Ethiopia Mountain

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Ethiopia’s Soil

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In this generalized soils record only the dominant soil types are indicated. The area percentages given for each soil unit are the percentage of occurrence of the soil type over the country as dominant soil, as well as in association with other soil types.

The nomenclature used is the FAO/UNESCO legend for the soil map of the world 1966 E.C (1974).

A. Orithic Acrisols (4.5 %)
These soils have a distinct argillic B horizon and a low base saturation. The topsoil can have a coarse texture.

Orthic Acrisols occur mainly on sloping terrain. They have limited agricultural potential. The soils are chemically poor; the contents of weatherable minerals is generally low; the PH is less than 5.5. and available P contents are very low.

Physically these soils have few limitations. The rooting depth might be limited by the argillic B horizon, or by rock at shallow depth.

The moisture storage capacity is, depending on the depth of the soil, moderate to good. Only when the topsoil is very sandy do tillage operations create problems like compaction or erosion.

Be. Chromic, Eutric and Calcic Cambisols (7.5%)
These soils have a cambic B horizon and a base saturation of 50 per cent or more. Chromic Cambisols have a strong brown or red colour.

Those with a calcic horizon or with lime accumulation are Calcic Cambisols. The latter mainly occur in limestone areas with limited precipitation.

Most Cambisols have little agricultural value, as they occur dominantly on slopes, are often shallow of have many stones or rock outcrops. Where Cambisols are deep and not stony they are good for agriculture.

Bh. Dystric and Humic Cambisols (2%)
These soils have a low base saturation and a cambic B horizon (Dystric Cambisols) or a deep umbric A horizon. The latter are Humic Cambisols. They mainly occur at high altitude. Dystric Cambisols are found on steep slopes in high rainfall areas.

Their agricultural value is limited, as they occur on slopes, they are shallow and have many stones or rock outcrops.

Bv. Vertic Cambisols and Vertic Luvisols (3%)
These soils are Cambisols and Luvisols with vertic properties. As the Vertisols, these vertic soils have fairly good, but limited agricultural potentialities. Land preparation is difficult, dry soils are hard and wet soils are sticky.

Only during a short period is the moisture condition of the topsoil favourable for tillage practices. Chemically these soils have no limitations.

H. Rendzinas, Haplic and Luvic Phaeozems (4%)
These are soils with a mollic A horizon. Rendzinas and Haplic Phaeozems mainly occur in the highlands, where soil depth is often limited by hard rock at shallow depth.

Rendzinas have only a mollic A horizion resting directly on calcareous rock.
Their agricultural value is limited, because generally they occur on steep slopes, rooting depth is small and there are many stones and rock outcrops. when they are deeper, they are suitable for agriculture.

Luvic Phaeozems have an argillic B horizon. They occur in the Rift Valley. As most of them are sodic, their agricultural value is limited.

I. Lithosols (17%)
These soils are less than 10 cm thick, developed over hard rock. They occur on steep slopes and in area with very limited precipitation. These soils have no agricultural potential.

J. Calcaric and Eutric Flovisols (8.5%)
Fluvisols are young soils developed in recent alluvial deposits of river plains, deltas, former lakes and coastal areas.

Soil conditions are highly variable. In arid regions many soils are saline. Fluvisols with calcareous material are Calcaric Fluvisols, those which are non-calcareous, having a base saturation of 50 per cent or more, are Eutric Fluvisols.

Fluvisols are generally good agricultural soils and often intensively used, although land use has to be adapted to floods, inundations or high groundwater.

L. Chromic and Orthic Luvisols (5%)
Luvisols are soils with an argillic B horizion and a base saturation of 50 per cent or more. Those with a strong brown or red B horizon are Chromic Luvisols.

Most Luvisols have good agricultural potentialities. Base saturation is high and they have weatherable minerals. In soils with a heavy textured B horizon, permeability might be low, and drainage and good root distribution can be hindered.

Nd. Dystric Nitosols (7.5%)
Nitosols are deep, clayey red soils with an argillic B horizon. Dystric Nitosols have a base saturation of less than 50 per cent. They are found on almost flat to sloping terrain in high rainfall areas.

They have rather good potentialities for agriculture. These soils have very good physical properties. They have a uniform profile, are porous, have a stable structure and a deep rooting volume. Their moisture storage capacity is high.

Chemically these soils have some restrictions. The base saturation is rather low, PH’s are less than 5.5 and available P contents are low.

