Question

The water held tightly to the surface of soil particles by adsorptive forces is called:

• A. Capillary water
• B. Hygroscopic water
• C. Gravitational water
• D. Free water

Hint:

Think of soil water in terms of availability to plants: - \textbf{Gravitational water:} Drains away too quickly. - \textbf{Hygroscopic water:} Held too tightly. - \textbf{Capillary water:} Just right (this is the "plant available water").

Answer 1

The Correct Option is B

Step 1: Classify soil water based on retention mechanisms.
Soil water's classification depends on how it is retained within soil pores.
- Gravitational water: Freely drains from soil due to gravity.
- Capillary water: Held in micropores by surface tension; it is the main water source for plants.
- Hygroscopic water: Forms a thin film on soil particles, tightly bound by adhesion/adsorption, rendering it unavailable to plants.
Step 2: Correlate definitions with descriptions.
The description "held tightly to the surface of soil particles by adsorptive forces" precisely matches hygroscopic water, which can only be removed by soil heating.