The influence of land use and pesticides on methane oxidation in some Belgian soils

 In a first experiment, the effect of land use on the uptake rate of atmospheric CH₄ was studied in laboratory incubations of intact soil cores. A soil under deciduous forest showed the highest CH₄ oxidation. Its overall CH₄ uptake during the measuring period (202 days) was 1.03 kg CH₄ ha^–1. Natural grassland showed the second highest CH₄ oxidizing capacity (0.71 kg CH₄ ha^–1). The overall amount of CH₄ uptake by fertilized pasture was 0.33 kg CH₄ ha^–1. CH₄ oxidation in arable soils with different fertilizer treatments varied between 0.34 and 0.37 kg CH₄ ha^–1. Undisturbed soils had a higher CH₄ uptake capacity than agricultural soils. The moisture content of the soil was found to be an important parameter explaining temporal variations of CH₄ oxidation. Different methods of fertilization which had been commenced 10 years previously were not yet reflected in the total CH₄ uptake rate of the arable soil. In a second experiment, a number of frequently used pesticides were screened for their possible effect on CH₄ oxidation. In a sandy arable soil lenacil, mikado and oxadixyl caused significantly reduced CH₄ oxidation compared to the control. Under the same conditions, but in a clayey arable soil, mikado, atrazine and dimethenamid caused a reduction of the CH₄ uptake. In a landfill cover soil, with a 100-fold higher CH₄ oxidation rate, no inhibition of CH₄ oxidation was observed, not even when the application rate of pesticides was tenfold higher than usual. Received: 1 December 1998