DYNAMICS OF CARBON FOOTPRINT OF MAIZE PRODUCTION WITH DIFFERENT FUNCTIONAL UNITS IN SHANXI PROVINCE, CHINA

The reduction of greenhouse gases (GHGs) emissions from agricultural production is an efficient solution to mitigate global climate change. Maize (Zea mays L.) is most important grain crop in Shanxi Province, China. The environmental pressure due to large GHGs emissions associated with agricultural inputs during the process of maize production cannot be ignored. Based on the dataset from the National Cost-Benefit Survey for Agricultural Products, changes in carbon footprint (CF) with different functional units were assessed for maize production using life cycle assessment in Shanxi Province, China. The results showed that GHGs emissions sourced from maize production increased from 3633.7 kg CO2-eq ha(-1) in 2004 to 4043.3 kg CO2-eq ha(-1) in 2013 in Shanxi Province. Fertilizers application, soil N2O emission and irrigation contributed more than 85% of total GHGs emissions. Excluding soil organic carbon (SOC) storage, the CF of maize produced with different functional units (i.e., at yield-, production value-, cost-, net income-scale) showed a decreasing trend from 2004 to 2013. Taking SOC storage into account, the CF of maize with different functional units decreased by 38.3-44.7% compared with that excluding SOC storage. In summary, reasonable fertilizer application and increasing SOC sequestration could be some potential solutions to reduce carbon footprint of maize production in Shanxi Province.