华北平原作物生产碳足迹分析

Carbon Footprint Analysis of Crop Production in North China Plain

【目的】分析华北平原作物生产碳足迹的动态、分布以及构成,为发展低碳农业提供理论支撑与科学依据。【方法】基于中国华北平原河北、北京、天津、山东、河南5个代表省(市)的47个市的耕地面积、农作物播种面积、产量、产值及作物生产投入等统计数据,利用农业领域碳足迹理论及生命周期评价法,估算作物生产的单位播种面积碳足迹(CFs)、单位耕地面积碳足迹(CFc)、单位产量碳足迹(CFy)及单位产值碳足迹(CFv)。以2002年为节点,把1993—2012年分为两个时间段,分析作物生产碳足迹的变化趋势以及华北平原47个市的作物生产碳足迹的分布、构成情况。根据1993—2012年不同市的平均单产,取5个单产最高与5个单产最低的市,分析华北平原高产市与低产市的碳足迹、单位面积投入以及作物构成。【结果】华北平原作物CFs、CFc在过去20年里呈增加趋势,CFs平均值从时段Ⅰ的4.08 t CO2eq·hm-2升高到时段Ⅱ的4.72 t CO2eq·hm-2,平均变化率为0.66t CO2eq·hm-2·10a-1;CFc平均值从时段Ⅰ的6.81 t CO2eq·hm-2升高到时段Ⅱ的8.12 t CO2eq·hm-2,平均变化率为1.16t CO2eq·hm-2·10a-1。华北平原作物CFy、CFv在过去20年里呈降低趋势,CFy平均值从时段Ⅰ的0.54 t CO2eq·t-1下降到时段Ⅱ的0.42 t CO2eq·t-1,平均变化率为-0.12 t CO2eq·t-1·10a-1;CFv平均值从时段Ⅰ的3.91 t CO2eq·$10-4下降到时段Ⅱ的2.51 t CO2eq·$10-4,平均变化率为-1.60 t CO2eq·$10-4·10a-1。华北平原不同区域作物生产碳足迹差异较大,沿海地区(唐山、天津、秦皇岛、东营、烟台等)CFs、CFc较大,CFy、CFv较小,河南南部地区(驻马店、信阳、平顶山、洛阳)CFs、CFc较小,CFy、CFv较大。高产市CFs、CFc显著高于低产市,CFy、CFv显著低于低产市(P<0.05);高产市单位面积投入显著高于低产市,且蔬菜种植面积比例高于低产市(P<0.05)。在华北平原作物生产的碳足迹构成中,灌溉用电(30.25%)、氮肥投入(23.07%)以及农田N2O直接排放(19.83%)所占比例较大,其他投入所占比例较小。【结论】在过去20年里,华北平原作物单位播种面积碳足迹、单位耕地面积碳足迹呈增加趋势,而单位产量碳足迹、单位产值碳足迹呈降低趋势。在华北不同区域中,沿海各市前两者较大,后两者较小,而河南南部各市前两者较小,后两者较大。碳足迹构成中,灌溉用电与氮肥投入所占比例较高,高产市单位面积投入及蔬菜种植比例较大。

[Objective]Based on the statistic data of cultivated area, sown area, crop yield, production value and farmland investment of the crop production in the period of 1993 to 2012, the dynamics, distributions and compositions of carbon footprint （CF） of the crop production were estimated in North China Plain （NCP）, which will provide a theoretical support and scientific basis for the development of low-carbon agriculture. [Method]Based on the historical statistic data of cultivated area, sown area, crop yield, production value and farmland investment of the crop production of 47 prefecture-level cities in 5 provinces and cities （Hebei, Beijing, Tianjin, Shandong and Henan） in North China Plain, and used the theory of carbon footprint and life cycle assessment method in the agricultural sector, CF per unit sown area （CFs）, CF per unit cultivated area （CFc）, CF per unit yield （CFy） and CF per unit production value （CFv） of the crop production were estimated in North China Plain. The dynamic and distributions of carbon footprint were analyzed briefly. In addition, the proportions of different agricultural inputs in carbon footprint of crop production were explored. [Result] CFs and CFc of crop production showed an increasing trend in the last twenty years. The CFs of crop production was 4.08 tCO2eq·ha^-1 in period I （1993-2002） and 4.72 tCO2eq·ha^-1 in period II （2003-2012）, respectively; The CFc of crop production was 6.81 tCO2eq·ha^-1 in period I （1993-2002） and 8.12 tCO2eq·ha^-1 in period II （2003-2012）, respectively. CFy and CFv of crop production showed a decreasing trend in the last twenty years. The CFy of crop production was 0.54 tCO2eq·t-1 in period I and 0.42 tCO2eq·t-1 in period II, respectively. The CFv of crop production was 3.91 tCO2eq·￥10^-4 in period I and 2.51 tCO2eq·￥10^-4 in period II, respectively. The carbon footprints were different in different regions of the NCP. Most coastal regions （Tangshan, Tianjin and Yantai, etc.） have bigger CFs and CFc and smaller CFy and CFv. On the contrary, most cities of South Henan （Zhumadian, Xinyang, and Pingdingshan, etc.） have smaller CFs and CFc and bigger CFy and CFv. The agricultural inputs per unit sown area and the vegetable crops sown area percentage in high yield region were significantly higher than that in low yield region, respectively. The results presented here indicated that the main components of carbon footprint were electricity for irrigation （30.25%）, N fertilizer （23.07%）, and direct emissions of N2O （19.83%）.[Conclusion]In the last twenty years, the CFs and CFc of crop production increased, but the CFy and CFv decreased in North China Plain. Most coastal regions have bigger CFs and CFc and smaller CFy and CFv, but the regions of southern Henan province were the opposite. In addition, the electricity for irrigation and N fertilizer were the major resources of emissions in North China Plain.