Vegetative Buffer Strips for Reducing Herbicide Transport in Runoff: Effects of Buffer Width, Vegetation, and Season

Abstract

The effectiveness of vegetative buffer strips (VBS) for reducing herbicide transport has not been well documented for runoff prone soils. A multi‐year plot‐scale study was conducted on an eroded claypan soil with the following objectives: (1) assess the effects of buffer width, vegetation, and season on runoff transport of atrazine (ATR), metolachlor (MET), and glyphosate; (2) develop VBS design criteria for herbicides; and (3) compare differences in soil quality among vegetation treatments. Rainfall simulation was used to create uniform antecedent soil water content and to generate runoff. Vegetation treatment and buffer width impacted herbicide loads much more than season. Grass treatments reduced herbicide loads by 19‐28% and sediment loads by 67% compared to the control. Grass treatments increased retention of dissolved‐phase herbicides by both infiltration and adsorption, but adsorption accounted for the greatest proportion of retained herbicide load. This latter finding indicated VBS can be effective on poorly drained soils or when the source to buffer area ratio is high. Grass treatments modestly improved surface soil quality 8‐13 years after establishment, with significant increases in organic C, total N, and ATR and MET sorption compared to continuously tilled control. Herbicide loads as a function of buffer width were well described by first‐order decay models which indicated VBS can provide significant load reductions under anticipated field conditions.

Improved APEX Model Simulation of Buffer Water Quality Benefits at Field Scale

“…Overall low simulated buffer effectiveness by any type of buffer configuration, compared to reported values (82%; Helmers et al, 2012), may be attributed to low infiltration rates as a result of low K sat values of soils for both types of buffers: 16 to 32 mm h -1 and 1 to 13 mm h -1 in agroforestry and grass buffers, respectively (Seobi et al, 2005). Indeed, a recent experiment on claypan soils led to 19% to 28% buffer effectiveness for trapping herbicide loads with varying adsorption coefficients and for varying buffer widths (Lerch et al, 2017). Herbicide and phosphorus are comparable in movement and are simulated with similar equations, although they are characterized by different adsorption coefficients (Neitsch et al, 2011;Williams et al, 2012).…”

“…Permanent vegetation in buffers removes sediment, nutrients, and pesticides from surface runoff water through filtration, deposition, adsorption, and infiltration (Dillaha et al, 1989, Lerch et al, 2017 and by increased degradation of some compounds (Lin et al, 2008). Studies have documented increased infiltration rates in buffers (Schmitt et al, 1999) due to improved soil porosity and hydraulic conductivity (Udawatta and Anderson, 2008;Kumar et al, 2011;Larson and Safferman, 2012).…”

Exposure and potential effects of pesticides and pharmaceuticals in protected streams of the US National park Service southeast region

“…While residential, lawn, and ornamental pesticides are frequently reported in wastewater in the southeast (Bradley et al, 2019) and elsewhere (Le et al, 2017;Münze et al, 2017;Sprague and Nowell, 2008), elevated occurrences in surface waters are typically attributed to spatially distributed, landscape-scale sources such as agriculture (Gilliom, 2007;Moschet et al, 2014;Ryberg and Gilliom, 2015;Shen et al, 2005;Smalling et al, 2013;Stone et al, 2014;Van Metre et al, 2017). The instream influence of such non-point sources can be substantially mitigated by establishment and maintenance of riparian buffers (Aguiar et al, 2015;Broadmeadow and Nisbet, 2004;Lerch et al, 2017;Orlinskiy et al, 2015;Turunen et al, 2019). The protective efficacy of riparian buffers, however, is undermined by hydraulic short-circuits that extend across the buffer into developed landscapes, including illicit piped discharges, agricultural tile drains, drainage ditches, or tributaries (Bereswill et al, 2012;Ghirardini and Verlicchi, 2019;Stehle et al, 2016).…”

Atrazine Transport through a Soil–Epikarst System

“…A particularly relevant aspect of karst aquifer systems is related to the typically high soil infiltration and percolation rates and absence of surface drainage networks. Thus, practices such as vegetative buffer strips and soil incorporation of herbicides that protect surface waters from contaminated runoff (Staddon et al, 2001; Krutz et al, 2005; Ghidey et al, 2010; Lerch et al, 2013, 2017) may not be effective for protecting karst aquifers that are vulnerable to leaching of herbicides and their metabolites. Further, implementation of vegetative buffer strips in cropped sinkholes will not be effective, as only the area immediately surrounding the sinkhole insurgence is protected.…”