Wei Zhang - Tracer movement through paired vegetative treatment areas receiving silage bunker runoff

Version 1

      Publication Details (including relevant citation   information): Faulkner, J.W., Zhang, W., Geohring, L.D.,   Steenhuis, T.S., Journal of Soil and Water Conservation  , 2011, 66 (1 ), pp 18 -28

      Abstract: The need for less resource-intensive   agricultural waste treatment alternatives has lately increased.   Vegetative treatment areas (VTAs) are considered a low-cost   alternative to the collection and storage of various agricultural   wastewaters. As VTAs become more widespread, the need for design   guidance in varying climates and landscapes increases. The   purposes of this study were to investigate runoff movement and   nitrate-nitrogen concentrations within two VTAs and to use the   results to improve VTA design and recommendations for management.   Silage bunker runoff movement through the selected VTAs following   a 7.8 mm (0.31 in) rainfall event was characterized using a   chloride tracer. Both surface and subsurface runoff movement was   analyzed using tracer concentrations and a simple binary mixing   model. Results show that concentrated surface flow paths existed   within both VTAs, and surface flow in general was more prevalent   in the VTA that received a higher hydraulic loading. Rapid   preferential flow to shallow monitoring wells was also observed.   A shallow restrictive soil layer likely exacerbated surface flow   but restricted runoff water and nitrate-nitrogen from leaching to   deeper groundwater. The nitrate-nitrogen did not appear to be   directly linked to runoff movement, but concentrations as high as   28 mg L−1 were observed in downslope surface flow in the wetter   VTA. A more comprehensive VTA design process is called for that   accounts for shallow soils and antecedent moisture conditions.   Regular maintenance and design measures to prevent the formation   of concentrated flow paths are also critical to the prevention of   surface discharge.

      Address (URL): http://www.jswconline.org/content/66/1/18.abstract