Sustainability of wheat and maize production in the warm climate of southwestern Iran: An emergy analysis.

Jahrom is one of the warm grain production areas in southwestern Iran, and the winter wheat-summer maize double-cropping system dominates the region. The ecological sustainability and environmental behavior of these two annual farming systems in the region need critical attention. In the present paper, emergy evaluation was introduced to explore the impacts of the wheat and maize cropping systems on the environment. In the emergy analysis, renewable and non-renewable inputs besides purchased fuel, goods, labor and services were considered. 193 farmers were chosen for the study using simple random sampling without replacement. The results revealed that the unit emergy value of wheat and maize were 4.05E+05 sej/J and 4.23E+08sej/J, respectively. The environmental loading ratio of maize was much higher than that of wheat cropping, i.e. 570 vs. 115. The investment ratio of wheat was higher than that of maize, indicating that wheat is more dependent on the purchased materials than "free indigenous" emergy inputs. Nevertheless, the analyses of different scenarios indicated that unit emergy value and all the sustainability ratios of the systems can be enhanced by around 20–55% via using appropriate water, nutrient, and agronomic management measures. It is recommended that the maize production should be continued with much more care, especially on the nitrogen utilization and water consumption, compared to the wheat production in this warm area of the country. [ABSTRACT FROM AUTHOR]