Front Cover
 Table of Contents
 Irrigation water quantity
 Irrigation water quality
 Effluent wastewater use on...
 Back Cover

Group Title: Bulletin
Title: Irrigation management practices for Florida golf courses
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00008447/00001
 Material Information
Title: Irrigation management practices for Florida golf courses
Series Title: Bulletin
Physical Description: 27 p. : ill. ; 28 cm.
Language: English
Creator: McCarty, L. B ( Lambert Blanchard ), 1958-
Cisar, J. L ( John L )
Dudeck, A. E ( Albert Eugene ), 1936-
Publisher: University of Florida, Institute of Food and Agricultural Sciences, Florida Cooperative Extension Service
Place of Publication: Gainesville Fla
Publication Date: 1993
Subject: Turfgrasses -- Irrigation -- Florida   ( lcsh )
Golf courses -- Maintenance -- Florida   ( lcsh )
Turf management -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 26-27).
Statement of Responsibility: L.B. McCarty, J.L. Cisar, and A.E. Dudeck.
General Note: Title from cover.
General Note: "May 1993."
 Record Information
Bibliographic ID: UF00008447
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA6712
ltuf - AJQ6712
oclc - 29019429
alephbibnum - 001833171

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Table of Contents
        Table of Contents 1
        Table of Contents 2
    Irrigation water quantity
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
    Irrigation water quality
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
    Effluent wastewater use on turf
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
    Back Cover
        Page 28
Full Text

S-ay 1993

Irrigation Management Practices

for Florida Golf Courses

L.B. McCarty, J.L. Cisar, and A.E. Dudeck

University of Florida
Institute of Food and Agricultural Sciences
Florida Cooperative Extension Service
John T. Woeste, Dean

. ,, 'ul7-

Bulletin 283

L.B. McCarty is Associate Professor and A.E. Dudeck is Professor, Environmental Horticulture De-
partment; J.L. Cisar is Associate Professor, Fort Lauderdale Research and Education Center; IFAS,
University of Florida, Gainesville, FL 32611.

Table of Contents
Irrigation Water Quantity 1

I. Introduction 1

II. Water Use and Turf Stress 1
a. Soil-Water Relationships 1
b. Soil Characteristics 2
c. Cultural Practices 3
d. Determining When to Irrigate 3
e. Turf Response to Water Deficit 5
f. Environmental Influence on Evapotranspiration 5

III. Turfgrass Evapotranspiration Rates 5
a. Potential Evapotranspiration Rates in Florida 6
b. Irrigation Strategies for Turfgrass Managers 11

Irrigation Water Quality 13

I. Salinity 13
a. Principal Soluble Salts 14
b. Measuring and Classifying Irrigation Salinity 14
c. Salinity Effects on Plants 15
d. Saline Irrigation Influence on Soils 16

II. Sodium Hazard (Permeability) 17
a. Sodium Adsorption Ratio 18
b. Exchangeable Sodium Percentage 18

III. Bicarbonates 18

IV. pH 21

V. Toxic Ions 21

VI. Soil Amendments 21
a. Gypsum 22
b.Sulfur 24

Effluent Wastewater Use on Turf 25

I. Introduction 25

II. Levels of Treated Water 25

III. Characteristics of Effluent Water 25
a. Dissolved Solids 26
b. Permeability 26
c. Nutrient Content 27
d. Heavy Metals 27
e. Storage Ponds 27
f. Golf Greens 27
g. Irrigation System Design 28
h. Other Information and Suggestions 28

References and Further Reading

Irrigation Water Quantity


Water is the primary requirement for growth and
survival of turfgrasses. Plants consist of cells which
are containers of water. Plants maintain turgor (are
rigid) when their cells are filled with water. Cells
collapse when they lose water. If enough cells lose
their turgidity, the leaf rolls and turns a blue-green
color, while the stem droops. The plant is then
considered wilted. Plant water content typically is
between 75 to 85 percent by weight. Plants begin to
die if water content drops to 60 to 65 percent within
a short period of time.

Unfortunately, rainfall is not frequent enough to
provide adequate water to sustain turfgrasses under
today's intensive golf course management culture.
This is further intensified by Florida's year-round
warm subtropical weather and soils that are primarily
sand. Irrigation with acceptable quality water is
therefore is an important part of golf course mainte-
nance. To ensure efficient watering, golf courses
require well-designed irrigation systems that are based
on soil infiltration rates, soil water holding capacity,
plant water-use requirements, depth of root zone,
conveyance losses from the surrounding area, and
desired level of turfgrass appearance and perfor-


Soils contain a reservoir of water for turf plants.
Water enters the plant through root hairs near the
root tip and diffuses into the xylem, made up of
water-conducting cells. Water then moves through
the stem up into the leaves and then into the atmo-
sphere through leaf stomates. This process is termed
transpiration. When transpiration occurs, water is
literally "pulled" up a pressure gradient from the soil
through the stem and eventually up to the leaves.
Generally, the gradient becomes steeper from the soil
through the plant's vascular system to the leaf stomata
and into the atmosphere. This gradient is termed
water potential and is expressed in negative values.

The chemical potential of water within this system is
lower than that of pure free water. Water potential
is generally expressed as bars or megapascals where
1 megapascal equals 10 bars. Classic soil water
potentials have been defined as 0 bar when saturated,
to -15 bars when soils are so dry that plants are
considered to be permanently wilted. Forplant water
potential, 0 bar represents fully turgid plants and
ranges to -20 bars for severely wilted ones. In the
atmosphere, 0 bar represent water saturated air, or
100% relative humidity while, -1000 bars is a very low
relative humidity (e.g., arid). Due to this gradient,
water will move from a site of high-water potential
(e.g., 0 bar) in soil to one of lower potential (e.g.,
negative value) in air.

Transpiration serves several other important
functions in addition to providing water to living plant
tissue. Mineral nutrients are transported through the
transpiration stream. Evaporation of water from the
leaf surface results in evaporative cooling, thus
moderating canopy temperature. This is important
for maintaining plant cell metabolism. Humans have
a similar process in which perspiration evaporates and
cools our bodies.

Evaporation is the flow, or loss, of water from the
soil directly to the atmosphere. Collectively, evapo-
transpiration (ET) is the total water lost by encom-
passing transpiratory movement of water from soil,
through turf, and ultimately into the atmosphere, and
by evaporation that occurs from soil directly into the
atmosphere. Parameters largely controlling ET are
light intensity and duration, humidity, wind velocity,
and temperature. Other parameters that affect ET to
a lesser extent include soil-water content, turf-root
system development, and turf cultural practices.

Soil-Water Relationships

Major soil water sources include precipitation,
irrigation, and capillary rise of moisture from below
the root zone. Capillary rise of moisture into the root
zone is important in some areas of Florida where high

Irrigation Management Practices

water tables are present. Golf greens built to USGA
Green Section specifications or those built with the
PURR-WICK methods also use the principal of
"perched" water tables. Dependence on capillary
action to provide water to plants can result in prob-
lems such as the lack of adequate water rising quickly
enough to supply turfgrass needs during high evapora-
tive demand periods. In addition, if the water table is
left near the surface for extensive periods, decreased
rooting may occur. Inadequate drainage in the event
of heavy precipitation may also occur.

Turf areas lose water by evaporation, transpira-
tion, runoff, leaching, and conveyance losses. Turf
managers have a degree of control over these water
loss mechanisms; therefore, they should have a good
understanding of each mechanism in order to con-
serve water.

Soil Characteristics

Soils ideally consist of equal amounts of solids
and pore spaces. Moisture resides in the pore spaces.
Pores are either large, referred to as macropores, or
smaller spaces, called micro or capillary-pores. The
number of micropores will influence soil water
content, and macropores will determine air content.
Macropores contain the largest percentage of air since
they hold water poorly. Micropores, meanwhile, due
to their smaller size, are able to hold water longer
than macropores.

Soil texture and structure are inherent properties
influencing soil pores. Sand grains or particles, being
relatively large and spherical, cannot "pack" close
together and the result is many macropores which
usually drain well. Clay and silt particles are very
small and platelike, and can pack together. This
results in numerous micropores that drain slowly. If
micropores predominate, soil water holding capacity
will be high, but drainage and air movement may be
inhibited due to lack of adequate macropores. If
macropores predominate, excessive drainage and
aeration result at the expense of adequate water
holding capacity.

Infiltration and percolation rates identify a soil's
ability to absorb and move water through the soil
profile. Soil texture and structure influence these
factors. Fine-textured soils, such as clays, tend to
have slower infiltration and percolation rates while
coarser-textured sandy soils have increased rates.
Bulk density is the mass (or weight) of dry soil per
unit volume, including solids and pores. Compacted

soils have less large pore space and thus have higher
bulk densities. This results in slower infiltration and
percolation. Non-compacted sandy soils have lower
bulk densities and can have an infiltration and perco-
lation rate as high as 4 feet per hour while compacted
clay loams have one-fourth the rate due to higher
bulk densities.

Soil texture also influences the water holding
capacity (WHC) of a soil. Clay soils have a much
higher WHC than sandy soils. In general, fine
textured soil can hold approximately twice as much
water as a loam soil and four times that of a sand.
This can be demonstrated by the depth a particular
amount of applied water will reach (Figure 1). For
example, one-inch of applied water will penetrate
approximately 5, 8, and 15 inches for clay, loam and
sand soils, respectively. Fine-textured soils will
require water less frequently relative to coarse-tex-
tured soils because of their greater WHC. Organic
matter, loamy soil, and other amendments often are
added to improve the WHC of a sandy soil while clay
soils are often amended with sand to decrease WHC
and increase soil aeration. One aim of various
culture practices, such as aerification and topdressing,
is to provide better water and air penetration to the
root zone and to allow, over time, a slow change
toward increased WHC and aeration.


\ Clays
_- 12

Q \ Loams`


36 ---
0 1 2 3

Water Applied (in.)
Figure 1. Expected depth reached from applying 1 inch of
water to three soil types (redrawn from Emmons, 1984).

