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United States Department of Agriculture

Agricultural Research Service

Title: Enhancement of subsurface distribution and reduction of surface emissions of the fumigants 1,3-dichloropropene, chloropicrin, and methyl isothiocyanate in field sandy soil

Authors
item Ou, Li-Tse - UNIV. OF FLORIDA
item Thomas, John - UNIV. OF FLORIDA
item Allen, Leon
item Vu, Joseph
item Dickson, Donald - UNIV. OF FLORIDA

Submitted to: Symposium in Pesticide Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2007
Publication Date: August 1, 2007
Citation: Ou, L., Thomas, J.E., Allen Jr, L.H., Vu, J.C., Dickson, D.W. 2007. Enhancement of subsurface distribution and reduction of surface emissions of the fumigants 1,3-dichloropropene, chloropicrin, and methyl isothiocyanate in field sandy soil, pp. 347-356. IN: A.A.M. Del Re, E. Capri,G. Fragoulis, and M. Trevisan (eds.) Environmental Fate and Ecological Effects of Pesticides, XIII International Symposium in Pesticide Chemistry. 1015 pp. La Goliardica Pavese, Pavia, Italy

Interpretive Summary: The use of methyl bromide in US agriculture was suspended in 2005. Three fumigants, 1,3-dichloropropene, chloropicrin, and metam sodium--which forms methyl isothiocyanate in soil, are potential alternates for pre-plant soil fumigation. USDA, ARS scientist and collaborators studied the use of various plastic mulches and five fumigant application methods (both injection and drip-tube application) in Florida sandy fields for improving subsurface distribution and reducing surface emissions to the atmosphere. All standard polyethylene films (PE) were permeable to fumigants and resulted in rapid emissions to the atmosphere and rapid decrease of concentrations in the root zone. Virtually impermeable films (VIF) were always much less permeable than PE and therefore always retained fumigants in the root zone better. Metallic-coated polyethylene (MPE) films ranked between PE and VIF in fumigant retention. Avenger coulter injection reduced surface emissions and retained fumigants in the root zone better than any other application method, particularly in combination with VIF cover. Finally, improved retention of fumigants in soil could lead to lower amounts of chemicals being used in production of high-value vegetable crops.

Technical Abstract: Use of methyl bromide in US agriculture was suspended in 2005. Three registered fumigants, 1,3-dichloropropene, chloropicrin, and metam sodium/methyl isothiocyanate, are potential alternatives for pre-plant soil fumigation. The purpose of this ongoing study was to develop and assess strategies for enhancing subsurface distribution and reducing surface emissions of these fumigants in fields of Florida sandy soil. Strategies include use of various plastic mulches, fumigant delivery methods, and dispersion enhancement. Except for metallic-coated polyethylene films (MPE), all high- and low-density polyethylene films (PE) were permeable to fumigants resulting in rapid volatilization into the atmosphere and rapid decrease of concentrations in the root zone. Virtually impermeable films (VIF) were much less permeable than PE and retained fumigants in the root zone better. MPE were between PE and VIF in fumigant retention. Avenger coulter injection reduced surface emissions and retained fumigants in the root zone better than five other application methods, particularly in combination with VIF cover. Chemical and microbial degradation contribute to the reduction of both subsurface concentration and surface emissions of the fumigants.

Last Modified: 8/29/2014
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