Question

The pF range of soft or friable consistency of soil is-

• A. More than 4.5
• B. 2.8-4.5
• C. 0.5-2.8
• D. Less than 0.5

Hint:

Recall key pF values: Field Capacity is \( \text{pF} \approx 2.54 \), and Permanent Wilting Point is \( \text{pF} \approx 4.2 \). The friable range lies primarily between these two limits.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Soil consistency describes the resistance of soil to deformation or rupture at various moisture contents.
The pF scale, introduced by Schofield, represents the logarithm of the soil moisture tension (suction) in centimeters of water head.

Step 2: Detailed Explanation:
The physical states of soil consistency correspond to distinct ranges of soil moisture tension (pF):
- Hard or harsh consistency occurs in very dry soils, typically corresponding to a pF value greater than 4.5.
- Soft or friable consistency is observed in moist soils, spanning a pF range of 2.8 to 4.5, which represents optimal workability and plant growth conditions.
- Plastic or sticky consistency occurs in wet soils, typically falling below a pF of 2.8.

Step 3: Final Answer:
Thus, the pF range for soft or friable consistency of soil is 2.8 to 4.5.