Nitrous oxide emissions from clover in the Mediterranean environment

Introducing nitrogen N₂-fixing crops into cereal-based crop rotations reduces N-fertiliser use and may mitigate soil emissions of nitrous oxide (N₂O). However, the effect of the cultivation of N₂-fixing crops on N₂O emissions is still not well understood. N₂O from N₂-fixing crops can be emitted in two ways: during biological N₂ fixation itself and when legume residues are returned to the soil. A field trial was carried out on clover (Trifolium squarrosum Savi) to test the role of leguminous crops on N₂O emissions in the Mediterranean environment. Monitoring was performed from December 2013 to September 2014. Cumulated N-N₂O fluxes were calculated for the growing season (Phase 1) and the post-harvest period (Phase 2) in order to assess the importance of each phase. Our results did not show statistically significant differences between the two phases in term of contribution to the total cumulative N-N₂O emissions, in fact Phase 1 and Phase 2 accounted respectively for 43 and 57% of the total.