Question

Total nitrogen in soil is measured by

• A. Kjeldahl method
• B. Walkley & Black method
• C. Colorimeter method
• D. Hydrometer method

Hint:

Soil analysis methods:
- Kjeldahl: Total nitrogen.
- Walkley & Black: Organic carbon.
- Hydrometer: Soil texture.
- Colorimeter: Nitrate, phosphate.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
This question tests knowledge of analytical methods for soil nitrogen determination.

Step 2: Detailed Explanation:
Total nitrogen in soil is measured by the Kjeldahl method (A).
The Kjeldahl method involves digestion of soil with sulfuric acid, followed by distillation and titration.
It measures organic and inorganic nitrogen (excluding nitrate).
Other methods:
- Walkley & Black method (B): For soil organic carbon (not nitrogen).
- Colorimeter method (C): For nitrate, phosphate, etc.
- Hydrometer method (D): For soil texture (particle size).
Thus, the Kjeldahl method is used for total nitrogen.

Step 3: Final Answer:
Thus, total nitrogen in soil is measured by the Kjeldahl method, which corresponds to option (A).
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