Comparison of CH4 oxidation rates in woodland, arable and set aside soils

CH4 fluxes and various soil properties were measured over three successive years at a field site on a loamy sand soil in eastern Scotland, to determine which factors influence CH4 oxidation rate. This site included three adjacent areas with contrasting land use: woodland, arable land and set aside land. The CH4 oxidation rates in the arable soil were less than half the corresponding rates in the woodland soil. The CH4 oxidation rates in the set aside soil were even lower, indicating that there is no immediate recovery when cultivation and fertilisation are abandoned. In the woodland and set aside soils, a seasonal variation in CH4 oxidation rate was found, but in the arable soil there was no such trend. The CH4 oxidation rate was negatively correlated with soil moisture content (P < 0.001) in the woodland soil and positively correlated with soil temperature (P < 0.001) in the set aside soil. In the arable soil, CH4 oxidation rate was related to moisture content only in dry summer conditions, when the relationship was positive (P < 0.001). These relationships suggest that CH4 oxidation was controlled partly by diffusion and partly by biological activity. A negative correlation was found between soil ammonium concentration and CH4 oxidation rate in the woodland soil (P < 0.001), indicating that ammonium inhibited CH4 oxidation in that environment.