CALCULATION OF SOIL COLOR FROM REFLECTANCE SPECTRA

Procedures were developed for obtaining visible spectra of dry and moist soil powders on a Cary 17D spectrometer. Accuracy and precision were checked by measuring the colors of: (i) 28 chips of the Inter-Society Color Council-National Bureau of Standards (ISCC-NBS) Centroid Color Chart, (ii) 279 chips of the Munsell Soil Color Chart, and (iii) 12 selected soil samples. Measured Munsell values were not significantly different from nominal values. Measured hue and chroma were significantly different from nominal hue and chroma, but the difference was approximately 0. 25 units of chroma and, thus, is relatively small. Increased accuracy and precision make it possible to quantify small differences in soil color that are difficult to quantify using only visual color matching.