Question

Match List-I with List-II regarding soil physical properties and their measurement instruments

List-I (Property)	List-II (Instrument)
(A) Particle density	(I) Wet sieving
(B) Soil moisture suction	(II) Psychrometer
(C) Humidity	(III) Pycnometer
(D) Aggregate stability.	(IV) Tentiometer.

Choose the correct answer from the options given below

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

Hint:

To easily recall these matches: Pycnometer is used for density measurements (A-III), and Tensiometer is used to measure soil moisture tension in the field up to \(0.85\text{ bar}\) (B-IV).
Wet sieving is the standard method used to measure water-stable soil aggregates (D-I).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Measuring soil physical and environmental properties requires using specialized laboratory and field instruments calibrated for specific physical parameters.

Step 2: Detailed Explanation:
Let us match each property with its corresponding instrument:
- (A) Particle density: This is the mass per unit volume of soil solid particles (excluding pore spaces).
It is determined in the laboratory using a pycnometer (a constant-volume glass bottle) by measuring the volume of water displaced by a known mass of dry soil solids.
This matches with (III).
- (B) Soil moisture suction: This is the tension with which water is held by the soil matrix.
It is measured in the field using a tensiometer (or tentiometer), which consists of a porous ceramic cup connected to a vacuum gauge through a water-filled tube.
This matches with (IV).
- (C) Humidity: Relative humidity of the air (or soil air) is measured using a psychrometer (consisting of dry-bulb and wet-bulb thermometers) or thermocouple psychrometers.
This matches with (II).
- (D) Aggregate stability: This represents the resistance of soil aggregates to breakdown by water action.
It is measured using Yoder's wet sieving apparatus, where soil aggregates are placed on a nest of sieves and oscillated vertically in a container of water.
This matches with (I).
Therefore, the correct matching sequence is: (A)-(III), (B)-(IV), (C)-(II), (D)-(I).

Step 2: Final Answer:
The correct matching sequence corresponds to option (C).