Buffer zone and windbreak effects on spray drift deposition in a simulated wetland

Abstract

The amount of agricultural spray that drifts into a wetland from an adjacent crop field is influenced by vegetation along the field boundary or any intentional setback distance (buffer zone) between the sprayer and the edge of the arable field. In this study, spray tracer drift deposits were measured in a simulated wetland area under different conditions of wind speed and buffer zone width. The effect of an artificial windbreak at the upwind edge of the simulated wetland was also evaluated. A level of tolerance of 0.1% of the in-swath spray deposition was established as a no-effect level for the response of aquatic plants to common herbicides. Our results indicate that a vegetated 10-m field margin (eg a fencerow) alone provides adequate protection from herbicide drift into a wetland area under wind conditions normally considered acceptable for spraying. For high winds (> 4m s(-1)) when field spraying would not normally be advised, adequate protection was afforded by the same 10-m margin plus a dense windbreak (25% porosity) or by the margin plus a 20-m buffer zone.

Effects of the herbicide dicamba on nontarget plants and pollinator visitation

“…]/ha, 0.0056 g a.e./ha, 0.056 g a.e./ha, 0.56 g a.e./ha, 5.6 g a.e./ha, and 56.1 g a.e./ha) were arranged in a randomized complete block design (6.1 Â 2.4-m plots) and replicated 4 times. Based on a 561 g a.e./ha field application, a current label rate for corn [37], these values correspond to the lowest observed effect rate for dicamba exposures on sensitive soybean plants (0.0056 g a.e./ha [14]), vapor drift exposures (< 0.56 g a.e./ha [14,17]), a particle drift exposure (5.6 g a.e./ha [38][39][40]), or a serious misapplication event (56.1 g a.e./ha). The farm manager established the alfalfa field in April 2004 with Genoa 1 NK seed (Helena Chemical) at a rate of 20 kg/ha.…”

Spray particle drift mitigation using field corn (Zea mays L.) as a drift barrier

“…Another particle drift mitigation effort includes placing windbreaks or barriers on the field boundaries to reduce the within-crop wind speed and capture further off-target movement of spray particles. [24][25][26][27] Cereal crop hedgerows were shown 30 Similarly, they hypothesized that very dense vegetation would exacerbate this problem. Modeling efforts were used to evaluate this porosity effect of border crops on the entrapment of spray particles and particle drift reduction principles.…”

Measuring Sub-Second Wind Velocity Changes at One Meter above the Ground

“…Popular methods include Lagrangian, Gaussian, Random Walk, Regression, and CFD models (Holterman, Van de Zande, Porskamp, & Huijsmans, 1997;Baetens, et al, 2007;Teske, et al, 2002;Tsai, et al, 2005;Frederic, Verstraete, Schiffers, & Destain, 2009;Smith, Harris, & Goering, 1982). Through the use of such models, applicators gain knowledge of when drift potential is high and can adjust buffer zones to minimize the risk for spray drift (Craig, 2004;Brown, Carter, & Stephenson, 2004). Attention is given to the development and progression of the droplets, but less attention is devoted to the random nature of weather surrounding the droplet, such as the distribution of wind speed and direction with which the droplet interacts.…”