Ne. Eutric Nitosols (5%)
Eutric Nitosols are Nitosols with a base saturation of 50 per cent or more. They are found on almost flat to sloping terrain in the highlands.

They are among the best agricultural soils. Their physical properties are similar to those of the Dystric Nitosols. Chemically these soils are better, although available p contents are low.

Q. Calcic Arenosols (5%)
These are coarse-textured soils. The sub-soil has the characteristics of a cambic B horizon, but does not classify as such, because the soil texture is too coarse. Arenosols are developed on sandstone.

Arenosols have very limited agricultural potentialities. They have a low water retention, are very permeable, have a low natural fertility and a low CEC. Rooting depth is often restricted by limited soil depth.

R. Calcaric and Eutric Regosols (11%)
Regosols are soils without profile development, consisting of loose, non-alluvial soil material.

They occur in areas with little precipitation; or on steep slopes subject to severe erosion. Those with lime accumulation are Calcaric Regosols. Eutric Regosols have a base saturation of 50 per cent or more.

They have limited agricultural value, especially where soil depth is limited. Water retention in Regosols is low.

T. Humic, Mollic and Vitric Andosols (1%)
Andosols occur in volcanic regions. They are formed in volcanic ash material. The ash material being very light, their bulk density is less than .85 g/cm3. Vitric Andosols have more than 60 per cent volcanic glass, they occur in rather arid zones.

Mollic Andosols have a mollic A horizon, Humic Andosols have an umbric A horizon. The latter mainly occur in cool and humid regions, at altitudes.

Most Andosols are good for agriculture. They can absorb much water and are very porous. The CEC is high (35-70/me/100gr soil) and the organic matter content is often high. Some Andosols, especially in the rift valley, have a high sodium content and thus a limited agricultural value.

V. Chromic and Pellic Vertisols (10%)
These are heavy clay soils in flat areas, having a pronounced dry season during which they shrink and have deep cracks in a polygonal pattern.

During the wet season the clay swells and causes pressure in the sub-soil. Pellic Vertisols are dark, usually occupying areas which are water-logged during the rainy season. Chromic Vertisols are brownish and better drained.

Vertisols have fairly good, but limited agricultural potentialities. Land preparation is difficult, dry soils are hard and wet soils are sticky. The moisture condition of the surface layer is only during a short period favourable to prepare land.

Another difficulty is that the permeability of the subsoil is very low. Very often these soils are flooded or have stagnant water during the rainy season.

The soil has a high water retention, but relatively a small amount of water is available for plant growth. Rooting depth might be restricted because of the swelling and shrinking properties of the soil.

Chemically these soils are good. The CEC is very high (often over 70 me/100g soil) and the base saturation is over 50 per cent, mainly with Ca+++ and Mg++ ions.

Free CaCo3 is often present as nodules in the profile. When precipitation is limited, salinity problems might occur. Because of the low permeability and the difficult drainability of the subsoil, it is very difficult to improve such soils.

X. Haplic, Calcic and Luvic Xerosols (5%)
Xerosols are soils in arid and semi-arid regions, with a weakly developed A horizon. Those with an argillic B horizion, mostly at shallow depth, are Luvic xerosols.

Those without a calcic horizon are Haplic Xerosols, those with a calcic horizon are Calcic Xerosols.

The calcic horizon may harden, forming a petrocalcic horizon.
The agricultural value of Xerosols is low, except when they can be irrigated and when physical properties are good for irrigated crops.

Y. Gypsic Yermosols (3%)
The moisture regime of these soils is aridic and they have a weakly developed ochric A horizon.

They consist of highly gypsiferious parent material, and have a gypsic horizon. The gypsic horizon may harden, forming a petrogypasic horizon.
Gypsic Yermosols are not suitable for agriculture in irrigation projects.

Z. Gleyic and Orthic Solonchaks (4.5%)
Solonchaks are highly saline soils containing soluble salts that influence plant growth. These are poor soils because most plants cannot grow at all.

Most solonchaks are Orthic Solonchaks. If they have hydromorphic properties within the first 50 cm, they are called Gleyic Solonchaks.

In saline soils that have a moderate to rapid permeability to a depth of at least 3 m, and that can be drained, the harmful soluble salts can be washed out, and carried away, in drain water. When this is completed, soils may have agricultural potential, although it is necessary to take care that salts do not accumulate in the rooting zone again.

(Source: National Atlas of Ethiopia)


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