Minimum tillage mitigated soil N2O emissions and maximized crop yield in faba bean in a Mediterranean environment

A two-year study was carried out on a faba bean (Vicia faba L. var. minor Beck) crop as part of a long-term tillage experiment (> 20 years) in a Mediterranean environment. We evaluated the effects of two tillage systems, ploughing (P) and minimum tillage (MT), on the following parameters: N2O emissions, grain yield, N assimilated in plant biomass and biological N2 fixation. Our results showed grain yield to be higher in MT than P in the first year and roughly similar in the second. Moreover, cumulative N2O emissions were lower in MT than P in both years (up to −80%). Indeed, MT was identified in our environment as a sustainable means of achieving N2O emissions mitigation while also maximizing grain yield. Furthermore, the percentage of N derived from N2 fixation (Ndfa%) in plants stood at 80% on average, affected by tillage only in the second year, with higher values in P than MT. Moreover, a positive relationship between N2 fixation and N2O emissions was reported, particularly in P, and during the fallow period.