退耕植茶对川西低山丘陵区土壤活性有机碳组分的影响

为探讨退耕植茶对土壤活性有机碳组分的影响,选取退耕2~3年(RT 2~3)、9~10年(RT 9~10)和16~17年(RT 16~17)的茶园为研究对象,以邻近撂荒地为对照(CK),测定其土壤颗粒有机碳(POC)、微生物量碳(MBC)、水溶性有机碳(WSOC)、可矿化有机碳(MOC)含量,并分析其分配比例随退耕植茶年限推移的变化.结果表明,POC、MBC和WSOC对退耕植茶的响应较为一致,与对照相比,退耕植茶初期(RT 2~3),各组分含量均降低,但随着植茶时间的推移,各组分含量逐渐增加,在植茶9~10或16~17年后显著高于撂荒地;退耕植茶后MOC含量显著降低,总体表现为CKRT 16~17RT 9~10RT 2~3,0~10 cm土层,RT 2~3、RT 9~10和RT 16~17土壤MOC含量分别较对照显著下降35.25%、23.89%和16.87%,10~20 cm土层中分别下降32.31%、13.09%和23.22%,20~40 cm土层中分别下降36.43%、28.79%和30.76%.植茶后,土壤活性有机碳在总有机碳中的比例整体现为0~10 cm高于20~40 cm,相较于表层土壤,深层土壤碳库的稳定性更强.退耕植茶有利于土壤肥力的保持,对提升土壤有机质水平起到积极作用,且随植茶时间的推移,土壤对碳的固持作用增强,土壤质量得到提升.

Effects of converting farmland to tea plantations on soil labile organic carbon fractions in the hilly region of Western Sichuan, China

In order to study the effects of converting farmland to tea plantations on the soil active organic carbon, soil samples were obtained from tea plantations with different conversion years (2~3, 9~10 and 16~17 years old), with the control of the abandoned land, and analyzed for the concentrations and proportion of soil particulate organic carbon (POC), microbial biomass carbon (MBC), water soluble organic carbon (WSOC), and mineralized organic carbon (MOC). The POC, MBC and WSOC showed similar response to tea plantation. Compared with the control, the content of POC, MBC and WSOC decreased in the early stage of tea plantation (RT 2~3), then gradually increased with the tea plantation ages. Meanwhile, the MOC content decreased obviously after tea plantation. Compared with the control, the MOC decreased by 16.87%~35.25%, 13.09%~32.31% and 28.79%~36.43% in 0~10, 10~20 and 20~40 cm soil layer, respectively. The soil of RT 16~17 presented greater MOC content, followed by the soil of RT 9~10 and RT 2~3. The active organic carbon content and proportion in 0~10 cm soil layer were higher than that in 20~40 cm soil layer. The organic carbon in the topsoil presented greater activity. Converting farmland to tea plantations is beneficial to keep better soil fertility, and plays a positive role in improving soil organic matter content. Soil carbon sequestration improved with the increasing tea plantation age, thus keeping better soil quality.