Soil organic carbon (SOC) is essential for maintaining soil fertility and promoting sustainable agricultu-ral development. We investigated the impact of long-term tillage practices on soil organic carbon storage (SOCS) and its components in dryland farming areas of the black soil region, based on a 39-year tillage practice experiment. We compared the effects of different tillage practices (conventional rotary and ridge tillage, CT; no-tillage, NT; subsoiling tillage, ST; moldboard plowing, MP) on SOCS, active organic carbon components, and microbial necromass carbon (MNC) content in the 0-40 cm soil layer. The results showed that, compared to CT, NT significantly increased the contents of SOCS, SOC, dissolved organic carbon (DOC), microbial biomass carbon (MBC), easily oxidizable organic carbon (EOC), and MNC in the 0-20 cm soil layer. Both ST and MP significantly improved the contents of SOCS, SOC, and EOC in 0-20 and 20-40 cm soil layers compared to CT and increased MBC content in the 20-40 cm soil layer. Additionally, MP treatment significantly improved the contents of DOC, particulate organic carbon, and MNC in the 20-40 cm soil layer compared to other treatments. ST and MP significantly reduced the contribution rate of MNC to SOC in both soil layers compared to CT and NT treatments. Results of structural equation modeling showed that enhancing the mean weight diameter of soil aggregates, field capacity, and total phosphorus content, along with increasing the activities of β-glucosidase, amylase, and lignin peroxidase, could promote MNC accumulation. MP treatment facilitated the uniform distribution of SOC, active organic carbon, and MNC in the 0-40 cm soil layer, which was more conducive to the fixation of SOC in farmland in the black soil region.
土壤有机碳(SOC)对维持土壤肥力和农业可持续发展具有重要作用。为探究长期耕作对黑土区旱作农田土壤有机碳储量(SOCS)及其组分的影响,本研究基于39年的耕作试验,比较了不同耕作方式(旋耕起垄、免耕、深松、翻耕)对0～40 cm土层SOCS、活性有机碳组分和微生物残体碳(MNC)含量的影响。结果表明:与旋耕起垄相比,免耕处理显著增加了0～20 cm土层SOCS、SOC、可溶性有机碳(DOC)、微生物生物量碳(MBC)、易氧化有机碳(EOC)和MNC含量;深松和翻耕处理在0～20和20～40 cm土层中显著增加了SOCS、SOC和EOC含量,并在20～40 cm土层增加了MBC含量。此外,翻耕处理20～40 cm土层中DOC、颗粒有机碳和MNC含量显著高于其他处理。深松和翻耕处理相较于旋耕起垄和免耕处理,显著降低了0～20和20～40 cm土层中MNC对SOC的贡献率。结构方程模型表明,通过提升土壤团聚体平均重量直径、田间持水量和全磷含量,增强β-葡萄糖苷酶、淀粉酶和木质素过氧化物酶活性,能促进MNC的积累。深翻促进了0～40 cm土层SOC、活性有机碳和MNC的均匀分布,更有利于黑土区农田SOC的固定。.
Keywords: conservation tillage; enzyme activity; labile organic carbon fraction; microbial necromass carbon; soil amino sugar.