In late spring 2006, the National Oceanic and Atmospheric Administration (NOAA) stated the precipitation forecast for Oklahoma during July and August would be "normal" rainfall.

"As we all know, 'normal' summertime conditions are typically hot and dry," says Steve Upson, horticulturist at the Noble Foundation in Ardmore, Okla. "Whether you live in the city or the country, the cost of keeping your garden and landscape watered continues to escalate."

To get the most out of irrigation dollars, Upson suggests adopting some of the following moisture management strategies.

Select drought-tolerant plants when installing or replacing plants in the landscape. Trees such as golden raintree, bald cypress, fruitless mulberry, bur oak, Osage orange, Chinese pistache and western soapberry are a few trees that tolerate dry locations. Shrubs that tolerate dry conditions include Chinese and yaupon holly, crape myrtle, juniper and nandina.

"Remember to pay close attention to watering all newly planted trees and shrubs," Upson says. "Contact the Noble Foundation Ag Helpline at (580) 223-6500 for an extensive list of drought-tolerant plants."

Schedule irrigation based on plant requirements, not calendar date. Several factors influence plant water requirements, including the age, size and type of plant material. Watering based on a particular day of the month inevitably leads to over-watering young, small-sized plants and under-watering larger, more mature plants.

"Irrigating based on need is best for the plants and reduces waste, thereby saving money," Upson says.

Base wetting depth on rooting depth. Frequent, shallow watering does not encourage deep rooting. Light sprinklings often only wet the soil to a depth of less than 1 inch. Most plant roots go much deeper. When irrigating turfgrass, wet to a depth of 6 inches. Wet vegetable garden, orchard and landscape plantings even deeper. Depending on the water intake rate of the soil and the delivery rate of the irrigation system, six or more hours might be required to achieve a deep soaking.

To avoid wasting water, match water application rate to the intake rate of the soil. As a rule, finer-textured clay soils take in water slower than coarse-textured sandy soils.

"If you experience excessive puddling and/or runoff when operating your in-ground sprinkler system, adjust the system controller to make shorter, more frequent applications. For portable hand-move sprinklers, simply reduce the flow rate," Upson says.

Use drip irrigation where possible. Drip irrigation is the water delivery system of choice for garden and landscape beds. Drip is more efficient than sprinkle because the water is applied at ground level instead of through the air, where much of it is lost to evaporation.

"Water saved is money saved," Upson says. "There also is less incidence of foliar disease with drip irrigation because the foliage remains dry."

If sprinkle irrigating, do so during the early morning hours. This allows time for foliage to dry out before nightfall. Also, wind is typically lower during the early morning hours, reducing the amount of water loss caused by evaporation and overspray.

Decreasing the rate of nitrogen fertilizer applied to turfgrass will decrease the growth rate, which in turn reduces the water use rate of the grass. Applying a slow-release nitrogen fertilizer also will reduce the growth rate of the grass. Because moisture is necessary for roots to utilize mineral nutrients, there is no need to fertilize a lawn during the summer months if it is not being irrigated.

Improve the moisture-holding capacity of garden and flowerbeds by incorporating organic materials such as compost or peat moss. Greater water-holding capacity allows for extended intervals between irrigations. Apply a mulch layer to landscape plantings and garden. Organic or plastic mulch applied at the base of the plants creates a barrier to evaporation reducing water loss from the soil. Compost-based mulches have an advantage over plastic film mulches because they serve as a slow release source of nutrients upon decomposition.

In case of water rationing, prioritize what receives irrigation. Generally speaking, ornamental plantings (flowers, shrubs and vines) are more expensive to install and replace and more prone to drought stress than warm-season lawns and should receive priority when water is in short supply.

"Don't forget about your trees," Upson adds. "Try to give them a good soaking once every two to four weeks."

For more detailed information on moisture management, refer to the publication "Efficient Use of Water in the Home Landscape and Garden" at: www.hpwd.com/Conservation/efficientuse.pdf (729k).

Steve Upson is a horticulture specialist in the Agricultural Division of the Noble Foundation.

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News Release Issued: August 1, 2006

The Samuel Roberts Noble Foundation, Inc. (www.noble.org), headquartered in Ardmore, Okla., is a nonprofit organization conducting agricultural, forage improvement and plant biology research; assisting farmers and ranchers through educational and consultative agricultural programs; and providing grants to nonprofit charitable, educational and health organizations.