Irrigation Management Practices

Cultural Practices

Turfgrass cultural practices influence water-use
rates and efficiency. Mowing, fertilization, and
irrigation are primary cultural practices superinten-
dents can use to control water loss and to encourage


Mowing practices can impact turfgrass water use.
Managers should mow turf at the higher end of the
optimum mowing height range. Higher mowed turf
results in a deeper and denser root system that can
extract water from a larger volume of soil. Lower
mowing heights initially reduce water use because leaf
surface area is reduced and remaining leaves are
more compact. Initial water savings are later negated
because root depth and density are proportionately
reduced by the lower mowing height. Lower-mowed
turf tends to require more frequent but shallower
water applications than those mowed higher.

Turf managers also should mow frequently and
only use sharpened mower equipment. Dull or
improperly adjusted mower blades tend to shred turf
leaf tips. This results in poor recuperation. Mutilat-
ed leaf tips also results in ragged turf appearance.


Nitrogen influences turf plants in terms of color,
shoot and root growth, and water use. In general,
enough nitrogen should be applied to turf to meet its
nutritional needs for maintaining growth, recuperative
ability, color and quality. Nitrogen generally increases
shoot growth, shoot density, and leaf width which
increases leaf area exposed to the atmosphere. Shoot
growth also occurs at the expense of root depth and
density. Thus, excessive nitrogen generally reduces
root growth, which may adversely affect water extrac-

Potassium levels and their effect on water use are
generally opposite those for nitrogen. Potassium
nutrition increases leaf turgor, and thus delays wilting.
However, excessive nitrogen levels can negate the
positive effect of potassium fertilization.

Foliar iron applications also have been shown to
increase rooting of turfgrasses under certain environ-
mental conditions. Increased rooting adds to the
depth of available water and may reduce irrigation
needs. Iron and manganese also can provide desir-

able turf color without excessive growth from exces-
sive nitrogen use. Supplemental iron and manganese
should be applied to encourage turf color and root
growth without stimulating excessive shoot growth.

Turf managers should strive to maintain adequate
nitrogen for desirable turf color and for recuperation
from damage, but not to the extent that excessive
shoot-to-root ratios occur. Adequate potassium (e.g.,
equal to nitrogen) should be provided, especially
during stress periods such as drought.

Soil Compaction

Soil compaction increases a soil's bulk density and
soil strength while decreasing aeration porosity. As
soil compaction increases, turf roots cannot extract
adequate oxygen to sustain root growth. As a result,
reduced root and shoot growth occur. Soil cultivation
or coring on compacted soils enhances rooting and
turf quality.

Watering Practices

Irrigation practices, in terms of amount and
frequency, can significantly increase drought tolerance
by conditioning the turf. Irrigation schedules are
often based on calendar dates such as three or seven
times per week without regard to actual turf needs
and soil moisture status and availability. Studies have
shown that "calendar-based" irrigation may provide
excessive moisture and lowers turf quality.

Determining When to Irrigate

Several irrigation scheduling methods are avail-
able. These range from visual symptoms to more
precise soil moisture based irrigations. Watering
heavily but infrequently is a commonly accepted
turfgrass management practice. However, this can be
an ambiguous approach if the exact amount or
frequency of water application needed at a given time
is not determined.

Visual Symptoms

A simple method used to determine when irriga-
tion is needed is to water when there are symptoms
of moisture stress. However, golf course managers
should avoid prolonged moisture stress, especially on
greens. Moisture-stressed grass appears blue-green or
grayish-green in color, recuperates slowly (> 1
minute) after walking or driving across it, or wilts
continuously. These symptoms occur when plant

Irrigation Management Practices

moisture is insufficient to maintain turgor. As a
result, the plant rolls its leaves and wilts to conserve

The method of waiting until symptoms of mois-
ture stress appear before watering does have some
drawbacks. Certain areas or patches of turf tend to
wilt before others due to poor irrigation distribution
or due to localized dry spots or poorly developed root
systems. Adequately irrigating these "hot-spots" may
result in wasting water. Managers of golf greens also
cannot afford to wait until these symptoms occur
because unacceptable turf quality may result. Waiting
until visual symptoms appear before irrigating is best
used for low maintenance use areas such as golf
course roughs and, possibly, fairways.

Evaporatory Pans

Another method of irrigation scheduling is the
use of evaporatory pans. A United States Weather
Service Class A Evaporatory Pan is 122-cm in diame-
ter and 25-cm deep and is supported 15 cm above the
ground. Evaporatory pans are filled with water,
placed in a representative location, and water loss is
measured over time. The amount of water evaporat-
ing from the pan correlates to the amount lost by the
turf from evapotranspiration. This correlation is
generally accurate except during windy conditions.
Wind tends to exaggerate the amount of water lost by
the evaporatory pan compared to actual ET rates.

Although this water loss correlates to ET rates, in
general turf plants use less than the amount evaporat-
ed from the pan. Therefore, the amount of irrigation
applied should be 55 to 80 percent of the depth lost
from the evaporatory pan. More specifically, warm-
season grasses generally use 55 to 65 percent and
cool-season grasses from 65 to 80 percent of the
depth lost from pan evaporation.


Tensiometers are used to measure soil water
status. Tensiometers are tubes filled with water with
a porous ceramic cup at the base and a vacuum gauge
at the top. As soil moisture is depleted, a tension is
formed between the water in the soil and water in the
tube. This tension is registered by the vacuum gauge
and provides a relatively accurate reading on soil
moisture availability, registered in centibars. Soil field
capacity (water "held" after drainage) generally exists
between 5 to 30 centibars with higher values indicat-
ing decreasing soil moisture levels. Tensiometers

remain accurate when tensions are above 80 centi-
bars. Commercial tensiometer models are available
that can automatically regulate irrigation systems
based on at a pre-set tension threshold.

Drawbacks of tensiometers include their readings
only being appropriate in the area adjacent to the
placement of the ceramic tips. This necessitates
multiple units over different soil types, irrigation
zones, terrain and increases labor costs. Tensi-
ometers may affect play. Placing tensiometers in the
center of golf greens also poses a problem since this
interferes with plant and management practices such
as aerification. Tensiometers require maintenance
periodically and they have to be removed during
periods of cold weather to prevent ice formation in
the tube. Adequate contact between the ceramic tube
and surrounding soil also is essential.

Additional Methods

Other methods of estimating soil moisture are
available through gypsum, nylon, and fiberglass blocks
which contain electrodes measuring electrical resis-
tance. The porous blocks are buried in the soil and
water is allowed to move in or out of them depending
on soil moisture tension. These are accurate when
measuring low soil moisture content and can be left
in place for extended periods. However, they are
sensitive to saline conditions, and like tensiometers,
measure soil moisture only at the area immediately
surrounding them. They also are not as accurate in
predominately sandy soil.

Rough soil moisture estimates can be determined
by using a soil probe to feel the depth of moisture.
Resistance to penetration of a sharp object such as a
screwdriver also can be used. Rain gauges are
necessary measurement tools to track natural mois-
ture inputs on a golf course.

Predictive models based on weather station data
and soil types also are available. These are relatively
accurate and applicable especially as long-term
predictors of yearly turf water requirements. Models,
however, are only as effective as the amount of data
collected and the number of assumptions made.
Weather data such as rainfall, air and soil tempera-
ture, relative humidity, and wind speed are incorpo-
rated into certain model formulae and estimated soil
moisture content is made. Accessible weather data
must be available as well as specialized computer
equipment and programs.

Irrigation Management Practices

Turf Response to Water Deficit

In order to reduce water loss, an early response
by plants to internal water deficit is stomatal closure.
This normally occurs during peak water demand
periods. After these environmental stresses subside,
stomata usually reopen. Under extreme conditions,
stomata may close for extensive periods, which in turn
affects further plant functions.

Stomata are major vapor-gas exchange sites from
the leaf to the atmosphere. If closed from water
deficit, carbon dioxide exchange from plants and the
atmosphere is inhibited, as is the diffusion of water
vapor. This, in turn, reduces photosynthesis and
eventually retards leaf growth and emergence. Over
time, turf density will decline from this reduction in
leaf growth, emergence, and tillering.

Water stress has less immediate effects on root
growth. Plants tend to have continued root growth
relative to shoot growth during periods of water
stress. This results in an increase in the root-to-shoot
ratio and is an important mechanism for avoiding
drought stress. Turf managers should maximize root
systems by lengthening the interval between irriga-
tions. Excessive soil pH, salinity, nitrogen levels,
potassium deficiency, or improper mowing height and
frequency can limit root growth and can decrease
plant tolerance to increasing moisture stress.

Environmental Influence on

Environmental parameters are the controlling
influence of plant ET. These include relative humidi-
ty, temperature, and wind. Of these, solar radiation
is the driving force for evaporative demand by stimu-
lating stomata opening. Cloudiness can decrease ET
by blocking incoming radiation.

Atmospheric relative humidity and wind velocity
also influence ET rates. As air becomes more satu-
rated at higher humidities, the vapor pressure gradi-
ent between leaves and air is reduced, resulting in less
ET. Under calm air conditions, the existing vapor
pressure tends to form an external layer adjacent to
the leaf called the boundary layer. The boundary
layer, if not disturbed, acts as an insulator by protect-
ing the leaf from sudden vapor pressure changes, and
thus reduces ET. However, with increasing wind, the
boundary layer decreases and ET increases. As a
result, ET rates tend to increase with higher tempera-
tures, light, and wind, but tend to decrease with

higher atmospheric relative humidity and cloud cover.
Minimal ET rates occur when there are dark, cloudy
days with high relative humidity, low temperatures
and little wind. Conversely, highest ET rates occur
on bright sunny days with low relative humidity, high
temperatures, and moderate to high winds.


