Question

Arrange the following forms of soil consistencies with decreasing soil wetness
A. Soft
B. Friable
C. Plastic
D. Viscous
E. Sticky
Choose the correct answer from the options given below

• A. A, B, C, D, E
• B. A, C, D, E, B
• C. B, A, C, E, D
• D. D, E, C, A, B

Hint:

Remember that tillage is best performed in the "Friable" range. If tilled in the "Plastic" or "Sticky" range, soil structure can be severely damaged via puddling.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Soil consistency describes the physical state of the soil at various moisture contents and its resistance to deformation.
As water content decreases, soil passes through several consistency states: liquid, plastic, semi-solid, and solid.
Atterberg limits (Liquid limit, Plastic limit, Shrinkage limit) are used to quantify these transitions.

Step 2: Detailed Explanation:
The question asks to arrange the states from highest wetness to lowest wetness.
At the highest moisture content, the soil acts like a liquid or a viscous fluid.
1. Viscous (D): This corresponds to the liquid state where soil has almost no shear strength and flows under its own weight.
2. Sticky (E): As the soil begins to lose some water, it reaches a state where it adheres to objects. This is typically observed just below the liquid limit.
3. Plastic (C): At slightly lower moisture, the soil becomes plastic. In this state, it can be molded or rolled into thin threads without breaking. This occurs between the liquid and plastic limits.
4. Soft (A): As drying continues, the soil enters a moist state that is soft and easily deformed but loses its high plasticity.
5. Friable (B): This is the optimal moisture state for tillage. The soil aggregates can be easily crushed between the thumb and forefinger into smaller crumbs. It occurs at lower moisture than the plastic state.
Continuing to dry would lead to a "hard" or "harsh" consistency.

Step 3: Final Answer:
The correct sequence from wet to dry is Viscous \(\rightarrow\) Sticky \(\rightarrow\) Plastic \(\rightarrow\) Soft \(\rightarrow\) Friable. This corresponds to the order D, E, C, A, B.