Question 2
(a) Explain four ways each in which the following terms are important in crop production:
(i) soil profile;
(ii) soil texture. (8 marks)
(b) (i) Differentiate between a forest and a pasture. (2 marks)
(ii) List four pasture management practices in West Africa. (4 marks)
(c) Enumerate four characteristics of sedimentary rocks. (4 marks)
Observation
Question 2 was fairly popular among candidates although many candidates were describing the features of soil profile and soil texture rather than their functions; thereby losing marks. Some candidates also failed to use conjunction in differentiating between forest and pasture.
The expected answers include:
2.
- (a) Explanation of ways in which soil profile and soil texture are important
in crop production
(i) Soil profile
- Depth of horizon A indicates adequacy of soil for cropping
- Depth of horizon A is an indicator of soil fertility
- Type of parent rock indicates mineral composition of soil
- Used in soil classification/mapping
- Type of crops to be grown in an area depends on the soil profile/root
penetration
- The rate of percolation/prevention of soil erosion depends on the presence
of horizon A/ leaching
- Determines depth of tillage
(ii) Soil texture
- Determines the type of crops to be grown
- Indicates the fertility status of the soil
- Determines the rate of leaching of soil
- Influences the rate of soil erosion
- Influences the activities of soil microorganisms e.g. fine textured soils like
clay do not favour the growth of microbes
- Influences soil aeration
- Determines the water retention capacity of soils
(b) (i) Difference between a forest and a pasture
A forest is an area of land that is covered with trees and undergrowth of shrubs
While
a pasture is an area of land on which forage grasses and legumes grow
(ii) Pasture management practices in West Africa
- Adequate stocking rate - Pest control
- Controlled grazing/avoid overgrazing - Disease control
- Weed control - Rotational grazing/paddocking
- Fertilizer application - Mixed grazing
- Zero grazing/soilage - Reseeding
- Irrigation - Controlled burning
- Cultivation of grass-legume mixture
(c) Characteristics of sedimentary rocks
- Occur in layers/strata
- They are soft
- Non-crystalline
- Contain fossils of plants and animals
- Coarse texture
- React with weak acid e.g. carbonic acid
- Easy to break
- Do not dissolve in water
- Vary in colour