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 N2O 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 N2O 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. ©, 2015, Science Press. All right reserved.
