Assessment of Soil Organic Matter Quality in Vineyards With Cover Crops and Conventional Tillage in the Mediterranean Area

Abstract

Cover crops are widely considered as a sustainable management strategy to enhance soil quality and resilience in Mediterranean agroecosystems. This study evaluates the long‐term effects of spontaneous cover crops on soil organic matter (SOM) quantity, chemical composition, and biological activity in a vineyard under semiarid Mediterranean conditions in central Spain. Two adjacent plots with identical crop systems but contrasting management histories, 20 years of continuous cover crops (CC) and conventional tillage (TILL) were compared at depths of 0–10 and 10–30 cm. Results showed that CC significantly increased soil organic carbon (SOC) in topsoil compared with TILL management. Improvements in phosphorus and organic nitrogen availability were also observed in the topsoil under CC management. While general physicochemical properties (bulk density, pH, water holding capacity, granulometry) remained largely unchanged, SOM fractionation revealed greater stabilization of organic carbon under CC, whereas TILL soils exhibited higher extractability, suggesting reduced organo‐mineral associations. Spectroscopic analyses indicated similar humification levels across treatments but highlighted an enrichment of polysaccharide‐like structures in CC soils. Biological indicators further supported these findings, with higher enzymatic activities and greater microbial abundance (bacteria, fungi, and archaea) under CC, especially in surface layers. Functional genes related to carbon, nitrogen, and phosphorus cycling were also more abundant in CC soils, reflecting enhanced biogeochemical functioning. Overall, long‐term cover cropping improved SOC accumulation, SOM quality, and soil biological activity, contributing to enhanced soil health and stability. These findings highlight the potential of cover crops as a key strategy for sustainable vineyard management under Mediterranean climatic constraints.