KEEPING LANDSCAPES GREEN WITH LESS GREEN

Dennis Pittenger, M.S. Area Environmental Horticulturist

University of California Cooperative Extension

Los Angeles County/UC Riverside

Presentation © 2014 Dennis Pittenger

Dennis Pittenger Area Environmental Horticulturist dennis.pittenger@ucr.edu Phone: 951.827.3320 CENTER FOR LANDSCAPE & URBAN HORTICULTURE <www.ucanr.edu/cluh>

• B.S. & M.S. Horticulture, Ohio State University • 33 years experience

– Landscape & urban horticulture – Education and applied research programs – Landscape irrigation mgt., plant water needs,

weather-based irrigation control – Presentations, workshops, publications, Web

. • Los Angeles County/UC Riverside

Objectives

• Learn a simple, accurate climate-based method to estimate landscape water requirements.

• Understand cost-effective strategies for minimizing landscape irrigation.

• Learn how to prioritize irrigation when water is limiting

• Los Angeles County/UC Riverside

Average California Water Use Statewide Developed Water

20% Urban & 9% Landscape

77%

6%

7% 2% 4% 1%

3% Agriculture

Indoor Residential

Outdoor Residential

Large Landscape

Comm'l/Inst'l/Inds'l

Other

Environmental

Sources: Calif. Dept. Water Resources, 2013 Calif. Water Plan Update Chp. 3. UCLA Inst. of Env’t. and Sustainability, So. Calif. Environ’l. Report Card, Fall 2009.

California Statewide Urban Water Use Average, 1998-2005

Source: Calif. Dept. Water Resources, 2013 Calif. Water Plan Update Chp. 3

Essentiality of Landscape Water

• Function • Recreation • Aesthetics • Mental Well-being

• Los Angeles County/UC Riverside

Many Landscapes Are…

Overwatered!!!

• Drought is official • Perception:

• Landscapes are non-essential • Landscapes waste water

• Less or NO water for landscapes • We must be efficient water managers!

• Los Angeles County/UC Riverside

Landscapes Are Under Attack!!!

Estimating Landscape Plant Water Requirements

One-word term describing water use of a planted area due to soil evaporation and plant transpiration.

EVAPOTRANSPIRATION (ET)

Plant water use is driven primarily by the energy from the ____________.

SUN

Water needs of a particular landscape plant can be accurately estimated simply by knowing its plant type category (turf, tree, shrub, groundcover, etc.)

TRUE

Evapotranspiration (ET)

Climate-based reference Inches/day ETo = estimated water use of

well-watered cool-season turf Calculated from weather data

Sunlight, temperature, RH, wind

ASCE Penman-Monteith equation

Based on field research with agricultural crops

ETo = Reference Evapotranspiration An estimate of environmental water demand

over a planted area

Estimating Landscape Water Requirement

Accurate and Simple Equation

Gallons = ETo × PF × LA × 0.623 gallons = inches × % × sq. ft. × conversion

ETo = reference evapotranspiration; climate impact PF = plant material adjustment factor

LA = sq. ft. landscape area 0.62 = converts depth to volume [gal. ÷ (in. x sq. ft.)]

Estimating Plant Water Needs Through Science

Center for Landscape & Urban Horticulture University of California Cooperative Extension

Using & Adjusting PF & Kc Values

0.00

0.20

0.40

0.60

0.80

1.00

W

C

More Leaves & Growth High Expectations

Less Leaves & Growth Low Expectations

Turf Gc-Sh-Tr-Fl

Center for Landscape & Urban Horticulture University of California Cooperative Extension

Copyright © 2010-2013 D. Shaw and D. Pittenger

Simplified Landscape Irrigation Demand Estimation

S L I D E

…..for selecting Plant Factors

Principles: Plant factors accurately

estimated by broad plant type categories based on science and research

Landscape water need estimated by weighting sq. ft. of each plant type present

SLIDE Paradigm

SLIDE Features Simple to understand & use

Replaces need for huge data base Reduces number of factors or variables

Accommodates new plants Scientifically & conceptually sound

Assimilation and application of ≈20 yrs. of data Scientifically traceable

Provides reliable numbers for calculations Wide geographic & climatic application

SLIDE Rules (DRAFT)

Water Requirements of Plant Categories Turfgrass = 60% (40%) ETo (w-s) / 80% (60%) ETo (c-s) Tree/Shrub/Groundcover/Vine = 50% (30-40%) ETo Herbaceous Perennial Flowers/Foliage = 70% (50%) ETo Annual Flowers/Foliage = 80% (60) ETo Low Expectations/Native Adapted = 30% (20%) ETo

Applying SLIDE Rules Established Landscapes

Landscape Water Budget or Water Need Gallons = ETo × ∑(PF × LA)1-x × 0.623

∑ = (PF1 × LA1)+ (PF2 × LA2) + (PF3 × LA3)….. Divide each zone by its DU

• ETo = reference evapotranspiration, CIMIS, etc.; climate impact • PF = plant material factor (turf, shrub-tree-vine-gc, flowers, etc.)

