不同保护性耕作模式对农田的温室气体净排放的影响

Effect on Net Greenhouse Gases Emission Under Different Conservation Tillages in Jilin Province

【目的】研究吉林省不同保护性耕作模式农田的温室气体的净排放。【方法】以吉林省玉米主产区农田4种保护性耕作模式(玉米留茬垄侧种植技术、玉米宽窄行交替休闲种植技术、玉米留茬直播种植技术和玉米灭高茬深松整地种植技术)为例,分别计算土壤固碳量、农田土壤温室气体排放量及农业物资投入造成的温室气体排放量,并系统计算其温室气体净排放。【结果】4种保护性耕作模式均提高了耕层土壤有机碳(SOC)的含量,其中,玉米宽窄行交替休闲种植技术(CT2)固碳潜力最大,土壤有机碳含量提高了1 955.07 kg C.hm-2.a-1,玉米留茬直播种植技术(CT3)固碳能力最小,仅提高了1 492.26 kg C.hm-2.a-1,传统耕作模式(CK)则减少了173.70 kg C.hm-2.a-1;4种保护性耕作模式的CO2排放当量(CO2-eq)排放总量平均为5 259.25 kg.hm-2.a-1,而CK的CO2-eq排放总量为5 367.96 kg.hm-2.a-1;4种模式的温室气体排放均主要发生在农业生产物资投入环节,其中氮肥投入为主要的排放促进因素。综合计算表明,4种保护性耕作模式的温室气体减排潜力不同,CT2的温室气体减排潜力最大,其CO2-eq减排量为1 897.56 kg.hm-2.a-1,而CT3则最小,其CO2-eq减排量为225.75 kg.hm-2.a-1,而CK模式则为-6 004.87 kg.hm-2.a-1。【结论】吉林省4种保护性耕作模式均提高SOC含量,且抵消了土壤和物资投入排放的温室气体,是温室气体的汇,而传统耕作没有提高SOC含量,没有抵消土壤和物资投入排放的温室气体,是一个温室气体源。

[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 altemately（CT2） with a rate of 1 955.07 kg·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^-cq） 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 CO2eq mitigated was 1897.56 kg·hm^2·a^-1 by CT2 and least by CT3 with 225.75kg·hm^2·a^-1, while CK was -6 004.87kg·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.