Parts of Jenkins County finally received some welcome rain this past week. However, there are still sections of the county that are far behind schedule. Whether you are watering 500 acres of cotton or a 5,000 square foot lawn, proper irrigation is the key to maintaining a healthy lawn. Research has proven that a healthy beautiful lawn results in people being in a better mood and living a more healthy life!

Water use, also called evapotranspiration, is the total amount of water needed for turfgrass growth, plus the quantity evaporated from the soil surface. Turfgrass water use rates depend on soil type, grass species and/ or cultivar, management level and atmospheric conditions. Atmospheric water loss increases as temperature and solar radiation increase. Water loss also increases with increasing winds up to four mph, and as humidity decreases. In general, most turfgrasses grown in Georgia use about one inch of water per week to maintain normal growth and color.

Sandy or coarse-textured soils absorb water much faster than clay or fine-textured soils. However, sandy soils retain less water and therefore need water more often than clay soils. Since clay soils absorb water slowly, irrigation rates should be slow and extended over a longer period.

Most turfgrasses grown in Georgia need about one inch of water per week during the summer to remain green and growing. (Table 1). Some turfgrasses, like bemudagrass develop a deep root system to obtain the needed water. But other turfgrasses, like Zoysiagrass, have shallow root system and need weekly irrigation to remain green.

Table 1. provides summer water use rates/drought resistance rankings and irrigation frequency for turfgrass species in Georgia. The water use rate and drought resistance ranking is based on the amount of water used through evapotranspiration and the relative rate the turf begins to show drought stress. The days between irrigations are for mid-summer, high evaporative conditions. The differences between grasses reflect differences in daily evapotranspiration, root depth, viability, and quantity, and turfgrass drought resistance. Under nonirrigated conditions, the relative drought tolerance, or ability to survive without water, becomes more important. Generally, turfgrasses with high water use rates tend to have low drought tolerance.

During moisture stress periods, raising the mowing height and mowing often enough so that no more than one-third of the leaf tissue is removed can increase turf survival. Raising the mowing height helps the grass maintain a deeper root system which helps it find more water. Irrigate at the first sign of moisture stress. When a turfgrass is under moisture stress it becomes dull and bluish green, the leaf blades fold or roll and footprints remain after walking over the area. If dry conditions continue, the grass wilts. Begin irrigation on that portion of the lawn which first exhibits these signs. Irrigate between sundown and sunrise when the wind and temperatures are lower. Apply enough water to soak the soil to a depth of six to eight inches. This is usually equivalent to about one inch of water or 600 gallons per 1000 square feet but will vary with different soils. A sand would require 0.5 inch of water while a clay would need 1.75 inches to wet the soil to an eight-inch depth.

Most sprinklers apply about one-fourth inch of water per hour and thus must be on in one spot for up to four hours to apply one inch of water.
Table 1. Summer water use rates/drought resistance rankings and irrigation frequency of turfgrasses used in
Georgia.
  Common name           Water Used/Drought Resistance                     Days Between Irrigation
  Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass Bermudagrass                                     1                                                                     14 - 21
  St. St. St. Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass Augustinegrass                               2                                                                     12 - 18
  Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass Centipedegrass                                   3                                                                       8 - 12
  Tall Tall Tall Tall Fescue Fescue Fescue Fescue Fescue Fescue                                         4                                                                       6 - 8
  Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass Zoysiagrass                                       5                                                                       5 - 7