Transformation of 1,3-dichloropropene in soil by thiosulfate fertilizers

The pesticide 1,3-dichloropropene (1,3-D) is considered to be the most promising alternative to methyl bromide for soilborne pest control The high volatility of 1,3-D, however, has been shown to result in excessive atmospheric emissions that may impose toxicological effects on workers or residents. This study demonstrated that 1,3-D was rapidly transformed to nonvolatile products by thiosulfate fertilizers in soil, and that thiosulfate-facilitated fumigant transformation may be used to reduce 1,3-D emissions. Transformation of 1,3-D by thiosulfate was chemically based, and 1,3-D degradation in soil accelerated proportionally as thiosulfate level in soil increased. At a 4:1 thiosulfate to fumigant molar ratio, the half-hfe of 1,3-D was reduced to only a few hours, as compared with >10 d for nonamended soils. The rate of thiosulfate-facilitated 1,3-D transformation was independent of soil types and was higher in moist soils and at high soil temperatures. Transformation occurred at a similar rate for ammonium, calcium, and sodium thiosulfates. As these thiosulfate compounds are commercial fertilizers, amendment of these products at the soil surface during 1,3-D fumigation may offer an effective and inexpensive approach for reducing W-D emissions.