Maintaining Sod Quality - Even under Drought Stress. (Tool Box)
Fender, Douglas H., Landscape & Irrigation
For a small amount of water, a turfgrass landscape offers tremendous environmental benefits. Whether we're growing from seed, installing sod or maintaining turfgrass, we can increase those benefits by using today's science to develop the most efficient irrigation programs for water conservation, especially under summer drought stress.
One important way to conserve water is to use a turfgrass species that requires little water. Turfgrass water-use is quantified by evapotranspiration (ET) rate, the loss of water from the soil through evaporation and from the plant leaf through transpiration. Typical ET rates range from 0.12 to 0.32 inches per day for cool-season turfgrasses and 0.08 to 0.20 inches per day for warm-season grasses when the soil has adequate moisture.
Environmental conditions also influence ET rate. The rate will go up with increases in temperature, solar radiation and wind and decreases in relative humidity, water availability, and soil water holding capacity, or "field capacity," associated with soil type and texture. Wilting points also vary, depending on the soil.
You can insert a simple soil probe into the ground to test for soil moisture. If the soil is wet or moist do not water. At the high-tech end, new ET-signal irrigation controllers use wireless technology to receive local weather station data for establishing irrigation schedules.
Cultural practices that reduce water use include mowing, use of plant growth regulators (PGRs), and management of irrigation quantity and frequency.
When mowing, remember that a taller cut allows a more efficient water-using plant to develop, primarily because of a deeper root system. In general, the taller the turfgrass, the better the drought tolerance.
Extensive evaluation of PGRs has shown they contribute to the development of a short, compact turfgrass with reduced ET rates and mowing requirements. These regulators include flurprimidol and mefluidide acetamide.
Dr. Bingru Huang of Rutgers University has published studies indicating that you can, in effect, "train" your grass to tolerate heat stress. Infrequent or deficit irrigation that induces mild drought stress during spring can enhance physiological hardiness to heat stress during summer.
The less frequent watering lets surface soil dry between irrigations, stimulating root growth into deeper soil profiles by promoting carbon allocation and reducing carbohydrate consumption. …