Page 19 - Agriculture Form Two

Agriculture for Secondary Schools

2. Use your school farm/home set-up:
(a) To practice some good agronomic practices on maintaining soil fertility;
and
FOR ONLINE READING ONLY
(b) In a tabular form, show how each agronomic practice you carried out
contributes to the maintenance of soil fertility.
3. Summarise what you have learnt from this activity in you portfolio.

Soil water management

Soil water or soil moisture refers to the soil held between spaces of soil particles.
Usually, soil water contains dissolved nutrients to form a soil solution, which is
a source of water and nutrients for plants. Water is essential for the growth and
development of crop plants. Too much or too little water in the soil influences
crop plant development and productivity.

Plants lose water in the form of water vapour from their surfaces. This process is
termed transpiration. It occurs mainly at the surface of plants, particularly from
leaves. If this water is not replaced, plants will wilt and eventually die. Water
is also lost from the soil surface, especially during daytime, by evaporation. As
water evaporates, the amount of water in the soil is reduced. As a result, plant
roots find it more difficult to absorb water from the soil. If water is not added to
the soil through irrigation or rain, plants will wilt and die. Water must, therefore,
be present in the soil at an optimal level to prevent plants from wilting.

Critical stages of crops’ moisture requirements
Crop plants have growth and development stages, which are more sensitive to
soil moisture stress. The term critical period is commonly used to define the
growth stage when plants are most sensitive to a water shortage. If a farmer needs
to realise high yields, these stages should be known for effective production.
This is because inadequate water supply during moisture-sensitive periods will
irreversibly reduce the yield. Hence, the provision of adequate water to crop
plants during such periods or stages is essential to avoid yield loss that can occur.
For most crops, these stages are germination or establishment and grain/tuber or
seed formation.

Student’s Book Form Two 11

04/10/2024 18:07
Agriculture form 2.indd 11 04/10/2024 18:07
Agriculture form 2.indd 11