## 4 Discussion
### Environmental Sustainability Evaluation by DEXi-met  
The \"overall environmental sustainability\" of the cropping systems varied among the three evaluated management systems, passing from \"medium-low\" showed in NO ASC to the \"high\" in ECO. This response can be explained by the scores both of the aggregate nodal attributes (Figure 3) and the basic attributes (Figure 4), and it was a consequence of the intensification of the agro-ecological strategies adopted. In particular, the _DEXi-met_ output showed that the ECO strategy was the most sustainable one, mainly due to the differences detected in the nodal attribute \"biodiversity conservation\". In fact, the study of [PERSON] et al. [34] pointed out a general positive influence of the living mulch techniques on arthropods in plant/soil systems, as shown by a high level of soil biodiversity and a lack of negative impacts on the density of canopy insects. Also, the presence of ASC in the rotation as break crops enhances the \"biodiversity conservation\" and, at the same time, it may have impact on occurrence of weeds, diseases, and pests [4; 35]. Our results confirmed these findings, being the ECO system characterized by ASC presence both as break crops and living mulch, compared with the other two treatments (Table 1). For the \"production capacity\", differently from the yield performance and the energetic output, the _DEXi-met_ model considered not only the crop productions, but also the physico-chemical fertility and the systems control on pests and disease. The differences between ECO and GM were not perceivable by the model and scored \"medium\" value in both systems (Figure 3). Conversely, the NO ASC scored \"medium-low\", due to the \"low\" value of pests and disease control (Figure 4). The systems with the introduction of the agro-ecological service crops (ECO and GM) scored high soil erosion control, in agreement with the study of [PERSON] et al. [36]. This result was generated by a better soil cover, in particular during the winter/heavy rainy period. Therefore, the nodal attribute \"soil and water preservation\" was the highest in ECO, followed by the GM system. The differences in \"resources preservation\" was mainly due to the different fertilizers used. In fact, the composted anaerobic digestate, which was utilized in the ECO and GM plots, is a renewable, more sustainable fertilizer than the commercial organic one, and its application did not compromise the systems production capacity, thus confirming the findings of previous studies [11; 37]. Finally, the _DEXi-met_ output showed substantial differences in the aggregate nodal attribute \"biodiversity conservation\" among the systems, as explained above. In particular, the introduction of the ASC increased the score both in ECO and GM (\"high\" and \"medium-high\", respectively), compared to the NO ASC management strategy. Similarly, other studies indicated that the presence of ASC enhances the insect and arthropods communities [38], as well as the soil microbial activities [39]. Even if the _DEXi-met_ presents some aspects that should be improved, it showed some strengths and, therefore, its application gave us the possibility to analyze in detail the general structure of the overall sustainability, as well as the components and the single variables of the systems considered. We should also take into account that _DEXi-met_ model is one of the new ex-post tools, which considers some attributes derived from the field experiment. However, to better understand how the model tree structure affects the results and to find the most significant variables that contributed most to the output variability, a sensitivity analysis was necessary. The sensitivity index results were affected by the level of complexity of each component and by the number of variables. [PERSON] et al.