11
Turfgrass Water Requirements andFactors Affecting Water Usage
Bingru Huang
Introduction
Turfgrasses, like other agronomic, horticultural, and landscape vegetation, requires water for
growth and survival. Without adequate water, turfgrass becomes brown, desiccated, and may
die in severe instances. Loss of ground cover by turfgrass can have significant negative impacts
on the aesthetics and functionality of our environment because healthy turfgrass provides
many important benefits (see Section 2). Therefore, irrigation is desirable to maintain thefunctional benefits of healthy, actively growing turfgrass in areas where rainfall cannot meet thewater demand of plants. As water availability is becoming increasingly limited and more costly,water conservation in turfgrass culture has become extremely important.
Water use of turfgrasses is evaluated based on the total amount of water required for growth
and transpiration (water loss from the leaf ) plus the amount of water lost from the soil surface(evaporation). Transpirational water consumption accounts for over 90% of the total amount ofwater transported into the plants, with 1 to 3% actually used for metabolic processes (Beard
1973; Hopkins 1999).Water usage rates vary with species and cultivars and are affected by many
external factors, especially environmental conditions. This article reviews the water-use
characteristics of different turfgrass species and examines environmental factors affecting
turfgrass water use.
The amount of water used under deficit irrigation may be calculated based on the actual
evapotranspiration (ET) rate. One of the simplest and oldest methods to estimate ET is tomeasure the evaporation from a large standardized pan. Actual ET may be measured moreaccurately using weighing lysimeters. More recently, researchers have developed mathematicalmodels (or modified Penman equations) to estimate potential evapotranspiration (PET) using
climatic data of solar radiation, wind speed, relative humidity, and temperature. PET values
represent a nonlimiting plant water status and an extended cover of short, green vegetation
over the soil surface. Reference ET is a starting point for estimating irrigation needed forturfgrass areas by multiplying with the crop coefficient (Kc). The Kc for turfgrass depends on
the type of grass (warm- or cool-season), cutting height, and desired turfgrass quality.

193

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Water Use Characteristics of Cool-Season and WarmSeason Turfgrass Species
Turfgrasses are classified into two groups based on their climatic adaptation: cool-season andwarm-season. Cool-season grasses mainly grow in temperate and subarctic climates, whereas
warm-season grasses are adapted to tropical and subtropical areas (see U.S. climatic regions in
Section 5). These two groups of turfgrass species have different water requirements (Table 11.1)
and vary in water-use characteristics. Most cool-season grasses generally are higher water users
than warm-season grasses. Typical ET rates range from 3 to 8 millimeters (mm) per day for coolseason grasses and from 2 to 5 mm per day for warm-season grasses (Beard 1994). Declining
soil moisture levels will progressively lower the water-use rate by up to 80% (Figure 11.1). In
addition, the comparative water-use rankings for different species and cultivars may change
across different climatic conditions and cultural regimes, and also depends on individual species
and cultivar adaptation.
Table 11.1. The relative maximum evapotranspiration rates of 24 turfgrass species(Modified from Beard and Beard 2004)
Relative ranking

ET rate (mm d-1)aVery low<6*American buffalograss

Low

6

– 7

*Hybrid bermudagrass
Centipedegrass*Dactylon bermudagrass*Zoysiagrass

Moderate

7– 8.5

Hard fescue
Chewing fescue
Creeping red fescue
Bahiagrass
Seashore paspalum
St. AugustinegrassHigh

8.5 – 10Perennial ryegrass
Kikuyugrass>10

Tall fescue
Creeping bentgrass
Annual bluegrass*Kentucky bluegrass
Rough bluegrass
Annual ryegrass

Very highaTurfgrass speciesb

The ranges of ET are based on the most widely used cultivars of each species when grown in theirrespective climatic regions of adaptation and preferred culture regimes.
b
Asterisk (*) indicates cultivars within these species may vary significantly.

