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United States Department of Agriculture

Agricultural Research Service

Title: Drip Fumigation: Water and Fumigant Distribution in Soil.

Authors
item Ajwa, Husein - UNIV OF CALIF DAVIS
item Trout, Thomas
item Nelson, Shad - TEXAS A & M UNIVERSITY
item Schutter, Mary - COLORADO STATE UNIV.

Submitted to: Methyl Bromide Alternatives and Emissions Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2001
Publication Date: November 16, 2001
Citation: Ajwa, H.A., Trout, T.J., Nelson, S.D., Schutter, M. 2001. Drip fumigation: water and fumigant distribution in soil.. Methyl Bromide Alternatives and Emissions Research Conference Proceedings.

Interpretive Summary: Drip fumigation with alternative fumigants to methyl bromide [1,3- dichloropropene (1,3-D), chloropicrin (Pic), methyl isothiocyanate (MITC), iodomethane (IM), and propargyl bromide (PrBr)] may provide a more uniform distribution of chemicals in the soil than shank injection. Water distribution and soil gas concentrations of these fumigants in the soil profile were monitored following drip fumigation on three soil types with several drip tape and bed configurations commonly used in California. The distribution of Pic initially follows the water distribution pattern, but fumigant and water distribution patterns differ considerably 24 hrs after fumigation. A large portion of Pic remained within the upper 30 cm of the soil bed and its downward movement appeared to be less than that of other fumigants (e.g., IM), possibly due to its short half-life in soil (1 d) and low water solubility (0.20 %). All fumigants except MITC diffuse in the soil gaseous phase beyond the waterfront. MITC distribution in soil initially follows the water distribution patterns, but unlike other fumigants, the distribution patterns do not change over time. MITC disappears from the soil gaseous phase at faster rates than other fumigants. This research explains distribution patterns of various fumigants in relation to their physico-chemical properties and environmental conditions.

Technical Abstract: Drip fumigation with alternative fumigants to methyl bromide [1,3- dichloropropene (1,3-D), chloropicrin (Pic), methyl isothiocyanate (MITC), iodomethane (IM), and propargyl bromide (PrBr)] may provide a more uniform distribution of chemicals in the soil than shank injection. Water distribution and soil gas concentrations of these fumigants in the soil profile were monitored following drip fumigation on three soil types with several drip tape and bed configurations commonly used in California. The distribution of Pic initially follows the water distribution pattern, but fumigant and water distribution patterns differ considerably 24 hrs after fumigation. A large portion of Pic remained within the upper 30 cm of the soil bed and its downward movement appeared to be less than that of other fumigants (e.g., IM), possibly due to its short half-life in soil (1 d) and low water solubility (0.20 %). All fumigants except MITC diffuse in the soil gaseous phase beyond the waterfront. MITC distribution in soil initially follows the water distribution patterns, but unlike other fumigants, the distribution patterns do not change over time. MITC disappears from the soil gaseous phase at faster rates than other fumigants. This research explains distribution patterns of various fumigants in relation to their physico-chemical properties and environmental conditions.

Last Modified: 10/1/2014
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