The use of high spectral resolution imaging spectrometry in the delineation and identification of selected soil properties in the western sandhills of Nebraska

Light reflectance in the near and mid infrared wavelengths from plant cover can be used to discriminate among soil mapping units as well as to measure selected chemical properties associated with the mapping units. Airborne imaging spectrometry can provide the spectral sensitivity to detect subtle differences in the plant canopy response in the infrared wavelengths while maintaining the imaging capabilities of aerial photography for small scale soil mapping. Sixty-six field sites were examined for spectral discrimination among soil mapping units. An additional fifty-nine sites were selected for evaluation of spectral measurement of exchangeable bases, cation exchange capacity, and calcium carbonate equivalence. Spectral information was collected by the Jet Propulsion Laboratory\u27s Airborne Imaging Spectrometer over central Garden County, Nebraska. One hundred and twenty-eight channels of spectral data between 1.2 and 2.4 microns were obtained for each of the 125 sites. Soil and vegetation samples were georeferenced with the spectrometer data. Results indicated that soil mapping units can be identified with an accuracy of 97% using only spectral data from mid infrared wavelengths. The primary contributing factor associated with the separation was the absolute moisture content of the vegetation and/or soil surface. Linear discriminant analysis provided evidence to suggest that the spectral separations of mapping units paralleled the hydrosequence associated with the local soils. Measurement of soil chemistry was successful only in the case of exchangeable sodium. Models were developed using only spectral information as predictor variables. The derived models indicated that other variables, in addition to the spectral data, were needed in order to generate improvement in the prediction models