|Lin, Chung Ho|
|Lerch, Robert - Bob|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2011
Publication Date: 3/24/2011
Citation: Lin, C., Lerch, R.N., Goyne, K.W., Garrett, H.E. 2011. Reducing herbicides and veterinary antibiotics losses from agroecosystems using vegetative buffers. Journal of Environmental Quality. 40(3):791-799. Interpretive Summary: Vegetative buffer strips (VBS) have been shown to be effective at reducing sediment and nutrient transport from agricultural fields. However, their ability to reduce the transport of organic compounds used in agricultural production, such as herbicides and veterinary antibiotics (VAs), has not been thoroughly evaluated, especially for high runoff potential soils such as those in the Central Claypan Region. In addition, VBS design criteria for reducing transport of herbicides and VAs are needed to determine which grass species and buffer width will optimize their effectiveness. Three VBS designs were evaluated in this study: 1) tall fescue; (2) tall fescue with a switchgrass barrier; and (3) native warm-season vegetation (largely eastern gamagrass and switchgrass). These VBS were then compared to a control treatment of continuous cultivated fallow. The study was conducted using 50’ long X 5’ wide plots, with the upper half of the plots cultivated and sprayed with three herbicides (atrazine, metolachlor, and glyphosate) and three VAs (enrofloxacin, sulfamethazine, and tylosin). The lower half of the plots consisted of the VBS designs mentioned above. A rainfall simulator was used to generate runoff. Water and sediment samples were collected at four points along the VBS at 10-minute intervals once runoff reached the bottom of the plots. The results showed that all VBS reduced the transport of both dissolved and sediment-bound atrazine, metolachlor and glyphosate in surface runoff, with reductions of 58 to 72% compared to the un-vegetated control. All of the VBS grass treatments reduced sulfamethazine transport in surface runoff by more than 70%. The tall fescue VBS was overall most effective at reducing dissolved tylosin and enrofloxacin transport in the runoff (>75%). The developed relationships between buffer width and load reduction can be used to predict expected field-scale results and provide design criteria for effective implementation of grass buffers. This study will benefit land management agencies by providing specific information for designing VBS that effectively reduce herbicide and VA transport from crop or pasture fields. Farmers will benefit because an optimized VBS design will achieve desired agrochemical reductions while minimizing the amount of land taken out of production.
Technical Abstract: Multiple species vegetative buffer strips (VBS) have been recommended as a cost-effective approach to mitigate agrochemical transport in surface runoff derived from agronomic operations, while at the same time offering a broader range of long-term ecological and environmental benefits. However, the effect of VBS designs and species composition on reducing herbicide and veterinary antibiotic transport has not been well documented. An experiment consisting of three VBS designs and one cultivated fallow control replicated in triplicate was conducted to assess effectiveness in reducing herbicide and antibiotic transport for claypan soils. The four VBS treatments include: (1) continuous cultivated fallow (control), (2) tall fescue, (3) tall fescue with a switchgrass hedge barrier, and (4) native vegetation (largely eastern gamagrass). Rainfall simulation was used to create uniform antecedent soil moisture content in the plots and to generate runoff. Our results suggested that all VBS significantly reduced the transport of both dissolved and sediment-bound atrazine, metolachlor and glyphosate in surface runoff by 58 to 72%. Four to eight meters of any tested VBS reduced dissolved sulfamethazine transport in the surface runoff by more than 70%. The tall fescue VBS was overall most effective at reducing dissolved tylosin and enrofloxacin transport in the runoff (>75%). The developed exponential regression models can be used to predict expected field-scale results and provide design criteria for effective field implementation of grass buffers. Our study has demonstrated that an optimized VBS design may achieve desired agrochemical reductions and minimize acreage removed from crop production.