Influencia del uso y manejo agrícola sobre la dinámica de CH4 del suelo en el norte de España

Resumo

This study was carried out on soils of three adjacent plots of cropland, pasture and oak (Quercus robur) forest. The pasture and the forest were established in part of the cropland respectively 20 and 40 years before the start of the study. Soil organic matter dynamics, water-filled pore space (WFPS), soil temperature and inorganic N as well as fluxes of CO2 , CH4 and N2O were measured in these plots over a 25-month period. The cropland and pasture soils showed low CH4 uptake rates (< 1 kg C ha-1 yr-1) and the occurrence of episodes of CH4 emission, which coincided with a high proportion water filled pore space (WFPS > 70 %). Methane emissions in these soils may be due to the low availability of O2 , as a result of soil compaction. In the forest site, possibly because of the changes in soil structure and microbial activity, the soil always acted as an active sink for CH4 (4.7 kg C ha-1 yr-1). Up to 52 % of seasonal variation in CH4 flux rates was able to be accounted for by changes in the WFPS and NH4 + concentrations of this soil.