Major Soils of Africa


Africa and the nations that make up this continent have consistently trailed behind the rest of the globe in terms of both economic and agricultural growth, despite being one of the largest. This is largely because many (but not all) of the soil types in Africa are sandy and arid, which renders them highly unsuited for agricultural development on any significant scale.

Characteristics of Soils of Africa

Deeply weathered, acidic soils with large concentrations of iron oxides and a deficiency in vital plant nutrients characterize the central, more humid region of the continent (brown-orange Ferralsols, frequently coupled with light orange Acrisols). Dryer weather results in less severe weathering processes, which, when combined with inputs from wind-blown dust, produce soils with more clay and a somewhat higher pH (Lixisols are visible as pale pink regions). Large portions of West Africa are characterized by soils with surface layers that have been cemented by iron and clay compounds, frequently causing a landscape inversion (Plinthosols are indicated by the dark brown hue).

The soil types that predominate in the desert regions of the north and south are sandy (brownish yellow: Arenosols), shallow (grey: Leptosols), weakly developed (pale rose: Regosols), lime-rich (bright yellow: Calcisols), and gypsum-rich (pale yellow: Gypsisols). Soils with a large concentration of silica and an associated "hardpan" (pinkish grey: Durisols) can be found in the dry region of southern Africa.

The brilliant red colours on the map are linked with volcanic deposits (Andosols), which are particularly noticeable along the African Rift Valley. The dark purple colour on the map, prominent in Sudan and Ethiopia, indicates soils with significant quantities of swelling and shrinking clays. Additionally, the majority of Africa's richest soils (dark rose: Nitisols) are found here.

The colours light green and pale brown, respectively, denote soils that have grown beneath perennial grasslands in the Mediterranean region (Kastanozems and Phaeozems). The entire map is covered in soils that have been significantly influenced by water. These soils represent wet conditions brought on by high groundwater levels (dark blue: Gleysols), stagnant water (dark orange: Planosols), or sediments from Africa's river systems, deltas, or mangroves (bright blue: Fluvisols). In arid climates and coastal plains, ephemeral lakes are primarily connected with saline and sodium-rich soils (purple: Solonchaks; light purple: Solonetz).

Continent has a variety of soil types, including those that are recent and underdeveloped (orange: Cambisols) and those that are nutrient-rich (dark grey: Histosols). Local importance can sometimes be found in soil types like Umbrisols (dark green), Podzols, and Luvisols (dark pink). Highly disturbed soils, sometimes known as "Technosols," may be found in urban areas and close to sizable mines. Due to the small scale of this map, they are, nevertheless, too little to be seen.

Types of Major Soil of Africa

Although there are many more varieties of soils found in Africa. here are the few major types of soils found in Africa and description about them −

Histosols

Only a small portion of the African continent, including the coasts of West Africa and Madagascar, is home to this particular form of soil. The soil in this region of Africa is typically acidic. It often consists of sand or clay, combined with partially decomposed plant debris. Histosols can be utilized for grazing and some agricultural purposes if managed properly, despite not being as productive as some soils.

Andisols

The andisols are among the most fertile soil types in Africa, and they are mainly made up of volcanic ash and pumice as well as other debris that were thrown from the volcano. The areas with this type of soil are therefore agriculturally productive. Their main distribution area is the Great Rift Valley.

Arenosols

This variety of African soil is widespread across the continent, particularly in the Kalahari Desert region. Since sand makes up a large portion of this soil, it is frequently unfertile. Due to this, this type of soil is primarily utilized for grazing, though with the right irrigation, it is also suitable for subsistence farming.

Vertisols

Along the rift running from Sudan to South Africa, these soils can be found. Since they are primarily made of clay, they are difficult to till, which lowers agricultural output. They also become hard during the dry season and sticky during the wet season.

Ferrasols

Typically, tropical areas of Africa, primarily Central Africa, contain this kind of African soil. Although these soils are physically quite robust, they are chemically unstable, and the nutrients are frequently locked up in the biomass, making it impossible for plants to access them. Although these soils have good erosion resistance, they need a lot of irrigation and other agricultural effort to be productive.

