Abstract: 【Objective】 Reveal net greenhouse gases（GHGs）under conservation tillage in farmland in Jilin province. 【Method】 Experimental studies on conservation tillage with 4 treatments (technology of maize planted in ridge side with high stubble; technology of maize planted in wide line and narrow line alternately; technique of seeding straightly with stubble left in the field; technology of maize planted directly on ridge before smashing stubble plowing combined with fertilization) in main producing areas of maize in Jilin province were conducted to figure up the carbon accumulation, GHGs emission from field and input, thus the net emission can be calculated systematically.【Result】Four conservation tillage patterns increased soil organic carbon(SOC) content in arable layer. The highest potential of carbon sequestration was Technique of maize planted in wide line and narrow line alternately(CT2) with a rate of 1 955.07 kg C•hm-2•a-1, while the lowest was showed under technique of seeding straightly with stubble left in the field (CT3) with a rate of 1 492.26 kg C•hm-2•a-1. On the contrary, conventional tillage (CK) decreased SOC content with 173.70 kg C•hm-2•a-1. Average amount of CO2 equivalent (CO2-eq) emission under 4 conservation tillage patterns was 5 259.25 kg•hm-2•a-1, and 5 367.96 kg•hm-2•a-1 emitted from CK. GHGs from input contributed mostly to total emission and production of nitrogen accounted a large proportion for it. The calculated result showed that there was a diversity of GHGs mitigation among 4 conservation tillage patterns. Most CO2-eq mitigated was 1897.56 kg•hm-2•a-1 by CT2 and least by CT3 with 225.75 kg•hm-2•a-1, while CK was -6 004.87 kg•hm-2•a-1. 【Conclusion】 Four conservation tillage patterns in Jilin Province increased the SOC content and offset the GHGs emission form soil and input. They were sinks of GHGs while CK was a source because it decreased the SOC content without mitigation of GHGs.

Key words: conservation tillage, greenhouse gases, net emission, Jilin Province