Michael D. Dukes, Ph.D., P.E.

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Current Issues and Updates in Turf/Landscape
Irrigation
Michael D. Dukes, Ph.D., P.E. Agricultural
Biological Engineering Institute of Food and
Agricultural Sciences (IFAS)? 2008 UF-IFAS
Extension Symposium Gainesville Polycom, May
30, 2008
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Population Growth in Florida
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Development of Land in Florida
Maps from 1,000 Friends of Florida http//www.1000
friendsofflorida.org/planning/2060.asp
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Growth in Florida
Maps from 1,000 Friends of Florida http//www.1000
friendsofflorida.org/planning/2060.asp
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Municipal Water Use

• Population served by public supply
• 5.4 million 1970
• 17 million 2004
• 20 million 2020 (est.)?
• 15 U.S. new home construction in FL
• 1,000 people/day
• Most new homes in FL include irrigation
• 60 household water use for irrigation
• High quality landscapes and low water holding
  capacity

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Conventional (?) Residential Irrigation
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T1
T1 Existing landscape and irrigation, only
monitored, 75 turfgrass
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T2
T2 T1 landscape, reduced irrigation schedule,
75 turfgrass
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IFAS Scheduling Recommendations

• edis.ifas.ufl.edu/AE220
• Tables give run times for various application
  rates
• Application rates
• Catch can test
• Manufacturer catalog
• Estimated

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T3
T3 T2 irrigation schedule 65 microirrigated
ornamentals
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Irrigation Water Use Central FL
Significant reductions in water use (30 and
50) can be achieved by irrigation scheduling
(T2) and scheduling landscape changes (T3)?
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IFAS Scheduling Recommendations

• edis.ifas.ufl.edu/AE220
• Tables give run times for various application
  rates
• Application rates
• Catch can test
• Manufacturer catalog
• Estimated

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FAWN Urban Irrigation Scheduler
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FAWN Urban Irrig. Pick Region
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FAWN Urban Irrig. Pick Equipment
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FAWN Urban Irrig. Run Times-Spray Heads
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FAWN Urban Irrig. Pick Equipment
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FAWN Urban Irrig. Run Times-Rotors
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SMART WATER APPLICATION TECHNOLOGY (SWAT)?
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Industry Trends

• SWAT ? Irrigation technologies designed to
  conserve water
• SWAT concept created approx. 2001 by Irrigation
  Association (IA) water purveyors
• Current test protocols
• Evapotranspiration (ET) controllers
• Soil moisture sensor (SMS) controllers - draft
• Rain sensors (RS) draft
• EPA Water Sense
• Labelling for water efficient products

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Overall Objectives of UF Testing
Soil moisture controllers (SMS)
Evapotranspiration (ET) based controllers
Compare irrigation applied turf quality on SMS,
ET RS controlled irrigation to time clock
irrigation
Rain sensors (RS)
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SMS TESTING ON BERMUDAGRASS PLOTS
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Research (2004 - 2005)
12x12
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Experimental Setup 1, Gainesville

• 1 d/wk four brands SMS
• 2 d/wk four brands SMS
• 7 d/wk four brands SMS
• Time 2 d/wk with rain sensor
• 60 of time 2 d/wk with rain sensor
• Time 2 d/wk without rain sensor
• Non-irrigated

3 SMS frequencies
Comparisons
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Soil Moisture Controller Sensors
Rainbird
Irrometer
Water Watcher
Acclima
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Acclima
Rain Bird
Water Watcher
Irrometer
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How do Bypass SMS Controllers Work?
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How do Bypass SMS Controllers Work?
Common
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Common
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Water content below the set point
Common
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Water content above the set point
Common
X
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SMS Controllers in Experiment
1 Sensor Controllers 2Timer
2
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Expanding Disk Rain Sensor
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TIME vs. SMS Control 200405
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10.0
2.7
7.3
X SIC Bypassed O SIC Allowed
Soil Moisture Content in 2004
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Conclusions Experiment 1

• Significant differences in turfgrass quality
  among treatments were not detected ? no
  irrigation was necessary

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Turfgrass Quality
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Turf quality reduction
Soil moisture content and daily rainfall, 2004
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Conclusions Experiment 1

• Significant differences in turfgrass quality
  among treatments were not detected ? no
  irrigation was necessary
• WRS 34lt WORS ? a rain sensor at 6 mm threshold
  saved water

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Conclusions Experiment 1

• Significant differences in turfgrass quality
  among treatments were not detected ? no
  irrigation was necessary
• WRS 34lt WORS ? a rain sensor at 6 mm threshold
  saved water
• SMS savings 69-92 (3 of 4 brands), 2-3 times
  more than an RS