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Devitt and Morristhreatens to derail one of the key engines of the national economy: suburban sprawl. Despite
its negative image, sprawl is efficient and reflects consumer preference. In a nation where somuch developable land remains, sprawl is hardly the environmental threat it is made out to be.
The real threat is that the nation might adopt policies that halt development and frustrate themillions of people who seek their share of the suburban dream.”
Such a dream must be in balance with nature when it comes to the design and maintenanceof living spaces and landscapes. John Lyle (1993) argues, “For thousands of years, cities haveexisted apart from nature. They rush the water falling upon their roofs and streets as rain out
through concrete pipes and channels into the nearest bay or river and at the same time, bringwater in from distant landscapes through similar concrete channels.”

Urban Landscapes
Urban landscapes can provide beauty, decrease runoff from storm events, provide cooling, andremove environmental pollutants, to name just a few good reasons they are valuable.
Unfortunately, urban landscapes also can require significant amounts of water, and this water
often is applied inappropriately. In some regions of the United States, water issues are not as
critical as in other regions. For example, the Colorado River Basin is currently in an extended 5year hydrologic drought. During the twentieth century, at least six major droughts impacted
North America. Unfortunately, it is difficult to predict when droughts may occur, where they
may occur, and for how long they may last. It is essential that communities develop andimplement sustainable water management plans. Even the best-laid plans, however, will beseverely tested by unpredictable growth in populations. In times of drought whenmunicipalities look to other sectors of society for additional water, it is essential they first
demonstrate good stewardship of the water they use. The focus on water conservation
programs for urban landscapes in many communities is appropriate and can lead to significant
water savings.
Urban landscapes vary not only in size, composition, functionality, microenvironments, andedaphic factors, but also in the cultural management practices imposed. As such, the amountof water applied and the potential to conserve water varies with each landscape setting. But
it is clearly the species, size, and number of plants (density) used in a landscape that drive its
water requirement. Irrigations must satisfy transpiration and evaporation losses, irrigation
inefficiencies, and any leaching requirements, which in turn dictate the total amount needed.
Except under extreme drought conditions, the goal of conservation efforts in urban landscapes
is to apply water more closely in parallel with landscape requirements while meeting the quality
expectations of the end user.
Because of water restrictions, regulations, and pricing, landscape water managers in thesouthwestern United States (whether they are homeowners or professionals) have begun theprocess of decreasing total irrigation amounts, improving irrigation systems, and redesigning

11
Turfgrass Water Requirements andFactors Affecting Water Usage
Bingru Huang
Introduction
Turfgrasses, like other agronomic, horticultural, and landscape vegetation, requires water for
growth and survival. Without adequate water, turfgrass becomes brown, desiccated, and may
die in severe instances. Loss of ground cover by turfgrass can have significant negative impacts
on the aesthetics and functionality of our environment because healthy turfgrass provides
many important benefits (see Section 2). Therefore, irrigation is desirable to maintain thefunctional benefits of healthy, actively growing turfgrass in areas where rainfall cannot meet thewater demand of plants. As water availability is becoming increasingly limited and more costly,water conservation in turfgrass culture has become extremely important.
Water use of turfgrasses is evaluated based on the total amount of water required for growth
and transpiration (water loss from the leaf ) plus the amount of water lost from the soil surface(evaporation). Transpirational water consumption accounts for over 90% of the total amount ofwater transported into the plants, with 1 to 3% actually used for metabolic processes (Beard
1973; Hopkins 1999).Water usage rates vary with species and cultivars and are affected by many
external factors, especially environmental conditions. This article reviews the water-use
characteristics of different turfgrass species and examines environmental factors affecting
turfgrass water use.
The amount of water used under deficit irrigation may be calculated based on the actual
evapotranspiration (ET) rate. One of the simplest and oldest methods to estimate ET is tomeasure the evaporation from a large standardized pan. Actual ET may be measured moreaccurately using weighing lysimeters. More recently, researchers have developed mathematicalmodels (or modified Penman equations) to estimate potential evapotranspiration (PET) using
climatic data of solar radiation, wind speed, relative humidity, and temperature. PET values
represent a nonlimiting plant water status and an extended cover of short, green vegetation
over the soil surface. Reference ET is a starting point for estimating irrigation needed forturfgrass areas by multiplying with the crop coefficient (Kc). The Kc for turfgrass depends on
the type of grass (warm- or cool-season), cutting height, and desired turfgrass quality.

