SOIL REFLECTANCE MEASUREMENT USING A PHOTOGRAPHIC METHOD

The albedo of two soils, Avondale clay loam and Yuma sand dunes, was determined using a panchromatic film in a hand-held 35-mm camera. Samples with different volumetric moisture content, from air dry to saturation, were compared to calibrated reference surfaces of evenly distributed tones of gray. For the limited spectral sensitivity of the detector (panchromatic film), a correction factor K prime was derived graphically from known spectral reflectance of a different soil. The albedo is given by the product of the correction factor and the fraction of the reflected radiation that contributes to the detector signal. 4 refs.