Effects of Cover Crops and Tillage on Soil Biological and Physicochemical Properties in an Olive Grove Under Contrasting Rainfall Years

Cover crops in woody crops as a sustainable land management alternative to conventional tillage induce changes in soil properties that improve ecosystem functioning. Soil is highly dynamic, and disturbances in environmental conditions affect soil microorganisms, particularly in gypsiferous soils, where microbiological activity remains poorly understood. This study evaluated the effects of three cover crop systems: spontaneous permanent vegetation cover (SVE), annual legume cover (VIC), and permanent grass cover (BRA), compared with conventional tillage (TIL), on soil physicochemical and biological properties in an olive grove over two crop seasons. Overall, cover crops promoted higher microbial activity and carbon storage than tillage, with responses being more pronounced during the wetter year. Conventional tillage consistently exhibited the lowest levels of enzyme activities and carbon stocks, whereas permanent covers showed stronger positive effects on soil functioning. These findings indicate that the benefits of cover crops on soil processes are reinforced under favorable moisture conditions but also remain under drier years, highlighting their stabilizing role. The improvement of soil health induced by cover crops contributes to enhancing soil ecosystem services, including soil fertility, in olive groves, supporting their adoption as a sustainable management strategy in Mediterranean agroecosystems, even under lower rainfall conditions.