Investigation of the energy efficiency for raising crops under sprinkler irrigation in a semi-arid area

Agricultural production transforms energy input into energy output in the form of harvested products. Under suitable conditions, crops produced convert so much solar energy into energy stored in plant biomass that the energy input is more than offset. The amount of energy fixed in the harvested biomass depends on the yield level and its chemical components. The objective of this study was to determine the energy efficiency for raising crops under sprinkler irrigation in a semi-arid area. The amount of irrigation water applied was 287 mm for winter wheat (Triticum aestivum), 489 mm for dry bean (Phaseolus vulgaris), and 857 mm for sugar beet (Beta vulgaris) production. The total energy consumption was calculated for winter wheat, dry bean, and sugar beet production systems including the manufacture of fertilizer seeds, plant protection substances, and machinery, and all on-farm activities. Energy output in the form of the harvested products was calculated using the calorific value of grain, bean, and beet. Total energy input was 19,267 MJ/ha for winter wheat, 21,977 MJ/ha for dry bean, and 38, 100 MJ/ha for sugar beet plant. The efficiency of energy production was computed to be 3.86, 2.37, and 7.74 MJ/MJ, respectively, for winter wheat, dry bean, and sugar beet. The calculation of the energy efficiency factor of irrigation application revealed that the amount of energy obtained through the increase in harvested products due to irrigation exceeds 4.85, 3.63, and 11.65 times the energy input through irrigation application, respectively, for winter wheat, dry bean, and sugar beet. Results of this study indicate that energy input for irrigation should be reduced to increase efficiency of energy production. In practice, energy requirement for irrigation can be reduced up to 78% by switching from sprinkler irrigation to surface irrigation. In our semi-arid area, most of the areas are suitable for this type of irrigation. In addition, drip irrigation, micro-irrigation, and other new water and energy-saving irrigation technologies should also be considered.