Precision Irrigation Management Based on

Crop Canopy Temperature70th Annual SWCS Conference

July 26-29, 2015; Greensboro, NCSaleh Taghvaeian

(405) 744-8395Saleh.taghvaeian@okstate.edu

Presentation Outline

i. Irrigation scheduling methods

ii. Methods based on canopy temp.

iii. Crop Water Stress Index (CWSI)

iv. Case studies

1) Sunflower

2) Turfgrass

3) Corn

v. Question

Irrigation Scheduling Methods

• Based on weather data (evapotranspiration)

• Based on soil water content

• Based on leaf water potential (pressure bomb)

• Based on canopy temperature

3

• Water transpiration requires energy

• The higher the water use rate, the cooler the canopy

• Canopy temperature is affected by other variables

Canopy Temperature

Crop Water Stress Index (CWSI)

CWSI

Crop Water Stress Index (CWSI)

Questions:

1. How to measure the crop temperature?

2. How to identify the upper and lower limits?

3. How to use CWSI estimates?

Obtaining canopy temperature

Identifying dT limits

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

0.0 1.0 2.0 3.0 4.0 5.0

dTm

in (˚

C)

Vapor Pressure Deficit (kPa)

AZ, Maricopa CO, Greeley CO, Iliff CA, Davis ND, Oaks India

Theoretical vs. Empirical approaches

Case studies

• Sunflower

• Turfgrass

• Corn

Sunflower0

10

20

30

40

50

60-0.2

0.0

0.2

0.4

0.6

0.8

1.0

7/9 7/16 7/23 7/30 8/6 8/13 8/20 8/27 9/3

I + P (mm

)CW

SI

1000-1100 1100-1200 1200-1300 1300-1400

80/80

0

10

20

30

40

50

60-0.2

0.0

0.2

0.4

0.6

0.8

1.0

7/9 7/16 7/23 7/30 8/6 8/13 8/20 8/27 9/3

I + P (mm

)CW

SI

1000-1100 1100-1200 1200-1300 1300-1400

50/50

0

10

20

30

40

50

60-0.2

0.0

0.2

0.4

0.6

0.8

1.0

7/9 7/16 7/23 7/30 8/6 8/13 8/20 8/27 9/3

I + P (mm

)CW

SI

1000-1100 1100-1200 1200-1300 1300-1400

100/50

0

10

20

30

40

50

60-0.2

0.0

0.2

0.4

0.6

0.8

1.0

7/9 7/16 7/23 7/30 8/6 8/13 8/20 8/27 9/3

I + P (mm

)CW

SI

1000-1100 1100-1200 1200-1300 1300-1400

65/40

Sunflowery = -0.75x + 0.96

R² = 0.98

0.4

0.5

0.6

0.7

0.8

0.9

1.0

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

fIPA

R

CWSI

y = 3.81e-1.76x

R² = 0.89

1.0

1.5

2.0

2.5

3.0

3.5

4.0

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

LA

I

CWSI

y = 9.69x + 0.84R² = 0.95

1.0

1.5

2.0

2.5

3.0

3.5

4.0

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Rel

ativ

e ro

ot g

row

th

CWSI

Turfgrass

I-WSM

-1I-W

SM-2

I-WSM

-3I-W

SM-4

I-AKB-1

I-AKB-2

I-AKB-3

I-AKB-4

I-THB-1

I-THB-2

I-THB-3

I-THB-4

I-FF-

1I-F

F-2

I-FF-

3I-F

F-4

I-TF-

1I-T

F-2

I-TF-

3I-T

F-4

S-DN

S-DL

S-DH

S-SN S-SL

S-SH

GW

SI

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.35 0.45 0.55 0.65 0.75

GW

SI

Water Application Adequacy

WSM AKB THB FF TF

Thermal camera (Temp: 77 – 113 ˚F)

07/19/12

08/09/12

77 77

7777

113 113

113113

07/26/12

09/05/12

Thermal camera (CWSI: 0.0 – 1.0)

07/19/12

07/26/12

08/09/12

09/05/12

Questions