Surface Amendment of Fertilizer Ammonium Thiosulfate To Reduce Methyl Bromide Emission from Soil

Emission of methyl bromide (CH 3 Br) from soil fumigation contributes to stratospheric ozone depletion and imposes adverse toxicological effects on humans. We report the identification of fertilizer ammonium thiosulfate (ATS) as a potential surface amendment to reduce CH 3 Br volatilization from fumigated soils. In ATS-amended soil, CH 3 Br was rapidly degraded to Br -, with the degradation rate dependent on the ATS:CH 3 Br molar ratio and soil temperature. At 20 °C, the half-life of CH 3 Br in an Arlington sandy loam was >5 d, but was reduced to <5 h when 4 molar times of ATS was amended. Greatly reduced CH 3 Br emission was observed from soil columns when Thio-Sul, a 60% ATS fertilizer, was applied to the soil surface at 660 kg ha - 1 . The emission of CH 3 Br from the unamended column was 61% of the applied dosage following a 30-cm injection, but that from the ATS-treated columns was <10%. Field study showed that ATS amendment at 660 kg ha - 1 only had a limited effect on the efficacy for controlling nematodes and weeds. As ATS is an inexpensive fertilizer, the reported approach is promising for field application.