Greenhouse gas production and emission from a forest nursery soil following fumigation with chloropicrin and methyl isothiocyanate

Abstract

Soil fumigation is commonly used to control soil-borne pathogens and weeds. Our aim was to examine the effects of soil fumigation with chloropicrin (CP) and methyl isothiocyanate (MITC) on CH 4, N 2O and CO 2 production and emission. These effects on a SE USA forest nursery soil were examined in field and laboratory experiments. Following field fumigation, CH 4 surface emissions and concentrations in the soil atmosphere were unaffected. Both fumigants increased N 2O emissions rates significantly compared to non-fumigated controls, and the effects were still evident after 48 d. These findings are in contrast to fertilizer-induced N 2O emissions, which generally return to background within 2 wk after application. Depths of N 2O production were different for the two fumigants as determined by soil gas sampling, suggesting fumigant-specific stimulation mechanisms. CO 2 emissions (0–15 d) were not altered significantly, although sub-surface CO 2 concentrations did increase following fumigation with CP or MITC and remained elevated for CP treatment on d 48. CP-induced N 2O production was also stimulated in aerobic laboratory incubation studies, with surface soils exhibiting 10 to 100-fold greater production rates. MITC and a combination of CP/MITC also stimulated N 2O production, but the effect was significantly less than for CP alone. MITC suppressed and CP did not effect CO 2 production in the laboratory incubation. By comparing sterilized to non-sterile soils, >95% of these effects appear to be of biotic origin.