Three years of management with cover crops protecting sloping olive groves soils, carbon and water effects on gypsiferous soil

Soils of olive grove are usually managed by tillage, leading to organic matter depletion and soil structure degradation. Cover crops to protect soils have been revealed as a sustainable land management practice for erosion control and remediation of degraded soils, but in some cases, water competition can be a problem, all these effects (particularly soil water) are site and climate specific. A trial in a rainfed olive grove in gypsiferous soils under semiarid Mediterranean climatic conditions has been set up in Central Spain. Several parameters (plant cover, root density, organic carbon, organic nitrogen, aggregate stability, porosity, infiltration, water storage and soil penetration resistance) have been studied under different management practices: three types of cover crops, two annuals (legume and barley) and one permanent (Brachypodium distachyon); and minimum tillage. After three years of treatments, slight improvements in particulate organic carbon, aggregate stability, microporosity at 0-5 cm depth and soil water storage at 30 cm were found in cover crops; B. distachyon also increased organic carbon, and improved C/N ratio and available water. > 3 years of a sustainable land management are needed to recover olive groves soil quality in gypsiferous soils under semiarid climate. In this study, cover crops facilitated carbon stratification, higher SOC content in deeper layers are important in the context of carbon sequestration.