TEST OF PRACTICAL KNOWLEDGE QUESTION
Observe the experimental set-ups A and B in which 120ml of water was made to drain through each of the different soils contained in the funnels.
Use the experimental set-ups to answer Questions (a) - (d).
(a) State the volume of water collected in each of the measuring cylinders in setups A and B.
(b) Calculate the volume of water retained in each of the set-ups A and B.
(c) Calculate the percentage of:
(i) water which percolated through each of the soils in set-ups A and B
(ii) water retained in each of the soils in set-ups A and B.
(d) Which one of the soils in set-ups A and B will be better for crop production? Give three reasons for your answer.
Read the volume of water collected in each measuring cylinder. Let the volume collected under set-up A be x ml and the volume collected under set-up B be y ml. In each set-up 120 ml of water was poured through the soil.
(a) Volume of water collected
- Set-up A = x ml
- Set-up B = y ml
(b) Volume of water retained
Water retained = water added − water collected.
- Set-up A: \(120 - x\) ml
- Set-up B: \(120 - y\) ml
(c)(i) Percentage of water that percolated
- Set-up A: \(\dfrac{x}{120} \times \dfrac{100}{1}\%\)
- Set-up B: \(\dfrac{y}{120} \times \dfrac{100}{1}\%\)
(c)(ii) Percentage of water retained
- Set-up A: \(\dfrac{120 - x}{120} \times \dfrac{100}{1}\%\)
- Set-up B: \(\dfrac{120 - y}{120} \times \dfrac{100}{1}\%\)
(d) Better soil for crop production
The soil in set-up A is better for crop production. Reasons:
- It contains organic matter, which binds the soil particles and improves the soil structure.
- The organic matter is a source of nutrients for plant growth, and the rate of leaching of nutrients is lower in A than in B.
- It retains water better than B while still having moderate air space, so moisture is available to plant roots for a longer time.
Read the volume of water collected in each measuring cylinder. Let the volume collected under set-up A be x ml and the volume collected under set-up B be y ml. In each set-up 120 ml of water was poured through the soil.
(a) Volume of water collected
- Set-up A = x ml
- Set-up B = y ml
(b) Volume of water retained
Water retained = water added − water collected.
- Set-up A: \(120 - x\) ml
- Set-up B: \(120 - y\) ml
(c)(i) Percentage of water that percolated
- Set-up A: \(\dfrac{x}{120} \times \dfrac{100}{1}\%\)
- Set-up B: \(\dfrac{y}{120} \times \dfrac{100}{1}\%\)
(c)(ii) Percentage of water retained
- Set-up A: \(\dfrac{120 - x}{120} \times \dfrac{100}{1}\%\)
- Set-up B: \(\dfrac{120 - y}{120} \times \dfrac{100}{1}\%\)
(d) Better soil for crop production
The soil in set-up A is better for crop production. Reasons:
- It contains organic matter, which binds the soil particles and improves the soil structure.
- The organic matter is a source of nutrients for plant growth, and the rate of leaching of nutrients is lower in A than in B.
- It retains water better than B while still having moderate air space, so moisture is available to plant roots for a longer time.