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Conclusions Experiment 1

• Significant differences in turfgrass quality
  among treatments were not detected ? no
  irrigation was necessary
• WRS 34lt WORS ? a rain sensor at 6 mm threshold
  saved water
• SMS savings 69-92 (3 of 4 brands), 2-3 times
  more than an RS
• 7 d/wk frequency used less irrigation than 1 or 2
  d/wk by taking advantage of frequent rainfall

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SMS, ET, RS TESTING ON ST. AUGUSTINEGRASS PLOTS
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Experiment 2, Citra
St. Augustinegrass testing ongoing since March
2006
72 plots 18 treatments 4 replicates A Rain
Sensors B Soil Moisture Sensors ET Controllers
Photo May 2006, M.L. Shedd
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Experiment 2, Technology Being Tested
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Volumetric Water Content, Spring 2006

• Each plot monitored
• individually with TDR probes

• Non-irrigated plots
• Shows rainfall events
• Dry Spring Season

Turf quality reduction
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SMS RS TESTING ON COOPERATING HOMES, PINELLAS
CO.
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Experimental Design

• 60 residential cooperating homes
• 4 locations
• 4 treatments

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Treatments

• T1, Current irrigation system without rain sensor
  
• and with a soil moisture controller
• T2, Current irrigation system with rain sensor
• T3, Current irrigation system without a sensor
• T4, Current irrigation system with rain sensor
• and with educational materials

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Irrigation Depth on Homes to Date
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Irrigation Depth on Homes to Date
50 savings
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EVAPOTRANSPIRATION (ET) CONTROLLER TESTING,
HILLSBOROUGH CO.
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ET Controller StudyGCREC Hillsborough County

• Three ET controllers T1, T2, T3
• Weathermatic, Smartline SL800
• Toro, Intellisense TIS-612OD
• ETwater, Smart Controller 100
• T4 Timeclock with RS
• T5 60 of T4

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How Do ET Controllers Work?

• Three types of ET Controllers
• Historically-Based
• ET is derived from historical ET values
  collected over a long time period
• Stand-Alone
• ET is calculated from on-site weather data by
  the controller
• Signal-Based
• ET is calculated from a local weather station
  and sent by signal to the controller

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GCREC Plot plan
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GCREC Rainfall
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ET Controller Water Savings Potential
Water applied to turf vs. non-conservative
Florida homeowner
Time Period Time Period Weathermatic Toro ET Water Time 0.6Time
Year 1 Sum-06 -49 NA -11 -14 -42
Year 1 Fall-06 -15 -17 NA -1 -38
Year 1 Win-06 -50 -60 NA -21 -49
Year 2 Spr-07 -9 -15 -30 -18 -50
Year 2 Sum-07 NA -41 -45 -31 -63
Theoretical requirement vs. water applied
More savings ? Intermediate ? Low savings
There is currently no relationship between water
applied and turfgrass quality. More potential
savings??
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But will ET controllers work in the real world?!
Residential study in Hillsborough County

• 40 residential cooperators
• 20 homes will receive an ET controller
• 20 homes will act as a control group
• All volunteers are initially considered moderate
  to high water users

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Summary of UF Testing to Date

• Soil moisture sensor irrigation reduction
  compared to 2 d/wk seasonal adjustment no rain
  sensor
• 70-90 during normal to rainy conditions
• 15-40 during dry conditions
• Rain sensors (MiniCLIK) irrigation reduction
  compared to 2 d/wk seasonal adjustment no rain
  sensor
• 35 during normal to rainy conditions
• 0-15 during dry conditions
• ET controller irrigation reduction compared to 2
  d/wk seasonal adjustment
• 40-60 rainy conditions
• 0-30 dry conditions

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Take Home Messages

• For high water users, adjust clock monthly
  according to AE220 or FAWN Urban Irrig. Tool
• Moderate 20,000 gal/1,000 sq ft/yr
• High 25,000 30,000 gal/1,000 sq ft/yr
• Excessive gt40,000 gal/1,000 sq ft/yr
• Rain sensors DO work
• Set at 0.25 for 2 d/wk restrictions
• Set at 0.5 for 1 d/wk restrictions
• Soil moisture sensor controllers work
• 2-3 times more effective than rain sensors
• But, proper installation and set up is a must
• ET controllers adjust across the season
• Operation under normal rainfall patterns is
  unknown

Note 1 of water is equivalent to 620 gal/1,000
sq ft
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