THE INFLUENCE OF LAND-USE AND PESTICIDES ON METHANE OXIDATION IN SOMEBELGIAN SOILS

In a first experiment, the effect of land use on the uptake rate of at mospheric CH4 was studied in laboratory incubations of intact soil cor es. A soil under deciduous forest showed the highest CH4 oxidation. I: ts overall CH4 uptake during the measuring period (202 days) was 1.03 kg CH4 ha(-1). Natural grassland showed the second highest CH4 oxidizi ng 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 soi ls with different fertilizer treatments varied between 0.34 and 0.37 k g CH4 ha(-1). Undisturbed soils had a higher CH4 uptake capacity than agricultural soils. The moisture content of the soil was found to be a n 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 pesti cides were screened for their possible effect on CH4 oxidation. In a s andy arable soil lenacil, mikado and oxadixyl caused significantly red uced 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-f old higher CH4 oxidation rate, no inhibition of CH4 oxidation was obse rved. not even when the application rate of pesticides was tenfold hig her than usual.