Impacts of Biochar on the Fate and Transport of the Soil Fumigant 1,3-Dichloropropene.

Only a limited number of studies have quantified the impact of biochar on soil fumigant behavior; but these have demonstrated a potential to significantly reduce, via adsorption, the emissions of these toxic gaseous chemicals from soil to air. Although reducing emissions is of great significance in protecting environmental quality, the adsorption of fumigants within the soil system may have adverse impacts on their pest control efficacy. Using a 2-dimensional soil chamber, we measured the fate and transport of 1,3-dichloropropene (1,3-D) over time for bare soil, high density polyethylene covered soil (a standard emission reduction strategy for 1,3-D), and biochar amended soil (applied to the soil surface). Soil gas concentration distributions and soil-air emissions will be presented for each treatment. Based on observed adsorption/desorption kinetics, the role of biochar in reducing soil-air emissions of 1,3-D will be shown. Nematode control by 1,3-D in the presence and absence of biochar (based on additional batch experiments) will  be presented and considered in relation to the observed soil gas concentrations within the chamber experiments. It will be demonstrated that although 1,3-D adsorption by surface-applied biochar has the potential to reduce fumigant emissions from soil, this adsorbed chemical may be slowly released over time. Although the presence of biochar at the soil surface reduces soil concentrations of 1,3-D in the root zone, it is likely that nematode control is not adversely affected. However, if biochar were to be mixed (e.g., plowed) into the root zone soil, the rapid adsorption of 1,3-D is likely to negate nematode control.