Characteristic Variations in Spectral Reflectance of Selected Eroded Alfisols

Abstract

AbstractSoil cores taken at incremental depths from a Typic Hapludalf were examined to investigate the relationships among the chemical, physical, and spectral reflectance properties which occur as the proportion of various horizons change in the soil samples. Results of these studies were compared to soil samples taken from selected Typic Hapludalfs in Indiana which represented various degrees of natural erosion. Two important properties affecting the spectral reflectance of these soils were the organic matter and iron oxide contents. High organic matter contents tend to cause the reflectance to be low and give a concave character to the spectral response in the 0.5‐ to 0.8‐µm region. High iron oxide content along with the reduction in organic matter tends to cause an increase in the overall spectral response; however, the presence of iron oxides causes a leveling off of the spectral response in the 0.8‐ to 1.1‐µm region. Intermediate contents of organic matter and iron oxide affect the spectral response relative to their proportions within the soil sample. These distinctive reflectance characteristics can be related to the severity of erosion. Comparison of laboratory data to simulated Landsat data suggests that satellite multispectral scanner data can be useful in detecting eroded soils. Separability of erosion classes for the Alfisols studied was best determined by observing the slope of the simulated Landsat plots between 0.75 and 0.95 µm, bands 3 and 4. As the severity of erosion increases, the slope of the plot decreases in this region.