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Figure 11.1. Evapotranspiration rate of creeping bentgrass (cv. Penncross) irrigated once
per week (1x), twice per week (2x), and three times per week (3x). The test was performed
in turfgrass grown in loamy soil and mowed at 3/8 inch height in field plots at the Rutgers
University Turfgrass Research Farm, North Brunswick, New Jersey.

Cool-Season Turfgrasses
Commonly used cool-season turfgrasses in lawns, sports fields, parks, grounds, golf courses,
and roadsides include Festuca L., Poa L., Agrostis L., and Lolium L. Within the cool-season
turfgrasses, species vary in maximum ET rate, ranging from 7 to 8.5 mm per day to more than
10 mm per day (Table 11.1). Tall fescue (Festuca arundinacea Schreb.), creeping bentgrass(Agrostis stolonifera L.), and annual bluegrass (Poa annua L.) are considered to be the highest
water users, whereas hard fescue (Festuca longifolia Thuill.), Chewing’s fescue (Festuca rubra L.
ssp. commutata Gaud.), and creeping red fescue (Festuca rubra L. ssp. rubra) are the lowest water
users (Beard 1989, 1994). DaCosta and Huang (2006) in New Jersey compared water use among
three bentgrass species and found that velvet bentgrass (Agrostis canina L.) used less water
than creeping bentgrass and colonial bentgrass (Agrostiscapillaries L.).

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Figure 11.1. Evapotranspiration rate of creeping bentgrass (cv. Penncross) irrigated once
per week (1x), twice per week (2x), and three times per week (3x). The test was performed
in turfgrass grown in loamy soil and mowed at 3/8 inch height in field plots at the Rutgers
University Turfgrass Research Farm, North Brunswick, New Jersey.

Cool-Season Turfgrasses
Commonly used cool-season turfgrasses in lawns, sports fields, parks, grounds, golf courses,
and roadsides include Festuca L., Poa L., Agrostis L., and Lolium L. Within the cool-season
turfgrasses, species vary in maximum ET rate, ranging from 7 to 8.5 mm per day to more than
10 mm per day (Table 11.1). Tall fescue (Festuca arundinacea Schreb.), creeping bentgrass(Agrostis stolonifera L.), and annual bluegrass (Poa annua L.) are considered to be the highest
water users, whereas hard fescue (Festuca longifolia Thuill.), Chewing’s fescue (Festuca rubra L.
ssp. commutata Gaud.), and creeping red fescue (Festuca rubra L. ssp. rubra) are the lowest water
users (Beard 1989, 1994). DaCosta and Huang (2006) in New Jersey compared water use among
three bentgrass species and found that velvet bentgrass (Agrostis canina L.) used less water
than creeping bentgrass and colonial bentgrass (Agrostiscapillaries L.).

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There can be as much variation in the water-use rate among cultivars within certain species as
between turfgrass species (Beard 1989). The difference in ET between cultivars may range from
20 to 60% (Kjelgren, Rupp, and Kilgren 2000).

Warm-Season Turfgrasses
Warm-season turfgrasses include Cynodon L.C. Rich, Buchloe Engelm., Zoysia Willd., Paspalum L.,
Eremochloa ophiuroides [Munro] Hack., and Stenotaphrum secundatum [Walt.] Kuntze. Theirmaximum water use ranges from less than 6 mm per day to 8.5–10 mm per day (Table 11.1).
Among warm-season grasses, bermudagrass (Cynodon spp.), zoysiagrass (Zoysia spp.), andbuffalograss (Buchloe dactyloides [Nut.] Engelm.) have relatively low water-use rates, whereas
seashore paspalum (Paspalum vaginatum Swartz.) and St. Augustinegrass (Stenotaphrum
secundatum ([Walt.] Kuntze.) have relatively high water-use rates (Table 11.1). Within a warmseason turfgrass species, cultivars may vary in water-use rate.

