Note the page from a Munsell color book and the Earth Colors book, above. Soil color is determined by comparing the color of the soil to the chips in the color charts. Hue is the dominant spectral color of the rainbow - yellow, reds, orange. The value is the relative darkness or lightness, and the chroma is the purity or strength of the color. Value is expressed as the numerator of the fraction and is along the left hand margin of the page.
Value is the relative darkness or lightness of the soil color.
Chroma a is along the bottom, and is the denominator of the fraction. Chroma is the relative purity or strrength of the color, low chromas have dull colors, while high chromas have bright colors. Coloring soils, like texturing, takes practice. You also need to be able to note the Munsell notations and determine what kind of soil horizon the color might represent. The significance of soil color relates to the properties we can infer from certain colors.