Efficient irrigation combines two factors: managing your water to apply the right amount at the right time, and installing and maintaining an energy-efficient irrigation system. Good water management means matching the supply of irrigation water with your crop’s demand, since the less water you waste, the less electricity you’ll use for pumping. Good equipment design and maintenance means that your system should move the most water possible for each kilowatt-hour of electricity you use. These principles are the same whether you’re caring for a small lawn or a large commercial crop.
To improve your water management, you should first learn about your crop and its root system. Efficient irrigation will saturate the root zone, without causing surface runoff or allowing water to percolate below the root zone. Timing is vital to efficient irrigation, too. When you learn to judge the amount of water in the soil, and you understand your crop’s tolerance to soil-water depletion, you’ll know how much water to apply and when. These factors combined make up your application efficiency: the percent of applied water that ends up in the root zone. For most crops, flood irrigation has the lowest application efficiency, and sprinklers have the highest.
Your equipment is the other big factor in determining irrigation cost. The most common causes of high irrigation energy costs are a lack of system maintenance, improperly chosen valves or fittings, and pumps that are poorly matched to the irrigation system they serve. System maintenance problems include water leaks, missing sprinklers, worn pump bearings, and plugged sediment screens. Any of these can increase system pressure, reduce water flow, and increase electricity costs significantly.
Contact your Cooperative Extension Agent or Natural Resource Conservation Service for more information. The National Center for Appropriate Technology (NCAT) produces the Montana Irrigator’s Pocket Guide, an excellent irrigation information resource and the main information source for this article. For a copy of the Montana Irrigator’s Pocket Guide, call NCAT at 800-346-9140.