Back to: BIOLOGY NEW LOWER SECONDARY CURRICULUM BOOK 2
Activity 1.3 (c): Comparing the capillarity of water of different soil samples
Key question: What is the difference in the capillarity of the different types of soil?
What you need
- glass tubes (3)
- petri dishes (3)
- piece of cotton wool
- ruler or any other instrument for length
determination - soil samples: sandy soil, clay soil and
loam soil
What to do
- In groups, using the materials available at your school and in the environment, design an experiment to compare the capillarity of water in loam, sandy, and clay soils.
- Conduct the experiment you have designed and then write a report on your investigation.
- Present your report to the rest of the class.
Suggested
Observation: Water rises faster but to a lower level in sandy soil while in clay soil, water rises slowly but to higher levels. In loam soil water rises moderately to a moderate level.
Conclusion: Clay soil has the highest capillarity while sandy soil has the lowest capillarity and loam soil has medium water capillarity.
Explanation: Water rises fastest during the early stages of the experiment in sandy soil because sand has large spaces that enable water to rise more rapidly. Clay soil has the highest rise of water hence the highest water capillarity because it is composed of tiny soil particles which present a large surface area over which water molecules cling. Water rises at a slow rate in clay soil because clay has small spaces between its particles.
Application of knowledge: Trigger the learners to share their local experience of how the study of physical properties of soil have been put to use in their community. That knowledge can be used while preparing activities such as pottery and making of clay masks as shown in figure 1.5
Science and Society
Clay mixed with water, oil and honey can be used to make clay masks that ladies apply on their face to maintain beauty (figure 7.5). Basing on clay’s ability to remain sticky when wet, it binds germs on the surface of the skin deep in the poers and brings the dried up germs to the surface of the skin to be washed away
Chemical properties of soil Soil pH
Review with the learners what they studied about the term pH in chemistry. Help them to know that crop growth is also affected by the acidity and the alkalinity of soil. Therefore, it is important for farmers to know the pH of soils.
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