7/17/2015

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Improving Water Use in the Landscape

MAUREEN THIESSEN

COMMERCIAL ORNAMENTAL AREA SPECIALIST

TENNESSEE STATE UNIVERSITY, UNIVERSITY OF TENNESSEE

Purpose of irrigation

system

To deliver adequate water to plantings such that manual methods

are reduced as much as possible.

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Objectives

Identify problems associated with improper irrigation management

Understand landscape and environmental elements that should be considered in

irrigation design

Learn how to account for those elements in irrigation design using appropriate equipment and scheduling

Reasons to be conscientious

about water

Plant health, disease

Root Establishment

Water availability

Environmental conservation

Maintain a professional look

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Photo: Savelandscapewater.org

Photo: Forester University

Photo: Turfdiseases.org

Photo: University of Florida

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Cost of

Municipal WaterAlliance for Water Works

27,154 gallons

Cost of

Municipal WaterAlliance for Water Works

6,788 gallons

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Cost of

Municipal Water

One inch of water applied over an acre is 27,154

gallons

One-quarter acre-inch = 6,788 gallons

Within City:

$3.47/1000gal + base

($3.47 x 6.788gal) + ($4.46) =

$28.00 per inch of applied

water per quarter acre

Alliance for Water Works

Outside City:

$6.94/1000gal + base

($6.94 x 6.788gal + $8.92)

$56.03 per inch of applied

water per quarter acre

Johnson City Water Rates (not including sewer)

Scheduling considerationsMother Nature’s Resources

Plant type

Some plants require more than others

Soil

Infiltration - Different soil types absorb

water at differing rates

Water holding capacity - Some soils hold

more water than others

Topography

Weather

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Estimating plant requirements

Do not water entire landscape according to one

plant type’s needs

Separate zones with differing water requirements

Consider rooting depth

Minimum – separate beds and turf

Photo: Alliance for water efficiency Photo: LSU AgCenter

Turfgrass

Area of the landscape with highest density of photosynthesizing tissue -highest evaporative demand.

Up to 1.5 inches a week

More frequent

watering

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Ornamental – trees, shrub

beds

Do not need as much water as turf

Hardier than turf and annuals

Deep rooting

Fewer applications, higher volume

Pictures: Ball Seed

Ornamental – annual beds

Generally shallower root systems, dry out more quickly

Tender foliage

Water more often with less volume

Pictures: Ball Seed

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Water Requirements of Plants

Dry Soils

Box Elder

Redbud

Smoketree

Hawthorn

Walnut

Pines

Quince

Junipers

Photinia

Spirea

Wet Soils

River Birch

Silver Maple

White Ash

Magnolia

Sycamore

Bald Cypress

Japanese Cedar

Forsythia

Hydrangea

Beautyberry

Other considerations

New turf will need more frequent, smaller

applications of water

Reduce erosion, but supply adequate water to

young roots

Gradually increase time between

irrigations to encourage deeper rooting.

New ornamental plantings should be

watered-in, but allowed periods of

dryness to encourage rooting.

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Scheduling considerationsMother Nature’s Resources

Plant type

Some plants require more than

others

Soil

Infiltration - Different soil types

absorb water at differing rates

Water holding capacity - Some soils

hold more water than others

Topography

Weather

Why is the soil important?

Soil types hold different amounts of water and

for different amounts of time.

Water Holding Capacity (WHC) or Field

Capacity (FC)

Soil types absorb water at different rates

Infiltration Rate (IR)

Affects how much and how often you apply

water

Texture, structure, and topography

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Texture – the particles

Three textural classes –

sand, silt, and clay

Proportions of each

class determines ability

and length of time to

absorb and hold water

Sand Silt Clay

Loose, gritty

Very permeable

Easily leached

Low WHC

High porosity

Crumbly

Less permeable

Downward and lateral movement

similar

Higher WHC

Medium porosity

Sticky, moldable

Least permeable

Susceptible to runoff

Higher WHC

Low porosity

http://i3.photobucket.com/albums/y51/wilddog_202/Clayafteryearsoforganicmatter.jpgPhoto: https://ncptt.nps.govPhoto: Salinitymanagement.org

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Soil Water-Holding Capacity

Ron Sheffield, LSU AgCenter

COARSE >>>>>>>>>>>>>>>>>>>>>>>>>>FINE

Maximum water it can hold

Moisture content

at wilting (how

tightly water is

held.

