Assessment the effect of wheat farm sizes on energy consumption and CO2 emission

High population growth and providing the food for this population have increased the amount of energy consumption in agricultural production systems. One of the most important issues for high energy consumption in recent century is the global warming where greenhouse gas (GHG) emission plays an important role. This study evaluated the energy balance between the input and output and the amount of GHG emission per unit area of wheat production in Iran. The total energy input and output were calculated as 31.5 and 44.6 GJ ha(-1), respectively, where the highest energy consumer was chemical fertilizer with share of 64% of total energy. Total GHG emission was 1118.94 kgCO(2eq) ha(-1) in which chemical fertilizer and diesel fuel had the highest contributions. The results of regression analysis indicated that use of 10 MJ in forms of direct, indirect, renewable, and nonrenewable energy leads to 3.0, 0.4, 2.8, and 0.6 kg ha(-1) growth in wheat yield, respectively. The results of farm size analysis indicated that very large farms have better energy ratio and less GHG emission in comparison with other farm size levels due to better management. The results of this study indicated a list of choices which are available to reduce energy use and GHG emission in wheat production. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4800207]