Sugita and Marumo (1996) tested how color alone can be used
to differentiate between soils after each of the following treatments:
air-drying, moistening, organic matter decomposition, iron oxide removal, and ashing. Removing organic matter and iron
oxide produced the most distinguishable soil colors (97% of samples
were distinguishable). The results showed that various treatments
can help to distinguish the color between soil samples
when using only the Munsell Color Chart making soil color analysis
more accurate, and that color can be a robust indicator of organic
matter and iron oxide levels in soil. However, because different
regions have different soil properties, various other treatments
may be necessary to accurately determine color. This method also
eliminates the convenience of in-the-field color analysis that the
Munsell Color Chart offers.