1995-2012年宁夏盐池县种植业碳足迹变化特征

Changes in the carbon footprint of crop production in Yanchi County,Ningxia Hui Autonomous Region from 1995 to 2012

细化中小尺度农业系统碳足迹的研究既可为当地低碳农业的发展提供科学依据,也可为大尺度农业系统的碳足迹研究提供基本素材。本论文基于投入产出视角,以位于农牧交错带的宁夏盐池县为案例区,通过分析种植业碳排放源,细化碳吸收的各类作物,选定主要投入要素的碳排放系数和各种作物的碳吸收率,重点分析了1995-2012年研究区农作物的碳吸收对农业化学物质及能源投入碳排放的消纳情况。结果表明:盐池县种植业的碳平衡处于碳生态盈余状态,净碳汇稳步上升,年平均增长率达13.31%。碳排放、碳吸收和碳足迹在1995-2000年、2000-2007年和2008-2012年3个时段存在显著性差异。根据相应时段的变异系数和当地生态退耕政策的影响,将碳足迹变化分为3个时期,即不稳定期1995-2000年、较稳定期2000-2007年和稳定期2008-2012年。然而,上述碳生态盈余状态并不能掩饰农业化学物质和能源投入不断增加所带来的不可再生资源年损耗的增加和农业面源污染潜在风险的加剧。

The small-scale study of carbon footprints in agriculture systems is essential to the large-scale study of carbon footprint research in agricultural systems and the development of low carbon agriculture. Using Yanchi county as a case study and the input-output angle, we analyzed carbon emissions, carbon absorption and the carbon footprint of crop production from 1995 to 2012 by selecting main input factors and coefficients for carbon emissions, and carbon absorption rates of crops. The results indicate that the total carbon emissions from agricultural input and total amount of crop carbon absorption showed rising trends; however, carbon absorption was much higher than carbon emissions and the net carbon sink continued to increase with a yearly average growth rate of 13.31%. The largest contributor to carbon emissions was N fertilizer （up to 60.63%） but the contributor with fastest yearly average growth rate was plastic film （up to 37.06%）and the rate of N fertilizer was only 8.88%. Regarding carbon absorption, corn absorbed more than other farm crops, with a proportion of 56.76% for corn, and the yearly average growth rate of crop absorption showed that soybeans was up to 339.86%. Analysis of variance showed differences among the three periods 1995-2000, 2001-2007, and 2008-2012 for carbon emissions, carbon absorption and carbon footprint. Accordingly, based on variance coefficient and the implementation of local grain for green policy, changes in carbon footprints can be divided into three periods： unstable period 1995-2000, relatively stable period 2001-2007, and stable period 2008-2012. However, carbon ecological surplus cannot cover up increasing consumption of non- renewable resources, and increasing risks of agricultural nonpoint pollution resulting from increasing inputs of agricultural chemicals and energy.