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Difficulty: MediumAgricultural Systems, Crop Production, and Pastoralism in Nigeria

Commercial tree crops such as rubber and oil palm are densely cultivated in southern Nigerian states like Edo, Delta, and Cross River, but are absent as major commercial crops in northern Nigeria. Which environmental factor primarily accounts for this regional restriction?

  1. Insufficient annual rainfall and an extended dry seasonAnswer
  2. B
    High altitude and rocky relief along northern plateaus
  3. C
    High density of tsetse flies in the northern savannas
  4. D
    Excessive soil salinity and coastal tidal inundation

Answer

Insufficient annual rainfall and an extended dry season in northern Nigeria limit the commercial growth of humid rainforest tree crops such as rubber and oil palm.
Oil palm and rubber are indigenous to humid tropical rainforest environments. They require heavy annual rainfall (1,500 mm to 3,000 mm) evenly distributed throughout the year. Northern Nigeria experiences low annual precipitation and an extended dry season lasting five to eight months, making large-scale commercial cultivation of these tree crops ecologically impossible without massive irrigation.

Step-by-Step Solution

1
Identify the ecological requirements of rubber and oil palm.
Rubber and oil palm are tropical tree crops requiring warm temperatures, high humidity, and abundant annual precipitation exceeding 1,500 to 2,000 mm.
Plantation cash crops depend heavily on continuous moisture availability to support year-round vegetative and reproductive growth.
2
Analyze the climatic gradient of Nigeria from South to North.
Rainfall decreases progressively northward, dropping from over 2,500 mm along the southern coast to under 700 mm in the northern Sahel/Sudan belts, accompanied by a longer dry season.
The movement of the Inter-Tropical Discontinuity (ITD) dictates moisture availability across latitudinal zones in Nigeria.
3
Evaluate the choices against climatic constraints.
The acute moisture deficit and prolonged dry season in the north prevent the commercial viability of rain-forest cash crops.
Moisture supply is the principal limiting factor distinguishing southern tree crop zones from northern grain/groundnut belts.

Key Concept

Climatic controls and ecological zonation of crop production in Nigeria
Estimated Time:1m 0s
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Topics

Agricultural Systems, Crop Production, and Pastoralism in Nigeria

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