Effects of conservation agriculture practices on soil quality indicators: a case-study in a wheat-based cropping systems of Mediterranean areas

Conservation Agriculture approach could be strategic for Soil Quality (SQ) conservation under the Mediterranean conditions of Southern Europe’s environments. In this study, we reported the results obtained during a 2-year field experiment (split-plot design) of a 7-year experiment started in 2010–2011, combining two tillage practices (Conventional Tillage (CT) and Zero Tillage (ZT)) with two crop sequences (Wheat monocropping (WW) and Wheat-Faba bean (WF)). SQ was monitored through the selection of some chemical, physical, and biological indicators measured by both visual – Visual Soil Assessment (VSA) – and standard field or laboratory measurements. ZT produced higher values for some VSA indicators, i.e., ‘soil structure and consistence’ and ‘earthworms counts’, as well as for soil organic carbon content (0.84 vs. 0.75% in ZT and CT, respectively). CT+WW and CT+WF treatments released significantly higher CO2 fluxes of 35% and 41% than ZT+WW and ZT+WF, respectively. No clear effect of soil tillage practices on community-level physiological profiles was observed; conversely, WF induced higher values of well-color development, richness (R), and Shannon–Weaver index (H) than WW. Under dry Mediterranean areas, ZT practices, especially when combined with the other conservation principles (i.e., crop rotation), seem to ameliorate several SQ indicators already after 7-year period of adoption, allowing a positive trend for soil preservation.