长期定位双季稻田施用生物炭的温室气体减排生命周期评估

该文评估了双季稻田施用生物炭的温室气体排放和固碳及经济效益。采用生命周期（life cycle assessment，LCA）方法核算了生物炭原料收集与运输、生物炭生产、运输和撒播以及避免秸秆燃烧等过程中的温室气体排放和土壤碳储量；采用静态箱-气相色谱法监测了不同生物炭施入量在4 a 8个生育期的稻田CH4和N2O排放量；计算了不同生物炭施入量处理的净温室气体排放量和减排百分比。水稻生长季温室气体排放结果显示，CK处理（不添加生物炭）、BC1处理（5 t/hm2）、BC2处理（10 t/hm2）、BC3处理（20 t/hm2）的4 a田间温室气体排放总量分别为19.5、15.6、16.1、12.4 t/hm2，BC1、BC2和BC3处理相对CK处理的总减排百分比分别为19.70%、17.46%和36.40%。综合生物炭全生命周期各阶段温室气体排放，CK、BC1、BC2和BC3处理的4 a总净排放量分别为19.5、20.3、10.9、4.2 t/hm2，BC1处理的4a净排放相对CK处理增加4.3%，BC2和BC3处理的4 a净排放相对CK处理分别减少了44.0%、78.6%。3个生物炭用量中，生物炭施用量越低，经济效益越好。稻田施用生物炭能够降低其温室气体排放；全生命周期评估结果表明中量和高量生物炭能够起到减排效果，高量生物炭减排效果最好；经济效益分析结果表明随着生物炭施用量增加，经济效益降低。

Estimation on GHG emission reduction in double cropping rice paddy with application of biochar in long-term period using LCA method

Methane and N2O are two important greenhouse gases, which are the main emission in paddy ecology system. China is the highest rice planting country, so the greenhouse gas emission is huge in China. Application of biochar in paddy field can decrease the emissions of greenhouse gases. In this study, we investigated the greenhouse gas (GHG) emissions, carbon sequestration and economics of different rates of biochar application in a double rice cropping system. The experiment was carried out in rice variety area promotion experiment field in Huizhou of Guangdong from March 2012 to September 2015. Four treatments were designed as CK (famer traditional operation without biochar application), BC1 (biochar amendment at 5 t/hm2), BC2 (biochar amendment at 10 t/hm2), and BC3 (biochar amendment at 20 t/hm2), each treatment has 3 repeat. Biochar used in this study was obtained from wheat straw and produced by Henan Sanli New Energy Company. LCA (life cycle assessment) method was employed to calculate GHG emissions from the collection and transportation of raw materials, the production, transportation, and broadcasting of biochar, and from the avoidance of the straw burning and the soil carbon stocks. Static chamber-GC (gas chromatography) method was used to monitor the CH4 and N2O emissions under different rates of biochar application from 2012 to 2015. Then, the net GHG emissions and the percentage of emission reduction in the paddy field with different biochar amendment rates were calculated. The total GHG emissions from the double rice cropping system were 19.5, 15.6, 16.1, and 12.4 t/hm2 under CK, BC1, BC2, and BC3 treatments respectively in four years. Moreover, the total GHG emission reduction percentage of BC1, BC2 and BC3 were 19.70%, 17.46%, and 36.40%, respectively. Considering the GHG emissions of biochar in all stages of life cycle, the net GHG emissions of CK, BC1, BC2 and BC3 in the four years were 19.5, 20.3, 10.9, and 4.2 t/hm2, respectively, the treatment of BC1 increased the net emissions of 4.3% in the four years. BC2 and BC3 reduced the net GHG emissions by 44% and 78.6%, respectively in four years. The economic analysis indicated that the BC1treatment had more economic benefits compared to other treatments. The different biochar amendment rates significantly reduced the GHG emissions from the double rice cropping system, the highest application rate of biochar had the best emission reduction effect. The LCA of biochar application indicated that from medium to high application levels, biochar reduces emissions, for higher application rates of biochar, the effects are stronger. Moreover, the economic analysis indicated that the more amounts of biochar application, the least profitable to gain economic benefits.