Effects of soil compaction on N2O emission in agricultural soil

Abstract

We have studied the effect of soil compaction on N2O fluxes in relation to gas diffusion and N fertilization in the field, and N2O release rates in laboratory incubated soil samples. The fertilization and soil compaction field experiment was established in 1985, and the gas fluxes were measured in the period from 1992 to 1994. N2O emission was higher in compacted than in uncompacted soil. This compaction effect was four times higher in the NPK-fertilized treatment compared to the unfertilized one. Soil compaction decreased gas diffusivity and this may have contributed for increased N2O emission. This increased N2O emission due to soil compaction in the field became non-significant after the compacted soil was sieved (2-mm mesh) and N2O emission rates were measured in laboratory incubations. The sieving presumably removed diffusion barriers and increased the oxygen supply compared with that under the soil compaction in field. This reversibility of field compaction effects indicates that the soil compaction does not permanently increase the biological potential for N2O production in the soil.