Aridisols

According to most estimations, this type of African soil covers a sizeable area of the continent—about 26%. This kind of soil can be found in a variety of landscapes, such as dunes, salt pans, and rocky areas. These soils are largely useless for agriculture since they are composed of sand and are dry.

Division of Soils Based on Zones

Here are the divisions of African soils based on different zones of Africa −

Soils of the Very Humid to Humid Forest Zone

Ferralsols, Nitosols, Acrisols, Arenosols, Cambisols, and Lithosols are the main highland soils in this region. The development of ferralsols, nitosols, acrisols, and arenosols is exceedingly vast. However, because cambisols are more recent formations, they are naturally more fertile. All of Africa's agroecological zones have lithosols, which are relatively shallow soils that are typically found on steep slopes with exposed rock debris. Gleysols and Fluvisols make up the majority of the major lowland soils.

Soils of the Humid to Sub-humid Wooded Savannah Zone

Luvisols, Ferralsols, Arenosols, Acrisols, Nitosols, Cambisols, and Lithosols are the primary soils of this zone. The majority of the upland soils have good to fair drainage, are gravelly, and have a light-textured matrix that, in some places, rests on top of an iron pan that formed in situ at shallow depth.

Soils of the Semi-humid Wooded to Semi-arid Savannah Zone

The primary upland soils in this zone have a high clay activity and are typically referred to as Xerosols, Luvisols, Cambisols, Arenosols, Rendzinas, and Lithosols in the FAO/Unesco (1977) Legend. Fluvisols, Gleysols, Regosols, Planosols, Vertisols, Solonetz, and Solonchaks are the main lowland soils found in the semi-arid zone.

Soils of the Semi-arid to Arid Savannah Zone

Yermosols, Xerosols, Lithosols, Regosols, Solonetz, and Solonchaks are the main soil types in the region. These soils tend to be sandy, rocky, calcareous, or siliceous, with significant salt and gypsum deposits.

Soils of the Mediterranean Zone

The primary soils resemble those of the sub-humid woodland savannah, semi-arid savannah, and dry savannah zones. These include Solonchaks, Phaeozems, Cambisols, Kastanozems, and Rendzinas.

Conclusion

All around the continent, Africa's soils show a tremendous deal of diversity and variance. Histosols, Andisols, Arenosols, Vertisols, Ferrasols, and Aridisols are some of the common soil types in Africa. Each type of soil has unique qualities and usefulness for agricultural uses. Although certain soils are fertile and productive, others are sandy, dry, or chemically unstable, which presents difficulties for the growth of agriculture.

The division of soils into various zones, such as the Mediterranean zone, semi-arid to arid savannah zone, semi-humid to sub-humid wooded savannah zone, humid to sub-humid wooded savannah zone, and humid to sub-humid forest zone, further reflects the diverse soil composition and properties throughout Africa. In order to apply efficient agricultural techniques and encourage sustainable development on the continent, it is crucial to understand the character of these soils.

Frequently Asked Questions

What are the major soil types found in Africa?

The major soil types found in Africa include Histosols, Andisols, Arenosols, Vertisols, Ferrasols, and Aridisols.

Which soil type is most fertile in Africa?

Andisols are considered one of the most fertile soil types in Africa. They are mainly composed of volcanic ash and pumice, making them agriculturally productive.

Where can Andisols be predominantly found in Africa?

Andisols are predominantly found in the Great Rift Valley region of Africa.

What are the characteristics of Arenosols and their significance in agriculture?

Arenosols are sandy soils that are widespread in Africa, particularly in the Kalahari Desert region. They are often infertile but can be utilized for grazing. With proper irrigation, they can also support subsistence farming.

What are the challenges associated with Vertisols for agricultural activities?

Vertisols are clayey soils found along the Sudan to South Africa rift. They are difficult to till, as they become hard during the dry season and sticky during the wet season, posing challenges for agricultural productivity.

Which regions of Africa are characterized by Ferrasols?

Ferrasols are typically found in the tropical areas of Africa, primarily in Central Africa.

What percentage of Africa is covered by Aridisols, and why are they unsuitable for agriculture?

Aridisols, which are dry and sandy soils, cover approximately 26% of Africa. They are largely unsuitable for agriculture due to their low fertility and arid nature.

Updated on: 09-Nov-2023

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