Fallow is a pale brown color that is the color of withered foliage or sandysoil in fallowfields.[1] This however is a post factum rationalization, and the etymologies are distinct.
Fallow is one of the oldest color names in English. The first recorded use of fallow as a color name in English was in the year 1000.[2] The color was historically often used to describe the coats of some animals, such as fallow deer.[1]
ISCC-NBS Dictionary of Color Names (1955) - Color dictionary used by stamp collectors to identify the colors of stamps—See sample of the color Fallow (color sample #76) displayed on indicated page.