长期轮作施肥处理对植烟土壤有机碳组分和酶活性的影响

以贵州省遵义市烤烟长期(18年)定位试验为平台，研究两种种植制度(烤烟–玉米轮作和烤烟连作)下的3种不同施肥模式(不施肥、单施化肥、化肥有机肥配施)对植烟土壤有机碳组分、酶活性和碳库管理指数的影响，探究植烟土壤的碳素转化，为土壤碳素科学管理提供依据。结果显示：在相同种植模式下，化肥有机肥配施处理比单施化肥处理的土壤总有机碳(TOC)增加5.65% ~ 12.13%，其中，轻组有机碳(LFOC)、溶解性有机碳(DOC)和易氧化有机碳(ROC)分别提高23.33% ~ 28.71%、24.46% ~ 25.54%、10.26% ~ 18.99%，碳库管理指数增加12.89% ~ 23.34%；土壤纤维素酶、β-葡萄糖苷酶、淀粉酶、过氧化氢酶和蔗糖酶活性显著增强，且与土壤有机碳各组分含量和碳库管理指数呈显著正相关(0.59^* ~ 0.97^**，n=18)。在相同施肥条件下，轮作处理的土壤有机碳含量、酶活性和碳库管理指数分别比连作处理提高6.14% ~ 23.51%、9.00% ~ 37.92% 和4.74% ~ 14.44%，以烤烟–玉米轮作+化肥有机肥配施处理最优。综上，通过“轮作+化肥有机肥配施”不仅能显著提高植烟土壤有机碳含量和碳库管理指数，还能增加土壤微生物生物量和活性有机碳(LOC)组分，对于提高植烟土壤肥力和维持土地生产力具有重要意义。

Effects of Long-term Rotation and Fertilization Treatments on Organic Carbon Fractions and Enzyme Activities in Tobacco-planting Soil

Based on the long-term(18 years) field experiment in Zunyi of Guizhou Province, the effects of three different fertilization modes (no fertilization, chemical fertilizer alone, combined chemical and organic fertilizers) under two cropping systems (tobacco-maize rotation and continuous tobacco cultivation) on soil organic carbon (SOC) components, enzyme activities and carbon pool management index (CPMI) were investigated in order to explore carbon transformations in tobacco-planting soils and provide scientific management strategies for soil carbon. The results showed that under the same cropping system, combined chemical and organic fertilizers increased total soil organic carbon (TOC) content by 5.65%–12.13%, among them, light fraction organic carbon (LFOC), dissolved organic carbon (DOC) and readily oxidizable organic (ROC) increased by 23.33%–28.71%, 24.46%–25.54%, and 10.26%–18.99%, respectively. The CPMI also increased by 12.89%–23.34%. The activities of soil cellulase, β-glucosidase, amylase, peroxidase and invertase were significantly enhanced and were positively correlated with contents of SOC components and CPMI (0.59^*–0.97^**,n=18). Under the same fertilization conditions, SOC content, enzyme activities, and CPMI under the rotation were 6.14%–23.51%, 9.00%–37.92%, and 4.74%–14.44% higher than those under the continuous cropping system. In conclusion, tobacco-maize rotation with organic plus inorganic fertilizer application can not only significantly increase SOC and CPMI, but also enhance soil microbial biomass and labile organic carbon, which is of great importance for improving soil fertility and sustaining soil productivity.