Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2007
Publication Date: 2/28/2007
Citation: Ashworth, D.J., Yates, S.R. 2007. Surface irrigation reduces the emission of volatile 1,3-dichloropropene from agricultural soils. Environmental Science and Technology. Vol. 41:2231-2236
Interpretive Summary: Fumigant pesticides, such as 1,3-D, are increasingly used to control pest (e.g. nematodes) in high cash-crops such as carrots and strawberries. Such fumigants release volatile organic compounds (VOCs) which can be emitted in the gas phase from the soil to the atmosphere. These VOCs are thought to contribute to near-surface ozone formation and stratospheric ozone depletion, both of which are human-health concerns. Strategies are required to limit this transfer of the VOCs from the soil to the air. Such strategies should be of low cost and readily practicable. In this research, we evaluated the use of soil surface irrigation (a water seal) as an emission reduction strategy. In addition, we used more 'realistic' environmental conditions for a lab-based study than have previously been used. Irrigation halved the emission of 1,3-D from soil to air by limiting the diffusion of the gas through the soil pore space. The 1,3-D retained in the soil under these conditions, was ultimately degraded by biological and chemical processes. It is concluded that surface irrigation represents an effective, low-cost and readily practicable approach to lessening the environmental impact of 1,3-D fumigant use. In addition, the organic matter content of the soil had a large effect on emissions of 1,3-D with a higher organic matter soil exhibiting emissions of around one-fifth of a lower organic matter soil, due to markedly enhanced degradation of the fumigant. Organic matter amendment of soils may, therefore, also represent an extremely effective, relatively low-cost approach to reducing 1,3-D emissions.
Technical Abstract: Low-cost, practicable techniques are required to limit the release of volatile organic compound-containing fumigants such as 1,3-D to the atmosphere. In this study we aimed to quantify 1,3-D diffusion and emission from laboratory soil columns maintained under realistic conditions, and thereby assess the efficacy of soil irrigation as a technique for reducing emissions. In two soils (one relatively high, and one relatively low, in organic matter), irrigation led to a limiting of upwards diffusion of the fumigant and to the maintenance of higher soil gas concentrations. Therefore, rather than being emitted from the column, the 1,3-D was maintained in the soil where it was ultimately degraded. As a consequence, emission of 1,3-D from the irrigated columns was around half of that from the non-irrigated columns. It is concluded that surface irrigation represents an effective, low-cost and readily practicable approach to lessening the environmental impact of 1,3-D fumigant use. In addition, the higher organic matter soil exhibited emissions of around one-fifth of the lower organic matter soil in both irrigated and non-irrigated treatments, due to markedly enhanced degradation of the fumigant. Organic matter amendment of soils may, therefore, also represent an extremely effective, relatively low-cost approach to reducing 1,3-D emissions.