Head-to-head with Mother Nature
Natural disasters happen every year, and this year is no exception. Typically the West gets the press with its annual brush and forest fires, mudslides and earthquakes. The East Coast has its bouts with hurricanes, and the Plains states tussle with tornadoes every spring and summer. This year it's the North Central states' turn as flooding wreaks havoc. The power of natural forces is ominous, and it seems there is little you can do to control these forces. Your only course of action is to be prepared for the worst, should disaster strike. Drought is one force of nature we seem to have slight control over. By selecting drought-resistant plants and managing soil water with your irrigation system, you can combat drought and sometimes win.
Every year, irrigation manufacturers introduce system refinements that make your irrigation tasks easier. New sprinkler designs and improved computer-based control systems are examples. Coupled with a better understanding of how to use these systems on specific sites, you have more resources for dealing with water deficits. Considering these points, this issue focuses on irrigation.
Pan soils create some interesting irrigation challenges to turf managers. Natural cementing action of some soils, such as Caliche types, create pan layers that are impervious to water movement. These pan layers act as a bathtub, and any water you apply fills up the tub. Because plant roots can't survive for long in water-logged, anaerobic conditions, they die from lack of oxygen.
Consequently, you can't rely on standard operating procedures when you irrigate these soils. By closely matching your irrigation rate to your evapotranspiration rate, you can avoid the bathtub effect. Find out more about the intricacies of irrigating layered soils from Dr. David Kopec, turfgrass extension specialist at the University of Arizona (page 14).
To effectively deal with delicate irrigation situations, such as layered soils, you must ensure that your irrigation system is performing at tip-top efficiency. Irrigation uniformity is critical for you to achieve peak performance. One way to test uniformity is to perform a catch-can test. Tim Wilson and David Zoldoske show you how to perform the test and interpret the results in "How To: Evaluate sprinkler irrigation uniformity" (page 33).
Sprinkler-head design has a strong influence on the uniformity of irrigation evidenced by catch-can tests. Because of differing patterns of water application among sprinkler head designs, it is important that you know the particular distribution rate curve (DRC) for each sprinkler-head design you use so that you can adequately space heads for best uniformity. Some manufacturers will supply you with the these DRCs, and you also can obtain them from the Center for Irrigation Technology in Fresno, Calif. Learn more about DRCs and the sprinkler heads that are available in "What's New" (page 38).
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