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1 © 2014 Regents of the University of Minnesota. All rights reserved. 11 Auditing home lawn irrigation systems Sam Bauer, University of Minnesota Extension
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2 © 2014 Regents of the University of Minnesota. All rights reserved.
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3 REASONS FOR AUDITING YOUR IRRIGATION SYSTEM Every system will have a different precipitation rate –We need to convert minutes to depth To ensure that the irrigation system is operating as designed To identify any issues with irrigation uniformity and/or broken components To reset arcs and angles of sprinklers
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4 © 2014 Regents of the University of Minnesota. All rights reserved. Caroline Calcote
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5 © 2014 Regents of the University of Minnesota. All rights reserved. IRRIGATION SYSTEMS Key components of irrigation systems include: 1.Design (engineering) 2.Equipment: pipes, valves, controllers, etc 3.Installation 4.Water management: when and how much 5.Maintenance If not done correctly, any item will have a negative impact on water use efficiency
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6 © 2014 Regents of the University of Minnesota. All rights reserved. IRRIGATION HEAD TYPES 3 primary types –Fixed spray- horizontal flat fan pattern –Impact rotor- single or multiple nozzles –Gear rotor- single or multiple nozzles –Rotors may have multiple stream designs, from 2 to 8 nozzles –Generally more efficient than single stream because of better water placement
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7 © 2014 Regents of the University of Minnesota. All rights reserved. FIXED SPRAY NOZZLE Residential applications, 3-18ft spacing, high precipitation rates (up to 10”/hr), low DU compared to rotors, low operating pressures http://www.hunterindustries.com/
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8 © 2014 Regents of the University of Minnesota. All rights reserved. MATCHED PRECIPITATION RATE NOZZLES www.toro.com
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9 © 2014 Regents of the University of Minnesota. All rights reserved. GEAR AND IMPACT ROTORS www.rainbird.com www.toro.com Radius of 18 to 100 ft, lower precipitation rates (under 1” per hour), geared rotors more common, higher operating pressures
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10 © 2014 Regents of the University of Minnesota. All rights reserved. Beard and Kenna, 2008
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11 © 2014 Regents of the University of Minnesota. All rights reserved. SPRINKLER SPACING www.irrigationtutorials.com
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12 © 2014 Regents of the University of Minnesota. All rights reserved. OLD – VS – NEW SPRINKLER OR NOZZLE Coefficient of uniformity of an individual sprinkler
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13 © 2014 Regents of the University of Minnesota. All rights reserved. IRRIGATION UNIFORMITY Basic concept behind irrigation uniformity is to apply water as evenly as possible –Most irrigation scheduling is driven by dry spots –Applying more water to dry spots over-irrigates everything else How can this be achieved? –Uniformity adjustments –Soil improvement- aeration, topdressing –Tolerate a few dry areas
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14 Irrigation Uniformity Good Poor © Irrigation Association
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15 © 2014 Regents of the University of Minnesota. All rights reserved.
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16 © 2014 Regents of the University of Minnesota. All rights reserved. CONTROLLER TECHNOLOGIES Smart controllers: –Store historical data –Onsite sensors for calculating real time ET –Actual weather station utilization for ET adjustment –Rainfall, temperature, and moisture sensors www.cyber-rain.com www.hunterindustries.com
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17 © 2014 Regents of the University of Minnesota. All rights reserved.
