旱地测土配方施肥温室气体减排碳交易量核算

Quantitative analysis of carbon trade of upland greenhouse gas emission reduction from precise fertilization

碳排放交易是促进全球温室气体减排,减少全球二氧化碳排放所采用的市场机制。测土配方施肥对于减少中国集约化农业生产区化肥施用量,减排温室气体(greenhouse gas,GHG)具有重要作用。该研究按照碳交易方法学的基本流程,撰写了基于DNDC(denitrification-decomposition)模型的测土配方施肥减排GHG的碳交易计量方法,并以山东省桓台为例,测算了该县实施测土配方施肥减排GHG的可交易碳贸易量。主要结论有1)桓台县麦-玉轮作系统施肥存在着氮、磷过量,钾基本适度的现象,氮、磷、钾平均施肥量达到了515.1、289.5和145.7 kg/hm2。2)山东省桓台县麦-玉轮作系统实施测土配方施肥可交易的碳贸易量为26 485.8 t(以CO2当量计,下同),其中农田减排占35.3%、氮肥生产减排占58.3%、磷肥生产减排占6.8%、钾肥增加排放0.01万t,占-0.4%。各个乡镇由于耕地面积及施肥量的不同,减排量存在一定的差异。3)按照2016年3月深圳碳交易市场中国核证减排量价格计算,桓台县实施农田测土配方施肥GHG减排项目可实现总收入1 286.4万元,满足小型碳交易项目要求。4)以DNDC模型为主要计量工具的测土配方施肥碳交易方法学,可以实现县域或更大区域实施测土配方施肥减排碳交易量核算,对未来测土配方施肥GHG减排碳交易项目的实施具有重要意义。

Carbon trading is the market mechanism to reduce global greenhouse gas（GHG） emissions. Soil testing and formulated fertilization play an important role in reducing the fertilizer application and GHG emissions in intensive agricultural production area of China. In this paper, the methodology of upland GHG emission reduction in soil testing and formulated fertilization was proposed according to the basic process of carbon trade methodology. Huantai County, Shandong Province was chosen for the case study of tradable carbon calculation. The main conclusions were as follows： 1） Boundary of the project included the geolocation of upland crops and the production process of chemical fertilizers. Baseline of the project was CO2 emission in chemical fertilizer production and N2 O emission in upland crop planting without soil testing and formulated fertilization, while the project activities were GHG emissions in above processes under soil testing and formulated fertilization. 2） In Huantai County, too much nitrogen and phosphorus fertilizer were added to the cropland, while potassium fertilizer was suitable. The average application amounts of nitrogen, phosphorus and potassium in wheat-corn rotation system were 515.1, 289.5 and 145.7 kg/hm2, respectively. The investigation of nitrogen fertilizer production enterprises showed that the average CO2 emission for the production of 1 t urea was 2.23 t（CO2 equivalent, the same as below）. 3） The tradable carbon from soil testing and formulated fertilization was 26 485.8 t, and the farmland emission reduction, nitrogen fertilizer production reduction and phosphatic fertilizer production reduction accounted for 35.3%, 58.3% and 6.8%, respectively. Potassium production increased by 110 t emission, accounting for-0.4%. The situation was different in every town of the county because of the different crop area and fertilization. GHG reduction for Suozhen Town and Qifeng Town was 4848.6 and 6 180.3 t, respectively. The main reason was that too much fertilizer was used in these 2 towns. GHG reduction in Tianzhuang, Jingjia, Chenzhuang, Xincheng, Zhoujia and Guoli was between 1 700 and 2 300 t. GHG reduction in Xingjia, Maqiao and Tangshan was lower than 1 700 t, mainly because less fertilizer was used in these towns. 4） According to the carbon price of Shenzhen carbon trading market in March 2016, the emission reduction projects of soil testing and formulated fertilization in Huantai County could reach 12.86 million yuan, with 1.286 million yuan every year, which met the project requirement of small carbon trade. 5） The carbon trading methodology system that adopted the Denitrification and Decomposition（DNDC） model as the main measurement tool could achieve the carbon emission reduction calculation. The study has great significance to the implementation of GHG carbon emission reduction project from soil testing and formulated fertilization.