Water-Holding Capacity

and Retention

Hillel. Introduction to Environmental Soil Physics, 2004.

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Infiltration

Hillel. Introduction to Environmental Soil Physics, 2004.

Soil Texture and Infiltration

Clays have slow infiltration rates but stay wet longer

Sands have quick infiltration rates, and dry out more quickly

Application rate should not exceed the rate of infiltration

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Structure – how the

particles fit together

Aggregation increases

porosity (O2 and H20) and

infiltration

Often altered by construction

Severe compaction

Lack of OM and aggregation

Increased runoff, limited

rooting

Tillage, OM amending, and

mounding, adjust irrigation to

apply more slowly.

Photo: Colorado State University

Scheduling considerationsMother Nature’s Resources

Plant type

Some plants require more than

others

Soil

Infiltration - Different soil types

absorb water at differing rates

Water holding capacity - Some

soils hold more water than others

Topography

Weather

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Landscape Topography

Slopes lower infiltration rate

Increased runoff

Lower application rate or divide

total irrigation into multiple

applications

Slopes can cause different areas

of the landscape to be

wetter/drier than others.

Put low lying areas on different

zone

LandscapingNetwork.com

Slope and Soil Texture

Rainbird ® Irrigation Design Manual

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Scheduling considerationsMother Nature’s Resources

Plant type

Some plants require more than

others

Soil

Infiltration - Different soil types

absorb water at differing rates

Water holding capacity - Some

soils hold more water than others

Topography

Weather

Weather

Irrigation needs affected by

precipitation, temperature, sunlight

Evapotranspiration – water loss from

landscape to the atmosphere through

evaporation and plant transpiration

Consider season

Make sure your irrigation program

changes throughout the year

Differences in rainfall, temperature,

plant dormancy

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Weather

Average Annual PrecipitationTN Climatological Service

Weather patterns can be unpredictable

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Scheduling considerationsMother Nature’s Resources

Plant type

Some plants require more than

others

Soil

Infiltration - Different soil types

absorb water at differing rates

Water holding capacity - Some

soils hold more water than others

Topography

Weather

Design

The efficiency of an irrigation system is limited by its design.

Proper zoning

Proper output

Application rate awareness

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Hydrozones

Use zones to separate areas of different

water need, as well as deal with limited

available pressure.

Zones should take into account the plant

type needs and the soil characteristics

Separate areas that tend to stay dry/wet

If you water it differently, tap it differently!

Make sure design pressure of each zone

doesn’t exceed what is available.

Rainbird® Irrigation Basics Manual p.16

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Delivery Methods

Things to always keep in mind

Radius of throw

Operating pressure

Flow rate

Precipitation rate or application rate

Sprinklers

Impact, rotor, gear-driven

High flow (2-16gpm), high pressure requirements (30-80psi)

Bigger radius of coverage (65ft)

Single stream or multistream

Generally used on large, open turf areas

http://recreational-turf.wikispaces.com/file/view/40.jpg/186231979/40.jpg

Rainbird®

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Sprayers

Medium flow (1-5gpm), medium pressure

Smaller area of coverage (10-30 feet)

Come in variety of spray shapes

http://www.hunterindustries.com/irrigation-product/spray-bodies/ps-ultra#

Drip Irrigation

Most precise placement of water - applies directly to root

zone

Much lower flow rate (gallons per hour) and pressure

requirements (10 – 50psi)

http://www.hunterindustries.com/sites/default/files/styles/product_header/public/580x325_product_slider_00-pse-

7.jpg?itok=v1Tt31aM

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Drip Irrigation

Consists of tubing – emitter – microsprayer design to deliver

water to individual plants.

