Irrigation decisions: When and how much?

North Willamette Research andExtension Center

Jim Owen, Jr.

Irrigation Decisions:How much?

• Leaching fraction• Cyclic irrigation

How often?• Substrate• Grouping

• Plant Architecture

When?• Time of Day

USDA, 2004.

Leaching FractionLeaching Fraction = Volume Leached / Volume Applied

Irrigation volume determined by plant and substrate

Leaching Fraction

Lined or sealed Sealed outside pot

Leaching Fraction = Volume Leached / Volume Applied

Total Water Applied for container diameter area is measured as “total volume” to calculate leaching fraction

Leaching Fraction ~ 15%-20%

Plastic bags work for leaching fractions too!

Water Applied Water Leached

Leaching fraction

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Clay 0.10 LFClay 0.20 LF

Cu

mul

ativ

e in

fluen

t (L

)Treatment

Day after initiation

Leaching fraction

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Clay 0.10 LFClay 0.20 LF

Cum

ulat

ive

influ

ent

(L)

Treatment

Day after initiation

7 gal

Leaching fraction

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Clay 0.10 LFClay 0.20 LF

Cum

ulat

ive

influ

ent

(L)

Treatment

Day after initiation

90,000 gallons of water saved per growing acre

while maintaining growth

Leaching fractionAdvantages

Based on plant needDisadvantages

Management

USDA, 2004.

Cyclic Irrigation

Total water applied daily divided equally and applied in intervals to minimize water channeling and maximize subtrate rewetting

Cyclic Irrigation

Lateral unsaturated flow

Wetting front

0.2leaching fraction

1st irrigation cycle(some channeling)

2nd irrigation cycle 3rd irrigation cycle

Ted Bilderback (personal communication)

Cyclic irrigation

Fain, Tilt, Sibley. 2000. Less is More! Highlights of Agriculture Research

0

10

20

30

40

50

60

shoot dry wt (oz) shoot ht. increase(in)

1 cycle3 cycles6 cycles

red maple

0

300

600

900

1200

1500

1800

0:0

0

1:0

0

2:0

0

3:0

0

4:0

0

5:0

0

6:0

0

7:0

0

8:0

0

0.10.2

Wat

er g

ain

(ml)

Time (Sept.)

Leaching fraction

Cyclic Irrigation

Owen. 2006

0

300

600

900

1200

1500

1800

0:0

0

1:0

0

2:0

0

3:0

0

4:0

0

5:0

0

6:0

0

7:0

0

8:0

0

0.10.2

Wat

er g

ain

(ml)

Time (Sept.)

Leaching fraction

Cyclic Irrigation

1st Cycle

Owen. 2006

0

300

600

900

1200

1500

1800

0:0

0

1:0

0

2:0

0

3:0

0

4:0

0

5:0

0

6:0

0

7:0

0

8:0

0

0.10.2

Wat

er g

ain

(ml)

Time (Sept.)

Leaching fraction

Cyclic Irrigation

2nd Cycle

Owen. 2006

0

300

600

900

1200

1500

1800

0:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

0.10.2

Wat

er g

ain

(ml)

Time (Sept.)

Leaching fraction

Cyclic Efficiency3rd Cycle

Owen. 2006

Cyclic IrrigationAdvantages

Increases plant growth Increase water use efficiencyIncreases nutrient use efficiency

DisadvantagesIrrigation timingManagement

USDA, 2004.

Irrigation timing

c b a b

What time of day to apply irrigationPre-dawnAMPMAll day

Does it matter?

Irrigation timing

c b a b

Irrigation timing – micro-irrigation

Warren and Bilderback. 2002. J. Environ. Hort

0

20

40

60

80

100

120

140

Pre-dawn

AM PM All day

Co

ton

east

er d

ry w

eig

ht

(g)

c b a b

Irrigation timing – micro-irrigation

Warren and Bilderback. 2002. J. Environ. Hort

0123456789

10

11:00 AM 1:30 PM 4:30 PM

Co

ton

east

er P

ho

tosy

nth

esis

Pre-dawnAMPMAll day

Irrigation timing – micro-irrigation

Warren and Bilderback. 2002. J. Environ. Hort

20

25

30

35

40

45

50

7:00

AM

9:00

AM

11:0

0 AM

1:00

PM

3:00

PM

5:00

PM

7:00

PM

9:00

PM

11:0

0 PM

1:00

AM

Su

bs

tra

te t

em

pe

ratu

re (

C)

PMpre-dawn

Irrigation timing – micro-irrigation

Warren and Bilderback. 2002. J. Environ. Hort

20

25

30

35

40

45

50

7:00

AM

9:00

AM

11:0

0 AM

1:00

PM

3:00

PM

5:00

PM

7:00

PM

9:00

PM

11:0

0 PM

1:00

AM

Su

bs

tra

te t

em

pe

ratu

re (

C)

