Page 57 - Agriculture_Form_Three

Agriculture for Secondary Schools

growth and development. The soil organic matter prevents nutrient leaching and is
essential to the organic acids that make minerals available to plants. It also buffers
soil from strong changes in pH.

Activity 2.2
In groups, perform the following tasks:
1. List down the common organic materials in your area that are left to decompose
in the farm.
2. State the length of time allowed for each of the materials to decompose before
planting of crops.
3. Through library search, find out the C/N ratio of each kind of materials then
comment on their utilisation particularly in supplying nitrogen to crops.

4. Summarise your responses together with the lessons learnt from this activity in
your portfolio and present them in class.

Activity 2.3
Write a summary of what you have learnt from this chapter in your portfolio.

Exercise

Answer the following questions:

1. What do you understand by the term soil pH?
2. Why is soil pH important in crop farming enterprises?
3. Describe the method you can use in determining soil pH of your farm before
starting a crop farming enterprise. Why have you chosen that method? What else
can you do in order to know the soil pH of your farm?
4. (a) ‘Sandy soils are known to be less fertile as they possess low amount of soil
colloidsʼ. What does this statement mean?
(b) How can fertility of sandy soils be improved?
5. What will happen in a short period of time if straws of maize, sorghum or bulrush
millet are added into an infertile soil?

6. Explain the relationship between C/N ratio and decomposition of organic matter.
7. Elaborate the methods of correcting alkaline affected soils.
8. Explain the main sources of hydrogen ions in the soil solution.

Student’s Book Form Three
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10/01/2025 12:31
AGRICULTURE FORM 3 9.11.2022.indd 46
AGRICULTURE FORM 3 9.11.2022.indd 46 10/01/2025 12:31