Reducing Fumigant Emissions After Soil Application

Abstract

Volatilization and soil transformation are major pathways by which pesticides dissipate from treated agricultural soil. Volatilization is a primary source of unwanted agricultural chemicals in the atmosphere and can significantly affect fumigant efficacy. Volatile pesticides may cause other unique problems; for example, the soil fumigant methyl bromide has been shown to damage stratospheric ozone and will soon be phased out. There is also great concern about the health consequences of inhalation of fumigants by people living in proximity to treated fields. Because replacement fumigants will likely face increased scrutiny in years ahead, there is a great need to understand the mechanisms that control their emission into the atmosphere so these losses can be minimized without loss of efficacy. Recent research has shown that combinations of vapor barriers and soil amendments can be effective in reducing emissions. In this paper, some potential approaches for reducing fumigant emissions to the atmosphere are described.

Conversion of metam sodium and emission of fumigant from soil columns

“…Fumigation strategies that increase the fumigant residence time in soil are currently the most common and feasible approaches to reduce fumigant emissions. These include tarping with a film (plastic, paper or fabric), applying a water seal by irrigation, and increasing the depth of fumigation and the bulk density of the soil (Yates et al, 2002). Among physical containment approaches, surface water sealing is an economical and promising strategy to reduce fumigant emissions.…”

“…Initial or intermittent surface water sealing has shown great potential to improve field retention of MITC and reduce off-gassing rates of MITC from metam-sodium applications (Sullivan et al, 2004). Increasing the surface soil water content may reduce the soil air-filled pore space and thereby restrict fumigant diffusion into air (Jin and Jury, 1995;Yates et al, 2002).…”

Alternatives to Methyl Bromide: A Florida Perspective.

“…Agricultural films made from polyethylene plastic are highly permeable to soil fumigants and have marginal impact on fumigant retention in soil. (40,99,122,126). Virtually impermeable films (VIF) contain additional polymers that are impermeable to soil fumigants.…”

“…Other sources include, emissions from leaded gasoline (113) and biomass burning (6), as well as natural sources such as oceans (80), salt marshes (102), rice paddies (101) and litter decomposition. It is estimated that approximately 30% of methyl bromide emissions result from soil fumigation (126).…”

Evaluation of Crop Seed Powders as Amendments for Purple Nutsedge (Cyperus rotundus) Control Compared to the Traditional Herbicide, Roundup

“…It has been postulated that virtually impermeable film mulch provides better purple nutsedge control than low-density polyethylene mulch because it is thicker and tougher for weeds and fumigants to penetrate through and because it contains a polamide barrier permitting lower permeability for volatile compounds (Yates et al, 2002;Santos et al, 2007). Clear or transluscent polyethylene film mulches present another control measure which may work favorably with allelopathic plant residue treatments.…”