Question

Match List-I with List-II

List-I	List-II
(A) Alkalisation	(I) Low permeability
(B) Dispersed soil	(II) Increase in exchangeable sodium content
(C) CEC	(III) Degree of saturation
(D) ESP	(IV) Milliequivalents/100gm

Choose the correct answer from the options given below

• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (II), (B) - (I), (C) - (IV), (D) - (III)
• (A) - (IV), (B) - (III), (C) - (I), (D) - (II)
• (A) - (I), (B) - (II), (C) - (IV), (D) - (III)

Hint:

Sodic soils (ESP \( > \) 15%) suffer from clay dispersion and poor structure.
Adding gypsum (\( \text{CaSO}_4 \cdot 2\text{H}_2\text{O} \)) displaces the sodium with calcium, which helps flocculate the clay and restore soil permeability.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Soil chemical characteristics govern the physical structure and hydraulic behavior of agricultural soils.
Parameters like Cation Exchange Capacity (CEC) and Exchangeable Sodium Percentage (ESP) are used to diagnose and reclaim salt-affected soils.

Step 2: Detailed Explanation:
Let us analyze the terms and match them with their correct definitions:
1.Alkalisation (A): This refers to the process of accumulating exchangeable sodium on the soil's exchange complex.
This process leads to an increase in the exchangeable sodium content.
Thus, (A) matches with (II).
2.Dispersed soil (B): High exchangeable sodium causes soil clay particles to disperse when wet.
These dispersed clay platelets clog soil pores, leading to structural collapse and low permeability.
Thus, (B) matches with (I).
3.CEC (Cation Exchange Capacity) (C): This is the total capacity of a soil to hold and exchange cations.
It is expressed in units of milliequivalents per 100 grams of dry soil (\( \text{meq/100g} \)) or centimoles of charge per kilogram (\( \text{cmol}_c\text{/kg} \)).
Thus, (C) matches with (IV).
4.ESP (Exchangeable Sodium Percentage) (D): This measures the degree of saturation of the soil's exchange complex with sodium ions.
It is calculated as the ratio of exchangeable sodium to the total CEC, expressed as a percentage.
Thus, (D) matches with (III).
Combining these matches:
\[ \text{(A)-(II), (B)-(I), (C)-(IV), (D)-(III)} \]

Step 3: Final Answer:
The correct matching sequence is (A) - (II), (B) - (I), (C) - (IV), (D) - (III).