Impact of vineyard inter-row cover crops on soil organic carbon fractions

The dynamics of soil organic carbon (SOC) fractions and accumulation under inter-row cover cropping serve as fundamental determinants of soil carbon pool stability and sustainable vineyard management. We conducted an experiment with three inter-row cover crop treatments, including Vicia villosa (MS), Lolium perenne (HM), and natural grass cover (ZR), in the vineyard from 2022 to 2024, and taking clean tillage (CK) as the control, to determine the soil organic carbon fractions, physicochemical properties, enzyme activities, and the relationships between soil properties and organic carbon fractions in the 0-40 cm soil layers. The results showed that three cover crop treatments significantly increased the contents of available phosphorus, available potassium, and total organic carbon in the 0-20 cm soil layer, with increases of 55.6%, 20.5%, and 5.4%, respectively. Different treatments significantly affected soil properties in the 20-40 cm soil layer, with the MS treatment increasing ammonium content by 40.6%, the HM treatment increasing total phosphorus content by 9.5%, and the ZR treatment increasing total organic carbon content by 7.1%. In the 0-40 cm soil layer, all cover crop treatments increased the contents of soil microbial biomass carbon and dissolved organic carbon by 13.5%-57.6% and 30.9%-74.4%, respectively. In the 0-20 cm soil layer, the MS and HM treatments increased total soil enzyme activity (TEA) by 36.6% and 45.1%, respectively. The MS and HM treatments enhanced soil carbon pool management index (CPMI), while the ZR treatment diminished soil CPMI. In the 20-40 cm soil layer, the HM and ZR treatments significantly increased TEA and diminished soil CPMI, while the MS treatment enhanced soil CPMI. Correlation and redundancy analysis revealed that nitrate, available potassium, leucine aminopeptidase, and β-xylosidase were the key factors influencing the SOC fractions in the 0-20 cm soil layer. Total phosphorus and β-xylosidase were the key factors influencing the SOC fractions in the 20-40 cm soil layer. In conclusion, three consecutive years of inter-row artificial cover cropping significantly enhanced soil nutrients, promoted soil organic carbon accumulation and resulted in higher enzyme activities and active organic carbon content in the 0-20 cm soil layer of vineyards. Among the tested cover crops, V. villosa performed the best in optimizing the structure of soil carbon pool, making it a candidate species for enhancing carbon sequestration and efficiency in vineyards inter-row management.