Question

Arrange with the increasing level of energy required for disruption of soil aggregates:
(A). Ultrasonic dispersion
(B). Gently shaking in water
(C). Dry sieving
(D). Oxidation of organic matter
Choose the correct answer from the options given below:

• A. (A), (B), (C), (D).
• B. (D), (B), (A), (C).
• C. (B), (A), (D), (C).
• D. (C), (B), (A), (D).

Hint:

To remember this sequence, transition from the gentlest dry physical separation (Dry sieving) to wet physical shaking, then to high-frequency physical blasting (Ultrasonic), and finally to complete chemical destruction of the binding agents (Oxidation).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Soil aggregates are structural units of soil particles bound together by organic substances, iron-aluminum oxides, and clay minerals.
Disrupting these aggregates requires applying varying amounts of mechanical or chemical energy depending on the strength of the binding agents.

Step 2: Detailed Explanation:
Let us analyze the energy levels associated with each disruption method:
- Dry sieving (C): This is a gentle physical separation method.
It requires minimal mechanical energy, using gravity and mild shaking to separate loose clods and weak macroaggregates without breaking stable microaggregates.
This represents the lowest energy level.
- Gently shaking in water (B): Shaking soil in water applies hydraulic shear and slaking forces.
This requires moderate mechanical energy to overcome the surface tension of water and break down weaker aggregates.
- Ultrasonic dispersion (A): This physical method applies high-frequency sound waves to create localized acoustic cavitation.
The resulting high-energy micro-jets apply intense mechanical shearing forces, dispersing highly stable soil microaggregates.
This requires very high physical energy.
- Oxidation of organic matter (D): This is a chemical treatment using strong oxidizing agents like hydrogen peroxide (\(\text{H}_2\text{O}_2\)).
It chemically breaks down and oxidizes the organic binding agents (such as humic substances and polysaccharides) that hold microaggregates together.
Breaking these covalent and electrostatic organo-mineral bonds requires the highest thermodynamic energy equivalent.
Therefore, the correct increasing sequence of energy requirement is (C), (B), (A), (D).

Step 3: Final Answer:
The correct increasing sequence of energy is (C), (B), (A), (D).