Turf Management in Dry Times

Author: David R. Chalmers, Turfgrass Extension Specialist, Virginia Tech

Posted April 1997

Water comprises 75 to 85% of the weight of a healthy turfgrass plant. It is essential for turf seed germination, tissue formation, transpirational cooling, food manufacturing, and nutrient absorption and transportation. Water becomes the limiting factor in grass growth when the turfgrass plant requires more water than it can absorb effectively from the soil. When water becomes limited, the plant cannot effectively cool itself through transpiration and becomes susceptible to wilting.

Turfgrass species differ in wilting tendency and long-term drought tolerance. Some species, such as bermudagrass, zoysiagrass, and tall fescue, can avoid wilting for some time because they have deep root systems. However, this advantage is lost if they are grown on shallow soil.

Under drought conditions, Kentucky bluegrass wilts and becomes off color before tall fescue, and if water remains limited, Kentucky bluegrass turns straw-colored and becomes dormant. Once water becomes available again, Kentucky bluegrass initiates new growth from the crown of each plant. This is an important consideration when choosing the type of lawn grass since once Kentucky bluegrass goes dormant, it will require carbohydrate reserves to regrow. So, one should make the commitment to either provide an adequate, on-going, watering program for Kentucky bluegrass or to let it go dormant. If one relies upon repeated infrequent irrigation, regrowth will begin before the water stress is over. Repeated dormancy/regrowth cycles can deplete stored food reserves and effectively decrease the ability of the grass to survive a drought.

Perennial rye grasses have little tolerance to dry conditions and usually do not persist well in non-irrigated areas. Fine fescues, such as creeping red fescue, chewings fescue, and hard fescue, tolerate dry periods quite well due to their low water requirements.

Water loss is greatest under conditions of high light intensity, high temperature, low atmospheric water vapor content, and windy conditions. Application of 1 inch of irrigation water per week is the standard recommendation for watering when there is insufficient rainfall. One acre-inch of water is equal to 27,154 gallons of water. Using this amount of water, especially in times when water may be restricted, requires sensitivity as to how to effectively use every drop that comes out of the sprinkler.

Efficient use of water requires an understanding of soil properties and turfgrass species requirements, as well as an efficient way to deliver water. People with lawns to maintain can employ common turfgrass management practices to water effectively. Some examples follow:

Water only to the depth of the root system, at an application rate that can infiltrate into the soil. Deep and infrequent watering maintains a healthy root system and reduces weed infestation, as opposed to light and frequent irrigation.
Water during periods of low wind and solar radiation. Night watering minimizes water evaporation, but may increase fungal diseases. Early morning (5 to 8 am) irrigation is a good compromise in this regard. Make certain water is not being wasted by landing on driveways, sidewalks, or roads.
Raise the blade on your lawn mower to increase the grass blade length, thus increasing the depth of the root system. Longer grass blades also shade the soil reducing the amount of water loss from evaporation from the soil surface.
If your species of turf is not drought tolerant, consider replacing it with one that is. There are many new varieties of tall fescue to choose from that persist well in periods of limited moisture.
Do not over-apply nitrogen fertilization. A turf that is too lush requires more water than a moderately managed lawn.
Recognize that turfgrasses grown under water stress will not perform as well as those that receive irrigation. Remember, newly installed turf requires more frequent watering than established grass.

(By David R. Chalmers, Turfgrass Extension Specialist, Virginia Tech.)

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