LITOSOL: CHARACTERISTICS AND USES - ENVIRONMENT - 2025

Litosol or leptosol is a group of reference soils in the classification of the World Reference Base for Soil Resources. They are very thin soils, less than 25 cm thick and before reaching the rocky layer they can be deeper, with a high content of rocks or gravel.

The name lithosol derives from the Greek lithos (stone), referring to the stony condition, with abundant gravel of the soil. While leptosol comes from the Greek leptos (thin), alluding to the thinness of these soils.

Lithosol in Ethiopia (Africa). Source: Jan Nyssen / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

Today the term lithosol is not widely used and the term leptosol is more commonly used to refer to this reference group of soils. In some systems the term lithosol is restricted to those soils where only a thin A horizon is shown directly on the bedrock.

It is one of the groups of soils that owe their formation to topographic conditions, since they are created in mountainous areas with steep slopes. As well as on the banks of rivers that deposit more gravel than fine material or on plains with a calcareous rocky base.

Due to their physical limitations, mainly their shallow depth and great rock content, they have a restricted agricultural use. However, with proper management they can be productive soils for certain vegetable, potato and other crops, as well as for forest production.

On the other hand, when grasslands develop on them, with proper management they can be used for grazing in the wet season. Finally, these soils play an important ecological role, since they develop forests of different nature.

Lithosol characteristics

Lithosols or leptosols are poorly developed soils with shallow depth, generally not greater than 25 cm, and high content of stones of various sizes. At that shallow depth, a continuous rock layer develops, a calcareous layer or a layer of abundant loose rocks.

Also included within this group are soils with greater depth, but in this case with a high content of rocks. Under these conditions, the disintegrated material that makes up the soil does not exceed 20% by volume in relation to the rocky material.

Due to their shallow condition or in any case to their high content of rocks, they present free drainage, so they retain little water.

Parenting material and training

The parent material or rock that gives rise to these soils is highly variable and affects their chemical characteristics. In some classification systems, lithosols formed on acidic rocks are called Rankers and those on calcareous or basic rocks are called Rendzinas.

Lithosol Redzina. Source: High Contrast / CC BY 3.0 DE (https://creativecommons.org/licenses/by/3.0/de/deed.en)

The determining factor in the formation of this reference group of soils is the action of erosive processes that prevent soil genesis. That is, when erosion acts at a higher rate or speed than soil is capable of forming.

Profile

The profile of lithosols or leptosols is poorly developed, as they are soils in formation and of little depth. In some cases they only consist of an A horizon directly on the bedrock.

Likewise, between the A horizon and the mother rock, a calcareous or not underdeveloped B horizon can occur, with abundant rocks. There are several surface diagnostic horizons or epipedons, which can be found in lithosols or leptosols.

One of these is molic, a dark horizon, with a high content of organic matter and more than 50% saturation with bases. For its part, the umbric is similar to the previous one but with a base saturation of less than 50%.

Likewise, a vertic horizon can be found, with abundant expansive clay, or a yermic horizon, with its crust covered with gravel or stones. Another is ochric, which is a light-colored, low organic carbon, hard dry surface horizon.

Environments and regions where they develop

Lithosols are formed in mountainous areas with slopes where the drag of weathered material (fragments) is high. In such a way that there is no opportunity for a deep soil to consolidate with a profile of developed horizons.

The same happens on the banks of rivers, whose overflows deposit coarse materials (gravel) and drag the formed soil. They are also created in calcareous-based plains such as the Yucatan peninsula.

The largest proportion of soils in the world is represented by lithosols or leptosols, particularly abundant in mountainous areas in all climates. They cover about 1.7 million hectares in the world, especially abundant in large mountain ranges and deserts.

They are widely distributed in South America, North America (especially Canada and Alaska), Asia, and the Sahara and Arabian deserts.

Applications

Lithosols or leptosols present limitations for their use mainly due to their shallow depth and stony nature. However, with proper management it is possible to make them productive for the production of certain crops and in forestry production.

Limitations and handling

The fundamental limitation of lithosol or leptosol soils is their shallow depth and abundant rock content. This confers undesired properties in relation to low water retention even in humid environments and difficulties for root growth.

On the other hand, since they are soils in formation and generally in conditions of steep slopes, erosion is high. In any case, in some mountain areas these soils have been used through the construction of terraces, removing the stones manually.

The recovered stones are used to build the terraces, supporting the slopes, thus functioning as anti-erosion barriers. For example, this system was implemented by the Incas and other indigenous cultures for the use of Andean lithosols or the Mayans and Aztecs in the mountain ranges in Mexico and Central America.

Crops

Although given their physical characteristics and their topographic location, they are not normally used for cultivation, it is possible to do so. With proper management, crops such as potatoes, corn and various vegetables are produced.

Grasslands

Some of the original vegetation that develops on these soils includes grasslands that can be used as pastures in the wet season. However, it is important to take into account the topography of the terrain and the fact that they are shallow soils.

Due to these two factors, its use for extensive livestock is limited, and the animal load that they must bear must be restricted. In conditions of high slope it is preferable to leave them unaltered to avoid erosion.

Forests and forest production

Lithosols support forests of different types both in tropical and temperate and cold conditions. In this sense, they are useful for the conservation of these plant formations of such ecological importance.

Lithosol vegetation. Source: Milsto96 / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

For example, in temperate zones, mixed deciduous forests and pine forests are found on these soils. On the other hand, with proper management, forest plantations can be established on lithosols, as demonstrated with the teak and mahogany plantations in Asia.

References

1. Driessen, P. (Edit). (2001). Lecture notes on the major soils of the world. FAO.
2. FAO-Unesco. The FAO-Unesco Soil Classification System. The World Reference Base for soil resources. (Seen on April 11, 2020). Taken from:
3. ISRIC (International Soil Reference and Information Center). 2020. Leptosols. Available at:
4. Jaramillo, DF (2002). Introduction to soil science. Faculty of Sciences, National University of Colombia.
5. Lal, R. (2001). Soil degradation by erosion. Land Degradation and Development.