Question

Lime potential of soil is expressed as:

• A. \(\mathrm{pH} - (1/2 \mathrm{pCa})^{1/2}\)
• B. \(\mathrm{pH} - 1/2 \mathrm{pCa} + 1/2 \mathrm{pCO}_3^{2-}\)
• C. \(\mathrm{pH} + 1/2 \mathrm{pCa}\)
• D. \(\mathrm{pH} - 1/2 \mathrm{pCa}\)

Hint:

Lime potential: \(\mathrm{pH} - 1/2 \mathrm{pCa}\).
Indicator of calcium availability and soil acidity.
High lime potential: Good calcium availability.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Lime potential is a measure of the calcium activity in soil solution.

Step 2: Detailed Explanation:
Lime potential is defined as:
\[ \text{Lime potential} = \mathrm{pH} - 1/2 \mathrm{pCa} \] where:
pH = negative logarithm of H+ ion activity.
pCa = negative logarithm of Ca2+ ion activity.
Lime potential indicates the availability of calcium in soil.
It is used to assess soil acidity and calcium status.
Other expressions:
- (A) \(\mathrm{pH} - (1/2 \mathrm{pCa})^{1/2}\): Incorrect.
- (B) \(\mathrm{pH} - 1/2 \mathrm{pCa} + 1/2 \mathrm{pCO}_3^{2-}\): Incorrect.
- (C) \(\mathrm{pH} + 1/2 \mathrm{pCa}\): Incorrect.
Thus, the correct expression is \(\mathrm{pH} - 1/2 \mathrm{pCa}\).

Step 3: Final Answer:
Thus, lime potential is expressed as \(\mathrm{pH} - 1/2 \mathrm{pCa}\).
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