农作物秸秆综合利用生态价值量估算方法研究

Based on method and quantitative study, in accordance with the three steps of “Resources substitution volume → Greenhouse gas emission reductions volume →ecological value”, this study made a comprehensive estimation of ecological value of the utilization of straw resources. Its main researches are:① Established systematic estimation methods, quantitative formula and parameter system of resources substitution and protection of grassland with straw resources utilization, and then made a quantitative estimation from substituting fossil energy with utilization of straw as energy, less use of chemical fertilizers with utilization of straw as fertilizer, protection of grassland by substituting forage grass with utilization of straw as feed and protection of forest land by substituting wood with industrial use of straw and cultivation of edible fungi etc.; ②Established systematic estimation methods, quantitative formula and parameter system of fixing carbon and green gas emission reductios with straw resources utilization, and then made a quantitative estimation using the formula of ‘net green gas emission reduction with straw utilization= emission reduction with straw utilization under natrual compost baseline+ emission reduction with substitution of straw utilization+emission reduction with carbon fixation of straw utilization－green gas emission during the straw resources utilization process’ from substituting fossil energy and reducing green gas emission with utilization of straw as energy, less use of chemical fertilizers and fixing carbon of cropland with utilization of straw as fertilizer, protection of grassland and forest land, realizing biological carbon fixation, reducing green gas emission and fixing carbon of soil, and green gas emission during the straw resources utilization process; ③Had a quantitative estimation of the ecological value on carbon fixation andgreen gas emission reduction of the straw utilization and the ecological service value of protection of grassland and forest land using the model of ecological service value and uniform price of carbon sequestration.

以方法研究和定量研究为主，按照“资源替代量→温室气体减排量→生态价值量”三个步骤，实现对秸秆综合利用生态价值量的定量估算：①从秸秆利用替代化石能源、减施化肥、保护林草地等角度，构建秸秆利用资源替代和保护林草地的系统估算方法、数量关系式和参数体系，实现对秸秆利用资源替代和林草地保护的定量估算；②以秸秆自然腐烂为基准线，利用“秸秆利用净减排＝秸秆自然腐烂基准线减排＋秸秆利用替代减排＋秸秆利用固碳减排－秸秆利用过程能耗增量排放”的总公式，从秸秆利用替代化石能源减排、秸秆还田减施化肥和农田固碳减排、秸秆利用保护林草地生物固碳和土壤固碳减排、秸秆利用过程能耗温室气体排放等方面，构建秸秆综合利用固碳减排的系统估算方法、数量关系式和参数体系，实现对秸秆综合利用固碳减排的定量估算；③利用统一的碳汇价格和生态服务价值模型，分别进行秸秆利用固碳减排生态价值量和保护林草地生态服务价值量的定量估算。

中国农作物秸秆资源丰富，可用作燃料、饲料、肥料、原料、基料等多种用途，具有多方面的生态价值。准确估算秸秆综合利用的生态价值量，是编制秸秆综合利用规划，合理配置秸秆资源、优化秸秆利用结构的重要依据。国内外对秸秆资源综合利用生态价值量的综合估算研究开展较少，缺少系统的定量计算方法，已有指标参数存在一定的主观性，某些指标尤其是与区域环境相适应的指标参数体系还比较欠缺，有待进一步定量测定和完善。本研究旨在系统完成秸秆资源替代效用的系统估算方法研究、秸秆综合利用温室气体减排量的系统估算方法研究、秸秆综合利用生态价值量估算方法研究，构建秸秆资源综合利用生态价值量估算的方法体系，建立相应的数学表达式或数量关系模型，制定完善的定量估算技术参数体系，以实现秸秆综合利用的生态价值量估算。构建以秸秆自然腐解为基准线基的秸秆综合利用温室气体减排计量体系，对于完善秸秆综合利用温室气体减排估算方法学体系、全面评价秸秆综合利用温室气体减排效果具有重要意义。小麦、玉米、水稻秸秆自然腐解温室气体排放试验结果表明，模拟玉米秸秆堆放在土地上自然腐解，监测到其主要排放源为CO2，单位重量玉米（干重）秸秆CO2排放量830.18 g•kg-1；模拟小麦秸秆堆放于土地上自然腐解，主要排放源也为CO2，排放系数为462.5589g•kg-1；模拟水稻秸秆堆放于土地上自然腐解，CO2排放系数为557.9623g•kg-1。典型案例研究表明，秸秆综合利用具有良好的温室气体减排效果和生态价值。江西圣牛热解气化多联产工程项目的生态价值量约为20万元；河北临漳县生物天然气工程生态价值量约为15.3万元；河北省柯良农场秸秆打捆直燃集中供暖项目净减排量为2742.3tCO2；甘肃省临洮县5个秸秆成型燃料集中供暖示范工程净减排量1505.41 t CO2。本研究可为科学核算秸秆综合利用温室气体减排潜力提供科学依据，为实现我国3060双碳目标提供重要的理论指导。