Leaching of Methyl Isothiocyanate in Plainfield Sand Chemigated with Metam-Sodium |
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Authors: | Ibrahim A M Saeed John M Harkin Douglas I Rouse |
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Institution: | Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, Wisconsin 53706, USA |
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Abstract: | Soil column studies were undertaken to investigate the influence of soil water content and irrigation on leaching, distribution and persistence of methyl isothiocyanate (MITC) in a sandy soil chemigated with the soil fumigant metam-sodium. No leaching was obtained from columns at low water content (0·042 or 0·074 cm3 cm?3). However, 8·4 (±2·8), 34·2 (±7·4) and 119·4 (±8·3) μg of MITC leached from columns at 0·105, 0·137 and 0·168 cm3 cm?3 water content, respectively. Increased leaching resulted from sprinkler application of 25-mm of water to columns at 0·137 cm3 cm?3 water content. Leaching of MITC constituted only a small fraction of the amount applied even in the worst case. Methyl isothiocyanate persisted in soil for 15 days at 2°C in varying amounts under the different water regimes. Relatively high amounts of MITC residues (8–12 mg kg?1 soil) were detected in the top 25-cm layer of all the soil columns. Degradation was the major pathway of dissipation for the chemical despite the soil water regime. |
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Keywords: | fumigant percolation chemigation |
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