1. Remote Sensing in Precision Irrigation
Zhiming Yang

2. Remote Sensing in Precision Irrigation
Image-based remote sensing
Satellite
Aircraft
Radar
Synthetic Aperture Radar (SAR)
Field-based remote sensing
Infrared Thermometer(IRT)

3. Image-based remote sensing
Satellite
Thermal scanner (Thermal band)
Landsat TM, NOAA
Water stress detection and evaluation of irrigation system performance
Evaportranspiration (ET)

4. Image-based remote sensing
Evapotranspiration in Florida, Feb.29, Prepared from GOES satellite imagery ( NASA IITA Project. 9/96 )

5. Image-based remote sensing
Aircraft
Thermal scanner
Water stress detection
E.g. Aircraft-mounted sensors detect water stress of cotton in central California

6. Image-based remote sensing
E.g. A thermal image of a cotton canopy from a helicopter

7. Image-based remote sensing
Limitations
Satellite
Satellite Thermal band temporal
resolution resolution
Landsat TM m days
NOAA m days
Aircraft
High cost
Difficult for geometric correction

8. SAR
Advantage
SAR sensors are sensitive to soil moisture and can be used to directly measure soil moisture
Disadvantage
Data requires extensive use of processing to remove surface induced noise such as soil surface roughness, vegetation.

9. Field-based remote sensing
Advantages
High resolution
Being able to control monitoring conditions
Easy to quantify measurement results
Disadvantage
Difficult for large area
Infrared thermometer
Easy and convenient to use

10. Infrared thermometer
                             

11. Precision Irrigation by IRT
Where and when to irrigate
Temperature and time threshold
Crop water stress index (CWSI)
How much to irrigate
Evaportranspiration
Crop water requirement

12. Infrared thermometer

13. Temperature and time threshold
Temperature threshold(To)
A biologically determined optimum temperature for each crop
Time threshold (TT)
A specific quantity of time when canopy temperature is above the To

14. Temperature and time threshold
Irrigate where and when crop is warmer than temperature threshold and it lasts longer than time threshold in a day
Temperature threshold – crop-specific
Cotton and corn F, Soybean 84 0 F
Time threshold - location-specific(eg.Cotton)
Locations
Lubbock, TX
Shafter, CA
Missipipi State, MS
Threshold time(hour)
4.6
6.8
6.9

15. Crop water stress index (CWSI)
Many methods to calculate CWSI
CWSI =
TC = canopy temperature
TCi = Sensed for irrigation
TCmin = non-watered stressed and calculate from solar radiation and humidity readings or measured in a well-watered plot
TCmax = “completely” water stressed and calculate from air temperature and solar radiation

16. CWSI
Irrigate for sensitive crops where and when CWSI is between 0.2 and 0.5
Irrigate for drought-tolerant crops where and when CWSI is between 0.5 and 0.7
E.g., corn could go as high as 0.4 on the crop water stress index and still produce a harvest, whereas cotton has a much lower stress threshold

17. How much to irrigate Evaportranspiration(ET)
Integrate IRT data, weather station data and ET model to calculate ET
Crop water requirements
Software
IWR(Silsoe College)
KANSCHED (K-state Research and Extension)
IRT-Etc(Center for irrigation technology)

18. PI Example II Location: Florence, SC
Irrigation Systems: self-propelled center-pivot irrigation systems
Research team: Carl Ro Camp, Eo John Sadler and etc, Coastal Plains Soil, Water, and Plant Research Center, USDA-ARS

19. PI Example II

20. PI Example II Objective
To manage water and chemical applications to small areas within the total irrigation system area based on stored data, real- time plant and soil measurements, or a combination of the two on Coastal Plain soils

21. PI Example II
Methods
Modify two commercial center pivot irrigation systems with computer-aided management
The system is controlled by a computer using specialized software and soil, crop, and cultural information stored in a database to control all water and nutrient applications

22. PI Example II
Infrared thermometers are mounted on top of the vertical masts at right end of horizontal tubes to measure crop water stress. The modified application system has been used to apply water and nitrogen to a field experiment with fixed, regular plot boundaries
Current work includes improvements to make the system more reliable and to accommodate irregular-shaped areas of variation.

23. Limitations
IRT method is applicable only to mature plants with a well-developed canopy. It is not applicable to calculations of bare soil evaporation
Misleading
Sharp climatic changes may cause low canopy temperatures even when soil water is limited; Alternatively, under such conditions, high canopy temperatures may be observed when soil water is not limiting
Some other stresses such as pest infestation can also rising of canopy temperature

24. PI Example II

25. Any Questions ?