Many studies have been performed comparing the
relative ET rates of various turfgrasses. Warm-season
turf water use rates typically range from 0.1 to 0.25
inches per day, with maximum values reported as high
as 0.47 inches per day under exceptionally high
evaporative demand. Table 1 summarizes the report-
ed summer mean ET rates by turfgrass species. In
general, the major considerations contributing to low
water-use rate by a turfgrass are its ability to maintain
a dense shoot coverage, slow vertical leaf growth rate,
narrow leaf width, horizontal leaf orientation, and
color. As discussed, cultural practices and environ-
mental parameters also have considerable influence
on each of these contributing factors. It is interesting
to note that on a similar leaf index area, turfgrasses
generally are no different on their ET rates than
other plants used in Florida, such as citrus or forests,
and may be less than others, such as sawgrass. Again,
it bears repeating that climate conditions control ET
and not always the plant species, provided there is a
continuous canopy or coverage of the soil surface and
water is readily available.

Table 1. Generalized mean summer evapotranspiration rates
of turfgrasses.

ET Rates
Tugrass n/wk mm/day

Bahiagrass 1.7 6.2
Bermudagrass 1.0-2.0 4.0-8.7
Buffalograss 1.5-2.0 5.3-7.3
Centipedegrass 1.5-2.3 5.5-8.5
Creeping bentgrass 1.3-2.7 5.0-9.7
Kentucky bluegrass 1.1-1.8 4.1-6.6
Perennial ryegrass 1.8-3.1 6.6-11.2
Seashore paspalum 1.7-2.2 6.2-8.1
St. Augustinegrass 1.7-2.6 6.3-9.6
Tall fescue 2.0-3.5 7.2-12.6
Zoysiagrass 1.3-2.1 4.8-7.6

Cool-season turfgrasses have the C3 pathway of
carbon fixation or photosynthesis while warm-season
grasses utilize the C4 pathway. Cool-season turf-
grasses thus have a higher CO2 compensation point.

Irrigation Management Practices

Cool-season turfgrasses also require less light to
saturate photosynthesis and have a lower optimum
temperature for carbon fixation compared to warm-
season grasses. As a result, cool-season turfgrasses
generally have lower water-use efficiency rates corn
pared to warm-season turfgrasses, and require more
water to maintain plant growth.

Drought tolerance of warm-season turfgrasses is
listed in Table 2. Bermudagrass, zoysiagrass, and
bahiagrass have the best drought tolerance, followed
by St. Augustinegrass. Centipedegrass and carpet-
grass have the least drought tolerance of these turf-

Table 2. Relative drought resistance of warm-season

Excellent Bermudagrass

Medium St. Augustinegrass

Low Centipedegrass

Potential Evapotranspiration Rates in Florida

Potential ET rates can be calculated from a
variety of equations. In general, by using historical
climatological data as a reference and incorporating
this in the McCloud equation to determine specific
ET rates, potential ET rates have been calculated at
various locations throughout Florida using daily
average minimum/maximum temperatures. From this,
normal net irrigation requirement to maintain low to
medium maintenance grass are estimated (Tables 3-

Table 3. Fort Myers area turfgrass Irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (In) Potential ET Net Irrigation Re-
Month (In) quirement (In)
JANUARY 64 1.64 2.61 1.65
FEBRUARY 65 2.03 2.56 1.38
MARCH 69 3.06 3.66 1.86
APRIL 73 2.03 4.92 3.57
MAY 78 3.99 6.82 4.12
JUNE 81 8.89 8.31 2.51
JULY 83 8.90 9.46 3.26
AUGUST 83 7.72 9.61 4.06
SEPTEMBER 82 8.71 8.61 2.91
OCTOBER 76 4.37 6.26 1.54
NOVEMBER 69 1.31 3.78 2.96
DECEMBER 65 1.30 2.85 2.07
TOTAL -- 53.95 69.45 31.89

Irrigation Management Practices

Table 4. Gainesville area turfgrass irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (In) Potential ET Net Irrigation Re-
Month (in) quirement (in)

JANUARY 57 2.84 1.68 0.18
FEBRUARY 59 3.70 1.69 0.00
MARCH 64 4.26 2.63 0.38
APRIL 70 3.02 3.92 2.12
MAY 76 3.54 6.00 3.70
JUNE 80 6.81 7.71 3.21
JULY 81 8.03 8.59 3.09
AUGUST 81 8.25 8.65 2.85
SEPTEMBER 79 5.67 7.26 3.51
OCTOBER 72 3.67 4.58 2.38
NOVEMBER 63 1.92 2.49 1.44
DECEMBER 58 2.88 1.78 0.58
TOTAL --- 54.59 56.98 23.44
AVERAGE 70 -- _______-

Table 5. Jacksonville area turfgrass irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (in) Potential ET Net Irrigation Requir-
Month (in) ement (In)

JANUARY 55 2.78 1.43 0.00
FEBRUARY 56 3.58 1.45 0.00
MARCH 61 3.56 2.24 0.34
APRIL 68 3.07 3.45 1.70
MAY 74 3.22 5.43 3.34
JUNE 79 6.27 7.32 3.22
JULY 81 7.35 8.53 3.53
AUGUST 81 7.89 8.53 3.23
SEPTEMBER 78 7.83 6.84 1.94
OCTOBER 71 4.54 4.19 1.59
NOVEMBER 61 1.79 2.16 1.16
DECEMBER 55 2.59 1.51 0.00
TOTAL 54.47 53.08 20.05
AVERAGE 68 -- -

Irrigation Management Practices

Table 6. Orlando area turfgrass Irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (In) Potential ET Net Irrigation Re-
Month (in) quirement (In)
JANUARY 60 2.28 2.12 0.85
FEBRUARY 62 2.95 2.10 0.55
MARCH 66 3.46 3.16 1.26
APRIL 72 2.72 4.56 2.88
MAY 78 2.94 6.73 4.73
JUNE 81 7.11 8.37 3.57
JULY 82 8.29 9.39 3.59
AUGUST 83 6.73 9.58 4.68
SEPTEMBER 81 7.20 8.31 3.41
OCTOBER 75 4.07 5.67 3.17
NOVEMBER 67 1.56 3.21 2.28
DECEMBER 62 1.90 2.33 1.19
TOTAL --- 51.21 65.53 32.16
AVERAGE 73 ---- ---- .

Table 7. Pensacola area turfgrass irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (In) Potential ET Net Irrigation Re-
Month (in) quirement (In)
JANUARY 52 4.37 1.21 0.00
FEBRUARY 55 4.69 1.31 0.00
MARCH 60 6.31 2.05 0.00
APRIL 68 4.99 3.45 0.70
MAY 75 4.25 5.77 3.02
JUNE 81 6.30 8.04 3.74
JULY 82 7.33 8.99 3.89
AUGUST 82 6.67 8.99 4.39
SEPTEMBER 78 8.15 6.87 1.77
OCTOBER 70 3.13 4.03 2.13
NOVEMBER 60 3.37 1.93 0.13
DECEMBER 54 4.66 1.35 0.00
TOTAL -- 64.22 53.99 19.77
AVERAGE 68 ---

Irrigation Management Practices

Table 8. Miami area turfgrass irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (In) Potential ET Net Irrigation Re-
Month (in) qulrement (In)

JANUARY 67 2.15 3.35 2.09
FEBRUARY 68 1.95 3.16 1.99
MARCH 71 2.07 4.42 3.12
APRIL 75 3.60 5.50 3.24
MAY 78 6.12 6.97 3.05
JUNE 81 9.00 8.26 2.69
JULY 82 6.91 9.32 4.32
AUGUST 83 6.72 9.71 4.75
SEPTEMBER 82 8.74 8.66 2.74
OCTOBER 78 8.18 6.87 1.13
NOVEMBER 72 2.72 4.55 2.85
DECEMBER 68 1.64 3.61 2.61
TOTAL -- 59.80 74.38 34.58
AVERAGE 76 ---- --- --__--

Table 9. Tallahassee area turfgrass irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (In) Potential ET Net Irrigation Re-
Month (in) quirement (In)

JANUARY 53 3.74 1.25 0.00
FEBRUARY 55 4.77 1.31 0.00
MARCH 60 5.93 2.10 0.00
APRIL 68 4.07 3.39 1.09
MAY 75 4.04 5.58 3.28
JUNE 80 6.62 7.71 3.21
JULY 81 8.92 8.59 2.59
AUGUST 81 6.89 8.59 3.79
SEPTEMBER 78 6.64 6.78 2.58
OCTOBER 69 2.93 3.88 2.13
NOVEMBER 59 2.81 1.85 0.35
DECEMBER 53 4.22 1.30 0.00
TOTAL 61.58 52.33 19.02
AVERAGE 68 --- -

Irrigation Management Practices

Table 10. Tampa area turfgrass irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (In) Potential ET Net Irrigation Re-
Month (in) quirement (In)

JANUARY 60 2.33 2.12 0.82
FEBRUARY 62 2.86 2.10 0.57
MARCH 66 3.89 3.09 0.99
APRIL 72 2.10 4.50 3.15
MAY 77 2.41 6.60 4.90
JUNE 81 6.49 8.25 3.85
JULY 82 8.43 9.08 3.38
AUGUST 82 8.00 9.27 3.67
SEPTEMBER 81 6.35 8.16 3.96
OCTOBER 75 2.54 5.58 3.93
NOVEMBER 67 1.79 3.15 2.10
DECEMBER 62 .2.19 2.30 1.07
TOTAL -- 49.38 64.20 32.39
AVERAGE 72 ---- --- -

Table 11. West Palm Beach area turfgrass irrigation requirements based on long-term climatic records.

