Figure 9.14

Soil taxonomy. (A) The soil taxonomy classification system recognizes 12 soil orders based on soil color, texture, and chemical makeup. The 12 soil orders display a wide range of colors and horizons as a result of the different processes from which they form. (B) Climate is often an important factor in determining the geographic distribution of soil orders. This soil map bears many similarities to the map of Köppen climate zones (see Figure 8.2). In many areas, however, there is no spatial correspondence between soils and climate zones because many other factors, such as parent material and topography, determine soil types. Andisols, for example, are a product more of their parent material (volcanic ash) than of climate.

(All photos courtesy of USDA Natural Resources Conservation Service)