Question

The water which occurs within the spaces of soil particles is:

• A. Capillary water
• B. Ground water
• C. Surface water
• D. Hygroscopic water

Hint:

Capillary water is held in soil micro-pores by surface tension and is the primary form of soil water available for plant absorption.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Soil water is classified into different physical forms based on the forces holding it within the soil matrix, which determines its availability to plants.

Step 2: Detailed Explanation:
Let us analyze the forms of soil water:
1. Gravitational water: Water that drains rapidly through large soil pores under the influence of gravity.
It is not held in the soil and is generally unavailable to plants.
2. Hygroscopic water (D): Water held tightly as a thin, microscopic film on the surface of soil particles by strong adhesive forces.
This water is held at high tensions (above 31 atmospheres) and cannot be absorbed by plant roots.
3. Capillary water (A): Water held against gravity in the micro-pores (spaces) between soil particles by surface tension and cohesive forces.
It is held at tensions between 0.3 and 31 atmospheres, which is the range that can be absorbed by plant roots.
This capillary water is the primary source of water for plants.
4. Ground water (B) and Surface water (C): Ground water refers to water in the saturated zone below the water table, while surface water refers to open water bodies on the soil surface.

Step 3: Final Answer:
Therefore, the water held within the spaces of soil particles is capillary water.