Mean Temp. (F) Mean Rainfall (in) Potential ET Net Irrigation Re-
Month (In) quirement (In)

JANUARY 66 2.60 2.99 1.49
FEBRUARY 66 2.60 2.81 1.34
MARCH 70 3.32 4.00 1.95
APRIL 74 3.51 5.11 3.11
MAY 78 5.17 6.73 3.33
JUNE 81 8.14 7.98 2.68
JULY 82 6.52 9.07 4.47
AUGUST 82 6.91 9.32 4.32
SEPTEMBER 82 9.85 8.54 2.04
OCTOBER 77 8.75 6.60 1.30
NOVEMBER 71 2.48 4.20 2.65
DECEMBER 67 2.21 3.27 1.97
TOTAL --- 62.06 70.62 30.65
AVERAGE 75 ---- --- ----

Irrigation Management Practices

When using any predictive equation to determine
ET rates or net irrigation requirements to maintain
grass, a series of assumptions must be made. These
assumptions influence actual amounts of net irrigation
requirements since each location and golf operation
is designed and built differently. Allowances are
needed to account for these and to adjust for any

1. Net irrigation requirement is affected by irrigation
system efficiency. For example, if 1.0 inch water
is needed with a 75% efficient system, then 1.33
(1.0+0.75) inches of total "applied" water is re-
quired to uniformly apply this 1.0 inch.

2. Environmental parameters at the time of applica-
tion also influence the amount of water gallonage
usable by plants. Applications made during hot
temperature, windy conditions, and when relative
humidity is low as well as with finer mist irriga-
tion nozzles can result in evaporation before
reaching the plants. Irrigation should not be
scheduled during such periods. However, special
practices such as establishing new turf areas and
watering in fertilizer or pesticide applications,
often necessitate irrigation during adverse condi-

3. Net irrigation requirements listed are for taller
mowed grass. Closely maintained grass such as
greens and tees have significantly less rooting
depth compared to taller mowed plants, thus
requiring more frequent, shallow irrigations.

4. Rainfall amounts used in these calculations are
averages based on historical climatological data.
Deviations from these averages usually occur and
net irrigation amounts during exceptionally dry
years will have to be increased to compensate for

this. Values listed also assume even rainfall
distribution over the entire period. If uniform
rainfall distribution does not occur, irrigation
amounts higher than those listed in Tables 3-11
are required.

5. "On-site" computer assisted ET predicted models
calculate water needs based on local conditions.
Generally, a range of ET models is used and they
estimate between 0.8 and 1.2 of actual ET.

Irrigation Strategies for Turfgrass Managers

In light of previously discussed topics, strategies
for irrigating golf courses involve calibrating the
irrigation system to determine its output per hour;
determining when to irrigate; and, knowing appropri-
ate application rates.

Calibrating an Irrigation System

Calibrating an irrigation system can be achieved
by several means. One is to measure the gallonage of
water flowing through the system and, with informa-
tion on the area covered, an approximate amount
applied in a given period of time can be determined.

A direct and simple method is to randomly place
containers of the same size (e.g., coffee cans)
throughout each irrigation zone, run the system for a
set amount of time, and then measure depth of water
in each container. These amounts are then averaged
and multiplied to provide inches of water applied per
hour. For example, if an average of 1/ inch of water
is caught in 15 minutes, the irrigation system delivers
1.0 inch of water per hour:

av. inches caught x
per 15 minutes

60 minutes =

inches of water
applied per hour

Table 12. Conversions for determining turfgrass irrigation needs.


1 acre-inch
(amount of water
needed to cover
1 acre to the depth
of 1 inch)

1 inch/1000 sq ft

cu in
cu ft

1 acre-foot
(amount of water
needed to cover
1 acre to the depth
of 1 foot)

620 gal
83 cuft

7.5 gallons

S 325,851 gal
or 43,560 cuft

1 cuft
231 cu in

1 gallon

1 pound of water

S 0.134 cuft
S8.34 Ibs

S 0.1199 gal

1 million gallons

3.07 acre-feet

Irrigation Management Practices

This method indicates not only amounts being applied
but also distribution pattern of the irrigation system.

Determining When to Water

Once the water delivery rate is known, determin-
ing when to water is the next important step. As
discussed earlier, superintendents should not generally
irrigate on a calendar-based time schedule. Irrigation
should be based on ET rates and soil moisture
replacement. Supplementing these measurements are
the use of a rain gauge, soil moisture probe, visual
turf wilting, and tensiometers.

Determining Application Rates

Determining water amounts to apply is the next
step to water management. Enough water should be
applied to wet the entire root zone of the particular
turf. Wetting below the root zone is generally ineffi-
cient since this is beyond the use range of the plant.
Too shallow irrigation encourages shallow rooting,
increases soil compaction, and favors pest outbreaks.
Generally, for golf greens and tees, the majority of
roots are in the top six inches of soil. Therefore,
irrigate to wet this depth unless the root zone extends
deeper. For fairways and roughs, the top 12 inches of
soil should become wet to supply sufficient water for
the plant and to encourage deep rooting.

Amount of water required to wet these depths
will depend on several factors including soil type,
water infiltration and percolation rates, and soil slope.
Figure 1 shows the approximate amount of water
needed to wet various depths of clay, loam, and sand
soils while Table 12 indicates conversion factors to
determine gallonage required to irrigate various
amounts. Managers should double check depth of
moisture penetration by using a soil probe after
irrigating. Once the time needed to moisten soil to
the proper depth is determined, a turf manager will
know how long to water an area in the future.

Soils that are severely sloped, compacted, clayey
in nature, or have a cover of algae, may have low
infiltration rates. Gusty winds also adversely affect
uniform water distribution. As a result, soil may not
be able to absorb the required amount of water at
one time. The turf manager may, therefore, have to
apply water gradually in multiple cycles by turning the
sprinkler on and off several times until the required
amount of water is applied.

Time of Day to Irrigate

As discussed earlier, water loss rates decrease
with reduced solar radiation, little wind, high relative
humidity, and low air temperatures. The superinten-
dent can take advantage of these factors by irrigating
when conditions do not favor excessive evaporation.
Generally, irrigation should occur in early morning
hours before air temperatures rise and relative
humidity drops. Irrigating at this time also removes
dew from leaf blades and allows sufficient time for
infiltration into the soil but not encourage disease

A problem with this timing is that golfers often
begin play early in the morning since it is generally
cooler at this time of day. Therefore, superintendents
may have to water at night. However, some evidence
suggests that irrigating at night may increase the
incidence of certain diseases. On most summer days,
afternoon irrigation is not encouraged unless lowering
canopy temperature is important, fertilizer or pesti-
cide application must be irrigated-in, or overseeding
and turf establishment are being conducted. Watering
efficiency maybe reduced somewhat by mid-day
irrigation. In addition, mid-day irrigation may result
in compaction problems from concentrated play that
normally occurs at that time. Therefore, superinten-
dents should preferably irrigate in early morning,
secondly at night, or least desirably, during the day.
Irrigation during the day may be necessary to incorpo-
rate or activate fertilizer and pesticide applications,
but these usually involve applying /4 inch or less of

Irrigation Management Practices

Irrigation Water Quality


Turfgrasses continually irrigated with water con-
taining salts often become weak, eventually declining
to a point of no longer being acceptable. Salinity
problems usually occur with the combination of
insufficient rainfall and irrigation to leach excess salts;
poor drainage; saline irrigation water; upward move-
ment of leached salt from perched water tables; and
salt water intrusion. With Florida's increasing de-
mands on potable (drinking) supplies, superintendents
may have to use poorer quality water sources. The
following tests provide information concerning soil
and water quality: EC; pH; SAR (ESP); RSC; and,
toxic ions content, especially boron. Also influencing
water quality use are soil water infiltration rates and
differential salinity tolerance of the turfgrass species.

Principal Soluble Salts

Principal soluble salts found in water are chloride
and sulfate salts of sodium, calcium, and magnesium.
Table salt (sodium chloride) is also found in some
soils. Insoluble (gypsum and lime) salts occur but
excessive soluble salts are the primary ones which
may impede plant growth.

The original source of these materials is from
weathering of primary rocks and minerals. Oceans
have become the eventual reservoir of soluble salts as
water has moved through the hydrological cycle.
Along coastal regions of the country, seawater is
intruding into fresh water supplies due to depletion of
aquifers faster than they are naturally replenished and
contaminating them by increasing the level of soluble
salts. In interior regions of the country, ancient saline
marine deposits in geological layers add soluble salts
to groundwater as it passes through the layers. This
process has occurred throughout the country and
virtually all fresh water supplies have some amount of
dissolved salts. Amount of salts in water determines
the degree of salinity and, to a large extent, the
overall water quality.

Salts also can move upward from ground water.
Water is drawn to the surface by evaporation and
plants, and deposited on the soil and plant surface.
Formation of a white crust on the soil surface indi-
cates salt accumulation. This generally is a problem
in low humidity and rainfall areas such as arid western

Measuring and Classifying Irrigation Salinity

Salinity is determined by a meter which measures
the ability of water to conduct an electrical current
(electrical conductivity, EC). Currently, electrical
conductivity is reported in tenths of Siemens or
deciSiemens per meter (dS/m) which are equal to the
former standard of millimhos per centimeter
(mmhos/cm). Electrical conductivity expressed in
dS/m is the preferred salinity measurement because it
represents total salinity that may be associated with
possible salt stress on plants from saline irrigation.

Electrical conductivity and concentration of total
dissolved salts, TDS (in parts per million, ppm), are
related to EC, as shown:

1 dS/m = 1 mmhos/cm = 1000 micromhos/cm

A sodium chloride solution of 1 dS/m is approximately
equal to 640 ppm or milligrams per liter (mg/1) of
soluble salts. Note: some labs use 700 ppm to equal
1 mmhos/cm as a standard instead of 640.

ECw (mmhos/cm or dS/m) x 640 = TDS (mg/I or ppm)

Other salt solutions vary from 550 to 700 ppm for
every 1 dS/m. Water sample salinities are often
compared to those of seawater which has an average
EC of 43 dS/m and about 32,000 ppm dissolved salts.

Irrigation Management Practices

Table 13. Classification of saline Irrigation water.

