Chloropicrin Emission Reduction by Soil Amendment with Biochar.

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Biochar's sorption capacity can sequester volatile organic contaminants like pesticides in soil.
• Chloropicrin (CP) is a vital soil fumigant, but its emissions pose environmental and health risks.
• Minimizing CP emissions is crucial for sustainable agriculture and reduced air pollution.

Purpose of the Study:

• To assess biochar's capacity to adsorb CP.
• To evaluate the impact of biochar soil amendments on CP emission, soil gas concentration, and degradation.
• To determine the effect of biochar on CP's bioactivity for controlling soil-borne pests.

Main Methods:

• Soil columns were used to measure CP emission and soil air phase concentration after fumigant injection and biochar application.
• Laboratory incubation and fumigation experiments assessed CP adsorption, degradation, and bioactivity in biochar-amended soil.
• CP half-life and degradation rates in biochar and soil were quantified.

Main Results:

• Biochar amendment (2%-5% w/w) reduced CP emissions by 85.7%-97.7%.
• CP concentrations in soil gas, especially the top 5 cm, decreased within 48 hours.
• CP half-life reduced from 13.6 h to 6.4 h with increasing biochar rates (0%-5%); degradation was faster in biochar than soil.
• Low biochar adsorption capacity for CP (<5 mg g⁻¹) was observed, with no negative impact on pest control at <1% amendment rate.

Conclusions:

• Biochar amendment effectively reduces chloropicrin emissions and soil gas concentrations.
• Biochar accelerates CP degradation while maintaining efficacy for soil-borne pest control at appropriate rates.
• Findings support biochar's use as a soil amendment to mitigate fumigant emissions and enhance soil health.