Management Influence on the Quality of an Agricultural Soil Destined for Forage Production and Evaluated by Physico-Chemical and Biological Indicators

The European Common Agricultural Policy promotes the sustainable use of soils through the principle of cross-compliance that links direct payments to good farming practices. Thus, it is necessary to find sustainable alternatives to the conventional management for forage production in the Atlantic Arc dairy farms. Two alternative managements (faba bean in monoculture—FB—and faba bean–Italian ryegrass intercrop—FBIR) were cultivated with organic fertilization during two consecutive years, and compared to the conventional management (Italian ryegrass in monoculture—IR—under chemical fertilization) as winter crops. Maize was used as the summer crop to complete the rotations using organic and chemical fertilization, respectively. The forage yield of winter fodder was quantified. Soil samples and summer harvests were performed to analyse the physico-chemical and biological parameters. The best forage yield corresponded to FBIR with 9.2 t dry matter (DM) ha −1 vs. 7.2 and 5.7 t DM ha −1 for FB and IR, respectively. The soil organic matter did not show significant differences among treatments, suggesting that it may be a poor indicator of the management influence on edaphic quality in the short term. Biological indicators were more sensitive and faster to differentiate among managements than chemical indicators. Earthworm abundance was higher in FB and FBIR than IR ( p < 0.001), and consequently, soil infiltration was improved with the alternative management (13.90 vs. 2.08 and 0.90 min for IR, FB and FBIR, respectively, p < 0.01). As a result, the soil health diagnosis of the agroecosystem was better for alternative management.