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item Hubbard, Robert

Submitted to: Proceedings of the Symposium on the State of the Science of Animal Manure
Publication Type: Proceedings
Publication Acceptance Date: 12/15/2004
Publication Date: 1/6/2005
Citation: Hubbard, R.K., Newton, L. 2005. Land treatment of swine lagoon effluent using overland flow vegetated buffer systems. In: Proceedings of the Symposium on the State of the Science of Animal Manure. January 6, 2005, San Antonio, Texas. 2005 CDROM.

Interpretive Summary: Intensive animal production operations may result in high loading rates of nitrogen (N) to soils and waters. This excess N may contribute to eutrophication of surface water bodies or contamination of ground water used for drinking. Methods are needed to utilize animal wastes so that land managers receive financial return from the N while pollution does not occur. Both vegetated filter strips and constructed wetlands have been shown to be effective in treating animal waste. However, little is known about the effectiveness of combined grass-forest buffers on filtering N from animal wastes. Lagoon waste from a commercial hog operation was applied to grass-forest buffer systems based on either the N or P content of the wastewater. Transects of shallow groundwater wells at 1 and 2 m were used to determine impact of wastewater applications to the buffers on nitrates in shallow groundwater. Results from 4 years of wastewater application and sampling and analyzes of the shallow groundwater indicated that this technology can be useful to small producers. The research described will aid animal producers in designing grass-forest buffer systems for utilization of N so that agricultural pollution will be minimized and the nation's soil and water resources will be conserved.

Technical Abstract: Pollution of soils, surface water, and ground water from animal wastes is of growing environmental concern. Excess N from animal wastes may contribute to eutrophication of water bodies or contamination of drinking water. One method for utilizing nutrients from lagooned animal wastes is application to vegetated buffer systems by overland flow. A farm-scale test of a grass-forest buffer system was started in March 2000 on a local commercial hog producer's farm in south Georgia. The objective was to test low cost overland flow grass-forest buffer systems at the farm scale to determine if they can effectively utilize nutrients from wastewater while protecting environmental quality. Six sections of a grass-forested area were selected to receive the wastewater or serve as control areas. Wastewater (average N, 300 mg/L; average P, 30 mg/L) was applied to 4 sections (60 m wide) through slotted pipe such that the wastewater flowed first over a grassed buffer and then into either mature or planted pine forest. Two of the sections received wastewater based on N (target rate of 800 kg N/ha/yr) while two received wastewater based on P (target rate of 100 kg/P/ha/yr). The remaining 2 sections were used as controls and did not receive wastewater. Transects of shallow groundwater wells at 1 and 2 m depth were sampled at least twice annually and the groundwater was analyzed for N, P, and Cl. This paper reports on 4 years findings on the effectiveness of these vegetated filter systems in assimilating N from the wastewater. Results of both this farm-scale study and an earlier plot scale study indicate that this technology can be useful to small producers.