Plant Growth Characteristics Affecting Water Use
Water use of the turfgrass canopy is affected by water loss through shoot transpiration and soil
evaporation, and by water uptake from the soil via the root system. Therefore, turfgrass species
variations in water-use rates are associated with differences in shoot and root characteristics,
such as canopy configuration or leaf orientation, tiller or shoot density, growth habit, rooting
depth, and root density (Beard 1973; Huang and Fry 1999).

Canopy/Shoot Characteristics
Species that have a prostrate shoot growth habit typically have a lower water-use rate thangrasses with an upright growth habit (Kim and Beard 1988). The former group often has higher
resistance to evapotranspiration (Johns, Van Bavel, and Beard 1981, 1983). Generally, turfgrasses
with a rapid vertical shoot extension rate tend to have higher water-use rates than slowergrowing or dwarf-type grasses because of increasing leaf area from which transpiration occurs(Kim and Beard 1988; Shearman and Beard 1973). Shearman (1986) reported that shoot verticalextension rate was positively correlated with water-use rate for 20 Kentucky bluegrass cultivars
with upright growth pattern. No correlation was found, however, between water use and leaf
extension rate within several warm-season turfgrass species that have a prostrate growth habit,
such as bermudagrass (Beard, Green, and Sifers 1992) and zoysiagrass (Green, Sifers, and Beard
1991). The more horizontal growth characteristic may be dominant because of higher canopy
resistance. Dense and compact type turfgrass canopies have lower water loss from soil
evaporation than thin, open canopies. It is apparent that low-water-use grass species may
possess at least one of the combined characteristics of slow vertical growth, prostrate growth
pattern, and dense canopy. Under plant water stress, stomatal closure and cuticle formation
can be key factors controlling water use (Beard 1973; Kim 1983).

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Rooting Characteristics
An extensive, well-branched, deep root system is important for efficient water uptake from thesoil. Plants with deep and dense root systems typically have a high capacity for water extraction
from soil. Deep rooting enables plants to avoid water stress by taking up water from deeper inthe soil profile when the surface soil is dry. Tall fescue, which develops a deep, extensive rootsystem, has been shown to use more water than most other cool-season turfgrasses. But, not
all grasses with extensive root systems are necessarily high water users. For example,
bermudagrass has a prostrate growth habit, slow shoot growth rate, and a deep root system, but
exhibits a low water-use rate (Kim and Beard 1988; Youngner 1985).
Root distribution strongly responds to spatial variations in water availability. Generally, roots
tend to proliferate or extend in localized wet zones in a soil profile. For example, when soil
surface is maintained wet constantly because of frequent irrigation or rainfall, plants develop
extensive, shallow root systems. When a soil surface is allowed to dry periodically, productionof roots increases considerably in the lower layer where water is available. This root response
has been observed in various turfgrass species (Beard 1973; Huang 1999; Huang, Duncan, andCarrow 1997). The ability of roots to follow moisture into deeper layers of the soil profile
conditions the ability of a plant to tolerate or avoid short and long periods of drought.
Development of a deep root system could be related to a faster elongation rate of roots under
drying conditions. When limited soil water is stored in deeper soil profiles, however, faster root
extension into deeper soil profiles may be detrimental for plants because of rapid depletion ofwater.
As soil dries, root hairs increase in length and number (Huang and Fry 1998). Increases in root
hairs in dry soil have a pronounced effect on total root surface area. This response may be an
adaptive mechanism to maintain liquid continuity around the growing roots and to provide
greater root surface for nutrient absorption because the rate of nutrient diffusion to the root
decreases in drier soil. Root hairs can be sites for extensive mucilage production. Mucilage canenhance the ability of the hair to attach to soil particles and thereby prevent air gaps fromdeveloping between the soil and root surface when the soil dries; decrease water efflux fromplants into drying soils; and ultimately delay root desiccation. Extensive development of root
hairs enhances water uptake and facilitates water retention under soil-drying conditions.

