|ZWONITZER, MARTHA - Texas A&M Agrilife|
Submitted to: Journal of Soils and Sediments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2016
Publication Date: 3/3/2016
Citation: Gonzalez, J.M., Smith, D.R., Livingston, S.J., Pappas, E.A., Zwonitzer, M. 2016. Blind inlets: Conservation practices to reduce herbicide losses from closed depressional areas. Journal of Soils and Sediments. doi:10.1007/s11368-016-1362-0.
Interpretive Summary: Pesticides are used to improve agricultural production, but could unintentionally affect water quality negatively. Pothole areas are typical in the US upper Midwest and are usually drained with tile risers if the land is farmed, but sediment and contaminants in runoff are not treated to improve water quality. The blind inlet, an alternative to the tile riser, has been shown to be effective in reducing sediments and nutrients in agricultural runoff. In a six-year study, we investigated the effectiveness of blind inlets to reduce pesticide losses from two farmed pothole areas in the US Midwest in a 4-year crop rotation. Atrazine, metolachlor, 2,4-D, glyphosate, and an atrazine byproduct (DEA) were analyzed from the surface runoff of the pothole areas from 2008 to 2013. Relative to tile risers, blind inlets reduced, pesticide loss: atrazine (69%), DEA (57%), 2,4-D (58%), metolachlor (53%), and glyphosate (11%). Blind inlet is an effective conservation practice to reduce pesticide losses from surface runoff of pothole areas in the US Midwest.
Technical Abstract: Pesticides are designed to benefit agricultural production and may inadvertently affect water quality if environmental stewardship programs are not implemented. Closed depressional areas (potholes) are typical in the US Midwest and are usually drained with tile risers, however sediment and contaminant in runoff are not prevented or reduced by this practice. Blind inlets are an alternative conservation practice to tile risers which have been shown to reduce sediment and nutrient loads to nearby bodies of water. In a six-year study, we investigated the effectiveness of blind inlets in reducing pesticide losses from two closed farmed potholes in the US Midwest under a 4-year cropping rotation. Surface runoff collected from potholes from 2008 to 2013 was analyzed for atrazine, metolachlor, 2,4-D, glyphosate, and deethylatrazine. The blind inlets reduced the levels of pesticides analyzed in this study; however, reductions were compound dependent: atrazine (69%), deethylatrazine (57%), 2,4-D (58%), metolachlor (53%), and glyphosate (11%). The key factors by which the blind inlet may reduce herbicide losses relative to the tile riser are the reduced discharge and the increased flow tortuosity. This is the first study to document the impact of this novel conservation practice on pesticide fate and transport from farmed potholes. Results from this study found and corroborate previous research stating that blind inlets are an effective conservation practice to reduce sediment and contaminants, including pesticides from farmed pothole surface runoff in the US Midwest.