• LA = sq. ft. landscape area • 0.62 = converts depth to volume [gal. ÷ (in. x sq. ft.)]

Applying SLIDE #1 Landscape Site

• 10,000 sq. ft. of tall fescue general turf (cool-season) • 3,500 sq. ft. of mixed beds with various trees, shrubs, groundcovers • Annual ETo is 44 inches

Annual Water Requirement (gal.) = (ETo × AF × Sq. Ft. × 0.623) ÷ DU

Turf Requirement (gal.) = (44 in. × 0.8 × 10,000 sq. ft. × 0.623) ÷ 0.6 = 365,493 gal. = 59 in. Mixed Beds Requirement Gallons = (44 × 0.5 × 3,500 × 0.623) ÷ 0.9

= 53,301 gallons = 24 inches • Site Water Budget = 418,794 gallons

Isolated Trees Use Canopy Area for Landscape Area

Gallons = ETo × PF × Canopy Area × 0.623 Canopy Area (sq. ft.) = 3.14 × (radius × radius)

Estimating Canopy Area

Source: © 2014 American Forests

Useful Equations

Inches = Gallons ÷ (Sq. Ft. × 0.623)

Gallons = Inches × Sq. Ft. × 0.623

Billing Unit = HCF = 748 Gal.

• Los Angeles County/UC Riverside

WUCOLS Water Use Classification of Landscape Species

KL = KPLANTS × KVEG. DENSITY × KMICROCLIMATE

Landscape Coefficient (KL)

SLIDE Rules

Cost Effective Strategies & Actions

• Horticultural Practices to Aid Water Conservation • Irrigation System Management & Maintenance • Hardware Improvements • Landscape Design, Expectations, Retrofits

Horticultural Practices to Aid Water Conservation

• Aerate turf • Raise mowing height • Reduce fertilizer

– Slow release N

• Mulch exposed soil • Avoid heavy pruning

• Los Angeles County/UC Riverside

Turf Aeration

• Increases water and air entry into soil

• Reduces thatch • Reduces compaction

Horticultural Practices to Aid Water Conservation

• Keep irrigation heads clear • Forgo exotic products!

• Los Angeles County/UC Riverside

Landscape Irrigation System Management & Maintenance

Goal: supply plants with right amount of water at proper time as efficiently as possible

• Los Angeles County/UC Riverside

7 Habits of Highly Effective Water Managers

1. Accurately estimate landscape water requirement 2. Apply right amount of water at right interval 3. Maintain highly uniform irrigation system 4. Eliminate runoff & deep percolation 5. Irrigate when wind & evaporation are minimum 6. Evaluate/maintain hardware and landscape often 7. Adjust/evaluate schedules as conditions change

• Los Angeles County/UC Riverside

Effective Irrigation

• Apply amount of water needed by plants

• Plus extra water for: – Non-uniform distribution – Salt management

Effective Irrigation Management

• Distribute water uniformly

• Affected by system: – Design – Installation – Maintenance

Distribution Uniformity (DU)

• A measure of how evenly water is applied to a crop.

• Based on measurements which can be readily made.

• Affected by system design and maintenance. • Significantly affects water requirement

• Plant water requirement ÷ DU = Irrigation requirement

Distribution Uniformity (DU)

DU Irrigation Multiplier 0.5 2.00 0.6 1.67 0.7 1.43 0.8 1.25 0.9 1.11

Applying SLIDE #2 Landscape Site

• 10,000 sq. ft. of general turf - with irrigation system improvements • 3,500 sq. ft. of mixed beds with various trees, shrubs, groundcovers • Annual ETo is 44 inches

Annual Water Requirement (gal) = (ETo × AF × Sq. Ft. × 0.623) ÷ DU

Turf Requirement Gallons = (44 × 0.8 × 10,000 × 0.623) ÷ 0.7 = 313,280 gal. = 50 inches

Reduced Turf Water Budget ≈ 15% (313,280 gal vs. 365,493 gal or 50 in vs 59 in)

Focus on Maximizing DU!!