Electrical con- Concentration of
Salinity ductivlty (dS/m) dissolved salts
class (ppm) Comments
Low <0.25 <150 Low salinity hazard, generally not a problem

Generally not a problem with moderate leaching
Medium 0.25 0.75 150 500 and the use of salt tolerant plants

Good drainage is required as is the use of salt
High 0.75 2.25 500 1500 tolerant plants and special management such as
the use of gypsum and leaching

Requires good drainage, use of salt tolerant
Very High >2.25 >1500 plants, use of soil amendments (such as gyp-
sum) and excess irrigation for leaching

Irrigation water has been classified into four
categories based on the salinity hazard (Table 13).
These limits, which were determined by the United
States Salinity Laboratory, measure total salt concen-
tration of water. Water with EC readings of less than
0.75 dS/m is suitable for irrigation without any prob-
lems. Successful use of water with EC values above
this level depends upon soils conditions and plant
tolerance to salinity.

Blending Water Sources

Water containing excessive salt can be blended
with a better quality water to produce an acceptable
source. Quality of a poor water source should im-
prove proportionally to the mixing ratio with better
quality water. For example, a water source with a EC
of 5 dS/m mixed equally with a source with a EC of 1
dS/m should reduce a salinity blend to approximately
3 dS/m. A chemical analysis of the blend should be
determined to confirm this.

Salinity Effects on Plants

Saline water can cause stress and injury to plants
by several means. Direct salt injury occurs with
accumulation of salts in soil as well as ion accumula-
tion within the plant. The more salt in its rootzone,
the harder the plant must work to take up water.
This direct osmotic stress causes plant dehydration by
removing water from the planfinto the soil because
of a salt concentration gradient. Plant nutrient
deficiencies also are indirectly caused by reduction
and suppression of nutrient absorption by ion substi-
tution. The most common example of this is the

antagonistic effects of sodium and calcium on plant
uptake of potassium and magnesium.

Plant resistance to salt stress varies greatly. Some
plants avoid salt stress by either excluding salt absorp-
tion, extruding excess salts, or diluting absorbed salts.
Other plants tolerate salt stress by adjusting their
metabolism to withstand direct or indirect injury.
Others regulate their internal osmotic potential of
tissue fluid to compensate for increases in substrate
osmotic potentials. In most cases the mechanism of
salt tolerance in plants is a combination of several
methods. As a compensatory adaptive mechanism to
nutrients and water stress under saline conditions,
plants often increase root biomass to enlarge water
and nutrient absorbing area. Highest root weights
occur at intermediate salt levels but decline at high

Common symptoms of turf grown in saline or
sodic soils are spotty stands of grass. A white crust
develops in the bare spots when the environment is
saline whereas no white crust develops in conjunction
with the bare spots in a sodic environment.

Irrigation Management Practices

Table 14. Salt tolerance of turfgrass species grown in culture solutions.

EC at 50% yield reduction
Salt tolerance Species (approximate ppm)
Excellent Zoyslagrass 37 (24,000)
Bermudagrass 28 (18,000)
Seashore paspalum 26 (17,000)
St. Augustinegrass 24 (15,000)

Good Tall fescue 13 (8,000)
Perennial ryegrass 12 (8,000)

Fair Creeping bentgrass 10 (6,000)
Bahiagrass 9 (6,000)
Centipedegrass 9 (6,000)

Plant symptoms of salinity stress initially resemble
drought stress. The initial symptom is reduced
growth. Leaf blades become narrower and stiff, and
can become darker green or even blue-green in color.
Shoot growth generally decreases with increasing
salinity stress. There also is a tendency for turf to
wilt faster than normal as a result of osmotic stress.
Root growth initially increases, but over time, root
growth is reduced presumably as a response to
reduced shoot growth. Shoot and root growths are
reduced at high salt levels through both direct and
indirect salt injury. Leaf tipburn and a general
thinning of turf develop at higher salinity levels.
Severe salt stress will ultimately cause turf death,
leaving a patchy, thin turfgrass stand.

Turfgrass Salt Tolerance

Turfgrass species have been classified according to
salt tolerance (Table 14). Most turfgrass comparisons
are based on the salt levels which cause a 50 percent
reduction in top or root growth. Only a few species
grow well under saline conditions. Zoysiagrass,
seashore paspalum, bermudagrass, and St. Augustine-
grass are the best species to grow in Florida if irriga-
tion is limited to saline water. Under these condi-
tions, grasses require good drainage and moist soil
conditions to produce good quality turf. In addition,
adequate leaching is essential, whether it is from
rainfall or excess saline irrigation. Because of nema-
tode and insect pest problems with these turfgrasses,
maintenance necessities need to be carefully consid-
ered before planting.

Cultivars within a species often show a wide range
of salt tolerance (Table 15). Sometimes cultivar
differences are greater than species differences.

Tifdwarf and Tifgreen are the most salt-tolerant ber-
mudagrass cultivars available.

Table 15. Salt tolerance of various bermudagrass cultivars.

Salt tolerance Bermudagrass
Most Tifdwarf
Least Ormond

Saline Irrigation Influence on Soils

Soils are a key to continued use of saline irriga-
tion water. Good drainage is essential to leach soluble
salts through the soil profile. The better the drainage,
the more successfully proper saline irrigation can
keep the soil level of soluble salts within tolerable
limits. Sand soils are usually best suited for saline
irrigation because of easy drainage, but they must be
maintained at field capacity in order to prevent
intolerable salt levels.

Soluble salts are measured in soils by the same
basic method as water samples. A conductivity
instrument measures electrical conductivity either
from a saturated paste extract from a soil or from a
soil water dilution ratio. The IFAS Soil Testing
Laboratory uses the dilution method by diluting one
part dry soil to two parts water. Soils with EC
readings of 2.0 to 4.0 dS/m are considered to have low
salt levels (Table 16). Soils with EC readings of 4.0

Irrigation Management Practices

to 12.0 dS/m have medium levels. When readings are
above 12.0 dS/m, soils are considered to have high
salt levels and only salt-tolerant turfgrasses survive
above 16 dS/m.

Table 16. Classification of saline soils.

Salinity Class EC (dS/m) TDS (ppm)
(1:2 dilution
low 2 to 4 1300 to 2500
medium 4 to 12 2500 to 7500
high >12 >7500

Leaching to Remove Salts

Salt build-up from salt laden irrigation water
occurs when rainfall is low and evaporative demand is
high. This normally corresponds to mid-spring (April
and May) and late-summer through early fall (Sep-
tember and October) in Florida. As water evaporates
from the soil surface, salt deposits are left behind.
Frequent flushing of such areas with rainfall or
irrigating with good quality water are the best meth-
ods to prevent salt build-up. Unfortunately, many
irrigation sources contain varying levels of salt, forcing
soil salinity management with saline water.

If saline water is used to attempt to reduce the
salt level in the soil, irrigation must be applied at
rates exceeding evapotranspiration to leach excess
salts out of the root zone. To determine amount of
excess water required to leach salt below the
rootzone, the following equation is often used.

EC, equals electrical conductivity of the saline
irrigation source and ECd, is electrical conductivity
tolerable by the specific turfgrass being grown. For
example, an irrigation water source with a salinity
level of 2 dS/m used on a turfgrass tolerant of a
salinity of 4 dS/m would equal 2/4 or 50 percent extra
amount of irrigation water applied in addition to
normal irrigation requirement of the turf to leach salt
from the rootzone (e.g., 50% greater than 2 inches of
water applied would equal 3 inches) (Table 17).

As previously mentioned, leaching works well only
with soils possessing good drainage. If compacted
zones or abrupt changes in soil texture exist, less
leaching occurs as water movement through the soil
is reduced. Good soil drainage through use of
drainage tile is used for carrying away salty water.
Tile lines, spaced no more than 20 feet apart, are
used on golf greens for this purpose.


Another major water quality problem with saline
irrigation sources is that of deteriorating soil struc-
ture. Fortunately for Florida sandy soils, this concern
is greater on fine-textured soils. Sodium ions are
adsorbed by soils containing higher amounts of clay
particles which causes them to become dispersed
(deflocculate). This results in the clogging of soil
pores which reduces soil aeration and water infiltra-
tion or permeability. Increasing calcium and magne-
sium concentrations in clay soils will counteract
negative effects of the sodium, therefore, help main-
tain good permeability.

Table 17. Recommended Irrigation amounts for saline water.

Maximum plant ECdw tolerance level, measured by saturated soil paste
Irrigation Water extract (dS/m)
ECw (dS/m) 4 (low) 8 (medium) 16 (high)
(inches of water required to replace weekly ET losses and provide adequate
leaching in rootzone)
0.00 1.5 1.5 1.5
1.00 2.0 1.7 1.6
2.00 3.0 2.0 1.7
3.00 6.0 2.4 1.8

Irrigation Management Practices

Sodium Adsorption Ratio

The relationship between sodium, calcium, and
magnesium ions in irrigation water is expressed by
Sodium Adsorption Ratio (SAR), where:

SAR= [Na
[Ca ]+[Mg +

All ion concentrations are expressed as milliequiva-
lents per liter (meq/1). To convert meq/1 to mg/l (or
ppm), multiply the specific ion by its equivalent

meq/1 x equivalent weight = mg/l or ppm

Equivalent weights for sodium, calcium, and magne-
sium are 23, 20, and 12.2, respectively (Table 18).
Guidelines for correlating SAR values with potential
problems are provided in Table 19.

Exchangeable Sodium Percentage

ESP = Exchangeable sodium (meq/100 grams) x 10O
Cation exchange capacity

ESP indicates the impermeability of soil to water
and air. Usually little or only minor problems occur
when ESP values are less than 15 percent. Over 15
percent, soil physical changes occur which may cause
impermeability to water and air, especially if ECw of
irrigation water is less than 2 dS/m (Table 20).
Increasing problems occur with values approaching 80
percent. Symptoms of reduced permeability include
waterlogging, reduced infiltration rates, crusting,
compaction, and poor aeration.


Water that is low in sodium and dissolved salts
but high in bicarbonates (HC03') may result in in-
creasing soil pH to an approximate maximum pH of
8.0 to 8.5. Calcium carbonate and magnesium carbon-
ate may then precipitate out as lime. An increase in
effective sodium percentage of the water in place of
calcium and magnesium then occurs. In this way,
calcium- or magnesium-dominant soils can become a

An additional soil parameter to measure is ex-
changeable sodium percentage (ESP). This indicates
the percent of sodium that occupies cation exchange
sites of a soil (or soil sodium saturation):

Table 18. Laboratory analysis to determine water quality.

