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2012 WAEC Agricultural Science Practical a)(i) Give two examples of each of specimens A and B. (2 marks) (ii) State...

Agricultural Science
WAEC 2012

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)

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Explanation

a) Examples of Specimen A and B:

Specimen A (Organic fertilizer):

  • Green manure.
  • Compost.
  • Guano.
  • Farmyard manure/cattle/sheep/goat/rabbit/pig/fish, etc.

Specimen B(Inorganic fertilizer:

  • Urea
  • Sulphate of Ammonia
  • NPK
  • Muriate of Potash
  • Lime
  • Single superphosphate
  • Triple superphosphate
  • Calcium ammonium nitrate
  • Diammonium phosphate
  • Potassium nitrate

(ii) Advantages of the application of specimen A (Organic fertilizer) in crop production

  • Improves soil structure 
  • Increases activities of soil microbes
  • Increases water holding capacity
  • Increases Cation Exchange Capacity (CEC)
  • Reduces soil erosion
  • Improves buffering capacity of the soil
  • Nutrients not easily leached
  • Improves soil aeration
  • It stabilizes soil temperature
  • It stays longer in soil

(iii) Methods of applying Specimen B (Inorganic fertilizer)

  • Broadcasting
  • Band placement
  • Ring method
  • Side dressing/Row placement
  • Foliar application
  • Fertigation/Application through irrigation method
  • Plough-sole method
  • Top dressing

(b)(i) Determination of mass of fresh soil samples C and D

Soil Sample C;

Mass of crucible and fresh soil - Mass of crucible = 100g - 80g = 20g

Soil Sample D;

Mass of crucible and fresh soil - Mass of crucible = 140g - 80g = 60g

(ii) Determination of mass of water contained in soil samples C and D

Soil Sample C; Mass of crucible and fresh soil - Mass of crucible and soil after heating = 100g - 95g = 5g

Soil Sample D; Mass of crucible and fresh soil - Mass of crucible and soil after heating = 140g - 100g = 40g

(ii) Calculation of percentage of water in each soil sample (i.e.C and D) 

Mass crucible and fresh soil - Mass of crucible  = yg
Mass of crucible and soil after heating - Mass of crucible = zg
yg = mass of fresh soil 
zg = mass of soil after heating 
% water = \(\frac{y-z}{y}\)

For soil sample C
100g - 80g = 20g  \(\to/) y
95g - 80g = 15g  \(\to/) z

\(\frac{20g - 15g \times 100}{20g}\) = 25%

For soil sample D;

140g - 80g = 60g  \(\to\) y
100g - 80g = 20g  \(\to\) z

\(\frac{20g - 15g \times 100}{20g}\) = 25%

 

(c) Relationship that exists between the amount of water and the amount of air in soils: The amount of air in the soil is inversely proportional to the amount of water in the soil pore spaces which are not occupied by water.


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WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
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Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
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WAEC offline past questions - with all answers and explanations in one app - Download for free