(a) State five factors that should be considered in choosing an irrigation system in West Africa. (b) Mention four problems associated with irrigation in We...

(a) Five factors to consider in choosing an irrigation system in West Africa:

• The source and availability of water (rivers, dams, boreholes).
• The topography (slope and nature) of the land.
• The type of soil and its infiltration/drainage.
• The type of crop to be grown and its water requirement.
• The cost of installation and the capital available to the farmer.

(b) Four problems associated with irrigation in West Africa:

• High cost of installing and maintaining the system.
• Salinization/salt build-up and water-logging of the soil.
• Inadequate/irregular water supply and silting of channels.
• Spread of water-borne diseases such as bilharzia and pests/weeds.

(c) Area of the farmland in hectares:

Convert the length to metres: \(0.4\ \text{km} = 0.4 \times 1000 = 400\ \text{m}\).

\[ \text{Area} = \text{length} \times \text{breadth} = 400\ \text{m} \times 2400\ \text{m} = 960{,}000\ \text{m}^2 \]

Since \(1\ \text{hectare} = 10{,}000\ \text{m}^2\):

\[ \text{Area} = \frac{960{,}000}{10{,}000} = 96\ \text{hectares} \]

(d) Tillage implements:

• One primary tillage implement: Plough (disc or mould-board plough).
• Three secondary tillage implements: Harrow, ridger and cultivator.