Soil color is determined by comparison with standard colors on a soil color chart called the Munsell Soil Color Chart. Mixtures are identified numerically according to the amount of yellow or red used to produce the mixture. For example 5YR is an equal mixture of yellow and red. As the number increases, the amount of the first color increases relative to the second color. It is the degree of lightness or brightness of the hue reflected in the property of the gray color that is being added to the hue.
Value is made by mixing white and black.
The amount of gray of a particular value that is mixed with pure hue to obtain the actual soil color. The lower the chroma the closer the color is to the pure gray of that value. 13.4 Soil Drainage Classes 1. Soils with yellow color tend to occupy landscape positions or occur in climates that are naturally wetter than red soils. The grayest colors occur in permanently water saturated soil horizons and sometimes have a bluish hues.