Analysis Reporting symbol Reporting unit Equivalent weight
Electrical conductivity ECw mmhos/cm
Calcium Ca meq/l 20
Magnesium Mg meq/I 12.2
Sodium Na meq/I 23
Carbonate CO3 meq/I 30
Bicarbonate HCO3 meq/l 61
Chloride CI meq/l 35.4
Sulphate SO4 meq/I 48
Boron B mg/I -
Nitrate-nitrogen NO3-N mg/I 14
Acidity pH pH -
SAR --
Potassium K meq/I 39.1
Lithium Li mg/I 7
Iron Fe mg/l -
Ammonium-nitrogen NH4-N mg/I 14
Phosphate phosphorus PO4-P mg/I 31

Irrigation Management Practices

Table 18. Laboratory analysis to determine water quality.

Value Category Precaution
0-10 1 (low Na water) Little danger

10-18 2 (medium Na water) Problems on fine texture soils and sodium sensitive plants,
especially under low-leaching conditions. Soils should have
good permeability.

18-24 3 (high Na water) Problems on most soils. Good salt tolerant plants are required
along with special management such as the use of gypsum.

Unsatisfactory except with low salinity, high calcium levels, and
>24 4 (very high Na water) the use of gypsum.

dominant soil by use of high bicarbonate irrigation
water and a corresponding increase in SAR values
occurs. Residual sodium carbonate (RSC) equation
reflects this potential precipitation of calcium and
magnesium and resulting increase of effective sodium
percentage of water. RSC specifically measures
presence of excess carbonate (C03-2) and bicarbonate
(HCO3-) content over calcium (Ca+Z) and magnesium
(Mg+2) ions expressed each as meq/1:

RSC = (CO,-2 + HC03j (Ca+2 + Mg+2)

Table 21 lists quality of water in relation to RSC

RSC Value Potential Use
:1.25 Generally safe for irrigation

1.25 to 2.5 Marginal

>2.5 Usually unsuitable for irrigation

Table 21. Relative RSC values and range for irrigation water.

Table 20. Classification of soils based on their sodium Ion or soluble salt contents.

EC, Value
Designation (ds/m)* ESP Comments
Saline soil >4 <15 Soil pH is usually below 8.5. A white salt crust, referred
to as 'white alkali', forms on the soil surface as the soil
dries. Adequate water and drainage for leaching are
necessary to desalinize these soils.

Soil pH Is usually below 8.5. The soils resemble saline
Saline-sodic soils >4 >15 soils if the soluble salts are not leached. The soil re-
sembles sodic soils if soluble salts are leached but the
exchangeable Na remains constant.

Soil pH is generally above 8.5. Referred to as 'black
alkali' and does not form a white salt crust on the soil
Sodic soils <4 >15 surface. Clay particles are dispersed in these soils
when high levels of Na combined with low levels of Ca
and Mg. Structureless soils result with low water and air

*EC, values are based on saturated extracts.

Irrigation Management Practices

Bicarbonate levels alone are sometimes provided
without regard of calcium and magnesium ions.
Values in Table 22 reflect potential hazard of an
irrigation water source in relation to bicarbonate

Table 22. Relative hazard of an irrigation water source as
related to bicarbonate levels.

In addition to affecting soil permeability of clay
soils, a high bicarbonate content in water can increase
soil pH to unacceptable levels. Alkaline water has a
high pH, relative high level of sodium and bicarbon-
ate, and relatively low calcium and magnesium levels.

Table 23. Potential trace element tolerances for irrigation water.

Use of acidifying materials may be necessary to
reduce impact of bicarbonates on pH. Usually,
irrigating with water sources containing low bicarbon-
ate concentrations can be managed by use of acidify-
ing fertilizers (e.g., ammonium sulfate) or application
of granular elemental sulfur. High bicarbonate
containing water may require acidification (via injec-
tion into the irrigation system) with sulfuric or phos-
phoric acids to correct the problem. .This process
requires specialized equipment and constant monitor-
ing to ensure successful acidification of water without
phytotoxic effects occurring to turf. Normally, a
desirable pH range for turfgrasses is 5.5 to 7.0.
Levels above and below these may have detrimental
effects and is discussed in further detail in this and
the soil chemical property chapters of this book.


Irrigation water quality is also influenced by other
specific ions. Most irrigation water sources contain
low levels of a variety of elements. Normally these
pose no problems but can increase under conditions
of inadequate leaching with quality water, poor soil
permeability and during periods of high evaporation.
Amount of sodium is of prime concern because it is
often found in the largest amount. Sodium is also an

Continuous use Short-term use on fine-textured
Element (ppm) soils (ppm)
Aluminum (AI) 1.0 5.0 20
Arsenic (As) 1.0 10
Beryllium (Be) 0.5 1.0
Boron (B) 0.75 2.0
Cadmium (Cd) 0.005 0.0005 0.05
Chorine (CI) 10
Chromium (Cr) hexavalentt) 5.0 20
Cobalt (Co) 0.2 10
Copper (Cu) 0.2 5
Fluorine (FI) ? ?
Fluoride 1.0 ?
Iron (Fe) ? ?
Lead (Pb) 5.0 20
Lithium (U) 5.0 5.0
Manganese (Mn) 2.0 20
Molybdenum (Mo) 0.005 0.05
Nickel (Ni) 0.5 2
Selenium (Se) 0.05 0.05
Tin (Sn) ? ?
Tungsten (W) ? ?
Vanadium (V) 10 10
Zinc (Zn) 5 10

Irrigation Management Practices

Table 24. Guidelines for interpreting the quality of irrigation water.

Minor Prob- Increasing Severe
item lems Problems Problems
Specific ion toxicity from ROOT absorption
Sodium (meq/1) <3 3-9 >9
Chloride (meq/1) <4 4 10 >10
(mg/I) <142 142-355 >355
Boron (mg/I) <0.5 0.5 2 2 10

From FOLAR (sprinkler) absorption
Sodium (meq/l) <3 >3 ---
(i11g/l) <69 >69
Chloride (meq/l) <3 >3 ---
(mg/I) <106 >106 ---

NH4-N (for sensitive crops) (mg/I) <5 5 30 >30
N03-N (mg/I) <5 5 30 >30
HC03'(sprinklers) (meq/l) <1.5 1.5 8.5 >8.5
(mg/I) <90 90 520 >520

antagonistic ion which displaces potassium and can
limit availability of iron and manganese in soils.
Boron in irrigation water is rarely a problem for
turfgrasses because boron accumulates in leaf tips
which are removed by regular mowing. However,
other landscape plants may be more sensitive to
boron levels. High concentration of chloride, sulfate,
and bicarbonate ions also can cause specific ornamen-
tal plant injury under certain soil conditions. Tables
23 and 24 offer general ranges of elements and some
expected results at.various concentrations.


Several soil amendments are used for soil recla-
mation in conjunction with leaching to remove salts
from the rootzone. The soil amendments react with
soil sodium to cause it to be released. These released
salts must then be leached out of the soil profile. It
has been reported that one acre-foot of quality water
applied per acre will reduce salinity by about 50
percent whereas two acre-feet per acre passing
through one foot of soil will reduce salinity by about
90 percent.

Amendments used for treatment of clay-textured
sodic soils include gypsum, sulfur, sulfuric acid, lime
sulfur, ferric sulfate, calcium chloride, calcium nitrate,
and calcium carbonate. Table 25 lists several amend-
ments and their equivalent amounts to pure gypsum.

Because of their expense, calcium chloride and
calcium nitrate are not widely used. Sulfuric acid is

dangerous to handle and can be corrosive to some
types of equipment. Ferric sulfate and lime sulfur
also are usually too expensive for practical applica-
tions. Ground limestone is effective on acid soils, but
its usefulness drops in high pH soils, which most sodic
soils are. Thus, gypsum is the material most often
used for reclaiming clay-textured saline soils.

Table 25. Equivalent amounts of several soil amendments
in relation to pure gypsum.

Amendment Equiva-
lence to
pure gyp-
Gypsum (CaSO4 2H20) 1.00
Sulfur (S) 0.19
Sulfuric acid (H2SO4) 0.61
Ferric sulfate [Fe2(SO4 9H2)] 1.09
Lime sulfur (CaSx; 9% Ca + 24% S) 0.78
Calcium chloride (CaCl2 H20) 0.86
Calcium nitrate [Ca(NO3)2 H20] 1.06


Gypsum is used because of its effectiveness and
low price. Gypsum is a by-product of phosphorus
acid mining. It is low-to-moderately soluble in water
and supplies soluble calcium to replace sodium, as

Irrigation Management Practices

2NaX + CaSO4 -> CaX2 + NaiSO441
soil sodium gypsum soil sodium
calcium sulfate
by leaching)

The letter X indicates the exchange site for cations on
the soil colloid. Gypsum, by mass action, drives
sodium off the soil exchange complex and replaces it
with calcium. It leaves sodium sulfate, which is
soluble, and readily leaches downward with percolat-
ing water.

Irrigation is needed to dissolve gypsum. Several
irrigations usually are required to dissolve gypsum and
leach sodium. Generally, if the sodium problem is
slight, passage of one foot of water through the soil is
sufficient to leach out the salt. Two feet of water are
needed on moderate sodium problem soils while
three or more feet are needed on severe sodium soils.

Increased soil-water infiltration and percolation
rates also occur with addition of gypsum. However,
this occurs only to soils with excess sodium or potas-
sium. Even though gypsum supplies calcium, gypsum
is a neutral salt and does not appreciably affect soil

A method to provide a rough estimate of a soil's
amendment need follows:

1. Take a one-quart soil sample from the surface of
the impermeable area. Thoroughly dry and pul-
verize it until the largest particles are about the
size of coffee grounds.

