Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Salt-affected soils in India are a threat to national food security and economic development
Reason (R) : Arid and semi-arid regions with high evaporation rates and with limited freshwater availability to flush out the excess salts from the soil, favoring the formation of saline soils
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:

Arid and semi-arid climates promote salinization because potential evapotranspiration is higher than rainfall, causing upward capillary movement and surface accumulation of soluble salts.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Salt-affected soils are characterized by an excess accumulation of soluble salts (saline soils) or exchangeable sodium (sodic/alkali soils), which adversely affect plant growth and soil physical properties.
The reclamation and management of these problem soils is a major challenge in sustainable agriculture.
The genesis of these soils is closely tied to climatic conditions, hydrological factors, and poor water management practices (such as canal irrigation without adequate drainage).

Step 2: Detailed Explanation:
Let us evaluate both statements and their logical relationship:
Assertion (A) is correct:
Salt-affected soils in India represent a severe threat to national food security and agricultural economy.
It is estimated that over \(6.73\text{ million hectares}\) of land in India is affected by salinity or sodicity, leading to drastic yield reductions of major crops like rice and wheat, or rendering the land completely barren.
This degradation reduces total food production, affects farmers' incomes, and leads to land abandonment, posing a major socio-economic challenge.
Reason (R) is correct:
The formation of saline soils is highly favored in arid and semi-arid regions.
In these regions, rainfall is insufficient to leach the naturally occurring soluble salts down and out of the root zone.
High potential evapotranspiration (PET) rates exceed precipitation, drawing water upward through capillary action.
As the water evaporates from the soil surface, the dissolved salts are left behind and accumulate in the topsoil.
Additionally, the limited availability of high-quality freshwater in these dry regions prevents farmers from flushing (leaching) the excess salts out of the root zone, reinforcing the salinity.
This climatic and hydrological reality explains how these saline soils are formed and why they continue to expand and threaten agricultural land.
Therefore, both Statements (A) and (R) are correct, and (R) provides the correct explanation for the threat and distribution of salt-affected soils described in (A).

Step 3: Final Answer:
Thus, the correct option is that both (A) and (R) are correct and (R) is the correct explanation of (A).