Least loss to evaporation

Higher installation cost, more likely to clog, but most

efficient

Keeps foliage from getting wet

http://www.hunterindustries.com/irrigation-product/micro-irrigation/micro-sprays#

https://rainbird.com/landscape/products/dripEmission/XeriBugEmitters.htm

Drip Irrigation

Filters and pressure regulators especially important

Some filters are pressure – regulating

Kits are available with included valve, filter,

pressure regulator components

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Precipitation Rate

Proper timing needs to take into account precipitation rate

For one given flow rate:

0.24” per

hour

0.32” per

hour

0.48” per

hour

0.96” per

hour

1X 4X2X1.3X

Know your precipitation rate

Rotating heads

usually do not adjust

flow rate for variable

arcs

Adjust GPM in your

calculations

accordingly

Always check

performance charts

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Know your precipitation rate

Matched Precipitation rate

(MPR) nozzles usually

available as “series”

Can also be variable /

adjustable arc nozzles

GPM is adjusted according

to arc to keep precipitation

rate constant.

Common in spray bodies

Always check performance

charts

Know your zone

precipitation rate…

Check performance chart data

BE CAREFUL – rotor performance data often based on

half circle operation

Therefore, divide precipitation by 2 if using 360˚ rotation

S

S

S

𝑃𝑅 =96.3 𝑋 𝐺𝑃𝑀

𝑆2𝑃𝑅 =

96.3 𝑋 𝐺𝑃𝑀

0.866 𝑋 𝑆2

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Know Your Precipitation

Rate…

AWS Irrigation

Controllers

Need to maintain flexibility

You/client are the irrigation manager, not

the clock

Consider user-friendliness, especially for homeowners

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Weather and

Location

Sensors

Rain

Soil Moisture

More sophisticated scheduling exists using ET data along with other weather parameters

Generally require weather station

Example: Hunter® ET System

When is the best time?

Efficiency

Midday irrigation offers cooling,

but is the most inefficient time of

day due to evaporative loss

Nighttime irrigation has greatest

chance for disease development

Early morning hours (5-9) allow time

for foliage to dry

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How Often?

Plant age

How established are the roots?

Consider season

Do not use one irrigation program for entire year

Differences in rainfall, temperature, plant dormancy

How Much?

Season

Imagine cost of 1” per week

for 52 weeks per year…

Rooting depth and establishment

Canopy Cover

How dense is the canopy, or

leaf area, of the area to be irrigated?

Turf vs. woody vs. annual

New plantings vs. established

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Remember

Design the system so water is placed uniformly and efficiently

Remember to consider plant type and establishment, soil type and condition, sloping, shading, and time of day.

Observe irrigation system performance after installation and routinely, adjust accordingly

Explore available technology that accounts for rain and existent soil moisture.

Reference Material

“Fertilization and Management of Home Lawns.” Publication 1038. University of Tennessee Agricultural Extension Service. <https://extension.tennessee.edu/publications/Documents/PB1038.pdf>.

Wells, Wayne. “Establish and Manage Your Home Lawn.” Publication 1322 Mississippi State University Cooperative Extension. http://msucares.com/pubs/publications/p1322.pdf.

“Growing Tree Fruits Successfully.” Online Presentation. Oregon State University Extension Service. http://extension.oregonstate.edu/lane/sites/default/files/documents/tree_fruit.tf_specialists.pdf.

Stein, Larry, and Welsh, Doug. “Efficient Use of Water in the Garden Landscape.” Texas A&M AgrilLife Extension. http://aggie-horticulture.tamu.edu/earthkind/drought/efficient-use-of-water-in-the-garden-and-landscape/.

Sheffield, Ron, and Thomas, Dan. “Irrigation Basics for Landscape Contractors.” Irrigation Contractor Class Manual. LSU AgCenter.

Sheffield, Ron. “Irrigation Basics of Irrigation Contractors.” LSU AgCenter. http://www.lsuagcenter.com/en/our_offices/departments/Biological_Ag_Engineering/Features/Extension/Agriculture_and_Environment/Irrigation/Irrigation-Basics-for-Irrigation-Landscape-Contractors.htm>.

Smith, Bryan W. “Irrigation.” Series on Landscape Irrigation Basics. Clemson University Extension. http://www.clemson.edu/extension/hgic/plants/other/irrigation/.

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Questions?

Contact Me:

Maureen Thiessen

Area Specialist

Commercial Ornamentals, Eastern Region

mthiesse@utk.edu

423 – 798 – 1710

Greeneville County Extension Office

Thank You!