Question

Given below are two statements :
Statement (I) : Saline soil has the characteristics of $\text{EC} > 4\text{ ds/m}$, $\text{ESP} > 15$, and $\text{pH} < 8.5$}
Statement (II) : Alkaline soils have the characteristics of $\text{EC} > 4\text{ ds/m}$, $\text{ESP} < 15$, and $\text{pH} > 8.5$}
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are true.
• B. Both Statement (I) and Statement (II) are false.
• C. Statement (I) is true but Statement (II) is false.
• D. Statement (I) is false but Statement (II) is true.

Hint:

To remember the differences: Saline soils have high soluble salts ($\text{EC} > 4$) but low sodium ($\text{ESP} < 15$); Sodic soils have low soluble salts ($\text{EC} < 4$) but high exchangeable sodium ($\text{ESP} > 15$).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Salt-affected soils are classified into three major classes based on their Electrical Conductivity (EC), Exchangeable Sodium Percentage (ESP), and soil pH: saline, sodic (alkaline), and saline-sodic soils.

Step 3: Detailed Explanation:
Let us review the standard US Salinity Laboratory classification criteria for salt-affected soils:
1. Saline Soils (White Alkali):
- These soils contain high amounts of soluble neutral salts (such as chlorides and sulfates of calcium and magnesium).
- EC is greater than $4 \text{ dS/m}$ at $25^\circ\text{C}$.
- ESP is less than $15\%$.
- pH is typically less than $8.5$.
Statement (I) incorrectly asserts that saline soils have $\text{ESP} > 15$, making Statement (I) incorrect.
2. Sodic Alkaline Soils (Black Alkali):
- These soils contain high amounts of exchangeable sodium and sodium carbonate/bicarbonate salts.
- EC is less than $4 \text{ dS/m}$ at $25^\circ\text{C}$.
- ESP is greater than $15\%$.
- pH is greater than $8.5$ (often ranging from $8.5$ to $10.0$).
Statement (II) incorrectly asserts that alkaline soils have $\text{EC} > 4 \text{ dS/m}$ and $\text{ESP} < 15$, making Statement (II) incorrect.
Therefore, both statements have swapped criteria and are false.

Step 4: Final Answer:
Both Statement (I) and Statement (II) are false, corresponding to option (B).