sol-, -sol +

(Latin: base, ground, soil, bottom; the lowest part of something; sole of the foot or a shoe)

Soil orders are named by adding the suffix -sol to a root word, as shown in the table of the United States Soil Taxonomy and the soil classification system of the Food and Agriculture Organization, FAO (agency of the United Nations).

Many of the applicable soilwords which are listed and defined in this unit do not use the -sol suffix; however, they are included because they are essential parts of the major listings of the U.S. Soil Taxonomy and the Food and Agriculture Organization presentations.

The soil groups are based on extensive sets of field and laboratory observations and on extensive technical criteria.

Ultisols with a water table at or near the surface for much of the year.
Arenosol, Arenosols
1. Sandy-textured soils that lack any significant soil profile development.

They exhibit only a partially formed surface horizon (uppermost layer) that is low in humus, and they are lacking subsurface clay accumulation.

Given their excessive permeability and low nutrient content, agricultural use of these soils requires careful management.

They occupy about seven percent of the continental surface area of the earth, and they are found in arid (dry) regions; such as, the Sahel of western Africa and the deserts of western Australia, as well as in the tropical regions of Brazil.

Arenosols are related to the sandy-textured members of the Entisol order of the U.S. Soil Taxonomy.

2. From the soil classification system of the Food and Agriculture Organization, FAO.
3. Etymology: from Latin arena, "sand".
Entisols which have been disturbed and contain fragments of diagnostic horizons that are not arranged in any evident order.
Aridisols with accumulations of clay.
Aridisol, Aridisols
1. Containing soils of arid regions which present at least some subsurface horizon development.

They are characterized by being dry most of the year and with limited leaching.

Aridisols contain subsurface horizons in which clays, calcium carbonate, silica, salts, and/or gypsum have accumulated.

Aridisols are divided into seven suborders: Cryids, Salids, Durids, Gypsids, Argids, Calcids, and Cambids; the definitions of which are presented in this unit.

2. From the U.S. Soil Taxonomy soil-order classification system.
3. Etymology: from Latin aridus, "dry".
Aridisols with accumulation of CaCO3, calcium carbonate.

Calcium carbonate is a chemical compound which is a common substance found in rock and in many parts of the world soils, and is the main component of shells of marine organisms, snails, pearls, and eggshells.

Calcium carbonate is the active ingredient in agricultural lime, and is usually the principal cause of hard water.

Calcisol, Calcisols
1. Soils which are characterized by a layer of translocated (migrated) calcium carbonate (whether soft and powdery or hard and cemented) at some depth in the soil profile.

They are usually well-drained soils with fine to medium texture, and they are relatively fertile because of their high calcium content.

Their chief use is for animal grazing. Occupying about 6.4 percent of the continental land surface of the earth, these soils are typically located in arid or Mediterranean climatic zones (southwestern United States, central and southern Argentina, central China, northern Africa, and the Arabian Peninsula).

Soils in the Aridisol, Inceptisol, and Mollisol orders of the U.S. Soil Taxonomy show strong calcium carbonate accumulation and are therefore closely related to the Calcisols.

Related FAO soil groups originating in arid regions and conditioned by limited leaching include Solonchak, Solonetz, Durisol, and Gypsisol.

2. From the classification system of the Food and Agriculture Organization, FAO.
3. Etymology: from Latin calix, "lime".
Aridisols with a weakly developed B horizon.
Cambisol, Cambisols
1. Soils which are characterized by the absence of a layer of accumulated clay, humus, soluble salts, or iron and aluminum oxides.

They differ from unweathered parent material in their aggregate structure, color, clay content, carbonate content, or other properties that give some evidence of soil-forming processes.

Because of their aggregate structure and high content of weatherable minerals, they usually can be utilized for agriculture projects depending on the limitations of terrain and climate.

Cambisols are the second most extensive soil group on earth, occupying 12 percent of the total continental land area; primarily in boreal polar regions, in landscapes with high rates of erosion, and in regions of material resistant to clay movement and they are not common in humid tropical climates.

For a soil to qualify as a Cambisol, the texture of the subsurface horizons must be sandy loam or finer, with at least eight percent clay by mass and a thickness of 15 cm (6 inches) or more.

These soils naturally form on medium-textured to fine-textured materials under any climatic, topographic, and vegetative-cover conditions.

They differ from Leptosols and Regosols because of their greater depth and finer texture and are often found in connection with Luvisols.

2. From the classification system of the Food and Agriculture Organization, FAO.
3. Etymology: from Latin cambiare, "to change".
Chernozem, Chernozems
1. Humus-rich grassland soils used extensively for growing cereals or for raising livestock.

They are found in the middle latitudes of both hemispheres, in zones commonly termed "prairie" in North America, "pampa" in Argentina, and "steppe" in Asia or in eastern Europe.

Chernozems account for 1.8 percent of the total continental land area on earth and are characterized by a surface layer that is rich in humus and in available calcium ions bound to soil particles, resulting in a well-aggregated structure with abundant natural grass vegetation.

They form in climatic zones with seasonal rainfall of 450–600 mille meters (18–24 inches) per year, coming in the spring or early summer; with cold winters; and with relatively short, hot summers.

In the colder areas of these climatic zones, a natural tall-grass vegetation develops on soil profiles whose surface layers can be as much as two meters (about six feet) thick, with up to 16 percent humus by mass.

Lime may accumulate below this layer because of limited downward percolation of calcium salts.

Chernozems are closely related to the soils in the Mollisol order of the U.S. Soil Taxonomy that form under tall-grass vegetation.

Related FAO soil groups originating in a steppe environment are the Kastanozems and Phaeozems.

2. From the classification system of the Food and Agriculture Organization, FAO.
3. Etymology: from Russian chern zemlja, "black earth".
Alfisols existing in cold climates.
Andisols of cold climates.
Inceptisols of cold climates.
Vertisols within cold climates.
Aridisols located in cold climates.

Much of the information presented in this unit was compiled from the following sources:

Encyclopædia Britannica Online; "U.S. Soil Taxonomy"; December 19, 2010.

Soil and Land Resources Division, by Dr. Paul McDaniel;
University of Idaho, Moscow, Idaho; College of Agricultural and Life Sciences;

The National Geographic Desk Reference; A Stonesong Press Book;
National Geographic Society; Washington, D.C.; 1999; pages 224-227.