Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/16/2006
Publication Date: 1/10/2007
Citation: Gao, S., Trout, T.J. 2007. Surface Seals Reduce 1,3-Dichloropropene and Chloropicrin Emissions in Field Tests. Journal of Environmental Quality, 36:110-119. Interpretive Summary: Methyl bromide has been phased out as a fumigant because it is a stratospheric ozone depleting compound. Reducing emissions of alternative fumigants to MeBr is essential to minimize their detrimental impacts on human health and the environment, and to maintain the practices of fumigation for production of high value crops. This research tested several surface treatments to reduce emissions of 1,3-dichloropropene and chloropicrin from Telon C35 (a currently registered product) application in field plots on a sandy loam soil in San Joaquin Valley, California. Treatments include plastic tarps, surface water applications or water seal, and combination of both. Results demonstrated the variability of these methods to reduce emission rates (flux) and total emissions. The information is useful to define potential methods that can achieve both fumigation efficacy and emission reductions.
Technical Abstract: Reducing emissions is essential for minimizing the impacts of soil fumigation on the environment. Surface water application (or water seal) had been demonstrated to reduce 1,3-dichloropropene (1,3-D) emissions in soil column tests. This study was conducted to determine if surface water applications can effectively reduce emissions of 1,3-D and chloropicrin (CP) under field conditions following shank-application of Telone C35 (a commercial mixture of 61% 1,3-D and 35% choropicrin). A field trial with small plots was conducted on a Hanford sandy loam soil in the San Joaquin Valley, CA. Treatments included control (no tarp and no water applied), standard high density polyethylene (HDPE) tarp, virtually impermeable film (VIF) tarp, pre-irrigated soil + HDPE, initial water application (19 mm water) only following fumigation, and intermittent water applications (five times of 4.2 mm water application following the initial water application). The gas-phase distribution in soil profile and atmospheric emissions of fumigants were monitored for 9 days. Among the surface seal treatments, VIF and standard HDPE tarp resulted in the lowest and the highest total emission losses, respectively. Intermittent surface water applications reduced 1,3-D and CP emissions significantly more than HDPE tarp alone and the initial water application only. Lower fumigant concentrations in the soil-gas phase, however, were observed in the intermittent water application treatment compared to others raising concerns about fumigation efficacy. The pre-irrigated soil + HDPE tarp has consistently shown promising results to reduce fumigant emissions, and also yielded the highest surface soil temperature that may benefit overall soil pest control.