This question was well attempted by the candidates. In 3(a), majority of the candidates were
able to list the crops that will be planted in the spaces marked I to VIII in the 4 year crop rotation plan. In 3(b), however, many candidates could not state the principles that a farmer must observe when planning crop rotation. In 3(c), and 3(d), most of the candidates were unable to give the main reason why cowpea is included in the rotation and name crops that can be grown in place of
cowpea in the rotation.
In 3(e), majority of the candidates were able to give the benefits of crop rotation. Also, in 3(f), many candidates were able to calculate the number of cassava cuttings that would be required to plant one hectare.
The expected answers include:
Principles that a farmer must observe when planning crop rotation:
- Crops that require high nutrient should come first in a rotation;
- Shallow rooted crop should be followed by deep rooted crop;
- Crops prone to the same disease attack should not be planted in succession;
- Crops susceptible to the same pest attack should not be planted in succession;
- Cover crops or leguminous crops should be planted in between the rotation to restore nutrients;
- Crops that require cleaner seed bed than the others should come before those that do not require so much clean seed beds.
- Crops must be planted in a definite order or cycle;
- Crops of the same family must not be planted together nor follow each other in rotation.
Reasons why cowpea is included in the rotation:
- Being a leguminous plant, it helps to fix atmospheric nitrogen into the soil;
- It helps to control erosion because of its growth habits.
Crops that can replace cowpea in the rotation:
- Mucuna sp
- Sun hemp
- Stylosanthes gracilis
- Pueraria phaseoloides
- Centrosema pubesens
- Calopogonium mucunoides
- Soyabean/Glycine max
- Groundnut/Arachis hypogea