|Qin, Ruijun - UC DAVIS|
|Mcdonald, Jason - CONDOR EARTH TECHNOLOGY|
Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 11, 2008
Publication Date: September 17, 2008
Citation: Gao, S. R. Qin, J. McDonald, B. D. Hanson, and T. J. Trout. 2008. Field tests of surface seals and soil treatments to reduce fumigant emissions from shank-injection of Telone C35. Sci. Total Environ. 405:206-214. Interpretive Summary: Reducing emissions of fumigants is important to minimize toxicity risks from soil fumigation. Although many emission reduction methods are available, not many effective, economically feasible and environmentally safe agricultural practices are defined. This research tested several potential surface seal and soil treatment methods to reduce emissions of 1,3-Dichloropropene and chloropicrin emissions from shank-injection of Telone C35 under field conditions in the San Joaquin Valley of California. Applications of potassium thiosulfate were most effective to reduce emissions but caused some unknown reactions in the soil that need better understanding. Pre-irrigation with the amount of water that did not reduce fumigant concentrations in soil air reduced more emissions than post-fumigation water seals. Irrigation prior to fumigation offers a favorable option in field practice because of its easy management and the least fumigant exposure risks to workers. Contrary to other findings, application of composted manure to soil surface followed by standard plastic tarp did not reduce emissions compared to the control, possible due to the higher temperature under tarp than bare soils.
Technical Abstract: Telone or 1,3-dichloropropene (1,3-D) and chloropicrin (CP) are increasingly used soil fumigants and their emission reductions are required to reduce contribution of volatile organic compounds to the atmosphere and improve air-quality. Research has identified various methods to reduce fumigant emissions but effective and economically feasible field methods, are mostly needed. The objective of this study was to determine the effectiveness of several surface seals and soil treatment methods including irrigation prior to fumigation (pre-irrigation), post-fumigation water seals with or without potassium thiosulfate (KTS) amendment, and standard high density polyethylene (HDPE) tarp over soils amended with either KTS or composted manure on emissions of 1,3-D and CP from shank-injection of Telone C35. Results showed that the pre-irrigation, that can be easily applied and with the amount of water unlikely to reduce fumigant concentrations in the soil-gas phase, reduced emissions more than post-water seals. The KTS treatments were the most effective to reduce fumigant emissions but caused some chemical reactions and changed soil color in surface soils. The composted manure incorporated followed by HDPE tarp resulted in highest emission peaks at day time, possibly due to the higher temperature under tarps than bare soils. As a result, this treatment did not reduce emissions in this field trial, which indicates the need for further research to specify field conditions for effectively use organic amendment to reduce fumigant emissions.