Meta分析生物质炭对中国主粮作物痕量温室气体排放的影响

Meta analysis on impacts of biochar on trace greenhouse gases emissions from staple crops in China

该文采用Meta分析方法定量分析生物质炭输入对中国主粮作物痕量温室气体的影响,研究可为农田痕量温室气体减排提供有效的途径。结果表明相对于不施加生物质炭,生物质炭输入对甲烷吸收/排放并无显著影响,而甲烷排放在不同耕作和施氮情况下发生显著变化。旋耕和不施氮情况下施加生物质炭分别显著提高稻田甲烷排放达30%和46%,而在翻耕和施氮的情况下施加生物质炭可减少稻田甲烷排放达9%和10%。生物质炭输入分别可显著减少主粮作物氧化亚氮、全球增温潜势(global warming potential,GWP)及温室气体排放强度(greenhouse gas intensity,GHGI)达41%、18%及25%。不同土地利用类型、耕作类型、生物质炭施用量及生物质炭类型均可显著影响农田氧化亚氮、GWP和GWPI。合理的管理主粮作物生物质输入可为减少温室气体排放做出贡献,建议生物质炭与施氮和翻耕2种农作措施相结合,施加小于10 t/hm^2及碳氮比(C/N)低于80的生物质炭,以利于主粮作物综合温室效应的减排。

Biochar inputs have important impliations for agricultural soils, also have a significant influence on greenhouse gas emissions. This paper conducted a meta-analysis to quantitatively synthesize influence of biochar inputs on trace greenhouse gases from staple crops in China, and explored available mitigation method. The data were collected from published papers before December, 2016. The effective data were selected from the literatures including： 1） both treatments with and without biochar input; 2） methane and nitrous oxide emissions; 3） field experiment; 4） greenhouse gases from rice planting to maturity; 5） reliable measurements; 6） clear and reliable yield data; 7） wheat, rice and maize in China. A total of 134 datasets were obtained. They were classified by rice paddy field and dry land, rotary tillage and plowing tillage, different biochar amount and biochar types. The response ratio was calculated with the biochar input as the treatment and no biochar input as the control. The global warming potential and the greenhouse gas intensity were calculated. The results showed that the biochar input averagely decreased the global warming potential by 18% compared with no biochar input. The global warming potential decrease by inputting biochar in the dry land was significantly higher than that in the paddy field （P〈0.01）. The reduction in global warming potential by inputting less than 10 t/hm2 biochar was higher than that by inputting the biochar higher than 10 t/hm2. Plowing tillage could significantly reduce the GWP by 19%. The rate of change in GWP was highest in the other biochar （41%）, followed by maize biochar （20%） and wheat biochar （13%）. The biochar input didn’t greatly affect the methane emission in paddy field. However, the rotary tillage could significantly increase the methane emission by 30% and the inputting biochar without N application also greatly increase the methane emission. The biochar input average decreased the nitric oxides by 41% for the three staple crops. The nitrous oxides emission was decreased by 44% in the dry land, 24% in the paddy field, by 52% by inputting smaller than 10 t/hm2 biochar. The nitrous oxides emissions were higher in the other biochar and maize biochar than the wheat biochar. Biochar input could increase the crop yield by 7% and decreased the greenhouse gas intensity by 25%. The decrease in the greenhouse gas intensity was higher in the dry land than the paddy field, in the smaller than 10 t/hm2 biochar input than the input higher than 10 t/hm2, and in the plowing tillage than in the rotary tillage. The rate of change in greenhouse gas intensity was 47% in the other biochar input, 26% in the maize biochar, and 20% in the wheat biochar. Different soil use types, tillage managements, biochar amount and biochar types could significantly impact nitric oxide, global warming potential and greenhouse gas intensity. In addtion, biochar input combined with reasonable agricultural management could reduce greenhouse gas emissions in staple crops soils. This paper indicated that for reduction in global warming potential from staple crops, biochar should combine application with nitrogen fertilizer and plowing tillage managements, and input the biochar with less 10 t/hm2 and C/N below 80, such as, field crop straw could directily carbonized.