There is only one reason for the application of water on turf and other planted areas – to aid in the continual vigor of the turf and plants which result in a pleasing visual scene.
But the application of water on landscaped areas is not always as easy as it may initially seem. The ultimate condition of soil in which the turf and plants grow must have the proper balance of air, water, and soil particles. When this balance is not achieved or maintained, burning or smothering may result, causing damage to the turf and plants. That is why it is important to understand a few basic principles of how your irrigation system and landscape work together.
When the installation of your irrigation system was completed, the controller of your system was programmed to deliver the amount of water a new landscape needs to properly establish itself. Two or three weeks after installation, you can begin to adjust the controller to deliver only the amount of water your landscape needs to maintain itself. Too much water is just as harmful to your landscape as too little water.
To get the most out of irrigation water, you need to constantly assess just how much water is needed and run the system to deliver proper amounts. For instance, within a given week, if Mother Nature is so kind to deliver the amount of free water to your landscape that you would normally apply through your irrigation system, do not allow your system to operate. Simply by-pass the operating times on your controller to prevent overwatering.
There are several ways, from simple to quite complex, that watering frequencies and amounts can be established. The appearance of grass can be used as a guide to when to water. Footprints that remain visible on the grass for several minutes after walking on it, loss of leaf luster, wilting appearance of shrubs and small trees, and a blue-grey appearance of the turf indicate a need for water. Irrigating shortly after these conditions are noticed will lead to rapid improvement to turf quality. If the water stress proceeds to the point where the leaves turn brown, it can take days or even weeks of irrigation to return the turf to the quality it had before it became stressed.
Soils act as a reservoir for storing and supplying water for turf use. A high percentage of turf roots are in upper 2 to 3 inches of soil; however, effective rooting and corresponding water extraction also occur at deeper soil depths. Because of better aeration, grass normally roots much deeper in sands and loams than in clay soils. Consequently, turf grown on a good, sandy loam soil does not require irrigation as frequently as that grown on a heavy clay soil. With heavy clay soils, the tendency is to overwater continuously, causing a shallow-rooted turf that is difficult to manage.
Estimating critical soil moisture amounts to use as a guide on when to irrigate can be done by probing the soil with a screwdriver, heavy wire, or similar simple probe. Usually, when a probe easily penetrates the soil to 3 to 4 inches, enough water is available to carry the grass for about a day, depending, of course, on the rate the water dissipates from the soil.
Irrigation scheduling needs to take into account whether an area is composed of heavy clay, is compacted, or is steeply sloped. Cyclic irrigation, or repeated, short applications of water throughout the day is effective to minimize runoff on slopes and heavy soils. Cyclic watering, especially with an automatic irrigation system, can be quite helpful in reducing runoff and preventing ponding. Other ways to prevent water loss is by aerating and dethatching. Aeration holes catch and hold water until it can infiltrate the soil. Breaking the thatch barrier by the use of a dethatching rake or dethatching machine will speed water movement into the soil.
If your soil is sandy, you can probably expect to water every 3 days. On clay soil, watering every other day seems to be the norm.
Look for part 2 in a few days