2. Add one heaping teaspoon of powdered gypsum
to one pint of pulverized soil and mix thoroughly.
Leave an equal amount of soil untreated.

3. Prepare two cans 3 to 4 inches in diameter and 4
to 6 inches tall. One open end should be covered
with a piece of window screen so water can
percolate but soil cannot. Put treated soil in one
can and untreated soil in a separate can. Fill
each can about % full with water and pack each by
dropping the can from a height of about one inch
onto a hard surface about ten times.

4. Fill the can with the irrigation water in question,
being careful not to disturb the soil.

5. Collect the water as it drains and when 1/2 pint or
more is collected from the gypsum-treated sam-
ple, compare this volume with that obtained from
the untreated sample.

6. If less than half as much water has passed
through the untreated as through the gypsum-
treated soil in the same length of time, this indi-
cates your soil contains excess exchangeable
sodium. If so, the addition of a chemical amend-
ment is likely to improve permeability and help
reclaim the soil.

Pure gypsum contains 26% calcium and 21%
sulfur. If gypsum contains impurities or is wet, it will
contain less calcium and/or sulfur and larger quanti-
ties will be necessary.

Effectiveness, in general, increases with the
fineness of the gypsum. Gypsum used for agriculture
should be fine enough so at least 80% should pass a
United States Standard No. 8 sieve. Finer, pulverized
gypsum, (like limestone), reacts quicker with soil but
becomes difficult to apply. Larger particles not able
to pass a No. 8 sieve are too slow to dissolve render-
ing them relatively ineffective.

Application Rates

The amount of gypsum required to reclaim high-
sodium soils depends upon sodium concentration of
the soil. This is determined by a soil test and by soil
texture. Rates required are listed in Table 26. The
objective is to achieve ESP values below 10% on fine-
textured soils and below 20 percent on coarser-
textured soils.

Table 26. Gypsum amounts required as related to soil
texture and sodium percentage.

Exchangeable Sodium Percentage
Soil Texture 15 20 30 40 50
Coarse 2 3 5 7 9
Medium 3 5 8 11 14
Fine 4 6 10 14 18

Irrigation Management Practices

These values reflect gypsum use on non-estab-
lished soils. Rates should not exceed 5 tons per acre,
per application. Rates over 5 tons per acre should be
split with successive applications not made until
sufficient time for some leaching has occurred.
Additional needs should then be verified by a second
soil test.

Gypsum should be applied during mild tempera-
tures (e.g., 580OF). It is slow reacting and does not
normally burn foliage. Due to its low water solubility,
some time will be required before gypsum will disap-
pear from the soil surface.


Elemental sulfur also is used for soil reclamation.
Commercial sulfur ranges in purity from 50 to 99%.
Value of sulfur for reclamation depends on its purity
and fineness. Like gypsum, the finer the material, the
faster it is oxidized in soil.

Sulfur furnishes calcium indirectly in a two-step
process. Sulfur must first be oxidized by soil bacteria
to sulfuric acid.

28 + 302 + 2H20-----------> 2H2S04
sulfur oxygen water sulfuric acid

Sulfuric acid then generally reacts with lime in the
soil to produce gypsum.

CaC03 + H2SO4 -----> CaSO4 + H20 + C02t
lime sulfuric acid gypsum water carbon

Gypsum then reacts with sodium ions to produce
soluble sodium sulfate.

2NaX + CaSO4 <-------> CaX + Na2S041
sodic gypsum calcium sodium
soil soil sulfate

In soils lacking free lime, the reaction is:

2S +302 + 2H0 ------------> 2H2S4

Sulfuric acid produced then reacts directly with
sodium ions as follows:

2NaX + H2S04 <----- > 2HX + Na2SO4

Oxidization of sulfur to sulfuric acid is by soil
bacteria, a slow process that requires warm, well-
aerated and moist soil. Sulfur application, therefore,
should not be made during cooler fall and winter

Irrigation Management Practices

Effluent Wastewater Use on Turf


Use of effluent wastewater for irrigation purposes
is a possible alternative water source for many turf
growers. Irrigation with effluent water is an old prac-
tice. It was used by the Greeks in Athens and was
used on golf courses in San Francisco as early as
1932. Turf may be a suitable commodity to use
effluent water since it absorbs large amounts of
nitrogen and other nutrients found in reclaimed
water. This reduces chances of groundwater contami-
nation from effluent water use. Since turf is a peren-
nial crop, a continuous supply is needed. Turf also is
often located near metropolitan areas; therefore,
conveyance costs could be reduced. Since turf is not
a food crop, potential health problems arising from
reclaimed water are minimized.


Effluent, reclaimed, or wastewater are terms used
synonymously to describe water that has gone through
one cycle of domestic use. Ideally, effluent or
wastewater used for turf irrigation should principally
come from a urban area without significant industrial
input. This should guard against the possibility of
excessive heavy metal content from industry. Treat-
ment level of wastewater also should be at least
secondary. Primary treatment begins with the prelimi-
nary operations such as screening and sedimentation
that removes organic and inorganic solids. After
screening and possible grinding of debris, dense
materials such as sand and stones are allowed to
settle in a grit chamber. This material is normally
washed and also is used as landfill.

Undissolved suspended matter is then removed in
a second settling tank or a primary clarifier. Settled
material forms a mass of raw sludge which is concen-
trated and used as landfill.

Remaining liquid in the settling tank is called
primary effluent and may be chlorinated to destroy
bacteria and reduce odor before it used. Primary
sedimentation removes approximately 60 to 70 per-

cent of the suspended solids and 25 to 40 percent of
the biochemical oxygen demand.

Non-chlorinated primary effluent water may be
further treated to break down complex organic matter
during secondary treatment. Up to 90 percent of
organic matter is removed by secondary treatment.
Water is then chlorinated and is the principal source
of water for agricultural irrigation purposes.

Advanced or tertiary wastewater treatment involves
using a charcoal bed for chemical coagulation and
flocculation, sedimentation, filtration, or adsorption of
compounds. This process can provide highly purified
water and is similar to potable water treatment.

An alternative method to these conventional
treatments of wastewater is land treatment. Overland
flow and rapid infiltration are methods utilizing the soil
surface and vegetative layer as a natural filter.
During these processes, water is applied to land. The
renovated water is collected either at the bottom of
an overland land flow slope (overland flow) or from
within the soil by a series of wells. It also is collected
by permanent underdrains (rapid infiltration). Rapid
infiltration requires less land to renovate wastewater
compared to overland flow but requires a permeable
soil, a series of wells or underground drainage tiles,
and has a host of environmental regulations.


Effluent water has three major categories of
characteristics that are modified during use: 1) biolog-
ical composition; 2) organic composition; and, 3)
dissolved inorganic salts. Although biological compo-
sition of effluent water is of great concern because of
pathogenic bacteria and viruses, renovated waters are
not released for irrigation without prior approval of
the public health officials.

Secondary treated wastewater has been disinfected
to a level of 23 total coliforms per 100 ml, so direct
contact with effluent water should be avoided. Treat-
ed areas should also be allowed to dry before golf

Irrigation Management Practices

course play resumes. To eliminate the possibility of
accidental contamination of a domestic water system,
a entirely separate delivery system should be con-

For irrigation purposes, the organic portion of the
effluent water is generally of minimal consequence.
The most influential characteristic of effluent water
irrigation is the higher salt load which results from its

Dissolved Solids

Soluble materials accumulate in water as the
result of it having been used once. Generally, water
going through one cycle of average home use accu-
mulates approximately 300 ppm of Total Dissolved
Solids (TDS). Any water having TDS greater than
1,000 ppm will have limitations as a successful long-
term irrigation source.


Water management and adequate drainage is the
key to successful effluent use in turf management.
Ability to leach out these salts is necessary to prevent
accumulation of toxic concentrates. High TDS-con-
taining effluent water also has a tendency to clog soil
pores and coat the land surface. Coarse-textured
soils, such as sandy loams, with a moderately perme-
able soil capable of infiltrating approximately two
inches per day or more on an intermittent basis, are
best for the use of wastewater. Soils with a hard pan,
clay pan or underlying rock may create a perched
water table which promotes surface accumulation of
salts and heavy metals.

Initial tests should be taken to show the Sodium
Absorption Ration (SAR) or Exchangeable Sodium

Percentages (ESP), which is an index of the effect of
sodium in reducing soil permeability (the rate which
water passes into and through soil) based on the ratio
of sodium to calcium and magnesium. A SAR of 10
or less is considered desirable. If greater than 10,
gypsum or gypsite could be incorporated into the
management program or alternate applications of
fresh water with effluent water should be followed to
help leach out sodium. A SAR above 10 indicates
increasing potential permeability problems. Sodium-
rich irrigation waters can replace soil exchangeable
calcium and magnesium with sodium resulting with
reduced permeability. Usually this is more of a
concern in arid states in which most irrigation water
sources have high a sodium content. This may,
however, be a concern in Florida during dry months
(e.g., April, May, October) and if salt intrusion has
occurred into the normal irrigation water source or
into the sewage system. Waterlogging, slow infiltra-
tion, crusting or compaction, poor aeration, weed
invasion, and disease occurrence are typical symptoms
of reduced permeability. A severe infiltration prob-
lem may develop if electrical conductivity (ECw) of
irrigation water is less than 0.2 mmhos/cm.

Effects of sodium in irrigation water can be
partially offset by dissolving gypsum in the wastewater
stream. However, high salinity concentrations cannot
be easily overcome. Dilution of high salinity waste-
water with freshwater is probably the most practical

Other potential problems with effluent irrigation
use include exposure of golf course maintenance
equipment and golf carts to salt when these are driven
through depressions holding standing effluent water.
Internal switches and underside bodies of carts are
susceptible to rusting from salinity as are seals and
bearings associated with maintenance equipment.

Table 27. Typical nutrient ranges in effluent water used for irrigation.

