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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Publications at this Location » Publication #189633
Title: A FARM-SCALE TEST OF NITROGEN ASSIMILATION BY VEGETATED BUFFER SYSTEMS RECEIVING SWINE LAGOON EFFLUENT BY OVERLAND FLOW

Author
item Hubbard, Robert
item NEWTON, G - UNIV. OF GEORGIA
item RUTER, JOHN - UNIV. OF GEORGIA

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2006
Publication Date: 2/1/2007
Citation: Hubbard, R.K., Newton, G.L., Ruter, J.M. 2007. A farm-scale test of nitrogen assimilation by vegetated buffer systems receiving swine lagoon effluent by overland flow. Transactions of the ASABE. 50(1):53-64.

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. Vegetated filter strips have been shown to be effective in treating animal waste, but little is known about the effectiveness of farm-scale grass-forest buffers in assimilating N from animal wastes. Lagoon wastewater from a commercial hog operation was applied to grass forest buffers based on either the N or P content of the wastewater. Transects of shallow groundwater wells (10, 20, 30, and 40 m downslope) at 1 and 2 m were used to determine the impact of wastewater applications to on nitrates, ammonium, and chloride in shallow groundwater. Results from five years of wastewater application and analyses of the shallow groundwater indicated that this technology can be useful to small producers for assimilating a portion of their N load. 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: A farm-scale study was conducted from 2000 – 2004 to determine the effectiveness of grass-forest buffers in assimilating N from overland flow application of swine lagoon effluent. Wastewater was pumped from a single stage anaerobic wastewater lagoon to vegetated buffers composed of grass and mature or planted pines. Six buffers were instrumented for wastewater application and water quality monitoring. Two buffers received wastewater at a 1 N rate (600 kg N ha-1 yr-1), 2 at a ¾ N rate (450 kg N ha-1 yr-1), and 2 served as Controls. Transects of shallow wells were used to determine the effectiveness of the buffers in assimilating N. Study results were impacted by N sources in addition to the wastewater. During spring-summer 2002 the animal producer installed a wastewater sprayfield immediately upslope of three of the buffers. Also, winter cabbage, which requires high N inputs, was grown directly upslope of the wastewater sprayfield during winter-spring 2003. The study showed mixed results concerning N assimilation by the buffers. The buffers located downslope from the sprayfield and cabbage production were unable to assimilate sufficient N to protect shallow groundwater quality. In contrast, shallow groundwater under the buffers receiving N only from the overland flow maintained nitrate concentrations lower than 10 mg L-1. On these buffers, downslope NO3-N concentrations in shallow groundwater were near background levels five years after wastewater applications commenced.