Effects of soil fumigants on methanotrophic activity

Abstract

Negative impacts on methane (CH 4) oxidation capacity have already been observed for a variety of agronomic practices, but the effect of soil fumigation on CH 4 oxidation has not been investigated. Fumigation is a common practice in agricultural crop and nursery seedling protection. Soils from various agricultural experiment stations, forest nurseries, and a landfill were evaluated for effects of 1,3-dichloropropene (1,3-D), methyl isothiocyanate (MITC), and chloropicrin (CP) on CH 4 oxidation capacities. All three fumigants significantly reduced CH 4 oxidation rates in historically non-fumigated soils (>50%). 1,3-D enhanced CH 4 oxidation in 3 out of 5 previously fumigated soils and MITC increased CH 4 oxidation rates in all historically MITC-fumigated soils compared to controls. CP universally decreased oxidation capacity regardless of fumigation history. These results support the conclusion that CH 4 oxidation effects are fumigant specific and that prior fumigation history plays a vital role in determining the impact on CH 4 oxidizer community functionality, which may have implications on the global CH 4 cycle.