Rating (ppm)
Element Low Normal High Very High
Calcium <20 20-60 60-80 >80
Magnesium <10 10-25 25-35 >35
Potassium <5 5-20 20-30 >30
Phosphorus <0.1 0.1-0.4 0.5-0.8 >0.8
Nitrogen <1 1-10 10-20 >20
Nitrates <5 5-50 50-100 >100
Sulfur <10 10-30 30-60 >60
Sulfates I<30 30-90 90-180 >180

Irrigation Management Practices

Using cart paths and the frequent rinsing of the
equipment with fresh water will minimize these

Nutrient Content

Application of wastewater to crops can be benefi-
cial because of nutrients in the liquid. Virtually all
essential plant nutrients are found to some degree in
wastewater. Constant monitoring of effluent water
should be maintained to determine amounts of these
individual nutrients and the fertility management of
turf be adjusted to account for these. Potential
nitrogen levels range from 10 and 35 mg/l, phospho-
rus 0 to 5 mg/l and potassium 5 to 25 mg/l (Table 27).
To convert ppm to pounds of salt-per-acre foot of
irrigation water, multiply ppm by 2.72.

Heavy Metals

Heavy metal concentrations usually are not a
problem with urban effluent water sources but are
potential major concerns with certain industrial
effluent sources. This is why industrial effluent water
sources are not generally recommended for turf

There are several trace elements in domestic
effluent water which could be present in potentially
toxic amounts under certain conditions. They there-
fore should be monitored periodically. These include
chlorine, boron, cadmium, copper, nickel, and zinc.
Groundwater contamination is the main concern of
their presence. Recommendations include a mini-
mum soil depth of five feet to groundwater supplies
and a upper irrigation limit of four inches per week.
Groundwater monitoring wells are normally required
in areas using effluent water. Suggested maximum
levels of trace metals in effluent water are listed in
Table 23.

Turfgrasses usually are tolerant to these levels but
many trees and shrubs may be sensitive, especially
when grown on heavy soils where their amounts of
chloride often increase. Certain trees and shrubs are
especially sensitive to chloride levels approaching 350

Storage Ponds

A seasonal problem for turf managers using
wastewater is most contracts require a specific
amount be accepted daily, regardless of weather
conditions. In other words, a pre-set level of waste-

water must be accepted per-day whether it is needed
or not. Storage capability, therefore, is a major
requirement when using effluent water and must be
adequate to store enough water for the maximum
days of non-irrigation (usually a minimum of three).

Storage ponds generally are acceptable for waste-
water storage as long as storage amount does not
impair the pond's ability to function as a stormwater
management system. Generally, storage ponds do not
have to be lined but should be at least six feet deep,
with good aeration, and have a 3-to-1 bankside slope
to minimize aquatic weed problems. Use of a filter
system also is suggested to reduce algae that may
enter the sprinkler system and clog nozzles. Even
distribution by the irrigation system also helps prevent
buildup of any harmful substances.

A weeks's supply of water (assuming 11/2 inches of
water applied on 100 acres of turf) would be 4 million
gallons or 533,300 cubic feet, translating into a lake
10 feet deep measuring approximately 180 feet by 300
feet in size. Several smaller ponds may fit a golf
course layout better than one large lake.

Golf Greens

In light of previous discussed advantages and
disadvantages of using effluent water for golf course
irrigation, it is suggested that only tertiary treated
wastewater be used on golf greens. Turf mowed
excessively low, such as golf greens, are constantly on
the management edge in terms of maintaining a
healthy, acceptable playing surface. Although primary
and secondary wastewater impurities are low, golf
greens do not need added stress in terms of salinity
and salts. Salinity can be extremely detrimental to
golf greens due to their relative shallow and weak
root systems. Continued use of wastewater with low
to moderately TDS may, in time, reduce water infil-
tration and percolation to the point of reducing turf
quality. For these and other reasons, primary and
secondary reclaimed water sources are not recom-
mended for golf greens.

If a turf manager must use one of these waste-
water sources for irrigating golf greens, several
prerequisites exist for any chance of turf survival.
The golf green should have excellent (>6 inches-per-
hour) infiltration and percolation rates to prevent
salinity buildup. A superintendent must also be
allowed to frequently aerify, spike and slice the soil
surface to minimize crusting and algae development.

Irrigation Management Practices

Regular flushing with a fresh water source also is
necessary to remove salts.

Higher mowed turf such as fairways and roughs
are better able to tolerate higher salinity and TDS
levels. Secondary wastewater, therefore, may be used
successfully on such areas, assuming cultural practices
such as aerifying and spiking are allowed. Exposure
and environmental concerns, however, must be
addressed before using this source on these areas.

Irrigation System Design

Corrosion of metallic parts and plugging of nozzle
orifices are two potential problems in irrigation
components when using wastewater. Chlorides and
ammonia are corrosive components of many waste-
water sources. Chlorides damage brass irrigation
valves and fittings as well as galvanized pipe and
fittings. Ammonia can be corrosive to copper pipe
with concentrations as low as 1.5 mg/l nitrogen.
Combination of chlorides and ammonia substantially
increase chances of corrosion.

Nozzle orifice clogging is potentially a problem
when using wastewater. This usually is not a problem
with secondary treated effluent if relatively large
irrigation nozzle sizes are used. Normally, the high
pressure used to irrigate serves as a self-cleaning

Problems from clogging may occur from algae
growing in the nutrient rich wastewater while in
storage ponds or in the piping system. A filtration
system should be provided to minimize algae intro-
duction into pipes, and valves should be designed to
handle wastewater.

Sprinkler heads should be placed so that a mini-
mum of 75 feet exists between the outside radius-
throw and potable wells and public areas. Part-circle
heads also should be used adjacent to wetlands and
estuaries. This may result in unwatered spaces that
look undesirable due to drought and untidiness.
Berms, or swales, also may be necessary to limit
runoff of wastewater from treated areas to private and
environmental sensitive areas.

Above-ground spigots, hose bibs, quick-couple
connections, etc., are not allowed when using effluent
water. These must be in below ground boxes that are
locked and marked clearly.

Other Information and Suggestions

* pH values for most urban effluent water range
between 6 to 8.

* Nematode concentrations have not been found to
.increase with effluent water use.

* Use of salt tolerant grasses, such as hybrid ber-
mudagrass, should be considered before applica-

* Effluent water should not be sprayed on domestic
water wells, reservoirs or near drinking fountains
or eating areas.

* Irrigation systems should have proper filters to
catch any damaging solids.

* Irrigation lines should be tagged, colored, and
designed so that unauthorized persons cannot
operate them.

* Communicate to all persons about the procedure.
Establish and maintain good relations with all
governmental agencies involved.

* All irrigation should be timed to minimize public
contact and to allow ample opportunity for land
to dry out before it is re-used.


Anonymous. 1972. Water quality criteria. Agricultur-
al Use of Water, Nation Academy of Science-National
Academy of Engineering, Washington, D. C. Sec. V.
p. 323-353.

Augustin, B. J., A. E. Dudeck, and C. H. Peacock.
1986. Saline irrigation of Florida turfgrasses. Florida
Coop. Ext. Service, Circular 701. 5pp.

Augustin, B. J. and G. H. Snyder. 1984. Moisture
sensor-controlled irrigation for maintaining bermuda-
grass turf. Agron. J. 76:848-850.

Ayers, R. S. and D. W. Westcot. 1976. Water quality
for agriculture. Irrigation and drainage paper 29.
Food and Agriculture Organization of the United
Nations. Rome, Italy. 97pp.

Beard, J. B. 1985. An assessment of water use by
turfgrasses. p.47-60. In V. B. Youngner and S. T.
Cockerham (ed.) Turfgrass water conversation. Proc.

Irrigation Management Practices

Symposium ASPA, San Antonio, TX. 15-16 Feb.
1983. Coop. Ext. Univ. of California, Oakland, CA.

Branson, R. L. and M. Fireman. 1980. Gypsum and
other chemical amendments for soil improvement. Div.
Agricul. Sciences, Univ. of California Leaflet 2149.

Butler, J. D., P. E. Rieke, and D. D. Minner. 1985.
Influence of water quality on turfgrass. p. 71-84. In
V. B. Youngner and S. T. Cockerham (ed.) Turfgrass
water conversation. Proc. Symposium ASPA, San
Antonio, TX. 15-16. Feb. 1983. Coop. Ext. Univ. of
California, Oakland, CA.

Carrow, R. N., 1985. Soil/water relationships in
turfgrass. In V. B. Youngner and S. T. Cockerham
(ed.) Turfgrass water conversation. Proc. Symposium
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Emmons, R. D., 1984. Turfgrass Science and Man-
agement. Delmar Publishers, Inc. Albany, NY.

Harivandi, A. 1991. Effluent water for turfgrass
irrigation. Coop. Ext. Ser. Univ. of California. Leaflet
21500. llpp.

Harivandi, M. A., J. D. Butler, and L. Wu. 1992.
Salinity and turf culture. p. 208-230. In D. V. Wad-
dington, R. N. Carrow, and R. C. Shearman (eds.)
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Kneebone, W. R., D. M. Kopec, and C. F. Mancino.
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In D. V. Waddington, R. N. Carrow, and R. C. Shear-
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McCloud, D. E. 1955. Water requirements of field
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Pound, C.E. 1973. Wastewater treatment and reuse by
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Shearman, R. C. 1985. Turfgrass culture and water
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Sullivan, D. L. 1970. Wastewater for golf course
irrigation. Water and Sewage Work 117(5), p. 153-159.

Tucker, B. 1984. The use of gypsum on turf.
Oklahoma Turf 2(1):1-3.

Watson, J. R. 1985. Water resources in the United
States. p. 19-36. In V. B. Youngner and S. T. Cocker-
ham (ed.) Turfgrass water conversation. Proc. Sym-
posium ASPA, San Antonio, TX. 15-16. Feb. 1983.
Coop. Ext. Univ. of California, Oakland, CA.

Wildmon, J. 1991. Converting golf courses to
effluent irrigation. Florida Turf Digest 8(5):17-18.

Youngner, V. B. 1985. Physiology of water use and
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