秸秆管理和施肥方式对绿洲棉田土壤有机碳库的影响

Effects of residue management and fertilizer application mode on soil organic carbon pools in an oasis cotton region

通过监测绿洲滴灌棉田不同秸秆管理和施肥方式下土壤有机碳库及碳库组分的变化,可揭示农田管理措施对棉田土壤有机碳库的调节机制,为干旱区提高农田土壤生产力以及农业固碳减排措施的制定提供科学依据.试验采用裂区设计,以秸秆还田(S)和秸秆不还田(NS)2种秸秆管理方式为主区,4种施肥处理为副区:包括不施肥(CK)、单施氮磷钾化肥(NPK)、单施有机肥(OM)和氮磷钾化肥与有机肥混施(NPK+OM).结果表明:施肥和秸秆还田均显著增加了土壤有机碳库,提高了有机碳(C_T)、易氧化有机碳(C_L)、微生物生物量碳(C_(MB))、水溶性有机碳(C_(WS)热水溶性有机碳(C_(HWS))的含量和有机碳累计矿化量(C_(TM))及碳库管理指数(CMI).秸秆还田较秸秆不还田土壤有机碳库提高了20.6%;处理NPK、OM、NPK+OM分别较CK提高了7.8%、29.5%、37.7%.不同施肥处理下C_T、C_L、C_(MB)、C_(WS)、C_(HWS)均表现为NPK+OM>OM>NPK>CK.秸秆还田较秸秆不还田C_(TM)提高了5.9%;NPK、OM、NPK+OM处理较CK分别提高了32.7%、59.5%、97.3%.对CMI与SOC及其组分间的相关性分析表明,CMI与C_T、C_(MB)、C_L、C_(WS)、C_(HWS)、C_(TM)、C库、固碳潜力均呈极显著相关关系,因此,CMI是评价绿洲棉田管理措施对土壤质量影响的重要指标.在干旱区建设高标准绿洲农田,发展棉花生产,采用秸秆还田和有机无机肥配施等农业技术措施,不仅能增加土壤有机碳及活性组分的含量,培肥地力,而且能促进土壤固碳,有利于农业资源高效利用和可持续发展.

To reveal the regulation mechanisms of agricultural management practices on soil organic carbon （SOC） pools and provide scientific basis for improving soil productivity and formulating agricultural fixed carbon and reducing discharge measures, we monitored the changes of SOC pools and organic carbon fractions in an oasis cotton field under different residue management and fertilizer application modes. A split-plot experimental design was used with differing residue management inclu- ding residue incorporation （S） and residue removing （NS） in the main plots and differing fertilizer application modes including no fertilizer （ CK）, NPK fertilizer （ NPK）, organic manure （OM） and NPK fertilizer plus organic manure （NPK＋OM） in the subplot. The results showed that fertilization and residue incorporation significantly increased SOC pool, soil organic carbon （CT） , labile carbon （CL） , microbial biomass carbon （ CMS ） , water-soluble organic carbon （ Cws ） , hot-water-soluble organic carbon （ CHws）, accumulative amount of soil organic carbon mineralization （CTM） and carbon management index （CMI）. The SOC pool was increased by 20.6% by residue incorporation compared to residue removing. SOC pools were increased by 7.8%, 29.5% and 37.7% in NPK, OM and NPK＋OM treatments compared to CK, respectively. The contents of CT, CL, CMB, Cws and Cnws under different fertilization treatments were shown as NPK＋OM〉OM〉NPK〉CK. CTM was in- creased by 5.9% by residue incorporation compared to residue removing and CT~ was increased by 32.7%, 59.5% and 97.3% in NPK, OM and NPK＋OM treatments compared to CK, respectively. There was a significant correlation between CMI and CT, CMB, CL, Cws, CHWS, CTM, C pool and C sequestration. Therefore, we concluded that CMI is an important index for evaluating the effect of agricultural management practices on soil quality. In order to construct high-standard oasis farmland in arid region and develop cotton production, we should consider adopting reasonable agricultural management practices （i.e. combining residue incorporation with NPK fertilizer plus organic manure）, which could increase the content of SOC, organic carbon fractions and soil fertility, promote soil carbon sequestration, and help the efficient use of agricultural resources and sustainable development.