Dormancy and Water Use
Another important plant characteristic of low water use is dormancy, a phenomenon in which
turfgrass leaves may turn brown in response to a water deficit, but the meristematic crowns
and stem nodes are not dead. Dormant turfgrass plants have limited or no transpirational water
loss, and thus, have low water usage. Limited water in dormant plants may be concentrated in
the crown and rhizomes. Dormancy is a mechanism of turfgrass escape from drought stresssuch that dormant plants survive (without growth) for extended periods of drought stress andresume growth when soil moisture becomes available (Beard 1973).

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In general, dormant turfgrasses, especially those with rhizomes (underground stems), cansurvive without water for several weeks or months with limited damage, depending on the airtemperature. After rainfall or irrigation, the grass will quickly recover. Allowing certain
turfgrasses to go dormant in low maintenance areas can result in significant water savings
without loss of turfgrass. The lengths of time turfgrasses can survive in a dormant condition
vary with temperatures and turfgrass species. In general, turfgrasses can be expected to survive
in a dormant condition for several weeks at temperatures at or below normal, but may survive
in dormant conditions for a shorter period of time during the summer when temperature iselevated. Kentucky bluegrass is a good example of a species that has the capacity for survival
during extended water stress because it has extensive rhizomes that generate new roots andshoots once soil moisture is replenished. But bunch-type turfgrasses such as perennial ryegrass
and tall fescue are slow to recover to their full canopy upon rewatering, once the turf canopy
becomes desiccated and thinned under nonirrigated conditions.

Environmental Factors Influencing Turfgrass Water Use
In addition to species and cultivar variations, water use of turfgrasses is influenced by many
external factors in their growing environment, including temperature, wind, solar radiation,
relative humidity, and edaphic factors such as soil moisture (Beard 1973). These factors affectboth plant transpiration and soil evaporation. Understanding major environmental factors
influencing water use is important for developing efficient cultural strategies for turfgrasses,
especially in areas with a limited water supply.
Water loss through transpiration from turfgrass plants is controlled by three major processes:
external boundary layer resistance, vapor pressure gradient between the leaf and air, andinternal leaf diffusion resistance (Fu, Fry, and Huang 2004; Johns, Van Bavel, and Beard 1981,1983). High transpirational water loss may be because of lower boundary layer resistance,
higher vapor pressure gradient, and/or lower internal diffusion resistance. Internal leaf diffusion
resistance is associated with stomatal density and conductance, intercellular space, cell sizeand density, and leaf cuticle thickness, which are all basically controlled by genetics. The
boundary layer is a layer of stagnant air over the leaf surface, which creates resistance to water
vapor escape from the leaf. Atmospheric environmental factors affect transpiration mainly
though alteration of the boundary layer resistance and vapor pressure gradient between theleaf and air.

Solar Radiation
Water use of turfgrasses typically is much higher in areas exposed to full sun than in shaded or
dark nocturnal conditions. Evapotranspiration is an energy-dependent process. If more energy
is available, there is potentially a greater rate of evapotranspiration. A linear relationshipbetween irradiance and water use rate has been reported in turfgrasses (Aurasteh 1983; Beard,
Green, and Sifers 1992; Feldhake 1981; Kim and Beard 1988; Shearman and Beard 1973 ). Our

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study in New Jersey with creeping bentgrass, velvet bentgrass, and colonial bentgrass found astrong correlation between water-use rate and solar radiation level with a correlation coefficientof 0.81.

