Energy analysis and life cycle assessment of wheat production in Iran

This study was done to evaluate the energy balance between the inputs and output per unit area and to examine the effect of different farm sizes on total energy inputs and output of wheat production in Esfahan province of Iran. For this purpose data were collected by using a face-to-face questionnaire. The total energy input and output are calculated as 31.5 and 44.6 GJ ha-1, respectively. The highest energy consumer was chemical fertilizer and followed by diesel fuel and seed energy with share of 64, 14 and 8%, respectively. Total green house gas emission was 756.11 kgCO2eq ha-1 where chemical fertilizer and diesel fuel had the highest contribution. The energy ratio, energy productivity and net energy values are 1.49, 9.82 kg MJ-1 and 13.1 GJ ha-1, respectively. The forms of direct, indirect, renewable and non-renewable energies of wheat production are calculated as 6.5, 25, 5.3 and 26.2 GJ ha-1 at 21, 79, 17 and 83% of the total energy input, respectively. The results of regression analysis which is applied to find the relationship between energy inputs and wheat yield indicate the significant effect of water for irrigation, seed, chemical fertilizer and machinery energy input on wheat yield. It is concluded 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 show very large farms have better energy use efficiency due to better energy management.   Keywords: Energy balance, life cycle assessment, green house gases (GHG) emission, sensitivity analysis, farm size, wheat, Iran.