Question

The characteristic of Saline-Alkali soil are

• A. $\text{pH} > 8.5$, $\text{EC} > 4 \text{ dSm}^{-1}$, $\text{ESP} > 15$
• B. $\text{pH} > 8.5$, $\text{ESP} < 15$, $\text{EC} > 4 \text{ dSm}^{-1}$
• C. $\text{pH} < 8.5$, $\text{ESP} > 15$, $\text{EC} < 4 \text{ dSm}^{-1}$
• D. $\text{pH} > 8.5$, $\text{ESP} > 15$, $\text{EC} < 4 \text{ dSm}^{-1}$

Hint:

Remember the diagnostic limits for Saline-Alkali (Saline-Sodic) soils:
- EC: $> 4\text{ dS/m}$
- ESP: $> 15\%$
- pH: Classically variable (typically $\ge 8.5$).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Salt-affected soils are classified into saline, alkali (sodic), and saline-alkali (saline-sodic) categories based on three main chemical criteria: electrical conductivity ($\text{EC}$), exchangeable sodium percentage ($\text{ESP}$), and soil pH.

Step 2: Detailed Explanation:
Let us review the standard classification criteria:
Saline Soils: $\text{EC} > 4\text{ dS/m}$, $\text{ESP} < 15\%$, and $\text{pH} < 8.5$.
Alkali (Sodic) Soils: $\text{EC} < 4\text{ dS/m}$, $\text{ESP} > 15\%$, and $\text{pH} > 8.5$.
Saline-Alkali Soils: These soils contain high concentrations of both soluble salts and exchangeable sodium. They are characterized by: - Electrical Conductivity ($\text{EC}$) $> 4\text{ dS/m}$
- Exchangeable Sodium Percentage ($\text{ESP}$) $> 15\%$
- Soil pH can range from $8.5$ up to $10.0$ depending on the salt balance, though it is classically described as variable or $\approx 8.5$.
Among the given options, Option (A) represents the characteristics of saline-alkali soils.

Step 3: Final Answer:
The characteristics of saline-alkali soils are $\text{pH} > 8.5$, $\text{EC} > 4\text{ dS m}^{-1}$, and $\text{ESP} > 15$.