Are we watering efficiently?
Master gardeners are researching irrigation in our area
July 21, 2005
Victoria County Master Gardener
As president of the Victoria County Master Gardener Association, I have emphasized this year the importance of the efficient use of water in practice and study.
Sharing reliable information and sustainable research are
our best means to educate on this subject. The master gardeners are undertaking
a several-year landscape irrigation monitoring project at
Water applied will be metered so we can determine the required amount of water needed by the plants to survive and maintain a good appearance. The collected data will later be used to develop a watering formula. This data will be shared with our readers and fellow researchers.
Many of you have read frequent articles in the Victoria
Advocate about the supply of water to the
There are three major sources of water supply for the
The Advocate published an article dated June 7, 2005,
titled, "Communities to Benefit Soon from New Water Source." This
article describes an $82 million project by the Guadalupe Blanco River
Authority (GBRA) to supply treated water to communities along with their golf
courses west of
The Edwards Aquifer, the other major supplier for the
The Texas Legislature has recently adjusted requirements for
An additional drain on
Now for the serious questions: "What are you doing to
conserve landscape water usage?" What are the chances that during the
summer months our water supply will be limited to household use and external
watering restricted to a hand-held hose? This event happened several years ago
During the summer months, about half of our water supply is
used on the landscape. So if the city of
It is not a question of "if" but "when"
our landscape water supply will be limited. So an adequate water supply to
The rule for efficient turfgrass watering is simple: Water the target area to dampen the top 6 inches of soil without letting the water run to non-targeted areas. For a sandy soil, this is about 1 inch of water, and for clay this is about 1 1/2 inches of water. Repeat watering only when plants show signs of distress.
A healthy plant is one with a deep strong root system, developed via watering so that the soil is moist 6 inches deep before you quit watering. Repeat this watering only when the plant is beginning to show stress. This includes all plants in the ground whether it is turf or a zinnia.
Efficiency is obtained if this is done without any water running off of your targeted site. For turf, this may require running several 15-minute cycles. Increased cycles prevent the water from going into the street. Thus you may only need to water your turf once per week or less.
Cutting your turf at 3 inches or higher will encourage deeper root growth and the longer top will shade the soil and reduce evaporation.
Shrubs and large trees should be watered to a soil depth of 12-16 inches in a 6-foot-wide band. The center of the band is the drip line for the tree. This deep watering is only required when the tree is showing signs of distress such as curling leaves or dropping leaves.
Some methods for water distribution are more efficient than others. The most inefficient method of distributing water is in the middle of a windy, hot day using an oscillating overhead sprinkler. Much of the water will evaporate before reaching the ground. A drip irrigation system is most efficient, especially if it is covered with a thick layer of mulch.
Underground sprinkler systems should be checked frequently. Unfortunately, sprinkler heads frequently come off or get adjusted by the lawnmower so they are watering the street rather than the turf. If it rains sufficiently, the system cycles should be adjusted to account for the rainwater. Thus, watering efficiency depends on how the system is maintained and knowledge of the electronic controls.
A quick or light watering every day is unhealthy for the plants and encourages shallow roots. When watering with an open-ended hose, the rate of flow should be reduced and the water should penetrate the soil to the 6-inch depth. Don't just spray water wetting the soil and the leaves of plants. This doesn't soak deep enough and causes fungal diseases.
In watering by laying a hose down for a slow soaking, set a kitchen timer as a reminder so you don't water beyond your target area. Use your fingers or a probe to measure how deep you've watered.
Watch The Gardeners' Dirt for future articles on watering.