Life cycle Assessment Of Greenhouse Gas Emissions From Agriculture

The life cycle assessment (LCA) of this multi-institutional project concentrated on determining the greenhouse gas emissions involved in pre-farm, on-farm and post-farm activities involved in the use of maize for the manufacture of corn chips. When the emissions are all expressed in terms of CO2 equivalents (CO2-e), pre-farm emissions comprise about 6 % of the life cycle emissions, on-farm activities comprise about 36%, and post-farm activities account for about 58 % of life cycle greenhouse gas emissions. We have used one 400 g packet of corn chips delivered to retail as the functional unit for the study. The single largest source of greenhouse emissions is the emission of nitrous oxide on the farm as a result of application of fertiliser. This accounts for 0.126 kg CO2-e per packet of corn chips. The next largest source is the electricity used during the manufacture of the corn chips (0.086 kg CO2-e per packet). The oil for frying the corn chips is the third largest source of greenhouse gas emissions (0.048 kg CO2-e per packet). The greenhouse gas emissions from fertiliser application are primarily nitrous oxide (N2O), which has a global warming potential of 310 kg CO2-e/kg N2O. In typical irrigated farm systems, these emissions, when converted to CO2-e, are almost three times more than the greenhouse gas emissions that result from energy used to pump water. However, pumping irrigation water from deep bores currently produces greenhouse gas emissions that are almost three times those from irrigation using surface waters. Greenhouse gas emissions from the use of tractors on typical farms are about one-third of the emissions from pumping water. The pre-farm and on-farm operations add $0.4 value per kg of CO2--e greenhouse gas emitted. The post-farm processing adds $2 value per kg of CO2-e greenhouse gas emitted