不同耕作措施对渭北旱塬土壤碳库管理指数及其构成的影响

Effects of Different Tillage Methods on Soil Organic Carbon Pool Management Index and Its Composition in Weibei Highland

以渭北旱塬9 a(2007—2016年)的不同耕作定位试验为对象,研究了在秸秆还田条件下3种连年单一耕作即翻耕(CC)、免耕(NN)、深松(SS)和3种轮耕措施即免耕-深松(NS)、深松-翻耕(SC)、翻耕-免耕(CN)对农田土壤固碳速率(CSE)、碳库管理指数(CPMI)、小麦产量和秸秆还田后表观腐殖化系数的影响。结果表明:以翻耕(CC)作为参照土样,免耕提高了0～10 cm表层土壤的固碳速率、有机碳(SOC)及其易氧化组分(EOC)的含量,并增加了表层(0～10 cm)土壤的碳库管理指数(CPMI),在>10 cm土层SOC、EOC含量虽有所减少,但提高了有机碳的稳定系数(KOS);深松则提高了表层和35～50 cm土层的SOC、EOC含量、CSE及CPMI,并增加了0～10 cm、35～50 cm土层的EOC/SOC值和10～20 cm土层的KOS;轮耕处理各土层的CSE、SOC和EOC含量均有所增加,且增加了0～10 cm、35～50 cm土层的EOC/SOC值,其中NS和CN轮耕处理各层CPMI都有所增加。深松、免耕和轮耕处理提高了小麦产量和小麦秸秆量,其中NS处理增加幅度最大,分别为14.3%(籽粒)和12.9%(秸秆);进行9 a小麦秸秆还田,免耕、深松和轮耕措施提高了还田秸秆的表观腐殖化系数,其中NS处理的表观腐殖化系数显著高于翻耕处理。

To investigate the effect of different tillage methods on soil carbon pool management index (CPMI), carbon sequestration rate (CSE), wheat yield and straw returning apparent humification coefficient, a nine-year (2007-2016) field experiment with six tillage measures under straw returning condition in Wei Highland was conducted. The tillage measures included three single continuous tillages (no-tillage (NN), subsoiling (SS) and conventional tillage (CC)), and three rotational tillages (no-tillage-subsoiling (NS), subsoiling-conventional tillage (SC) and conventional tillage-no-tillage (CN)). The results showed that, compared with the conventional tillage, the measure of NN increased carbon sequestration rate, soil organic carbon content (SOC) and its oxidative components (EOC), and carbon pool management index in surface soil (0 to 10 cm) while decreased SOC and EOC, but increased the stability coefficient of organic carbon (KOS) in soil layer deeper than 10 cm. The measure of SS increased the SOC, EOC content, CSE, CPMI in the surface soil layer and 35-50 cm soil layer, improved the EOC/SOC values in the soil layers of 0-10 cm and 35-50 cm, and increased KOS in 10-20 cm soil layer. Rotational tillages increased the SOC, EOC content and CSE in each soil layer, and increased the EOC/SOC value in the soil layers of 0-10 cm and 35-50 cm, NS and CN rotational tillages increased CPMI in each soil layer. Compared with the conventional tillage, the yield of wheat grain and the dry mass of wheat straw were increased in the treatment of SS, NN and rotational tillage, and the maximum increment was found to be in the treatment of NS which was 14.3% for grain yield and 12.9% for straw dry mass, respectively. After the nine-year straw returning, the apparent humification coefficient of returning straw increased in the SS, NN and rotational tillage, and the apparent humification coefficient of NS treatment was significantly higher than that of the conventional tillage.