the dynamic interaction between transport and source factors in spite of soil P buildup. These results support several practical implications, specifically: 1) combining organic and inorganic nutrient sources can be environmentally friendly and economically sound if application rates are carefully managed; 2) high runoff N and P concentrations can occur from well managed fields, which presents difficulty in regulating edge-of-field water quality; and 3) change in the animal industry mindset to view by-products as marketable resources would mitigate environmental problems, provide alternative fertilizer sources, and enhance animal industry revenue opportunities.

Technical Abstract: The recent expansion of land applying litter and other organic by-products offsite of animal production facilities has created both environmental concerns and agro-economic opportunities, but limited long-term, field-scale data are available to guide management decisions. Thus, the objective of this study was to determine the water quality effects of repeated annual poultry litter application. Eight years of data collected on ten field-scale watersheds indicated several significant water quality differences based on litter rate (0.0-13.4 Mg/ha) and several notable temporal patterns. Increasing litter rates (with corresponding decreases in inorganic N) increased PO4-P concentrations in runoff but reduced extreme high NO3-N concentrations on cultivated site. Runoff NO3-N concentrations were much lower on cultivated sites, but PO4-P concentrations were similar between land uses. Runoff NO3-N and PO4-P concentrations generally decreased as time since fertilizer application increased, but few long-term temporal trends in N and P runoff occurred due to the dynamic interaction between transport and source factors in spite of soil P buildup. These results support several practical implications, specifically: 1) combining organic and inorganic nutrient sources can be environmentally friendly and economically sound if application rates are carefully managed; 2) high runoff N and P concentrations can occur from well managed fields, which presents difficulty in regulating edge-of-field water quality; and 3) change in the animal industry mindset to view by-products as marketable resources would mitigate environmental problems, provide alternative fertilizer sources, and enhance animal industry revenue opportunities.

Last Modified: 12/18/2014
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