**5. Conclusions**

Our results demonstrate that N recycling at the agroecosystem level was greatly improved by CC practice, independently from the soil managemen<sup>t</sup> strategy (no till or inversion tillage). The improved Nsurplus was not retained in the system without CC (INT), so high yield (and Noutput) was not a su fficient condition to guarantee a high environmental e fficiency of INT. On the contrary, the practices adopted in ORG+ (cover crop and temporary intercropping) considerably improved the N self-su fficiency of the system, thus the Nsurplus did not give rise to N loss, but the low Noutput (Yield) consistently reduced the e fficiency of the external N input (Y/Nextra). The yield obtained per unit of N lost by leaching suggests that ORG was the most interesting system, while the potential sustainability of MBNT systems (i.e., ORG+) needs a substantial improvement, otherwise the grea<sup>t</sup> potential for the regulation and maintenance of ecosystem services can hardly be expressed.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2073-4395/9/11/718/s1, Table S1: Dates of the agronomic operations, Table S2: N balance with separate main crops.

**Author Contributions:** Conceptualization, G.T. and M.G.; data curation, G.T.; methodology, A.O.; software, A.O.; formal analysis, A.O.; writing—original draft preparation, G.T.; writing—review and editing, all authors; supervision, M.G.; project administration, G.T.; funding acquisition, G.T.

**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:** We would like to thank: Patrizia Cannoni, Antonella Tizzi, Daniele Luchetti, Enzo Luchetti, Piero Bonciarelli, Fabio Ferretti and Daved Sforna for their invaluable help with the field work at the FieldLab in Papiano (PG, Italy).

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