Temperature
Plants transpire more water at higher temperatures because water evaporates more rapidly
with increasing temperatures under nonlimiting water availability. This is reflected by increasingwater demand of turfgrass during midday and summer months. Increasing water use rate was
highly correlated with increasing temperatures, with a correlation coefficient of 0.81 (1.0 =perfect correlation) in our New Jersey study. A leaf exposed to 30°C may transpire three times
as fast as it does at 20°C when leaves are fully hydrated.
Temperature influences transpiration through its effect on vapor pressure, which in turn affects
the vapor pressure gradient between the leaf and air (Beard 1973). Leaves of a well-wateredplant maintain a near 100% relative humidity or high vapor pressure within the leaf. Hightemperature dries the air or lowers the relative humidity of air, creating a larger gradient invapor pressure between the air and the leaf, thereby resulting in high transpirational water loss
(Shearman and Beard 1973).

Relative Humidity
Relative humidity of the atmosphere affects water use mainly by influencing the vapor pressure
gradient between the leaf and air. Low relative humidity, or dry air, surrounding the leaf causes
rapid water loss from the leaf because of the increased vapor pressure gradient (Beard 1973).
Therefore, water use typically increases with decreases in relative humidity. Carrow (1995)
reported turfgrass ET was 40 to 60% less in a humid environment compared with the same
cultivar in an arid environment.

Wind
Water-use rate of turfgrasses typically is higher on windy days than on calm days and in open
areas compared with areas enclosed with trees, shrubs, and other structures. The effects of windon water use are associated with changes in the water vapor pressure gradient between the leaf
and air and the external boundary layer resistance, particularly the latter factor (Beard 1973).
Wind above the leaf dries the air adjacent to the leaf and therefore causes increases in thevapor pressure gradient. Also, the thickness of the boundary layer is primarily a function of leaf
size and shape, the presence of leaf hair, and wind speed. The thickness of the boundary layer
decreases with increasing wind speed, which may lead to increases in the transpiration rate ata lower wind speed; however, high wind speed may cause stomatal closure and lowtranspiration rate before the leaves become desiccated (Hopkins 1999). Grace (1974) reported
that the transpiration rate of a tall fescue cultivar increased as wind speed increased from

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1 m s-1 to 3.5 m s-1. Beard, Green, and Sifers (1992) also observed a positive relationship between
water-use rate and wind speed.

Soil Moisture
Water-use rate can be restricted by water supply from the roots and in turn depends on theavailability of soil moisture. When soil moisture supply is not enough to replace what is lostfrom the shoots, stomata will be closed and a plant cannot continue to transpire. Therefore,
plants in general tend to use less water when the soil water content is low. Water-use rates ofboth cool-season and warm-season turfgrasses have been found to decline with decreases insoil water content (Biran et al. 1981; DaCosta and Huang 2006; Kim 1983). Not all water in thesoil can be used by plants. Only water retained in the soil by capillary forces can be extracted
by the plant. Available soil water is the water held by the soil between field capacity, definedas the amount of water remaining in the soil when drainage ceases, and permanent wilting
point, defined as the soil water content below which there is no available water and plants wilt
and do not recover. Soil moisture availability is affected by water supply through rainfall or
irrigation. Efficient irrigation should maintain soil moisture above the permanent wilting point,
but below field capacity. Irrigation above field capacity results in waste of water.
Frequently irrigated turfgrasses (soils that are kept wet constantly) use more water thanturfgrasses that receive less frequent irrigation (allowing soil to dry between irrigation events)(Gibeault et al. 1985; Kneebone, Kopec, and Mancino 1992). For example, creeping bentgrass
irrigated three times per week had a higher ET rate than that irrigated once per week or twice
per week on many days from June to September 2005 (Fig. 11.1). Vertical shoot growth may bepromoted with increasing irrigation frequency or quantity, resulting in increased demand forwater. Maintaining wet soil constantly also promotes shallow root systems, which decreases
water utilization in deeper soil profiles.
Turfgrass maintained under water deficit conditions typically uses less water than well-irrigatedplants. Deficit irrigation can decrease water uses in various turfgrass species (see Section 12).
The level of deficit irrigation varies with plant species, soil types, and climatic conditions. Many
turfgrass species—such as Kentucky bluegrass, perennial grass, tall fescue, creeping bentgrass,velvet bentgrass, colonial bentgrass, zoysiagrass, and bermudagrass—are able to tolerate
certain levels of deficit irrigation with little or no loss of aesthetic turfgrass quality.

