Benefits of organic olive rainfed systems to control soil erosion and runoff and improve soil health restoration

International audienceAbstractThe soil erosion rates are high in the rainfed olive (Olea europaea L.) mountain plantations applying conventional practices in a semi-arid Mediterranean environment, which compromise their long-term sustainability. The implementation of sustainable soil management strategies is vital for hillslopes and low-fertility soils where plantations cover vast tracts of land. In Lanjarón (Granada, Spain), the soil erosion and runoff patterns over a 4-year monitoring period were studied in erosion plots on a mountainside under four types of production systems: (1) organic (spontaneous vegetation and leguminous covers), (2) conservation agriculture (combinations of minimum tillage with spontaneous and leguminous strips), (3) integrated (combinations of no-tillage with spontaneous vegetation and leguminous strips), and (4) conventional tillage. The olive yield responses to each production system were evaluated, and the selected physico-chemical soil properties (pH, bulk density, soil organic carbon, cation exchange capacity, and total N, P, and K), soil enzymes (β-glucosidase, protease, dehydrogenase, and phosphatase activities), and soil-microbial biomass C and N were monitored. Throughout the study period, the erosion rates for organic, conservation, integrated, and conventional systems averaged 0.70, 2.10, 1.52, and 3.25 t ha−1 year−1 with runoff of 5.8, 6.3, 11.9, and 17.6 mm year−1, respectively. The mean olive yield was not significantly affected by the production system applied, being 2.43, 2.10, 2.04, and 2.11 t ha−1 year−1 for integrated, organic, conservation, and conventional, respectively. Here, we show a substantial improvement in soil health restoration using the organic rather than a conventional system. Our findings suggest that sustainable cropping systems on hillslopes integrating a blend between organic and conventional doctrines better maintain or improve soil ecosystem functioning. This study highlights a balanced design for an integrated production system for rainfed olive orchards that can maintain productivity while suitably encouraging environmental quality and ecosystem services