3 Planting Dates (May 2, 16, and 30) 3 Plant Populations (25,000, 50,000 and 75,000 plants per hectare) 2 Soil Types (Chalmers, "darker" and Fincastle, "lighter")A split plot design with two replications was used. Spectral measurements, along with agronomic characterizations of the canopies and surface soil, were made at approximately weekly intervals throughout the growing season.
The spectral reflectance measurements were made with a Landsat band radiometer (Exotech Model 100). Radiant temperatures and overhead color photographs of the canopies were obtained simultaneously with the reflectance measurements.
The major agronomic measurements of the plots included growth stage, percent soil cover, height, leaf area index, biomass, and surface soil moisture and condition. Grain yields were measured at harvest time.