PMpre-dawn

Irrigation timing

c b a b

Irrigation timing - overhead

Williamson et al. 2005. SNA

0

50

100

150

200

250

Co

ton

east

er d

ry W

eig

ht

(g)

Pre-Dawn

All Day

PM

aab

Irrigation timing - overhead

Williamson et al. 2005. SNA

20

25

30

35

40

45

50

1 7 13 19 1 7 13 19 1 7 13 19

pre-dawn

all daypm

Su

bst

rate

tem

per

atu

re (

C)

Aug 26 03 Aug 27 03 Aug 28 03

20

25

30

35

40

45

50

pre-dawnall daypm

Irrigation timing - overhead

Williamson et al. 2005. SNA

Su

bst

rate

Tem

per

atu

re (

C)

Aug 26 Aug 27

20

25

30

35

40

45

50

pre-dawnall daypm

Irrigation timing - overhead

Williamson et al. 2005. SNA

Su

bst

rate

tem

per

atu

re (

C)

Aug 26 Aug 27

12:0012:00

3:003:00

6:006:00

Pre-DawnPre-Dawn

Irrigation timing - overhead

Williamson et al. 2005. SNA

Irrigation Treatment

Volume Applied

(L)

Total dry mass (g)

WUE

(mls/g)

Predawn 40.5 b 173 b 175 a

All day 37.5 b 219 a 134 b

PM 50.5 a 231 a 177 a

Irrigation timing

Williamson et al. 2005. SNA

AdvantagesIncreases plant growth Regulate substrate temperatureIncrease water use efficiency

DisadvantagesIrrigation timingManagement

Plant Grouping

USDA, 2004.

Group plants by similarities to increase irrigation effeciency

Plant GroupingGroup by:

Size• Container

• Plant

Species• Plant type

• Water needs

Architecture

USDA, 2004.

Plant Architecture

Williamson et al. 2005. SNA

How does the architecture of a plant’s canopy affect its demands for overhead irrigation?

Plant Architecture

Williamson et al. 2005. SNA

Plant Architecture

Williamson et al. 2005. SNA

0

100

200

300

400

500

600

700

800

900

22 29 32 40 47 49 54 66 73 82 92 99 105

Days After Initiation

Dai

ly V

olu

me

app

lied

(m

l)

Cotoneaster

Vitex

Cotoneaster Cotoneaster dammeridammeri ‘Skogholm‘Skogholm

Vitex trifoliaVitex trifolia ‘Variegata‘Variegata’’

Plant Architecture

Williamson et al. 2005. SNA

60

80

100

120

140

160

180

200

220

240

260

33 50 72 92 105

Days

Per

cen

tage

irri

gati

on C

aptu

re

CotoneasterGardenia

Cotoneaster Cotoneaster dammeridammeri ‘Skogholm‘Skogholm

Gardenia augustaGardenia augusta ‘Chuck Hayes’ ‘Chuck Hayes’

Plant Architecture

Williamson et al. 2005. SNA

0

100

200

300

400

500

600

700

800

900

22 29 32 40 47 49 54 66 73 82 92 99 105

Days After Initiation60

80

100

120

140

160

180

200

220

240

260

33 50 72 92 105

Days After Initiation

Cotoneaster

Gardenia

Vitex

Daily Volume AppliedDaily Volume Applied Percentage CapturePercentage Capture

Substrate

Water buffering capacityClayPeatParticle size

• Fine : coarse

Substrate

Industrial Mineral Aggregate Processing

• Particle Size• 0.25 to 0.85 mm• 0.85 to 4.75 mm

Substrate

0

40

80

120

160

200

0 20 40 60 80 100 120

0.25-0.85 mm0.85-4.75 mmControl

Cum

ulat

ive

wat

er a

pplie

d (L

)

Day after initiation

Substrate amendment

Substrate

0

40

80

120

160

200

0 20 40 60 80 100 120

0.25-0.85 mm0.85-4.75 mmControl

Cum

ulat

ive

wat

er a

pplie

d (L

)

Day after initiation

Substrate amendment

5 gal

Substrate

0

40

80

120

160

200

0 20 40 60 80 100 120

0.25-0.85 mm0.85-4.75 mmControl

Cum

ulat

ive

wat

er a

pplie

d (L

)

Day after initiation

Substrate amendment

8 gal

Substrate

0

40

80

120

160

200

0 20 40 60 80 100 120

0.25-0.85 mm0.85-4.75 mmControl

Cum

ulat

ive

wat

er a

pplie

d (L

)

Day after initiation

Substrate amendment

8 gal

WUE 731 ml g-1

to 599 ml g-1

Substrate

0

40

80

120

160

200

0 20 40 60 80 100 120

0.25-0.85 mm0.85-4.75 mmControl

Cum

ulat

ive

wat

er a

pplie

d (L

)

Day after initiation

Substrate amendment

107,000 gallons of water saved per growing acre

while maximizing growth

Questions