TEST OF PRACTICAL KNOWLEDGE QUESTION
a)(i) Give two examples of each of specimens A and B. (2 marks)
(ii) State three advantages of the application of specimen Ain crop production. (3 marks)
(iii) Mention two methods of applying specimen B in crop production. (2 marks)
(b) An experiment was conducted to determine the percentage of water in soil samples C and D.
The results are as shown in the table below:
|
Soil Sample |
| Data Recorded |
C |
D |
| Mass of crucible |
80g |
80g |
| Mass of crucible and fresh soil |
100g |
140g |
| Mass of crucible and soil after heating |
95g |
100g |
(i) Determine the mass of fresh soil for each of soil samples C and D (2 marks)
(ii) Determine the mass of water contained in each of soil samples C and D. (2 marks)
(ii) Calculate the percentage of water in each of soil samples C and D. (2 marks)
(c) What type of relationship exists between the amount of water and the amount of air in soils? (2 marks)
(a)(i) Examples of the specimens (specimen A being an organic manure and specimen B an inorganic fertilizer):
- Specimen A (organic manure): poultry droppings and cow dung (also compost or green manure).
- Specimen B (inorganic fertilizer): NPK 15:15:15 and urea (also sulphate of ammonia or single superphosphate).
(a)(ii) Three advantages of applying specimen A (organic manure) in crop production:
- It improves soil structure and increases the water-holding capacity of the soil.
- It adds humus and releases its nutrients slowly over a long period.
- It improves soil aeration and encourages the activity of useful soil organisms.
(a)(iii) Two methods of applying specimen B (inorganic fertilizer):
- Broadcasting (spreading it evenly over the field).
- Band or ring placement near the plant (or foliar spraying of soluble types).
(b) Percentage of water in the soil samples. Working from the recorded masses:
| Data recorded | Sample C | Sample D |
|---|
| Mass of crucible | 80 g | 80 g |
| Mass of crucible + fresh soil | 100 g | 140 g |
| Mass of crucible + soil after heating | 95 g | 100 g |
(b)(i) Mass of fresh soil = (mass of crucible + fresh soil) - mass of crucible.
- Sample C = \( 100 - 80 = 20 \) g
- Sample D = \( 140 - 80 = 60 \) g
(b)(ii) Mass of water = (mass of crucible + fresh soil) - (mass of crucible + soil after heating), that is the loss on heating.
- Sample C = \( 100 - 95 = 5 \) g
- Sample D = \( 140 - 100 = 40 \) g
(b)(iii) Percentage of water \( = \dfrac{\text{mass of water}}{\text{mass of fresh soil}}\times100 \).
- Sample C \( = \dfrac{5}{20}\times100 = 25\% \)
- Sample D \( = \dfrac{40}{60}\times100 = 66.67\% \)
(c) There is an inverse (antagonistic) relationship between the amount of water and the amount of air in the soil: both share the same pore spaces, so as the water content rises the air content falls, and vice versa.
(a)(i) Examples of the specimens (specimen A being an organic manure and specimen B an inorganic fertilizer):
- Specimen A (organic manure): poultry droppings and cow dung (also compost or green manure).
- Specimen B (inorganic fertilizer): NPK 15:15:15 and urea (also sulphate of ammonia or single superphosphate).
(a)(ii) Three advantages of applying specimen A (organic manure) in crop production:
- It improves soil structure and increases the water-holding capacity of the soil.
- It adds humus and releases its nutrients slowly over a long period.
- It improves soil aeration and encourages the activity of useful soil organisms.
(a)(iii) Two methods of applying specimen B (inorganic fertilizer):
- Broadcasting (spreading it evenly over the field).
- Band or ring placement near the plant (or foliar spraying of soluble types).
(b) Percentage of water in the soil samples. Working from the recorded masses:
| Data recorded | Sample C | Sample D |
|---|
| Mass of crucible | 80 g | 80 g |
| Mass of crucible + fresh soil | 100 g | 140 g |
| Mass of crucible + soil after heating | 95 g | 100 g |
(b)(i) Mass of fresh soil = (mass of crucible + fresh soil) - mass of crucible.
- Sample C = \( 100 - 80 = 20 \) g
- Sample D = \( 140 - 80 = 60 \) g
(b)(ii) Mass of water = (mass of crucible + fresh soil) - (mass of crucible + soil after heating), that is the loss on heating.
- Sample C = \( 100 - 95 = 5 \) g
- Sample D = \( 140 - 100 = 40 \) g
(b)(iii) Percentage of water \( = \dfrac{\text{mass of water}}{\text{mass of fresh soil}}\times100 \).
- Sample C \( = \dfrac{5}{20}\times100 = 25\% \)
- Sample D \( = \dfrac{40}{60}\times100 = 66.67\% \)
(c) There is an inverse (antagonistic) relationship between the amount of water and the amount of air in the soil: both share the same pore spaces, so as the water content rises the air content falls, and vice versa.
