**5. Conclusions**

The ORG+ system registered a tendency of higher CO2 emissions and lower N2O emissions respect to INT and ORG systems. The lower N2O emissions were probably related to the low N rate supplied in ORG+, while the higher CO2 emissions could have been due to the higher supply of organic material with organic fertilizer and to the higher autotrophic respiration due to living mulch. No di fferences among the three systems were observed concerning CH4 emissions. Based on our results, the organic conservation system did not show a clear tendency towards mitigating soil GHG emissions in vegetable rotation in a Mediterranean environment.

Further soil GHG monitoring campaigns are needed to compare the three systems in the long term. Moreover, other studies will be needed to assess the overall sustainability of the three cropping systems from an agronomic, economic and environmental (e.g., life cycle assessment) point of view.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2073-4395/9/8/446/s1, **Figure S1**: (a) Relationship between WFPS and N2O daily flux; (b) relationship between soil temperature and CO2 daily flux., **Table S1**: Bibliographic references for C:N of each crop in the green manures., **Table S2**: Estimated values of C:N for the green manure mixtures (ORG) during the field experiment period.

**Author Contributions:** Conceptualization, S.B., D.A. and C.F.; data curation, S.B. and I.V.; formal analysis, I.V.; methodology, S.B. and D.A.; project administration, C.F.; software, I.V.; supervision, S.B. and C.F.; validation, G.R.; visualization, S.B. and I.V.; writing—original draft, S.B. and I.V.; writing—review and editing, D.A. and G.R..

**Funding:** This research was carried out within the project SMOCA "Smart Management of Organic Conservation Agriculture" (http://smoca.agr.unipi.it/) funded by the Italian Ministry of University and Research (MIUR) within the program FIRB-2013 (*Future in Research*), MIUR-FIRB13 (project number: RBFR13L8J6).

**Acknowledgments:** The authors would like to acknowledge Enrico Bonari for helpful discussions and comments and Cristiano Tozzini, Fabio Taccini, Jonatha Trabucco and Tommaso Bambini of the Institute of Life Sciences, Scuola Superiore Sant'Anna, for facilitating our field work. We thank the sta ff at the "Enrico Avanzi" Centre for Agro-Environmental Research of the University of Pisa, who managed the field trials and provided technical support throughout.

**Conflicts of Interest:** The authors declare no conflicts of interest.
