Center pivot irrigation systems are often favored among irrigators due to their flexibility and efficiency. Obtaining the best watering and fuel efficiency from sprinkler irrigation systems requires some adjustment and monitoring to properly establish the system. With the cost of fuel and the importance of water conservation, gauging irrigation efficiency and making adjustments to sprinkler irrigation systems as well as other irrigation practices is essential and actually not that difficult.
Efficient Irrigation Through Uniformity
Getting the most yield from crops requires that each plant receive enough water for optimal growth. The biggest challenge in proper irrigation is how to provide the proper amount of water uniformly, so that all plants get enough without wasting water. Center pivot irrigation systems must be measured to ensure all plants being irrigated receive necessary water without any fluctuations in water application. Using a variety of ways to measure water application, growers can determine if their system is irrigating properly or if adjustments are necessary.
Measuring Irrigation with Center Pivot Irrigation Systems
The most commonly used method for measuring water application uniformity with center pivot irrigation systems is the Christiansen Uniformity coefficient. This formula helps growers determine how each section of their center pivot systems is functioning and whether water distribution to the plants is uniform.
Another formula used to determine uniformity is the Heerman and Hein Uniformity coefficient. This is a complex formula that is normally determined using a data collection program that interprets input data based on water collections made while irrigators are functioning. Using both of these calculations, it is possible to pinpoint exactly which sprinklers on a center pivot irrigation system need adjustment and how much in order to provide the most uniform irrigation.
Collecting and Analyzing Irrigation Samples
Both of the above irrigation uniformity formulas require the collection of water samples from the field while the irrigation system is in use. Using a method that requires cups, rain gauges, or other catch containers set up in a straight line from the center of the pivot, the sprinkler system is run at normal speed and capacity and allowed to pass over the rain gauges. This is done to catch whatever water is delivered by the sprinkler. For the most accurate calculations, gauges should be spaced anywhere from 10 to 30 feet apart, and extended up to 150 feet beyond the last functioning sprinklers on the system. This makes it possible to collect more samples and get a better idea of the amount of water each sprinkler nozzle is delivering and the ground area that nozzle is covering.
After collecting water samples, each sample is measured for volume. The data is entered into a program that is based on the amount of water and the position along the line on the sprinkler to determine if there are areas getting more or less water than other areas. The calculations also take into account aspects such as weather conditions, where evaporation may be higher or lower, or other conditions that may affect how much water is reaching the plants - or in this case, the cups.
Using one of these two methods, crop growers should consider gauging their center pivot irrigation systems to ensure efficient irrigation results. Over or under watering are both detrimental in different ways, reducing crop yield and increasing irrigation costs. With these simple tests, it is possible to determine how efficiently sprinkler irrigation systems are performing, and whether or not setting adjustments are required to increase efficiency. Uniform irrigation is the goal in order to achieve the most optimal irrigation, accomplished with the least amount of water and fuel.