Irrigation Energy is part of a series of Efficiency Checklists and Topics that can help you to assess all areas of your farming operation for energy efficiency and find ideas to save energy and reduce costs. For links to other articles in the Efficiency Checklists and Topics series, see Additional Resources at the end of this article.
Irrigation Energy Efficiency
Agricultural irrigation is an energy intensive operation. Pressurized irrigation systems, especially center pivot sprinkler installations, use a high flow rate pump and require a large electric motor or engine. The major causes of increased energy use are associated with pipeline leaks, engine and pump efficiency and well maintenance. Poor uniformity of water application can also affect energy use by increasing pumping time. On center pivot systems, the major causes of poor water application uniformity are sprinkler nozzles that are worn or sized wrong, missing sprinkler heads, and leaking boots. Using a consistent method of irrigation scheduling during the growing season can optimize water application.
Questions to ask
- Do the sprinkler nozzles on your center pivot provide a uniform application pattern along the full length? Have the sprinkler heads and nozzles been on the pivot more than seven years? Have you checked nozzle sizes on the center pivot to make sure they match the nozzle sizes listed in the sprinkler package printout from your dealer?
- Do you annually check for pipeline leaks, missing nozzles, and nozzles that are not rotating properly?
- If you have an engine powering the pump, do you change the oil and filter according to manufacturer recommendations? Do the pump and motor or engine receive regular annual maintenance?
- Do you record the static and pumping water levels in the well every year?
- If you have iron in the irrigation water, do you chlorinate the well each year?
- If you have an electric motor, can you subscribe to controlled electric rates (off-peak) from your electric supplier?
Facts and Actions: Irrigation
- Use of a consistent method of irrigation scheduling can often reduce energy use by 7 to 30%. Using an ET-based irrigation scheduling system can ensure you are not under or overwatering the crop.
- The average life expectancy of a sprinkler head is about seven to 10 years. The diameter of the sprinkler head nozzle is very important for uniform water application; and the nozzle diameter can grow with use, especially if there is sand or grit in the water. Poor application uniformity increases water pumping time and therefore energy use. Replace broken sprinkler heads as soon as possible. Do a “can test” to check the uniformity of the application pattern. Repair all leaks on the center pivot as soon as you notice them.
- Buried pipelines rarely leak, unless they were not pumped out before winter. However, above ground pipelines frequently have worn gaskets and up to 30% of the water can be lost before it gets to the discharge point. Replace leaking gaskets and plug any holes in the pipeline.
- The drawdown in a well increases if the screen becomes plugged. Increased drawdown greatly increases pumping costs. Screens become plugged due to mineral incrustation or from iron bacteria. Mineral incrustation occurs over time. By measuring the static and pumping water levels each year, the increase in drawdown can be measured and corrective action taken. Iron in the water usually means iron bacteria are present in the well. Annual chlorination will control the iron bacteria.
- Maintain pumps regularly, including proper greasing and filling oil reservoirs every year. Adjust packing glands and adjusting impellers on deep well turbines regularly for efficient pump operation. Replace diesel engines with electric motors – that can have significant cost savings, depending on the price difference.
- Most electric suppliers offer controlled (off-peak) electric rates for irrigation pumping systems. Using off-peak power rates can reduce pumping costs significantly when compared to regular power rates. However, off-peak rates should not be used with high-value crops like potatoes and onions. Talk with your electric supplier to determine if off-peak power rates would work for your operation. Typically, off-peak use will require a well capacity of 1400 gpm on a 130-acre center pivot or the capacity to irrigate in 100 hours per week. It works best for deep-rooted crops like corn or soybeans.
Tools and Guides for Efficient Irrigation
- Irrigation Scheduling Checkbook Method. University of Minnesota Extension. Tutorial on how to do irrigation scheduling.
NRCS Irrigation Page Natural Resource Conservation Service. Includes information on water management models and irrigation components.
Irrigation Testing University of Wisconsin, Madison. Various resources include uniformity testing procedure and spreadsheet for calculating Coefficient of Uniformity.
Irrigation Practices, Scheduling
Scheduling Irrigation details Water Balance Method, Soil Moisture Measuring, Computer Models, and Charting. University of Georgia Cooperative Extension, Bulletin 974, 2009.
The UGA EASY (Evaporation-based Accumulator for Sprinkler-enhanced Yield) Pan Irrigation Scheduler is designed to provide in-field monitoring of crop water needs in humid areas for a fraction of the management time and cost associated with other irrigation scheduling methods; based on the direct relationship between pan evaporation and soil water removal. University of Georgia Cooperative Extension, Bulletin 1201, 2009.
Renewable Power Sources for Irrigation
Maintaining Electric Motors Used for Irrigation Utah State University Cooperative Extension. This fact sheet describes factors that affect electric motor performance and service life and describes procedures for controlling internal motor heat.
Maintenance of Wheelmove Irrigation Systems Utah State University Cooperative Extension. This bulletin describes regular maintenance activities including pre-operational procedures, a schedule of regular maintenance, and guidelines for winter storage, that will maximize the life of wheelmove systems and keep irrigation efficiency at design levels.
Regional Irrigation Guides
Irrigation in the Pacific Northwest - Scheduling Aids and Tools. Resources provided by Washington State University Extension, Oregon State University Extension, and University of Idaho Extension. Includes a variety of practical and useful tools referenced here depending on what works best for your particular skills, operation, habits, and preferred methods of doing business.
Irrigation Scheduling Tools. Michigan State University Extension and Purdue University. Four different checkbook irrigation scheduling tools that will adapt to irrigation in the Michiana area.
Irrigation Information by Crop
Efficiency Checklist and Topics:
Contributors to this Article
This publication was adapted from the Farmstead Energy Audit, North Dakota State University Extension.