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Considerations for Improving Water
Use in the Landscape
TRICITIES LANDSCAPE SEMINARAPRIL 14TH, 2015
MAUREEN THIESSENCOMMERCIAL 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.
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
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
Alliance for Water Works
Outside City:$6.94/1000gal + base
($6.94 x 6.788gal + $8.92)$56.03 per inch of applied
water
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
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
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
Water Requirements of PlantsDry 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.
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
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 WHCHigh porosity
CrumblyLess permeableDownward and
lateral movement similar
Higher WHCMedium porosity
Sticky, moldableLeast permeable
Susceptible to runoff
Higher WHCLow porosity
http://i3.photobucket.com/albums/y51/wilddog_202/Clayafteryearsoforganicmatter.jpgPhoto: https://ncptt.nps.govPhoto: Salinitymanagement.org
Soil Water-Holding Capacity
Ron Sheffield, LSU AgCenter
COARSE >>>>>>>>>>>>>>>>>>>>>>>>>>FINE
Maximum water it can hold
Moisture content at wilting (how tightly water is held.
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
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
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
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
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
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.
Delivery Methods
Things to always keep in mindRadius of throwOperating pressureFlow ratePrecipitation 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®
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
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
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
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=96.3𝑋 𝐺𝑃𝑀
𝑆2𝑃𝑅=
96.3𝑋 𝐺𝑃𝑀0.866 𝑋 𝑆2
Controllers Need to maintain flexibility You/client are the irrigation manager, not
the clock Consider user-friendliness, especially for
homeowners
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?
EfficiencyMidday 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
How Often?
Plant ageHow established are the roots?
Consider seasonDo not use one irrigation
program for entire yearDifferences 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
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/.
Questions?Contact Me:
Maureen ThiessenArea Specialist
Commercial Ornamentals, Eastern [email protected] – 798 – 1710
Greeneville County Extension Office
Thank You!