Given below are two statements, one is labelled as Assertion (A) and other one labeled as Reason (R).
Assertion (A): Crop residue on soil surface in conservation tillage systems can decrease the rate of soil temperature change.
Reason (R): Surface residue increases the reflection of incident solar radiation.
In light of the above statements, choose the most appropriate answer from the options given below.

Correct option is A

Explanation of the Correct Option (a): Both (A) and (R) are correct and (R) is the correct explanation of (A)
Why Assertion (A) is CORRECT:
· In conservation tillage, crop residues remain on the soil surface.
· Surface residues act as an insulating layer.
· This insulation:
· Reduces rapid heating during the day
· Reduces rapid cooling at night
· As a result, the rate of soil temperature change decreases.
Why Reason (R) is CORRECT:
· Crop residues increase the albedo (reflectivity) of the soil surface.
· More incoming solar radiation is reflected back to the atmosphere.
· Less heat is absorbed by the soil surface.
Why (R) Correctly Explains (A):
· Increased reflection of solar radiation reduces heat gain by soil.
· Reduced heat gain leads to moderated soil temperature fluctuations.
· Hence, the reason directly explains the assertion.
Explanation of Other Options
Option (b): Both (A) and (R) are correct but (R) is NOT the correct explanation of (A)
· Incorrect because:
· Reflection of solar radiation is a key mechanism behind reduced soil temperature change.
Option (c): (A) is correct but (R) is not correct
· Incorrect because:
· Residue does increase reflection of solar radiation.
Option (d): (A) is not correct but (R) is correct
· Incorrect because:
· Assertion (A) is scientifically valid and well documented.
Key Points Related to the Question
· Conservation tillage retains crop residues on soil surface
· Residues act as mulch
· Increase soil albedo and reduce heat absorption
· Moderate soil temperature fluctuations
· Improve soil moisture conservation and microbial activity