Reducing Fumigant Air Emissions at the Agricultural/Urban Interface
This study seeks change in current center pivot chemigation application practices to reduce fumigant off-gassing of methyl isothiocyanate (MITC) from large field production agriculture to near-by residential communities. The study design is appropriate for assessing field volatilization flux density (flux) from putative fumigant emission-reducing technologies such as soil incorporated shank injection and recent modifications for low pressure center pivot system designs. Based on near-field MITC emission studies conducted in 2006, we anticipate that appreciable reductions can be realized in fumigant emissions through grower/consulting agronomist adoption of shank injection or implementation of cost-effective modifications to current pivot chemigation application practices. Anticipated grower benefits will include enhanced MITC soil retention and improved quality and consistency of product efficacy thus resulting in possible reductions in fumigant application rates. Investment in this integrated field flux/field efficacy program will also aid state/federal regulatory agencies for ascertaining the effectiveness of these emission-reducing technologies when assessing human inhalation exposures to MITC at the agriculture/urban interface. Moreover, this program will provide a mechanism though university outreach for communicating product stewardship. This combined research/outreach effort will not only benefit growers, residential bystanders, and regulatory customers in Washington State, but will be of importance for developing alternative fumigant reducing tactics in other large acreage field crop production regions within the Pacific Northwest with similar shared residential/agricultural land use practices. Funding will be leveraged in 2008 -2009 with existing moneys from the State Department of Health, State commodity/pesticide registration commission (pending), and in-kind support from custom applicators and the grower community.
Project goals and objectives
PROJECT GOALS AND OBJECTIVES
1. Assess emission rates and total cumulative field loss of metam sodium’s gaseous by-product, methyl isothiocyanate (MITC) during and four days post-application under conditions typical for Pacific Northwest (PNW) potato pre-plant fumigation to aid growers in evaluating putative reduced emission application practices particularly when deciding on application practices/timing near residential communities.
2. Provide regionally specific MITC emission rate information to the United States Environmental Protection Agency Office of Pesticide Programs (EPA-OPP).
Following Cal DPR technical procedures, the estimated total cumulative MITC loss by drizzle boom was 47% compared to 12.6% by soil incorporated shank injection. These two application demonstrations provide a range of regionally-specific emission flux data typical of the cooler fall climatic conditions when PNW fumigations are occurring for U.S. EPA to consider.