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
See the plot_number_801810.txt file under the Supporting docs tab
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.
See the parameter2_801810.txt file under the Supporting docs tab.
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 position 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.
The test took place in 1980.
The supporting docs include a brief summary of used instruments, a wavelength table (Wavelength_ASCII.txt), reflectance note and reflectance tables (ReflectanceTable206.txt and ReflectanceTableMulti.txt), and file format description (ExperimentDataFormat3.txt). The format description file is in ASCII format in lines of 80 characters.
This research dataset is part the Field Research Data Library that consists of over 200,000 spectral observations of soils and vegetation that have been collected since 1972 till 1991 as part of the research focused on vegetation and soils at the Laboratory for Applications of Remote Sensing (LARS) located at the Purdue University.
Cite this work
Researchers should cite this work as follows:
- Daughtry, C. (2015). Purdue Agronomy Farm Soybean Row Direction (801810). Purdue University Research Repository. doi:10.4231/R7GH9FV5
Location: Purdue Agronomy Farm, West Lafayette, IN
Latitude/Longitude: 0402813N / 0865927W
Experiment Type: Crops - Soybeans, Soil, 3M Flat White, 3M Flat Black
Radiometer: Exotech 100
Wavelength Range: 0.50-1.10 um