Photo Credit: © Can Stock Photo Inc. / welcomia
People often talk about balance—a balanced diet, balance between work and home, and balancing checkbooks for some of us Baby Boomers, who do things “old school.” Similarly, when irrigating landscapes—especially during times of drought like some people are experiencing in the West—there is talk about balancing water applications. Applying the right amount of water to keep plants alive but not too much to cause drainage or excessive water loss is a challenge all irrigators face. For example, bermudagrass in Arizona thrives in the summer at high temperatures well above 100 F on almost a daily basis. To make turf healthy, safe to use, and aesthetically pleasing, it must be irrigated regularly and adequately. But how much is enough, and how much is too much? The Arizona Meteorological Network, consisting of over 20 weather stations, collects daily data for temperature, wind speed, solar radiation, and other climate parameters to enable calculating turf water use. Visit http://ag.arizona.edu/azmet/az-data.htm and click the tab for turf to see a link for turfgrass water use in Phoenix, Tucson, and northern Arizona. Check the Web to see if a similar service is offered in other states. Turfgrass, however, is just one type of plant in park landscapes, so what about trees, shrubs, flower gardens, etc.? How does one ensure that various types of plants are adequately watered?
Group Plants
One approach is to categorize different plants into hydrozones by water-use requirements and frequency of water applications. For example, most trees require less frequent and deep irrigation to thoroughly wet the soil around the deeper extensive roots. Shrubs, on the other hand, may require more frequent irrigation and usually less water per irrigation. Meanwhile, flowers and bedding plants require more frequent and shallow irrigation on nearly a daily basis for a comparatively short duration. This method has been used for years in home landscaping (Figure 1) but is more difficult to apply when dealing with larger areas found in parks. However, the concept is the same: The logistics of adapting a current irrigation system to address the zones may be the greatest challenge.
Reality Versus Theory
Splitting landscapes into hydrozones isn’t as easy as it seems, especially for existing landscapes. The balance here is cost. The technology exists to control multiple hydrozones with only one irrigation controller (up to 48 valves or more). Also, the wide variety of emitters from drippers to bubblers to microsprays—some pressure-compensating, others with adjustable flow—can be used on almost any type of plant. The challenge is finding the money to run pipes and controller wires under sidewalks and around playgrounds, connecting thousands of feet of poly tubing, and installing multiple-valve boxes. It doesn’t take too long before more money is being spent to save water than the cost of paying for the water. Many of these systems pay for themselves over the years, but the initial layout of cash is often hard to find.