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

The pesticide 1,3-dichloropropene (1,3-D) is considered to be the most prom ising alternative to methyl bromide for soilborne pest control The high vol atility of 1,3-D, however, has been shown to result in excessive atmospheri c emissions that may impose toxicological effects on workers or residents. This study demonstrated that 1,3-D was rapidly transformed to nonvolatile p roducts by thiosulfate fertilizers in soil, and that thiosulfate-facilitate d fumigant transformation may be used to reduce 1,3-D emissions. Transforma tion 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 reduc ed to only a few hours, as compared with >10 d for nonamended soils. The ra te of thiosulfate-facilitated 1,3-D transformation was independent of soil types and was higher in moist soils and at high soil temperatures. Transfor mation occurred at a similar rate for ammonium, calcium, and sodium thiosul fates. 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.