irrigation of xeric-adapted landscape...
TRANSCRIPT
Irrigation of Xeric-Adapted Landscape Plants
Southwest Turfgrass AssociationRecreational Landscape Conference and Expo
Albuquerque, NM October 27‐29, 2014
Daniel Smeal (CID, CLIA) New Mexico State University Agricultural Science Center at Farmington
Overview
• Xeriscaping – introduction
• Irrigation – turf vs. xeriscape
• Irrigation scheduling – review
• Drip irrigation for xeriscapes
• Irrigation requirement of xeriscape plants
• Xeriscape plants – some examples
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
What is a xeriscape?
• Term derived from Greek word ‘xeros’ meaning dry.
• Water-efficient landscaping that’s appropriate to the natural environment.– Usually consists of native plants or plants native to similar arid
environments
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
To some, it might be ‘zero’scaping.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
To others, it might be a cactus garden
Cactus can be an attractive component of a xeriscape garden.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Most would agree that this is not a SW xeriscape.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Xeriscape Demonstration Garden at NMSU’s ASC -Farmington
Aesthetically pleasing colors, scents, etc.Habitat for humans, wildlifeFunctional: screens, windbreaksProvides food and shelter for wildlife (e.g. birds, butterflies, etc.)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Irrigation Management
Turf vs. Xeriscape
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
TURF• Single species or type• Uniform water req. over large area• Sprinkler irrigated (DU < 0.70)• Frequent irrigations required (e.g. 3
times/week) with short run times• K = 0.8 (CS Turf); 0.6 (WS Turf)
XERISCAPE• Variety of species • Variable water requirements• Drip irrigated (DU > 0.85)• Low irrigation frequency (e.g. weekly
or more) with longer runtimes• K = ranges from < 0.1 to ~ 0.5
Turf vs. Xeriscape
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Irrigation Scheduling
A Review
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Effective landscape irrigation scheduling requires:
– An estimate of the plant’s daily water-use or evapotranspiration (ET) for acceptable quality.
– Knowing the output (e.g. precipitation rate) and irrigation efficiency (distribution uniformity or DU) of the irrigation system.
– Knowing the soil’s water characteristics.• Water holding capacity• Intake rate
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
ET estimation using weather data and an adjustment factor (K). • ET = ET(ref) x K
Where:o ET = estimated evapotranspiration (or water-use) of the plants in
the landscape o ET (ref) = a reference ET calculated from weather datao K = adjustment factor to account for plant species, size, growth
stage, etc. Most smart controllers use this method!
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Sources of ET(ref) and K?
• ET(ref) – New Mexico Climate Center website (http://weather.nmsu.edu/), or climate networks in other states
• K values (KL) – various references
• Most cited K values for turf:– Cool season (KBG, TF, PR) – 0.80– Warm season (Bermuda, buffalo, grama) – 0.60 – 0.65
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Example: Cool‐Season Turf (e.g. Kentucky bluegrass)
• Location: Los Lunas
• Time of year: Last week in May
• Reference ET obtained from NM Climate Center website: http://weather.nmsu.edu/
• Adjustment factor (Kc) = 0.80 for cool season turf when uniformly green
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Reference ET from NMCC
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Example: Daily ET estimate for cool‐season turf
• ET = ET(ref) x K
• Avg. daily ET(ref) (in this case ETo) = 0.22 in.
• Adjustment factor (K) = 0.80
• Estimated ET/day = 0.22 x 0.80 = 0.18 inch
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Irrigation requirement (IR)• Depends on the efficiency (DU) of the irrigation system and
the effective rainfall or R (60 to 75% of amounts > 0.20 inch) between irrigations.
