70th SWCS International Annual Conference July 26-29, 2015 Greensboro, NC

1. 70th Annual SWCS Conference
July 26-29, 2015; Greensboro, NC
Saleh Taghvaeian
(405) 744-8395
Saleh.taghvaeian@okstate.edu

2. 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

3. 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

4. • Water transpiration requires energy
• The higher the water use rate, the cooler the canopy
• Canopy temperature is affected by other variables
Canopy Temperature

5. Crop Water Stress Index (CWSI)
CWSI =
𝑑𝑇𝑎𝑐𝑡−𝑑𝑇 𝑚𝑖𝑛
𝑑𝑇 𝑚𝑎𝑥−𝑑𝑇 𝑚𝑖𝑛

6. 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?

7. Obtaining canopy temperature

8. 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
dTmin(˚C)
Vapor Pressure Deficit (kPa)
AZ, Maricopa
CO, Greeley
CO, Iliff
CA, Davis
ND, Oaks
India
Theoretical vs. Empirical approaches

9. Case studies
• Sunflower
• Turfgrass
• Corn

10. Sunflower
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)
CWSI
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)
CWSI
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)
CWSI
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)
CWSI
1000-1100 1100-1200 1200-1300 1300-1400
65/40

11. Sunflower
y = -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
fIPAR
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
LAI
CWSI
y = 9.69x + 0.84
R² = 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
Relativerootgrowth
CWSI

12. Turfgrass
I-W
SM
-1I-W
SM
-2I-W
SM
-3I-W
SM
-4I-AKB-1I-AKB-2I-AKB-3I-AKB-4I-THB-1I-THB-2I-THB-3I-THB-4I-FF-1I-FF-2I-FF-3I-FF-4I-TF-1I-TF-2I-TF-3I-TF-4S-DN
S-DLS-DH
S-SN
S-SL
S-SH
GWSI
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
GWSI
Water Application Adequacy
WSM
AKB
THB
FF
TF

13. Thermal camera (Temp: 77 – 113 ˚F)
07/19/1208/09/12
77 77
7777
113 113
113113
07/26/1209/05/12

14. Thermal camera (CWSI: 0.0 – 1.0)
07/19/12
07/26/12
08/09/12
09/05/12