Suduan Gao and Tom Trout. USDA-ARS, 9611 S Riverbend Ave., Parlier, CA 93648
Reducing emissions is critical to minimize the detrimental impact of fumigation on the environment and to assure future uses of alternative fumigants to methyl bromide. The objective of this study was to determine the potential of using water applied to the soil surface to reduce emissions. Column experiments were conducted under laboratory controlled conditions. Cis 1,3-dichloropropene (1,3-D) was applied to soil (Hanford sandy loam) columns. Emissions and distribution of the fumigant in soil gaseous phase were monitored for up to two weeks. Treatments included control (dry soil with no surface water application and no plastic tarp), initial water application (16 mm water right before fumigant application) with or without standard HDPE tarp, intermittent water applications (2.6 mm water at 12 and 24 h following the initial water application) without tarps, and dry soil with plastic tarps (HDPE and VIF) without water applications. Intermittent water applications were more effective in reducing emissions within a short period of time after water application. Seventy-two hour cumulative emissions were reduced 20% and 45% for 1,3-D from the columns with initial water application and the two intermittent water applications post treatment, respectively. However, reduction on the overall emission over a 2 week period was relatively small. This study shows that using surface water application to reduce emissions can be comparable to or more effective than using HDPE tarp (23 % emission reduction) but much less than using VIF tarp (up to 90% emission reduction). The results indicate that more frequent surface water applications can maximize fumigation emission reductions by maintaining a continuous high water content surface layer. Water application effects will likely vary with soil texture, fumigant properties and weather conditions.
Handout (.pdf format, 1600.0 kb)
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