Energy balance in Iran's agronomy (1990–2006)

In this study data from 17 years (1990–2006) were collected to determine energy intensive areas and evaluate energy parameters of Iran's agronomy sector. All the direct and indirect inputs of energy for the production of 19 agricultural commodities were evaluated. The inputs and outputs were calculated by multiplying the amounts of inputs and outputs by their energy equivalents. The results indicated that total energy input increased from 32.40 GJ ha−1 in 1990 to 37.20 GJ ha−1 in 2006. At the same period, total output energy increased from 30.85 to 43.68 GJ ha−1. The results show that irrigation with 40.0% and fertilizer (28.4%) had the highest share in energy consumption. The average net energy gain was a positive value; however, about 87% of the input energy emanates from non-renewable sources of energy. The mean energy ratio was estimated to be 1.07 and showed an increasing trend during the period rising from 0.95 in 1990 to 1.17 in 2006. This indicates that increased use of inputs ha−1 in production was accompanied by a larger increase in the output levels. It can be inferred from the results that improvements in irrigation and fertilizer application can significantly affect the energy efficiency of Iranian agriculture.