TEMPERATURE AND N-FERTILIZATION EFFECTS ON METHANE OXIDATION IN A DRAINED PEATLAND SOIL

The short-term effects of N addition on CH4 oxidation in a drained peat soil were investigated by incubation of peat material from fertilized and unfertilized plots in the laboratory. CH4 oxidation was observed only in the surface depth interval (0-5 cm) of the peat profile. Rate constants as high as -0.084 h(-1) g(-1)d.w. were measured. Fertilization affected the magnitude of the reaction rate constants with the greatest inhibition observed in those samples that were amended with NH4Cl. KNO3 and urea addition resulted in less inhibition. A weak temperature effect on CH4 consumption was observed. Apparent activation energies (E(a)' were measured at - 54 to - 16 kJ mol(-1). Only the addition of KNO3 significantly affected the temperature response of the surface peats. The nitrogen fertilizers had also decreased the CH4 uptake in situ. However, our study showed that the effect is not simply dependent upon NH4+ concentrations, e.g. the added salts, K+ and Cl-, might possibly contribute to the inhibitory effect.