SURFACE AMENDMENT OF FERTILIZER AMMONIUM THIOSULFATE TO REDUCE METHYL-BROMIDE EMISSION FROM SOIL

Emission of methyl bromide (CH3Br) from soil fumigation contributes to stratospheric ozone depletion and imposes adverse, toxicological effe cts on humans. We report the identification of fertilizer ammonium thi osulfate (ATS) as a potential surface amendment to reduce CH3Br volati lization from fumigated soils. In ATS-amended soil, CH3Br was rapidly degraded to Br-, with the degradation rate dependent on the ATS:CH3Br molar ratio and soil temperature, At 20 degrees C, the half-life of CH 3Br in an Arlington sandy loam was >5 d, but was reduced to <5 h when 4 molar times of ATS was amended. Greatly reduced CH3Br emission was o bserved from soil columns when Thio-Sul, a 60% ATS fertilizer, was app lied:to the soil surface at 660 kg ha(-1). The emission of CH3Br from the unamended column was 61% bf the applied dosage following a 30-cm i njection, 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 o n the efficacy for controlling nematodes and weeds. As ATS is an inexp ensive fertilizer, the reported approach is promising for field applic ation.