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Difficulty: HardSoil Types, Distribution, and Soil Conservation in Nigeria

In the extreme northern savanna belt of Nigeria bordering the Niger Republic, agricultural productivity is severely threatened by wind erosion and topsoil desiccation during the long dry season. Which major soil group characterizes this semi-arid zone, and which soil conservation strategy is specifically designed to combat this wind-driven soil loss?

  1. Regosols and Brown soils; establishment of shelterbelts and tree windbreaks perpendicular to prevailing windsAnswer
  2. B
    Ferrallitic soils; construction of contour terraces and stone lines along gentle hill slopes
  3. C
    Hydromorphic soils; installation of sub-surface tile drainage networks and dykes
  4. D
    Ferruginous tropical soils; application of annual controlled bush burning to clear crop residues

Answer

Regosols and Brown soils paired with the establishment of shelterbelts and tree windbreaks perpendicular to prevailing winds
In Nigeria, soil distribution closely follows latitudinal climatic zones. The extreme northern fringes (Sudan and Sahel savanna belts) are dominated by weakly developed, sandy Regosols and Brown soils. Because these loose soils are susceptible to severe wind erosion during the dry Harmattan season, establishing shelterbelts—lines of deep-rooted trees planted perpendicular to the prevailing winds—serves as the primary biological conservation technique to break wind force and stabilize topsoil.

Step-by-Step Solution

1
Identify the soil zone based on geographical position and climatic conditions.
The extreme northern boundary of Nigeria (e.g., northern Sokoto, Katsina, Jigawa, Yobe, and Borno states) lies in the semi-arid zone where weakly developed sandy soils (Regosols and Brown soils) predominate.
Nigerian soil distribution mirrors latitudinal climatic and vegetation belts from south to north.
2
Determine the dominant soil degradation process in this environment.
Desiccation caused by high temperatures and strong dry Harmattan winds blowing from the Sahara Desert leads to severe wind erosion.
Sparse vegetation cover in semi-arid zones leaves topsoil exposed to wind action during dry periods.
3
Select the appropriate targeted soil conservation technique.
Afforestation through shelterbelts (strips of trees planted across the path of prevailing winds) reduces wind speed, retains moisture, and traps shifting sand.
Water-focused measures (such as terracing or contouring) target water runoff on slopes, whereas shelterbelts specifically target wind-driven erosion on flat arid plains.

Key Concept

Spatial distribution of major soil groups in Nigeria and implementation of process-specific soil conservation techniques.
Estimated Time:2m 0s
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Topics

Soil Types, Distribution, and Soil Conservation in Nigeria

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