Impact of afforestation on SOC components across soil depth

This dataset captures ​​depth-dependent SOC accumulation mechanisms​​ following afforestation in subtropical karst soils of Southwest China (22°59′52″–24°51′53″ N, 106°37′37″–108°43′53″ E). Using a paired-site design, we compared ​​14 maize fields​​ with adjacent ​​~20-year-old plantation forests​​. At each 20 m × 20 m plot, composite samples were generated by homogenizing soil from ​​10 random locations per depth layer​​: ​​topsoil (0–15 cm)​​ and​​subsoil (30–45 cm)​​ (sampling period: 27 Sep–19 Oct 2022).Site Information​​:Sample site ID, sample ID, land use type (maize field/plantation forest), depth, altitude, mean annual precipitation, mean annual temperature;Soil Organic Carbon Data:lignin phenol and its components (Vanilly, Syringyl, Cinnamyl), lignin degradation indicators ((Ad/Al)ₛ and (Ad/Al)ᵥ), and microbial necromass carbon and its components (Fungal necromass and Bacterial necromass carbon).​​Soil biotic and abiotic variables​​:pH, SOC, TN, C/N ratio, MBC, MBN, MBC/MBN ratio, imbalance of C/N between soil and microbial biomass, LOC (labile C), LON (labile N), Clay content, CaCO3, Caexc, Mgexc, (Ca+Mg)exc, Feo, Alo, Fed, Ald, (Fe+Al)o, (Fe+Al)d, total Ca, total Mg, total Fe, total Al, sum of total Ca and Mg, sum of total Fe and Al.Data UtilityThis dataset is valuable for studying the effects of afforestation on soil organic carbon dynamics in karst regions. It provides insights into the roles of ​​biotic and ​​abiotic factors in SOC accumulation in the topsoil and the subsoil​​, respectively. This can enhance understanding of​​microbial-mediated carbon sequestration​​ and support precision strategies to maximize SOC gains. The data may also be useful for researchers investigating soil ecology, carbon cycling, and the impacts of land-use change on soil properties.