evaluation of energy use in wheat production in gorgan

concerns related to conservation of fossil fuels and greenhouse gas emission has increased energy balance studies in crop production systems. in the present study, six wheat (triticum aestivum) fields were selected from east and west of gorgan, golestan province, iran. during three consecutive growing seasons, data were gathered on energy use in all production practices. then, all the energy uses were classified into eight categories, i.e. seed bed preparation, plant protection, weed control, irrigation, harvesting and transportation to the storage places. results indicated that average input energy was 15579 mj ha-1. maximum was 21179 mj ha-1 and maximum output energy was 120531 mj ha-1. the greatest contribution to input energy belonged to energy from chemical fertilizers (45.8%), especially nitrogen fertilizers (38.3%), and then energy from fuels (22.5%). average output-input energy ratio was 6.3 with a minimum of 3.7 and maximum of 9.3. average specific energy was 4 gj t-1 and average energy utilization was 0.3 t gj-1. it was concluded that implementation of desired changes can result in reduction of energy use and hence their environmental impacts.