Soil Texture and Physical Properties
The amount of water that turfgrass can actually use also is affected by soil type and texture.
Both soil texture and type affect water retention and infiltration, and thereby influence water
use and irrigation quantity or frequency. Generally, larger-particle-size soils, such as sandy soil,
have better drainage and hold on to less water than fine-particle soils, such as clay and silt, andhave about 50% of the soil water available to plants. Therefore, sands and sandy soil requireTurfgrass Water
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more frequent irrigation to meet plant needs, but with smaller amounts of water per irrigation
event. Conversely, fine-textured soils, such as clay loams and clay, hold larger amounts of water,
but only about 30 to 35% of the total water in the soil is available to plants. Deep, infrequentirrigation of fine-textured soils may be needed to meet plant needs. Compared with plants
grown in clay soils, Kentucky bluegrass grown in a sand-peat mix had a 6% higher ET in a study
conducted during the summer in Colorado (Feldhake, Danielson, and Butler 1983).
Traffic and compaction are major problems in recreational turfgrass areas. Both stresses may
adversely affect soil infiltration, water holding capacity, and plant growth, and thus, indirectly
affect water use. Soil compaction increases bulk density, water retention, and soil strength, anddecreases aeration porosity and oxygen needed for root growth. O’Neil and Carrow (1983)
reported a 21 and 49 % decrease in water use for perennial ryegrass grown in moderate andseverely compacted soils, respectively, than that under noncompacted soils in Kansas. Similarly,
Kentucky bluegrass grown in compacted soils also exhibited a lower water-use rate (Agnew
and Carrow 1985).

Summary
As discussed, turfgrass water use is a function of plant growth characteristics and environmental
conditions. Therefore, an effective conservation program should be developed based on plantneeds and environmental conditions. Use of less water and/or drought-resistant turfgrass
species and cultivars is a primary means of decreasing water needs. Selection of turfgrass
species and cultivars adapted to local climatic conditions can result in significant water savings.
For example, in arid and semi-arid regions, warm-season turfgrasses provide a better turfgrass
and use less water than cool-season turfgrasses. Quantification of actual water use bymeasuring evapotranspiration rate under local environmental conditions at different times ofthe year helps to decide how much to irrigate under different conditions, as has been described
for San Antonio, Texas, in Section 15. Knowledge of critical plant physiological status and soil
moisture content of different types of soils also is important for scheduling when to irrigate,
how much water to apply by irrigation to replenish water lost through evapotranspiration, andhow deep to irrigate in the soil (see also Section 15).

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Kentucky bluegrass. I. Soil aeration, water use, and root responses. Agron J 77:872–877.
Aurasteh, R. M. 1983. A model for estimating lawn grass water requirement considering deficit
irrigation, shading and application efficiency. PhD dissertation, Utah State University, Logan,
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Beard, J. B. 1973. Turfgrass: Science and Culture. Prentice-Hall, Inc., Englewood Cliffs, New Jersey.
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Huang, B. 1999. Water relations and root activities of Buchloe dactyloides and Zoysia japonica in
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Huang, B. and J. D. Fry. 1998. Root anatomical, morphological, and physiological responses of
two tall fescue cultivars to drought stress. Crop Sci 38:1017–1022.
Huang, B. and J. Fry. 1999. Turfgrass evapotranspiration. Pp. 317–334. In M. B. Kirkham (ed.). Water
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turfgrasses in response to localized drought stress. Int Turf Res J 7:681–690.
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