(a) Factors considered in choosing an irrigation system in West Africa
- Cost of irrigation system
- soil type
- availability ofwater
- topography/slope of land
- type of crop to be cultivated
- size of farmland
(b) Problems associated with irrigation in West Africa
- Irrigation equipment is expensive to install
- Inadequate water supply for irrigation in certain areas and periods
- Maintenance cost is high
- Inadequate technical know
- how on the use of irrigation schemes among farmers
- The high relative humidity on irrigated land favours the growth of disease-causing organisms
- Salts that are toxic to crops could be introduced to the farmland through irrigation water
- Some irrigation systems disturb free movement of farm machinery
- Damage of source of water supply may render the irrigation system ineffective or cause destruction of immediate environment
- Water loving plants are likely to proliferate as a result of moisture in the soil leading to weed infestation

(c) Area of farmland in hectares Length = 0.4km = 400m lmk
Breath = 2,400m
Area of rectangle = length x breath lmk
Area of farmland 400m x 2,400m = 960,000m\(^2\) lmk
1 Hectare = 10,000m\(^2\) Area of farmland in hectares = \(\frac{960 000}{10,000}\) Imk
= 96 hectares lmk
(d) Primary and secondary tillage implements
Primary tillage implement
Plough/mouldboard plough/disc plough/chisel
plough 1mk
Secondary tillage implemens
- harrow/disc harrow ridger
- cultivator
- rotavator