Question

If the pH of soil $>$ 8.5; EC of saturated extract $<$ 4.0 $\text{dSm}^{-1}$; ESP $>$ 15.0 and SAR $>$ 13.0 the soil is called as .......

• A. Saline soil
• B. Alkali soil
• C. Degraded Alkali soil
• D. Saline -Alkali soil

Hint:

To easily identify these soils:
- Low EC ($<$ 4.0) + High ESP ($>$ 15) + High pH ($>$ 8.5) = Alkali (Sodic) Soil.
- High EC ($>$ 4.0) + Low ESP ($<$ 15) + Low pH ($<$ 8.5) = Saline Soil.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Salt-affected soils are common in arid and semi-arid regions and are classified into saline, sodic (alkali), and saline-sodic categories based on their chemical properties.
These properties include pH, Electrical Conductivity (EC), Exchangeable Sodium Percentage (ESP), and Sodium Adsorption Ratio (SAR).

Step 2: Detailed Explation:
Let's alyze the classification criteria for salt-affected soils:
1. Saline Soils: These contain high amounts of soluble salts.
They have an \( \text{EC} > 4.0 \text{ dS/m} \), an \( \text{ESP} < 15\% \), an \( \text{SAR} < 13 \), and a \( \text{pH} < 8.5 \).
2. Alkali (Sodic) Soils: These are domited by exchangeable sodium on the soil colloid complex.
They have an \( \text{EC} < 4.0 \text{ dS/m} \), an \( \text{ESP} > 15\% \), an \( \text{SAR} > 13 \), and a high \( \text{pH} > 8.5 \) (often up to 10.0) due to the hydrolysis of sodium carbote.
3. Saline-Alkali Soils: These contain both soluble salts and high exchangeable sodium.
They have an \( \text{EC} > 4.0 \text{ dS/m} \), an \( \text{ESP} > 15\% \), an \( \text{SAR} > 13 \), and a variable pH (usually around 8.5).
Based on the parameters given in the question:
\( \text{pH} > 8.5 \), \( \text{EC} < 4.0 \text{ dS/m} \), \( \text{ESP} > 15.0\% \), and \( \text{SAR} > 13.0 \).
These parameters correspond directly to the definition of an Alkali soil.

Step 3: Fil Answer
The soil described by these parameters is classified as an Alkali soil.