中国小麦、玉米碳足迹历史动态及未来趋势

气候变化是当今国际研究的热点问题,小麦、玉米是中国主要粮食作物,分析小麦、玉米生产碳足迹的时空动态和中国相关农业政策对小麦、玉米生产的温室气体减排的引导效果对于合理应对气候变化具有重要的意义。本研究基于生命周期评价法（LCA）对2005—2015年中国小麦、玉米生产碳足迹进行了核算,并在此基础上,根据种植业结构及化肥、农药调整政策模拟分析了不同玉米种植面积和不同单位面积化肥及农药施用量等4种情景下2020年小麦、玉米生产的温室气体排放和单位面积碳足迹。研究结果显示：2005—2015年小麦、玉米生产的单位面积碳足迹和温室气体排放量均呈现出显著增加的趋势 （P < 0.05）;模拟分析结果表明：通过缩减种植面积,优化化肥、农药投入能够有效降低小麦、玉米生产的碳足迹,实现（168.89~ 560.07）亿kg CO₂-eq的减排潜力。因此建议构建科学施肥技术体系,提高农资投入品的利用效率,以实现中国的温室气体减排目标。

Historical dynamics and future trends of carbon footprint of wheat and maize in China

Risks for natural and human systems have been increasing during past decades due to global warming, which is one of the main consequences of the raising anthropogenic greenhouse gases (GHGs) emissions. Agriculture is one of the principal contributors to anthropogenic GHGs emissions. And wheat and maize are major cereal crops in China. Thus, assessing the carbon footprint (CF) of wheat and maize, investing the adjustment of agricultural policies and the effects on reduction in GHGs emissions will help to establish a reasonable strategy to mitigate climate change. A systematical analysis of the carbon footprint (CF) of wheat and maize production is critical to develop low carbon agriculture and enhance carbon sequestration in China. CF of wheat and maize production during 2005-2015 was computed, which was based on the Life Cycle Assessment (LCA). According to the completion of the relevant agricultural policy “National crop adjustment plan (2016-2020), ” “Fertilizer usage by 2020 zero increase action plan, ” and “Pesticides usage by 2020 zero increase action plan, ” a predicted CF of wheat and maize production in the near future five scenarios was established. The result showed a significant rising trend in CF and total greenhouse gases(GHGs) emissions for both wheat and maize production during 2005-2015 (P < 0.01). The CF of maize production was lower than wheat production. The growth rate of CF per unit area of wheat production was higher than that of maize, while the total GHGs emissions showed an opposite trend. Simulation on different scenarios indicated that all the projections in 2020 experienced a reduction on carbon emission for about (16.89~56.01) billion kg CO₂-eq. Therefore, strategies to balance crop production and agriculture inputs application are of great importance to achieve China’s 2020 GHGs emission targets.