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中国是世界秸秆资源最丰富的国家之一,2007-2009年年均产量达到7.35亿t,其中约有21%秸秆露天焚烧,不仅是资源浪费,同时也加剧了温室效应。据估计农田土壤固碳潜力占自然固碳潜力巨大,通过合理的土壤管理措施可以增加土壤固碳能力60%~70%,高效利用秸秆资源就是其中很有效的一种管理方式。生物炭是废弃生物质材料热解产生的一类碳含量极高并具有一定的化学或生物学惰性的混合物,应用于土壤后其所具有的碳汇功能成为了近年来的研究热点。文章以2012年中国露天焚烧的水稻秸秆为原料,采用生命周期评价方法对水稻秸秆热解生产生物炭并还田过程的固碳潜力进行评估,结果显示“水稻秸秆-生物炭-还田”模式固碳潜力主要分为3个部分:(1)代替化石燃料燃烧排放7.78×10~6t;(2)土壤封存36.45×10~6t;(3)增加作物生长固碳3.46×10~6t,CO_2总固定量为47.69×10~6t。计算得到每热解1 t水稻秸秆将固定1.34 t的CO_2。根据评估结果认为热解水稻秸秆生产生物炭具有巨大的固碳潜力,这种模式可以推广处理农业废弃秸秆资源,以应对日益加剧的温室效应。
China is one of the countries with the most straw resources in the world. The average annual output in 2007-2009 reached 735 million tons. About 21% of the straw was open-air burning, which not only wastes resources but also aggravates the greenhouse effect. It is estimated that the carbon sequestration potential of farmland accounts for a huge potential for natural carbon sequestration. Soil rational carbon sequestration can be increased by 60% -70% through rational soil management practices. Effective use of straw resources is a very effective management method. Biochar is a kind of mixture with high carbon content and some chemical or biological inertia generated from the pyrolysis of waste biomass materials. It has become a research hotspot in recent years that its carbon sink function has been applied in soils. In this paper, the open field incineration of rice straw in 2012 was used as raw material to evaluate the carbon sequestration potentiality of bioflocs produced by pyrolysis of rice straw and the process of returning to the soil by life cycle assessment. The results show that the "straw - biochar - The carbon sequestration potential of the model is mainly divided into three parts: (1) the emission of fossil fuels is 7.78 × 10 ~ 6t; (2) the soil is sealed and stored at 36.45 × 10 ~ 6t; (3) the carbon sequestration of crops is increased by 3.46 × 10 ~ 6t , CO 2 total fixed amount of 47.69 × 10 ~ 6t. Calculated for each 1t rice straw will be fixed at 1.34 t of CO_2 per pyrolysis. According to the assessment results, biochar production by pyrolysis rice straw has great potential for carbon sequestration. This model can promote the treatment of agricultural waste straw resources to cope with the increasing greenhouse effect.