The predominant soil found in the deciduous forest biome is alfisol. This type of soil is characterized by a gray to grayish-brown coloration and a relatively high fertility. Alfisols form via the processes of weathering, eluviation and illuviation.
Soil is generally classified into 12 types or orders: alfisols, gelisols, histosols, andisols, inceptisols, entisols, aridisols, mollisols, vertisols, oxisols, spodosols and ultisols. The vegetation in deciduous forest biomes, as well as prairies and grasslands, contain an abundance of alfisols.
The deciduous forest biome is situated in the mid-latitudes, which lies between the tropics and polar regions. This biome is the most densely populated biome due to its temperate climate and lengthy growing periods. Deciduous trees that often shed dominate the landscape of the biome. When the leaves rot and decay, the organic nutrients and minerals are taken up by the soil, which largely contribute to the fertility of alfisols in deciduous forest biomes. In the United States, alfisols are commonly found in Indiana and Ohio.
Alfisols are further classified into suborders, great groups and subgroups. The major suborders of alfisols, which are based on temperature and moisture content, include aqualfs, xeralfs, boralfs, ustalfs and udalfs. Some of the great groups of alfisols include fragipans, duripans and kandic horizons while aeric, arenic and umbric are subgroup classifications.