Question

Given below are two statements, one is labeled as Assertion (A) and the other one is labeled as Reason (R).
Assertion (A) : Universal Soil Loss Equation A= RKLSCP
Reason (R) : Universal soil loss equation determination for the reduction of soil erosion to tolerable limits necessitates the adoption of properly planned cropping practices and soil conservation measures.

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

Hint:

To verify the explanation relationship: Ask "Why is $A = RKLSCP$?" The answer must define the components of the equation, not its agricultural applications. Since the Reason describes its application, it is not the correct explanation of the Assertion.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The Universal Soil Loss Equation (USLE) is an empirical model developed to estimate average annual soil loss caused by water erosion.
It helps land managers predict soil loss and select appropriate conservation strategies.

Step 3: Detailed Explanation:
Let us analyze the Assertion and the Reason individually:
- Assertion (A) is correct: The USLE is mathematically formulated as:
\[ A = R \cdot K \cdot L \cdot S \cdot C \cdot P \]
where $A$ is the computed average soil loss per unit area, $R$ is the rainfall-runoff erosivity factor, $K$ is the soil erodibility factor, $L$ is the slope length factor, $S$ is the slope steepness factor, $C$ is the cover-management factor, and $P$ is the support practice factor.
- Reason (R) is correct: To control soil erosion and keep it below the tolerable soil loss limit ($T$-value), land managers must modify the manageable variables in the USLE equation.
While climate ($R$) and inherent soil properties ($K$) cannot be easily altered, properly planned cropping practices (which reduce the $C$ factor) and soil conservation measures like terracing or contouring (which reduce the $P$ factor) are highly effective in mitigating soil erosion.
- Analysis of Explanation: Although both statements are scientifically true, the Reason does not explain the mathematical composition or formulation of the USLE equation mentioned in the Assertion. It merely states how the equation is applied for conservation planning.
Therefore, Both (A) and (R) are correct, but (R) is not the correct explanation of (A).

Step 4: Final Answer:
Both (A) and (R) are correct, and (R) is not the correct explanation of (A).