Energy balance and sensitivity analysis of inputs for forage maize production in Iran

ABSTRACT: The purpose of this study was to determine the amount of input–output energy for forage maize production in Zanjan province, Iran. Also the sensitivity of energy inputs on yield was analyzed using the marginal physical productivity (MPP) technique and partial regression coefficients on yield. The results showed total energy inputs were 77589.84MJ ha-1, and accounted for 38.31% of electricity 29.54% of diesel fuel energy. Energy ratio and energy productivity were 1.63 and 0.79 kg MJ-1 respectively. About 69% of the total energy inputs were direct and 31% indirect. The rate of renewable and non-renewable energies was determined as 10.27% and 89.73% of total energy input, respectively. The results of econometric model estimation of maize production showed that elasticity coefficients of human labour, machinery, chemical fertilizers, farmyard manure and seed energies were found to be statistically significant. Sensitivity analysis of inputs indicates that the MPP of machinery energy was biggest (9.68). It was concluded that additional use of machinery, and increasing mechanization level, would result more yield in the area.