Emission reduction of 1,3-dichloropropene by soil amendment with biochar.

Soil fumigation is an important treatment in the production chain of fruit and vegetable crops, but fumigant emissions contribute to air pollution. Biochar as a soil amendment has shown the potential to reduce organic pollutants, including pesticides, in soils through adsorption and other physicochemical reactions. A laboratory column study was performed to determine the effects of soil applications of biochar for reducing emissions of the fumigant 1,3-dichloropropene (1,3-D). The experimental treatments comprised of unamended and amended with biochar at doses of 0, 0.5, 1, 2, and 5% (w/w) in the top 5 cm soil layer. The unamended treatment resulted in the highest emission peak flux at 48 to 66 μg m s. Among the biochar amendment treatments, the highest peak flux (0.83 μg m s) was found in the biochar 0.5% treatment. The total emission loss was 35.7 to 40.2% of applied for the unamended treatment and <0.1 to 2.9% for the biochar-amendment treatments. A germination bioassay with cucumber seeds showed that ≥7 d of aeration would be needed to avoid phytotoxicity before replanting in biochar-containing fumigated soil. The results indicate that treatments with 0.5% or more biochar amendment reduced emission peak flux by >99.8% and showed total 1,3-D emission loss by >92% compared with that without biochar. The amendment of surface soil with biochar shows a great potential for reducing fumigant emissions.