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Remote Sensing in Precision Irrigation
Zhiming YangZhiming Yang
Remote Sensing in Precision Irrigation
Image-based remote sensing Satellite Aircraft
Radar Synthetic Aperture Radar (SAR)
Field-based remote sensing Infrared Thermometer(IRT)
Image-based remote sensing
SatelliteSatellite Thermal scanner (Thermal band)Thermal scanner (Thermal band)
Landsat TM, NOAALandsat TM, NOAA Water stress detection and evaluation of Water stress detection and evaluation of
irrigation system performanceirrigation system performance Evaportranspiration (ET)Evaportranspiration (ET)
Image-based remote sensing
Evapotranspiration in Florida, Feb.29, 1996. Prepared from GOES satellite imagery ( NASA IITA Project. 9/96 )
Image-based remote sensing
Aircraft Thermal scanner Water stress detection E.g. Aircraft-mounted sensors detect water
stress of cotton in central California
Image-based remote sensing
E.g. A thermal image of a cotton canopy from a helicopter
Image-based remote sensing
Limitations SatelliteSatellite Thermal band temporal resolution resolution
Landsat TM 60 m 16 days NOAA 1100 m 0.5 days
AircraftHigh costDifficult for geometric correction
SAR
AdvantageSAR sensors are sensitive to soil moisture
and can be used to directly measure soil moisture
DisadvantageData requires extensive use of processing to
remove surface induced noise such as soil surface roughness, vegetation.
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
Infrared thermometer
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
Infrared thermometer
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
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 82 0 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
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
minTCmaxTC
minTC
iTC
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
How much to irrigate
Evaportranspiration(ET) Integrate IRT data, weather station data and ET
model to calculate ET Crop water requirements
SoftwareIWR(Silsoe College)KANSCHED (K-state Research and
Extension)IRT-Etc(Center for irrigation technology)
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
PI Example II
PI Example II
ObjectiveObjective
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
PI Example II
MethodsMethods Modify two commercial center pivot irrigation Modify two commercial center pivot irrigation
systems with computer-aided managementsystems with computer-aided management The system The system is controlled by a computer using is controlled by a computer using
specialized software and soil, crop, and cultural specialized software and soil, crop, and cultural information stored in a database to control information stored in a database to control all water and nutrient applications all water and nutrient applications
PI Example II
Infrared Infrared thermometers are mounted on top of thermometers are mounted on top of the vertical masts at right end of horizontal the vertical masts at right end of horizontal tubes to measure crop water stress. The tubes to measure crop water stress. The modified application system has been used to modified application system has been used to apply water and nitrogen to a field experiment apply water and nitrogen to a field experiment with fixed, regular plot boundarieswith fixed, regular plot boundaries
Current work includes improvements to make Current work includes improvements to make the system more reliable and to accommodate the system more reliable and to accommodate irregular-shaped areas of variation. irregular-shaped areas of variation.
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
PI Example II
Any Questions
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