Comparison of CH 4 oxidation rates in woodland, arable and set aside soils

Abstract

CH 4 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 CH 4 oxidation rate. This site included three adjacent areas with contrasting land use: woodland, arable land and set aside land. The CH 4 oxidation rates in the arable soil were less than half the corresponding rates in the woodland soil. The CH 4 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 CH 4 oxidation rate was found, but in the arable soil there was no such trend. The CH 4 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, CH 4 oxidation rate was related to moisture content only in dry summer conditions, when the relationship was positive ( P < 0.001). These relationships suggest that CH 4 oxidation was controlled partly by diffusion and partly by biological activity. A negative correlation was found between soil ammonium concentration and CH 4 oxidation rate in the woodland soil ( P < 0.001), indicating that ammonium inhibited CH 4 oxidation in that environment.