801810 Description

Purdue Agronomy Farm Soybean Row Direction (801810)

The overall objective of this experiment was to determine and model the effects of rows and row direction (shadowing) on the reflectance of soybean canopies as a function of solar azimuth and zenith angles. A secondary objective was to determine how reflectance may vary with changes in percent soil cover and soil background conditions. Different row directions were used to introduce varying amounts of shadow in the composite of foliage, soil and shadow viewed by a sensor.

An apparatus was built for this experiment, to allow a four meter diameter pseudo plot to be rotated beneath a Landsat band radiometer mounted 8.8 meters above the `plot'. The pseudo plot consisted of several .3 x .3 x .6 meter boxes of soybeans aligned in rows. The backgrounds were trays of Russell soils or boards painted with 3M flat black and 3M flat white to allow for a wide range in reflectance backgrounds. The pseudo plot is easily rotated to obtain any desired row direction.

Data were obtained for three soil covers, three backgrounds, and 37 row directions for several solar zenith-azimuth ranges. Data were collected on three different days.

LARSPEC Identification Record Codes:

1. Plot Number

   _______________________________________________________

    Plot                 Description
    Number
   _______________________________________________________

    841     Soybeans - 100% soil cover
    842     Russell soil - 0% soil cover
    843     3M flat black - 0% 'soil' cover
    844     3M flat white - 0% 'soil' cover
    851     Soybeans in rows with soil background
    901     Soybeans in rows with 3M flat black background
    951     Soybeans in rows with 3M flat white background
   _______________________________________________________

2. Experimenter Parameter 02 (additional information)

Experimenter parameter 02 is a unique observation code for each scene (soil, 3M flat black, soybean/soil background, etc.) and row direction.

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  Experimenter                Description
  Parameter 02
  _______________________________________________________

     841         Soybean - 100% soil cover
     842         Russell soil
     843         3M flat black
     844         3M flat white
   851-887       37 row directions of soybeans/soil, 270,
                  265, 260, ... 90 degrees, respectively
   901-937       37 row directions of soybeans/black, 270,
                  265, 260, ... 90 degrees, respectively
   951-987       37 row directions of soybeans/white, 270,
                  265, 260, ... 90 degrees, respectively
  _______________________________________________________

This experimenter parameter is envisioned to be used when updating the identification records.

3. Scene Type

The number after the scene description, eg. SOY/SOIL 0, represents the angular postion of the turntable per predefined marks. The angular position given in the scene type is related to the row direction by: row direction = 270 - angular position of the turntable.

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