How Much Water Is In Snow?
This post is a more technical but important to understand turfgrass water usage.
This information is based on the research of J. B. Beard in 1973. It dealt with the total amount of water used for growth plus that lost by transpiration and evaporation from plant and soil surfaces. May or may not be related to drought resistance.
Below is a chart that indicated the Turfgrass Evapotranspiration (ET) Classification
|
RelativeET Ranking
|
mm day-1
|
Example
|
|
Very low
|
< 4.0
|
|
|
Low
|
4.0-4.9
|
Kentucky bluegrass, buffalograss
|
|
Medium-low
|
5.0-5.9
|
|
|
Medium
|
6.0-6.9
|
|
|
Medium-high
|
7.0-7.9
|
|
|
High
|
8.0-8.9
|
|
|
Very high
|
>9.0
|
Tall fescue
|
|
Turfgrass Species (Common Scientific Name)
|
ET* Rates
|
(mm day-1)
|
|
Tall Fescue (Festuca arundinacea)
|
7-13
|
2.0-3.8 inches/week
|
|
Perennial Ryegrass (Lolium perenne)
|
7-11
|
|
|
St. Augustinegrass (Stenotaphrum secundatum)
|
6-11
|
|
|
Seashore Paspalum (Paspalum vaginatum)
|
6-8
|
|
|
Bahiagrass (Paspalum notatum)
|
6-8
|
|
|
Kikuyugrass (Pennisetum clandestinum)
|
6-9
|
|
|
Creeping Bentgrass (Agrostis Palustris)
|
6-10
|
|
|
Centipedegrass (Eremochloa ophiuroides)
|
5-9
|
|
|
Bermudagrass (Cynodon spp.)
|
4-9
|
|
|
Zoysiagrass (Zoysia spp.)
|
5-8
|
|
|
Kentucky Bluegrass (Poa pratensis)
|
4-7
|
|
|
Buffalograss (Buchloe dactyloides)
|
3-6
|
0.8-2.0 inches/week
|
* ET rates when water is non-limiting; Potential Evapotranspiration
In other words, which turf can survive without water?
BEST: buffalograss, blue grama, bromegrass, wheatgrasses, bermudagrass can survive without ANY supplemental irrigation.
FAIR: Kentucky bluegrass, fine fescues, bentgrass and zoysiagrass can become dormant and survive for many (3-6) months without irrigation; some thinning will occur.
POOR: perennial ryegrass and tall fescue may survive 2-4 months without ANY irrigation, but will be severely thinned.
VERY POOR: annual bluegrass
Which factors affect drought survival?
- Condition/health of turf entering drought
- Exposure to sun, wind
- Soil type (better survival on fine-textured soils)
- Excess thatch will reduce survivability
- Varietal differences
- Traffic will reduce ability to survive prolonged drought
Source: Tony Koski’s Presentation at the ProGreen Expo on January 24, 2008. Mr. Koski is a Extension Turf Specialist at Colorado State University.
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