Methane oxidation in soils with different textures and land use

Intact core samples from soils with different textures and land use were tested for their capacity to oxidise methane. The soil cores were taken from arable land, grassland and forest. It was found that coarse textured soils (6.74-16.38 mu g CH4 m(-2) h(-1)) showed a higher methane uptake rate than fine textured soils (4.66-5.34 mu g CH4 m(-2) h(-1)). Increasing soil tortuosity was thought to reduce the methane oxidation rate in fine textured soils. The oxidation rate of forest soils (16.32-16.38 mu g CH4 m(-2) h(-1)), even with a pH below 4.5, was very pronounced and higher than arable land (11.40-14.47 mu g CH4 m(-2) h(-1)) and grassland (6.74-9.30 mu g CH4 m(-2) h(-1)). Within the same textural class arable land showed a faster methane uptake rate than grassland. In grassland with a fine texture, even methane production was observed. Nitrogen availability and turnover in these land use systems were thought to cause the different oxidation rates. Decreasing the moisture content slowed down the oxidation rate in all soils. This could be caused by an increased N turnover and a starvation of the methanotrophic bacteria.