IR = (ET – R) / DU • Example with measured DU of 0.75 and no rainfall:
IR = (0.18 inch – 0) / 0.75 = 0.28 inch per day
Then, the water to apply per irrigation would be the daily IR x irrigation frequency (days)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Irrigation runtime
• For turf:
Runtime = IR / Precipitation rate (PR) of sprinkler syst.– Example with PR of 0.70 inch per hour and irrigation frequency of
every-other day:0.24 x 2 ÷ 0.70 = 0.69 hour or 41 minutes
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
• IR for turf is in inches
• To convert to gallons multiply irrigation depth x area irrigated x 0.623 (takes 0.623 gal. to cover 1 sq. ft. to depth of 1 inch)
• Example
0.48 x (30 x 100) x 0.623 = 897 gallons
30 ft
100 ft.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Estimating (IR) for xeriscape plants (individual plant method)
IR = (ETr – R) x K x CA x 0.623 / 0.90 Where:
• IR = irrigation requirement, gallons/plant• ETr = total reference ET between irrigations, inches • R = effective rainfall between irrigations (inches)• K = adjustment factor for the species of plant • CA = canopy area, sq. ft. per plant (0.785 x D2)
where D = canopy diameter (feet)• 0.623 = conversion factor (inches to gallons)• 0.90 = assumed efficiency of drip system
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Sources of K values for xeriscape plants:
• Description of xeriscape garden and K values (adjustment factors) for xeric-adapted plants: http://irrigationmanagement.nmsu.edu/documents/2007xericrevproceedingsforia.pdf
• California WUCOLS http://www.water.ca.gov/wateruseefficiency/docs/wucols00.pdf
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Some xeriscape plant KL values based on research at ASC garden ‐ Farmington:
Species Common Name KL
Berlandiera lyrata Chocolate flower 0.05Buddleia davidii Butterfly bush 0.45Chilopsis linearis Desert willow 0.05Fallugia paradoxa Apache plume 0.05Helianthus maximiliani Maximilian sunflower 0.30Hesperaloe parviflora Red Yucca 0.15Perovskia atriplicifolia Russian sage 0.15Penstemon ambiguus Sand penstemon 0.10Sporobolis wrightii Sacaton 0.20
Plants with a K value of less than 0.1 may only require irrigation during drought
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Xeriscape Demonstration Garden
No Irrigation
40% ETTALL
20% ETTALL
60% ETTALL
80 ft
40 ft
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Example:
• Red yucca with canopy diameter of 4 feetCA = D2 x 0.785 = 4 x 4 x 0.785 = 12.6 sq. ft.
• Irrigating once per week
• Week of May 25 – 31 at Los Lunas– Total ETr for week = 1.8 inches (NMCC)– No rain
• K value from table (website) = 0.15
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Finding reference ET (example): New Mexico Climate Center (NMCC)
Total for week = 1.8 inches
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Some xeriscape plant KL values based on research at ASC garden - Farmington:
Species Common Name KL
Berlandiera lyrata Chocolate flower 0.05
Buddleia davidii Butterfly bush 0.45
Chilopsis linearis Desert willow 0.05
Fallugia paradoxa Apache plume 0.05
Helianthus maximiliani Maximilian sunflower 0.30
Hesperaloe parviflora Red Yucca 0.15
Perovskia atriplicifolia Russian sage 0.15
Penstemon ambiguus Sand penstemon 0.10
Sporobolis wrightii Sacaton 0.20
Plants with a K value of less than 0.1 may only require irrigation during drought
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Formula: IR = (ETr – R) x K x CA x 0.623 / 0.90
• IR = (1.8 – 0) x 0.15 x 12.6 x 0.623 / 0.90 =2.4 gallons for the week*
Irrigation runtime with a 1 gph emitter = 2.4 hours = 2 hours and 25 minutes
*This amount agrees with observations from the xeriscape demo garden at the no irrigation and 4 gallon per week irrigation level
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Problem• With the variety of plants and irrigation requirements,
how the heck do you irrigate them all efficiently (prevent over-irrigating or under-irrigating) if in a single zone?
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Drip Irrigation
For Xeriscapes
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Supertif Button PC1 emittersD001 (1) D002 (2) D004 (3.3) D006 (1)
Katif Low Profile PC emittersD043 (3.3) D044 (2) D045 (1)
DIG PC emittersD076 (1) D077 (2) D078 (4)
NC Flag emitters
D021 (1) D022 (2) D023 (4)NC2 Button emitters
D012 (1) D013 (2)
O1G (1)
Orbit NC
O2G (2)D079 (0.5) D080 (1)
Netafim PC
1PC – pressure compensating2NC – non-compensatingNumber in parentheses indicates manufacturer specified FR in gph
Orbit NC Flag
O4G (4)
Point Source Emitters ‐ Examples
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Getting water to the plant
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Adjustable flow emitter: good for providing variable rates of water as conditions change.
Drip line (¼ inch) with built-in emitters: good for watering evenly around trees or large shrubs
Connectors
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Emitter selection
• The ‘base-plant’ method is used to select appropriate emitters so that all plants in the landscape ‘hydrozone’ receive their specific irrigation requirement (IR) within the calculated run-time (RT) for the base plant.
