Soil Color Standards and Terms for Field Use—History of Their Development
Soil colors attracted some attention in Russia but little in the USA prior to the present century. Two of the first three soil survey reports published by the U.S. Department of Agriculture (USDA) in 1900 did not mention soil colors. A few year later, however, colors were considered in the definition and differentiation of soil series. Efforts were also being made to identify constituents responsible for different colors. Initial steps toward soil color standards and terms in both the USA and Russia were hesitant and faltering. The Bureau of Soils, USDA, published a list of 22 names for colors in 1914 but standards were not mentioned. During the 1920s, efforts to establish color standards in the USA were initially frustrated by the state of color technology. By the end of the decade, however, a method had been developed to determine the colors of dry soil samples in the laboratory and express those in proportions of white, black, yellow, and red. Somewhat comparable efforts were underway in the former Soviet Union. Progress seems to have stalled at that point for another 10 yr. The first set of color charts for field use in the USA was published in 1941. The charts are like those of the present in many ways but are smaller and lack the Munsell notations for hue, chroma, and value. Instead, each chip is assigned a name from the ISCC-NBS system. In addition to providing the charts and names, the 1941 bulletin summarizes earlier efforts in this country to identify colors, establish standards, and assign names. Beginning in 1945, the Division of Soil Survey, Bureau of Plant Industry, Soils, and Agricultural Engineering, USDA, launched a major effort to improve standards and terminology for properties of soil horizons such as color, texture, structure, and consistence. The effort lasted about 5 yr. Early in that period, a decision was made to use constant hue charts showing chromas and values of the Munsell system with their notations. Rather than the ISCC-NBS names, folk terms were adopted for soil colors. Several years were required to reach agreement on names. The Munsell color charts and the new set of names were adopted in the American soil survey program in 1949. Worldwide use of the color charts and names was recommended by the International Society of Soil Science about 10 yr later. A few modifications have been made of some charts since then and one chart for colors of wet soils (“Gley” chart) has been added. The intermittent efforts that extended over a period of 35 yr have provided a useful system to describe soil color in the field. “When the subject of soil colors is finally elucidated, it will become possible to compile soil maps that will be equally useful to peasants and to learned agronomists” (Dokuchaiev, 1948). Together with this optimistic view in Dokuchaiev's monograph on the Russian Chernozem, published initially in 1883, are comments on the perception of soil color in the field. That perception was said to depend upon several factors. Examples of these factors are moisture conditions, the quality of light, the time of day, and lumpiness of the soil surface. These remarks are still valid.
Early understanding of soil color, early practice in describing color, the changes with time, and the efforts that eventually led to the present standards and terms are summarized in this chapter. The summary covers efforts only in the USA and the former Soviet Union because I am not acquainted with any elsewhere. The history provides insight into the frequently tangled pathway toward greater accuracy in the description of soil color.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 1993 by the Soil Science Society of America, Inc., 5585 Guilford Rd., Madison, WI 53711 USA