Soils of Africa: map and 6 types of soils, their features and applications

Africa is the hottest continent, while the climatic zones in which it is located are diverse - from deserts to humid forests. The soils of the continent also differ. The diversity is explained by the amount of precipitation and the period of precipitation. Consider the characteristics of the soils of Africa, which types are most characteristic of the continent and their economic use.

Features

For the soils of the tropical zone, the lateritic process of formation is typical. The soils of moist equatorial forests are red-yellow (red color gives the soil iron oxide), well permeable to moisture and air, powerful, but contain little humus, although the top layer of organic matter decomposes quickly.Groundwater comes close to the surface. In the west of the Congo Basin, due to the slow flow of rivers, lateritic soils become gley, a large area is occupied by tropical swamp soils.

To the north and south of the central part of the mainland, red-yellow soils turn into red, which develop under wet savannahs and evergreen forests. Red-brown soils occupy large areas of southern and southeastern Africa.

The map shows that tropical deserts are occupied by primitive, gravelly or pebbly soils, semi-deserts are gray soils, in oases - alkaline saline and saline soils. Closer to the Mediterranean coast, in the humid regions of the Atlas and Cape Mountains, brown soils form, in the dry regions (the coast of Egypt and Libya) they are gray-brown, with a high content of gypsum and carbonates.

What soils are typical for Africa

African soils diverge symmetrically in both directions from the equator.

Reds

These are the predominant soils of the savannas and are formed by processes of constant change from wet to dry climates. In regions where there are more wet days than dry days, cracks form on the surface. There is little humus in red soils, they are acidic due to leaching processes. In those regions in which there are more dry days, the soil darkens and becomes more humus.

The red color of the soil of Africa is the result of a high content of iron oxides in it, the percentage of humus reaches 1.5 to 2%, fulvic acids predominate in its composition. In the northern part, closer to the desert, the ground is gradually turning into a reddish-black color.

During the period of drought, the soil acquires a lumpy appearance, during the rainy period it is washed away, erosive processes are actively operating in it. A dense layer passes under the upper horizon, which does not pass moisture well, and minerals washed from above remain in it.

Red-brown

Soils of this type are formed under typical dry savannas and tropical woodlands, in the eastern part of the mainland. Here the dry season lasts 6-7 months, 80-1200 mm of precipitation falls annually, such conditions (stable high temperature and alternation of dry and wet seasons) form a soil consisting of layers of different properties, composition and morphology.

The upper horizon is light in granulometric composition, sandy or sandy loam, it is moisture-absorbing, passes water and air well. Under it is a dense, very weakly structured clay layer. It is impregnated with iron oxides. Below it is a horizon with a high content of nodules of lime and iron oxides. A large percentage of iron in all layers of the soil gives it a specific color.

Primitive, gravelly or pebbly

These are the soils of tropical deserts, they are located mainly in the northern half of the mainland, in the southern part of the desert they stretch in a narrow strip near the western edge of the continent. They are completely infertile, structureless and often saline in large areas. Lime and gypsum barks are common, ranging in thickness from a few centimeters to 1-2 m.

Saline and alkaline saline soils

The upper layers of soils of this type are rich in soluble s alts, which makes them almost unsuitable for vegetation growth. The morphological structure of the solonchak soils of Africa is expressed in the fact that the upper horizon contains an accumulation of s alts in the form of a crust or a loose layer of whitish-gray or white color. In the soil profile, s alts are in the form of fine-crystalline accumulations in the form of shiny veins or inclusions.

The accumulation of s alts is due to the evaporation of moisture coming from close to the surface and mineralized groundwater.The solonchak layer contains almost no humus; under it there is a soil-forming rock, also saline. S alt marshes can have different capacities, but they always contain easily soluble s alts with a percentage of 5-15%. Their maximum number is located near the surface, usually in the crust, but the deeper, the less their number.

Sierozems

Formed in a dry subtropical climate on loam. These are loose, light-colored soils, with a high content of carbonates on the surface. Serozem contains more than 4% of humus, this layer does not exceed 50 cm. Soils of this type require the application of mineral fertilizers to increase their productivity.

Brown, taupe, rich in carbonates and gypsum

Brown African soils form under hardwood forests and shrubs in the northwest and southwest of the continent.Usually they are loamy or heavy loamy, if the soil is formed on dense sedimentary rocks, the thickness of the profile reaches 1 m, on loose rocks the thickness is greater. Humus in brown soils in the upper layer is up to 5%, it is also found at a depth of 1 m, where its content is 1%. Soil differentiation by iron or aluminum is weakly expressed. The acidity reaction in the humus layer is neutral, but as you move down, the acidity increases.

Grey-brown soil develops in dry subtropics, under arid shrub and grassy vegetation. Gray-brown soils of Africa are formed in conditions of non-leaching water regime and low occurrence of soil water.

The morphological structure of soils is as follows: at the top there is a humus layer 20-25 cm thick, heavy loamy. It gradually passes into the second horizon 0.5-1 m thick, dense, small-block structure, with a high content of carbonates, which are presented in the form of veins.In the next layer, carbonates are even greater and are visible as spots and concretions. The parent rock also contains carbonates, usually saline.

The amount of humus in the gray-brown soils of Africa is small, but it lies deep enough. The reaction is slightly alkaline or alkaline due to saturation with s alts. According to the mechanical composition, the soils are heavy, clayey throughout the thickness of the profile, but especially in the middle part. They have a low level of aeration and moisture permeability.

Soil applications

The African savannas are favorable for agriculture, significant areas of land have been cleared and plowed up. The crops grown here are cotton, corn, peanuts, tobacco, rice, sorghum. They are also used as pastures.

Citrus fruits, grapes, fruit crops, coffee are grown on brown and gray-brown soils. Agricultural techniques are used to increase yields: irrigation, fertilization, organic and mineral, measures are taken against erosion.Date palms, figs, fruit and olive trees, citrus fruits and some types of vegetables are cultivated in the oases.

A feature of the location of the soils of Africa is symmetry relative to the equator. As in other parts of the world, they are shaped by climate and underlying rocks. They differ in soil-forming rock, thickness of horizons, air and moisture capacity, content of organic matter and minerals. Various vegetation is distributed on them, from moist forests, shrubs, grasses; very rare vegetation exists even in deserts and saline soils.

Most African soils have a low humus content, which is why they are not very fertile in their natural state, but can be used for growing crops with constant irrigation, fertilizer application and other fertility improvement measures.

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