• The base plant is the species requiring the least amount of water in the zone.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Steps for emitter selection in a mixed‐plant xeriscape:
1. Calculate the daily IR of each species in the zone at a given ET based on the K value and canopy area.– This is most easily done by including all required data in a table.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Example: Table set‐up for IR of all plants on zone:
Plant Species
ETr(inch)
K D (feet)
CA (sq ft)
IR, gals
week - - D2 x 0.785 ETr x K x CA x 0.623/0.90 A 1.8 0.10 10 78.5 9.8B 1.8 0.35 2.5 4.9 2.1C 1.8 0.20 4.0 12.6 3.1D 1.8 0.40 4.5 15.9 7.9E 1.8 0.15 6.0 28.3 5.3
Each individual of the same species will normally have about the same IR unless they have different canopy areas due to replanting, etc.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Establishing zone runtime
2. Select the plant with the lowest IR and calculate the runtime (RT) to provide IR using an emitter with a low flow rate (e.g. ½ gph) to maximize RT.
• In the example, plant B is the base plant w/ IR of 2.1 gals.• With a ½ gph emitter, runtime would be 4.2 hours• IR / flow rate = 2.1 / 0.5 = 4.2 or 4 hrs. + 18 mins.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Calculating emitter flow rates for other plants3. Divide the IR of each other species in the zone by the
established runtime (RT) to get a total required flow rate (FR) for each plant (FR = IR / RT).Example – species A w/ IR of 9.8 gals.
FR = 9.8 / 4.2 = 2.3 gph4. Select a reasonable number of emitters for each plant
considering the plant’s canopy area.Note: one guideline suggests 1 emitter per 20 sq ft of canopy area on a sandy loam soil; refer to IA guidelines or Google• Example – plant A w/ canopy area about 80 sq. ft. • 80 / 20 = 4 emitters
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Calculate FR per emitter
5. Divide total FR for the plant by the number of emitters selected per plant to get the flow rate per emitter.
Example plant A: FR / 4 = 2.3 gph / 4 = 0.58 gph• Since there is no 0.58 gph emitter, a 0.50 gph emitter
could be selected and to avoid under-watering, 5 emitters (instead of 4) could be used.
• Total FR would then be 2.5 gph and total irrigation in the 4.2 hour runtime would be 2.5 x 4.2 = 10.5 gallons which is only 7 % above the IR
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Emitter placement
• Small plants (D < 3 feet) – near base
• Larger plants (shrubs and trees) – generally ½ the distance from the base to outer edge of canopy (Toro)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Xeriscape Plant Examples
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
No to Very Low Irrigation
K = 0.10 (10% of ETr) or less
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Yuccas
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Cylindropuntia imbricata (tree cholla)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Chamaebatiaria millefolium (fernbush)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Rhus trilobata (3-leaf sumac)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Fallugia paradoxa (Apache plume)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Amelanchier utahensis (Utah serviceberry)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Chilopsis linearis (willow-leaf catalpa)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Berlandiera lyrata (chocolate flower)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Low Irrigation
K value = 0.15 to 0.25
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Hylotelephium telephium (autumn joy sedum)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Hesperaloe parviflora (red yucca)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Juniperus scopulorum (Rocky Mountain juniper)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Penstemon palmeri (Palmer penstemon)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Penstemon pinifolius (pineleaf penstemon)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Perovskia atriplicifolia (Russian sage)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Penstemon ambiguus (bush penstemon)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Mirabilis multiflora (giant four o’clock)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Medium Irrigation
K = 0.25 to 0.35
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Caryopteris clandonensis (blue mist)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Salvia greggii (cherry sage)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Prunus besseyi (western sandcherry)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Zinnia grandiflora (desert zinnia)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Penstemon strictus (Rocky Mountain penstemon)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Penstemon barbatus (scarlet bugler penstemon)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Penstemon eatonii (firecracker penstemon)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Melampodium leucanthum (blackfoot daisy)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Liatris punctata (dotted gayfeather)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Higher Irrigation
K = 0.40 – 0.60
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Spartium junceum (Spanish broom)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Teucrium arogrium (Greek germander)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Agave utahensis (Utah agave)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Centranthus ruber (Jupiter’s beard)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Helianthus maximiliani (Maximilian sunflower)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Gaura lindheimeri (gaura)
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Other Considerations
• The K value shown for each species represents the adjustment factor to ETr for the minimum irrigation level providing acceptable quality (subjective rating) for that species.
• Most plants will exhibit a higher rate of ET (and more growth) if provided with more water.
• However, excessive watering may not enhance plant quality and in some cases, it can be detrimental to quality (root rot and other diseases, rangy appearance, etc.).
• Keep in mind that a xeriscape is dynamic and water requirements may change over time as the plants grow or die, need replacement, etc.
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington
Thank you!
Farmington ASC website: http://farmingtonsc.nmsu.edu
Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington