Application of organic amendments to reduce volatile pesticide emissions from soil

Atmospheric emission of volatile pesticides such as soil fumigants contributes to air pollution, and feasible strategies to reduce their emission are urgently needed. In this study, we investigated the potential of applying organic wastes to reduce the emission of two important fumigants, methyl bromide (MeBr) and methyl isothiocyanate (MITC), by enhancing their degradation in surface soil. The degradation of both compounds was significantly accelerated in composted manure or biosolid-manure amended soils, and the enhancement was greater for MITC than for MeBr. The difference in degradation kinetics between sterile and nonsterile amended soils indicates that degradation of MeBr in amended soils was chemically mediated, while that of MITC was mainly a result of stimulated microbial degradation. Applying 5% of composted manure to the 5 cm surface soil in packed columns reduced MeBr emission by 12%, and almost completely eliminated the volatilization of MITC. As certain organic amendments can suppress soil pathogens on their own, integrating fumigation with organic waste application may potentially provide complementary pest control activity. The applicability and benefits of such integrations should be further evaluated under field conditions.