Irrigation efficiency can secure profits amid drought
It’s tempting to think that a Band-Aid approach to irrigation maintenance can save you time and money. But the best way to keep your system in good shape is to examine it closely from the ground up. By doing so, farmers still hurting from the drought can improve application efficiency and maximize profitability, says Stephen Smith, a Colorado irrigation engineer.
One option is irrigation scheduling. Soil moisture monitors measure water activity in the effective root zone. By tracking this factor in conjunction with weather predictions, you can decide whether to irrigate now or wait for moisture. Delaying irrigation can save pumping costs and labor while fully using available precipitation, Smith says.
In addition to performing efficiently, it is imperative that irrigation systems provide uniform applications of water, says Jay Robbins of Robbins Association/Irrigation-Mart, Inc., Ruston, La. Non-uniform application can lead to water stress, which can affect crop vitality, growth, yield and quality and cause increased disease pressure. All of these factors affect the bottom line.
It all adds up. Many farmers use a center-pivot system with a nozzle that is not functioning properly or provides uneven distribution, says Dan Rogers of Kansas State University Extension. The nozzle could be replaced for $20 but often goes unnoticed or is ignored.
You might irrigate a corn field 10 times a year under the assumption that all of the land is getting an even 1" of water each time, when in fact 10 of your acres are getting only 8⁄10". During the year, 2" of water is lost. Assuming a typical yield loss of 15 bu. per acre per inch, that’s $210 in revenue lost.
Remote-control valves and automation can be helpful, Smith says. Valves are available for many pressurized irrigation systems and can be programmed to flow water on a weekly schedule. Alternatively, a device can be programmed to prevent a system from flowing water when rainfall reaches a specified level, saving thousands of dollars annually.
Robbins recommends best irrigation practices as a starting point for cutting expenses. Regular equipment maintenance can catch other problems, he says. Farmers who use center pivots, for example, should check joints for water leaks and look for worn or broken nozzles and sprinkler heads. Those who are concerned about water quality should flush their system routinely. Monitoring pressure and flow rates to identify leaks, plugging or a combination of the two is also important.
Farmers without an on-site weather station to help manage their system can take advantage of weather station networks operated by irrigation or conservation districts, Smith says.
Rogers advises using both soil moisture monitors and weather-based irrigation schedulers to get the best picture of field activity. If the information provided by these devices doesn’t match up, troubleshoot until it does. Tillage systems and crop rotation should also be considered.
Farmers who leave their soil relatively bare will need a different sprinkler package than those who have high-residue fields, which capture more water upon application, Rogers says. Use the smallest wetted-diameter nozzles to avoid creating runoff.
Farmers should tailor their irrigation efficiency practices to the requirements of the lands and crops in their region, Robbins says. "During times of drought, it is easy to focus on a single facet, rather than the entire picture," he says. "But what we really need is a more permanent solution to improving overall farm efficiencies."
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