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Vegetated Treatment Area Effectiveness at Reducing Nutrient Runoff from Small Swine Operations in Central Texas

K. D. Higgs, R. D. Harmel, K. Wagner, P. K. Smith, R. L. Haney, D. R. Smith, R. Pampell
Applied engineering in agriculture 2015 v.31 no.4 pp. 621-629
administrative management, animal feeding operations, animal pens, barns, chemical concentration, field experimentation, grasses, models, nitrate nitrogen, phosphorus, pollution load, runoff, sampling, small farms, soil, solids, sustainable technology, swine, swine production, volume, waste management, water quantity, Texas
Numerous modeling and field studies have evaluated the effectiveness of vegetative treatment systems in treating runoff from animal feeding operations; however, none have evaluated the effectiveness of vegetative treatment areas (VTAs) receiving direct runoff from small swine operations. The project objective was to determine whether a sufficiently sized VTA alone can effectively remediate direct runoff from small swine operations (<100 animals). Three study locations were established in 2012, and sampling sites were installed to measure runoff water quantity and quality at the VTA inlet, VTA outlet, and a nearby control. The VTAs reduced runoff volume by 17%-55%, nutrient concentrations by 23% 91%, and nutrient loads by 50%-96%, although some median NO3-N concentrations and loads increased. The Bell County VTA significantly reduced most nutrient concentrations and loads, many to the level of the control site, which represents "near ideal" performance. The Brazos County VTA also significantly reduced all nutrient concentrations and loads except for NO3-N, but the reductions were not adequate to match levels at the control. The Robertson County VTA inlet and outlet produced low nutrient concentrations and loads that were similar to the control, which is partially attributed to alternative management of solids and enclosed barn pens. Average soil N and P levels decreased from April 2013 to October 2014, although some nutrient build-up did occur near the VTA inlets in Bell and Brazos County. Based on these results, with proper consideration of design and management factors (e.g., solids management, perennial grass cover and subsequent haying and removal, and nutrient loads/VTA area), VTAs can be practical, environmentally-friendly waste management alternatives.