Question

Match List-I with List-II

List-I (Method)	List-II (Determination)
(A) Kjeldahl method	(I) Primarily assesses the available phosphorus content in the soil
(B) Bray P1 test	(II) Measures the potassium content in the soil solution
(C) Ammonium acetate extraction	(III) Determines the total nitrogen content in the soil
(D) Flame photometry	(IV) Quantifies the exchangeable ammonium and potassium content in the soil

Choose the correct answer from the options given below.

• A. (A)-(I), (B)-(II), (C)-(III), (D)-(IV)
• B. (A)-(I), (B)-(III), (C)-(II), (D)-(IV)
• C. (A)-(I), (B)-(II), (C)-(IV), (D)-(III)
• D. (A)-(III), (B)-(I), (C)-(IV), (D)-(II)

Hint:

Remember:
- Kjeldahl $\rightarrow$ Nitrogen
- Bray P1 $\rightarrow$ Phosphorus
- Flame Photometry $\rightarrow$ Potassium/Sodium

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Soil testing involves standardized chemical extractions and analytical techniques to quantify plant-available nutrients and total elemental reserves in the soil.

Step 2: Detailed Explanation:
Let us match the laboratory methods in List-I with their specific determinations in List-II:
- (A) Kjeldahl method $\rightarrow$ (III) Determines the total nitrogen content in the soil: Consists of digestion, distillation, and titration steps to quantify organic and ammonia nitrogen.
- (B) Bray P1 test $\rightarrow$ (I) Primarily assesses the available phosphorus content in the soil: Uses an acid fluoride solution ($0.03\,\text{N }\text{NH}_4\text{F} + 0.025\,\text{N }\text{HCl}$) to extract available phosphorus from neutral to acidic soils.
- (C) Ammonium acetate extraction $\rightarrow$ (IV) Quantifies the exchangeable ammonium and potassium content in the soil: Neutral $1\,\text{N }\text{NH}_4\text{OAc}$ is the standard extractant used to displace exchangeable base cations.
- (D) Flame photometry $\rightarrow$ (II) Measures the potassium content in the soil solution: An analytical instrument that measures the characteristic emission of light of specific alkali metals (like potassium and sodium) in a flame.

Step 3: Final Answer:
The matching matches Option (D).