Assess all areas of your farming operation for energy efficiency to save energy and reduce costs
Contributing authors: Tom Scherer and Carl Pederson, North Dakota State University
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.
Improve Irrigation Efficiency
- 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.