Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Tillage cause sub-surface soil compaction
Reason (R) : Splashed soil particles clog soil pores
In light of the above statements, choose the most appropriate answer from the options given below .

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A).
• C. (A) is correct but (R) is not correct.
• D. (A) is not correct but (R) is correct.

Hint:

To test if Reason (R) explains Assertion (A), read them together using "because":
"Tillage causes sub-surface compaction BECAUSE splashed particles clog surface pores."
This statement is logically incorrect, showing that while both are true soil degradation processes, they occur at different depths due to different causes.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Soil compaction and structural degradation can occur at the soil surface or at sub-surface depths, driven by distinct physical and mechanical processes.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Assertion (A): "Tillage causes sub-surface soil compaction."
This is correct.
Repeated tillage operations, especially when using heavy machinery or plowing at the same depth year after year, exert downward mechanical pressure.
This compresses the soil immediately below the plow layer, destroying macro-pores and forming a dense, compacted layer known as a "plow pan" or "tillage pan."
- Reason (R): "Splashed soil particles clog soil pores."
This is also correct.
When raindrops impact bare, unprotected soil, the kinetic energy of the water droplets disperses soil aggregates.
The dispersed, fine soil particles are splashed into suspension and physically clog the surface macro-pores, forming a thin, dense surface crust.
This process is known as soil crusting or surface sealing.
While both statements are scientifically correct descriptions of soil degradation processes, the clogging of surface pores by splashed particles (surface crusting) does not cause the mechanical sub-surface compaction caused by plowing (tillage pan).
Therefore, (R) is not the correct explanation of (A).

Step 3: Final Answer:
Both (A) and (R) are correct, but (R) is NOT the correct explanation of (A).