1998 WAEC Agricultural Science Practical (a) State the title of the experimental set-up for specimens A, B, and C. (b)…

Explanation

(a) Title of the experimental set-up: Experiment to compare the porosity, drainage, retention, permeability, or water-holding capacity of soil types.

(b) Amount of water retained by each soil type:

Amount of water poured in each sample = 50cm\(^{3}\);
Amount of water that drained into the measuring cylinder Å = X\(_{1}\), cm\(^{3}\);
Amount of water that drained into the measuring cylinder B = X\(_{2}\), cm\(^{3}\)
Amount of water that drained into the measuring cylinder C = X\(_{3}\), cm\(^{3}\)
Therefore, the amount of water retained bý Specimen ;

A is 50 - X\(_{1}\) = Y \(_{1}\) cm\(^{3}\) 
B is 50 - X\(_{2}\) = Y \(_{2}\) cm\(^{3}\) 
C is 50 - X\(_{3}\) = Y \(_{3}\) cm\(^{3}\) 

(c) Based on observations and results from the experimental set-up, identification of Specimen A = sand, B= clay, C= loam.

Reasons:

• A has large pore spaces hence retained the least amount of water.
• B has tiny pore spaces, it retained the largest amount of water.
• C has average pore spaces thus, retaining the average amount of water

(d) Conclusion of the experimental set-up: -

• Sandy soil (Specimen A) with larger particles, little organic matter, and larger pore spaces was most porous.
• Clay soil (Specimen B)with very fine particles and small pore spaces is the least porous.
• Loamy soil (Specimen C) with moderate air spaces, more organic matter, and slightly bigger particles than clay was second most porous.

(e) Functions of water to crop plants:

• It can be used for the utilization of soil minerals by crop plants.
• It is also an essential raw material in photosynthesis.
• It is used for hydrolyzing food nutrients e.g. starch, protein, fat., acceleration of enzymatic activities,
• For proper growth of plants,
• for turgidity of plant cells, translocation of foods, temperature regulation, and also to aid transpiration.