• Adjust/repair/replace heads or emitters • Add heads or emitters • Optimum pressure for heads and emitters • Goal:

≥70% DU for overhead systems ≥85% DU for drip

Effective Irrigation Management • Avoid runoff • Affected by:

– Site conditions – Horticultural practices – Irrigation system operation, mgt.,

maintenance

Avoid Runoff

• Site Conditions – Slope – Landscape design – Irrigation system

Avoid Runoff

• Horticultural Practices – Avoid soil compaction – Aerate/dethatch turf – Dethatch turf

Avoid Runoff • Horticultural Practices (cont.)

– Keep irr. heads clear • Turf cutting ht./raise heads • Prune/remove plant

– Judicious fertilization & use slow-release N

– Forgo exotic products!

Avoid Runoff • Multiple start times • Cycle and soak • Run irr. laterals across slope • Reduce precipitation rate

Evaluating Landscape Irrigation System & Management

Goals

• Measure effectiveness and efficiency of irrigation system and schedules

• Improve water conserving irrigation schedules and management practices

• Verify Smart Controller performance

Evaluating Landscape Irrigation System & Management

Questions • How efficient and effective am I irrigating my

landscape? • What can I do to conserve water and improve

my irrigation management? • Could a Smart irrigation controller help? • Is my Smart controller performing correctly?

Evaluating Landscape Irrigation System & Management

Process

• Walk-thru inspection & tune-up (maintenance) • Collect data about site & system • Run calculations & analyze data • Report findings • Modify and adjust system & schedules

Evaluating Landscape Irrigation System & Management

Data & Calculations • Verify irrigation zones or stations • Precipitation rate (PR) • Distribution uniformity (DU) • Record plant material, root depths, soil texture • Estimate plant water requirements • Calculate schedule for each zone or station

Irrigation System Evaluation

Irrigation System Evaluation

Good Maintenance Yields Improved Effectiveness

Be wary of in-field modifications!!

Hardware Improvements

• Smart controller? • 4+ programs/4+ starts • Precision, Press. Comp. emitters • No silver bullets • Integrated approach needed • Improve system performance

and management first!!

Landscapes require irrigation when…..

…..performance expectations exceed plant adaptation to precipitation

Expectations and Design Intent

determine landscape water need

Landscape Design, Expectations, Retrofits

• Hydrozones • Maximize irr. system performance

– High uniformity and no runoff

• Reduce turf - Functional turf only • Low expectation/low density zones

Landscape Design & Expectations

• Expectations Met and Water Conserved

Landscape Retrofits • Turf replacement • Difficult to irrigate areas

What About Sports Fields??

• Priority? • Highest water requirement

– Need to be actively growing – Turf must recover from wear – Injury potential

• Is artificial turf cost-effective?

Prioritizing Irrigation

• Focus water on most valuable & difficult to replace plants • Trees/Shrubs/Vines/Grdcvr > Perennials > Lawn/Annuals

Prioritizing Irrigation

Approx. Minimum Water Required to Keep Plants Alive

• Lawns – c-s: 0.5 inches every 3-5 days – w-s: 0.75 in. every 7-10 days

• Trees/Shrubs/Vines/Groundcovers – 1.0-1.5 in. every 10-14 days

• Perennials – 1.0 in. every 5-7 days

But how long can they go??

Take Home Highest ROI Priorities

• Landscape & Irr. Sys. Maint. • Improve DU and hardware • Improve schedules • Lower expectations • Reduce planted area • Prioritize irrigated areas • Retrofit/adjust plant spp. mix

– Turf = 31 gal./sq. ft. – G-S-T = 16 gal./sq. ft. – Color = 25 gal./sq. ft.

Dennis Pittenger Area Environmental Horticulturist

dennis.pittenger@ucr.edu Phone: 951.827.3320 Center for Landscape & Urban Horticulture <www.ucanr.edu/cluh>

• Los Angeles County/UC Riverside

Useful Reference Materials • U.C.C.E. Center for Landscape and Urban Horticulture

– www.ucanr.edu/cluh (Landscape Water Management tab on left)

• Irrigation Association’s Landscape Irrigation Auditor Man’l. 2nd Ed. (2011) or 3rd Ed. (2013). Chapter 7 and Appendix D.

• U.C. Cooperative Extension Handbook: Landscape Irrigation System Evaluation and Management. (D. Shaw and D. Pittenger, 2009) – www.ucanr.edu/cluh (Landscape Water Management tab on left)

• California Dept. of Water Resources – CIMIS – CIMIS (California Irrigation Management Information System) – http://www.cimis.water.ca.gov/cimis

• Los Angeles County/UC Riverside