|Wang, X -|
|Mao, L -|
|Yan, D -|
|Ma, T -|
|Liu, P -|
|Wang, R -|
|Guo, M -|
|Cao, A -|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 28, 2014
Publication Date: N/A
Interpretive Summary: Biochar is a fine-grained, highly porous charcoal substance that is distinguished from other charcoals in its intended use as a soil amendment. Compared to other soil amendments, the high surface area and porosity of biochar enable it to adsorb or retain nutrients and water and also provide a habitat for beneficial microorganisms to flourish. Some research also indicated that soil applications of biochar offer the possibility of mitigating climate change effects through long-term carbon sequestration and potentially also by reducing emissions of greenhouse gases. This study demonstrated the benefit of amending soil with biachar at soil surface as a means of reducing emissions of soil fumigant 1,3-dichloropropene for preplant soil fumigation. Application of biochar at a rate of 0.5% to 5% on a weight basis in the top 5 cm soil reduced total fumigant emission loses from 91.9% to 99.9% compared with conventional application without the biochar. The research also showed that fumigant gas concentrations in the soil air space were similar to that in the control therefore likely not affecting pest control efficacy. A bioassay test further demonstrated safe replanting after 7 days soil aeration. Overall the laboratory study clearly demonstrated the potential of biochar for reducing fumigant emissions while maintaining effectiveness for soil disinfection.
Technical Abstract: Soil fumigation is important for growing many fruits and vegetable crops, but fumigant emissions may contaminate the atmosphere. Biochar as soil amendments has the potential of mitigating climate change effects. In addition, its high surface area and porosity enable it to adsorb or retain nutrients, water, and greenhouse gases and also provide a habitat for beneficial microorganisms to flourish in soil. The objectives of this research were to determine the effects of adding biochar to the soil surface on reducing 1,3-dichloropropene (1,3-D) emissions after injection to soil columns. Surface treatments included a polyethylene (PE) tarp only, PE tarp + biochar at dosage of 5%, 2%, 1% and 0.5% on a weight basis in the top 5 cm soil. The volatilization rate was measured and the daily peak volatilization rates for biochar treatments ranged from 0.006 to 0.828 µg m-2 s-1. The total 1,3-D mass that volatilized to the atmosphere was approximately 0.03 to 2.88% of the applied active ingredient. This represents an approximately 91.9 to 99.9% reduction in the total emissions compared with conventional application. The results in the study also indicated that 1,3-D concentrations in the biochar treated soils were not significantly different from that found in the PE controls, therefore implying that pest control efficacy would not be compromised. A seed germination bioassay conducted after 7 days of soil aeration to remove residual fumigants showed 90-100% germination rate, therefore demonstrated absence of phytotoxicity risk. Amendment of surface soil with biochar showed great potential in minimizing fumigant emissions. Biochar dosages of 0.5% to 1% on a weight basis in the top 5 cm soil or a field application rate of 3.25 to 6.5 Mg ha-1 were recommended for reducing the emission of fumigants.