Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: The clayey soil can retain more water due to more pore space than sandy soil. Reason R: The sandy soil can release more water due to low soil water tension than clayey soil. In the light of the above statements, choose the most appropriate answer from the options given below:
• Both A and R are correct and R is the correct explanation of A
• Both A and R are correct but R is NOT the correct explanation of A
• A is correct but R is not correct
• A is not correct but R is correct

• 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:

Important comparison between sandy and clayey soils:
• Sandy soil:
• Large pores
• Fast drainage
• Low water retention
• Low soil water tension
• Clayey soil:
• Fine pores
• High water retention
• High capillary action
• Greater total porosity Memory Trick: \[ \boxed{\text{“Clay stores, sand drains”}} \]

Answer 1

The Correct Option is B

Concept: Soil-water relationships are extremely important in irrigation engineering, soil science, agricultural engineering, and hydrology. Different soils possess different:
• Pore size distributions
• Water holding capacities
• Permeability characteristics
• Soil water tensions The two most commonly compared soil types are:
• Sandy soil
• Clayey soil These soils behave very differently with respect to water retention and water movement. Clayey Soil Characteristics:
• Contains extremely fine particles
• Has very high total pore space
• Possesses a large number of micropores
• Retains large quantity of water
• Water movement is comparatively slow Sandy Soil Characteristics:
• Contains coarse particles
• Has larger pore sizes but lower total pore space
• Water drains quickly
• Water retention capacity is low
• Soil water tension is comparatively low Thus both soil texture and pore characteristics govern moisture behavior.

Step 1: Analyzing Assertion A carefully. Assertion A states: \[ \text{“Clayey soil can retain more water due to more pore space than sandy soil.”} \] This statement is correct. Clayey soils contain:
• Large number of micropores
• Higher total porosity
• Greater specific surface area Because of these characteristics, clayey soils can store much larger quantities of water compared to sandy soils. Hence: \[ \boxed{\text{Assertion A is correct}} \]

Step 2: Analyzing Reason R carefully. Reason R states: \[ \text{“Sandy soil can release more water due to low soil water tension than clayey soil.”} \] This statement is also correct. Explanation:
• Sandy soils possess larger pores.
• Water is held less tightly in sandy soils.
• Soil water tension is comparatively lower.
• Therefore water drains and becomes available more easily. In contrast, clayey soils hold water more strongly because of high capillary forces and greater matric suction. Hence: \[ \boxed{\text{Reason R is also correct}} \]

Step 3: Checking whether Reason R explains Assertion A. Now we must determine whether Reason R correctly explains Assertion A. Assertion A discusses: \[ Water retention capacity due to higher pore space \] Reason R discusses: \[ Ease of water release due to lower soil water tension \] Although both statements are individually true, the reason does not directly explain why clayey soil retains more water. The actual explanation for higher water retention in clayey soil is:
• Greater microporosity
• Higher surface area
• Stronger capillary action The statement about sandy soil releasing water easily is related to drainage and availability, not the direct explanation of clayey soil water retention. Therefore: \[ \boxed{\text{Reason R is NOT the correct explanation of Assertion A}} \]

Step 4: Selecting the correct option. Thus:
• Assertion A is correct
• Reason R is correct
• But R is not the correct explanation of A Hence the correct option is: \[ \boxed{(B)\ \text{Both A and R are correct but R is NOT the correct explanation of A}} \] Final Conclusion: Both statements are scientifically correct, but the reason does not properly explain the assertion. Hence: \[ \boxed{(B)} \]