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18 © 2014 Regents of the University of Minnesota. All rights reserved. ADD-ONS Soil moisture sensors Rain sensors –The bare minimum www.toro.com www.rainbird.com
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19 © 2014 Regents of the University of Minnesota. All rights reserved. Paul Eckholm
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20 © 2014 Regents of the University of Minnesota. All rights reserved. CHEAP ALTERNATIVE TO AN IRRIGATION SYSTEM
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21 © 2014 Regents of the University of Minnesota. All rights reserved. IRRIGATION AUDITING PROCEDURES 1.Site inspection –Check irrigation components, arcs and angles, programs 2.Performance testing –Catch cans. Longer test times = greater accuracy –Calculate precipitation rate and distribution uniformity 3.Scheduling –Set specific run times for each zone
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22 © 2014 Regents of the University of Minnesota. All rights reserved. DISTRIBUTION UNIFORMITY (DU) Measure by setting out several water collection cups on a grid DU = avg of lower 25% divided by overall average of collection cups Ohio Irrigation Association
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23 1.10.80 1.10.78 10.76 0.990.72 0.980.72 0.920.7 0.880.68 0.850.6 0.820.54 0.800.5 1 hour run time Overall average = 0.812 Lowest 25% average = 0.604 0.604 / 0.812 * 100 = 74.4% Distribution uniformity = 74.4% Precipitation rate = 0.812”/hr Catch can depth (in)
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24 © 2014 Regents of the University of Minnesota. All rights reserved. IRRIGATION ZONE ADJUSTMENTS Zone run time (min) Targeted irrigation depth (in.) Zone precip rate (in./hr) x 60 Zone run time (min) 0.5 inches 0.81 inch/hr x 60 37 minutes to apply 0.5 inches of irrigation = =
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25 © 2014 Regents of the University of Minnesota. All rights reserved. Precipitation and Infiltration Rates Precip. Rate < Infiltration Rate Precip. Rate > Infiltration Rate Turgeon, 2005
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26 © 2014 Regents of the University of Minnesota. All rights reserved. SOIL WATER INFILTRATION Soil Infiltration Rates (in/hour) Coarse sand1.0 and up Fine sand0.5 to 3.1 Sandy loam0.4 to 2.6 Loam0.08 to 1.0 Clay loam0.04 to 0.6 Clay0.01 to.10 Adapted from: Kopec, 1995
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27 © 2014 Regents of the University of Minnesota. All rights reserved. INFILTRATION TEST Materials: water, stopwatch, ruler, wooden board, rubber mallet Procedure: Double ring infiltrometer 1.Insert both rings into the soil to a depth of 2” 2.Fill both rings with water to a minimum depth of 4”, start clock 3.Record water level drop over 30 minutes 4.Repeat until infiltration stabilizes 5.Record stabilized infiltration rate
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28 © 2014 Regents of the University of Minnesota. All rights reserved. Once a day or once a week? –As infrequent as possible while still maintaining the health desired –Wet the soil to sufficient depths with each irrigation Possibly 0.5 to 1” to reach soil depths of 6” and greater (soil type dependent) –Utilize multiple cycles per night for soils with low infiltration –Increase frequency and reduce volume in summer, or let lawns go dormant IRRIGATION FREQUENCY
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29 © 2014 Regents of the University of Minnesota. All rights reserved. IRRIGATION TIMING Irrigate in early morning if possible. During breakfast or before you leave for work. –Daytime irrigation is less efficient Evaporation losses Wind –Late afternoon to late evening irrigation can increase the incidence of certain turfgrass diseases, weeds, and promote succulence
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30 © 2014 Regents of the University of Minnesota. All rights reserved. DETERMINING WHEN TO WATER Soil moisture probe
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31 © 2014 Regents of the University of Minnesota. All rights reserved. Dr. Aaron Patton, Purdue Dr. Dave Gardner, Ohio State
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32 © 2014 Regents of the University of Minnesota. All rights reserved.
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33 © 2014 Regents of the University of Minnesota. All rights reserved. ADDITIONAL INFORMATION UMN Turfgrass Science Website: www.turf.umn.eduwww.turf.umn.edu UMN Extension Turfgrass Management Website: www.extension.umn.edu/turfgrass www.extension.umn.edu/turfgrass Sustainable Urban Landscape Information Series: www.sustland.umn.edu www.sustland.umn.edu Yard and Garden Info: Facebook: “University of Minnesota Yard and Garden” Twitter: @urbanturfmn and @UMNyardgarden Blog: http://blog.lib.umn.edu/efans/ygnews/http://blog.lib.umn.edu/efans/ygnews/ Smart Gardens Radio Show WCCO AM830, Saturdays 8-9am Sam contact: 763-767-3518, sjbauer@umn.edu, twitter = @urbanturfmnsjbauer@umn.edu
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