Saudi Arabia

In Situ Observations

  1. Parameter: LAI
    Data Collection Protocol:

    LAI measurements on the ground (LAI(G)) were made on the dates of satellite pass using the Plant Canopy Analyzer (Model: PCA – 2200) of Licor Biosciences, USA. At each measurement location, one above canopy and five below canopy readings were recorded to compute a single LAI value. Above and below canopy measurements were made with a ‘‘fisheye’’ optical sensor with 148º angle of view. Respective geo-locations were collected using a handheld Trimble GPS receiver (Model-Geo XH 600). An azimuth mask of 180º view cap was used on PCA-2200 sensor during data collection to block the bright sky for eliminating the shadowing effect of instrument operator.

    Frequency:
  2. Parameter: Spectral Reflectance
    Data Collection Protocol:

    To detect the spectral differences between crop responses to imposed treatments on alfalfa and wheat at both farms, the hyperspectral spectroradiometer “FieldSpec-3” by ASD (Analytical Spectral Devices) was used to collect canopy reflectance data. The FieldSpec-3 spectroradiometer has a spectral range of 350 nm to 2500 nm with a field view of 25 degrees. At the initial stages of crop, in-vitro measurements using “direct contact probe” were made in the lab by collecting geo-referenced samples. At the later stages in-situ measurements were taken by holding the spectroradiometer at a height of 1.5 meters above the canopy with the viewing angle of 25 degrees.

    Frequency:
  3. Parameter: Crop canopy temperature (ºC)
    Data Collection Protocol:

    Canopy temperature measurements were made using a hand-held infrared thermometer of Spectrum Technologies, Plainfield, IL, USA. The mean of three measurements was recorded at the centre of the plot and approximately 0.5 m above the canopy with a 30 angle of view, detecting radiation in the 8–14 µm wave bands. Measurements were recorded between 12:00 to 16:00 hours on cloudless, bright days.

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  4. Parameter: NDVI
    Data Collection Protocol:

    NDVI(G) was measured in the field on the dates of satellite pass, using the Crop Circle (Model: ACS-470) of Holland Scientific, USA. It was calibrated by configuring with a 670-nm filter in channel 1, an NIR filter in channel 2 and a 550-nm filter in channel 3 of the sensor socket for measuring NDVI(G). Map mode measurement with two samples per second was used for field data collection. To determine field data coordinates, an Omnistar GPS receiver (Model 9200-G2) was connected to the Crop Circle at a baud rate of 9600.  Field data measurements were recorded by the crop circle at 1m above the canopy.

    Frequency:
©2015 Joint Experiment for Crop Assessment and Monitoring
© HER MAJESTY THE QUEEN IN RIGHT OF CANADA SA MAJESTE LA REINE DU CHEF DU CANADA (2015)