基于非线性规划的冬小麦生产碳足迹优化研究

Carbon footprint optimization of winter wheat production based on nonlinear programming

农田是重要的温室气体人为排放源,在全球气候变化研究中占有重要的地位.碳足迹是评估农作物生产生命周期温室气体排放的有力工具.因此,本研究以我国典型冬小麦生长区山西省晋中市为例,采用生命周期评价的方法估算该区单位质量小麦生产的碳足迹,并在此基础上用非线性规划的方法对冬小麦生产碳足迹进行优化,旨在寻求小麦增产减排的途径.结果表明,研究区在传统的耕作方式下,生产1 t小麦的碳足迹为1357.28 kg(以CO2当量计),其中,生长阶段的温室气体排放的碳足迹和尿素生产环节所占比例较大.通过优化尿素与有机肥的施用量,可将研究区生产1 t小麦的碳足迹降低到469.99 kg,同时使单位面积产量增加9.13%.本文结果与相关研究差异较大,可能与氮肥施用量及N2O排放系数的取值有关.本研究对于了解冬小麦生产的综合碳排放情况,探索农业增产减排途径等方面具有重要意义.

Farmland releases greenhouse gases,therefore is of great importance to climate change. Carbon footprint is an ideal method to evaluate comprehensive greenhouse gas emissions of crops through the entire life cycle. This study took Jinzhong City,Shanxi Province,a typical winter wheat planting area as an example. Carbon footprint of wheat production was calculated using life cycle assessment. Furthermore,carbon footprint was optimized based on nonlinear programming aiming at reducing carbon emission as well as increasing crop unit yield. Results showed that,after energy-based allocating,carbon footprint for 1000 kg wheat production was 1357. 28 kg CO2 equivalent under traditional farm management. Two major phrases of carbon footprint generation were N2 O emission from farmland and urea manufacture. Through altering the fertilizer amount and adjusting the ratio of urea and mature,carbon footprint of 1000 kg wheat production could be reduced to 469. 99 kg CO2 equivalent,with 9. 13% increase in unit yield. Carbon footprint of wheat production in Jinzhong City showed great difference with results from previous studies in China,which was most likely due to various fertilizer amounts and N2 O emission coefficients in different studies. This study provides important information in integrated greenhouse gas emissions of wheat production and quantitative methods to decrease carbon emission and increase crop yield.