Question

Give an account of the different types of soil water.

Answer 1

Hint: Soil, water, plant are the three that are interdependent on each other. Soil is responsible for the transportation of various solutes, water and organic matter to the plants as well as for the removal of metabolic waste from the plant to the soil.

Complete Answer:
Soil, water and plant relationship relates to the properties of soil and plants that affect the movement, retention and use of water. Due to inadequate or unevenness in the distribution of rainfall, it is necessary to supply water through different ways like irrigation.

Soil water is mainly comprises of 3 types:
- Gravitational water: It is the type of water that moves downward towards the soil due to the gravitational pull. It is also called free water. It is of no use because it drains out from the plant due to its gravitational force. It reduces aeration in the soil and thus its removal is necessary for the optimum growth of the plant.
- Capillary water: It is the water that is held in the capillary pores (micro pores). It is retained in the soil particles by the surface forces like adhesion (i.e. attraction of water molecules for soil particles) or cohesion (i.e. attraction between the water molecules and surface tension).
- Hygroscopic water: It is the water that is held tightly to the surface of soil particles by adsorption force. It is essentially non-liquid water and thus moves primarily in the vapor form. This water is unavailable to the plant because the plant needed the high pressure to extract it.

Note: Soil water is mainly responsible for the transportation of water to the plant. It takes place by the mechanisms like imbibition, osmosis, diffusion etc. but for the transportation of water for long distance different methods like root pressure, transpiration pull is responsible that produces negative pressure in the plant due to which the movement of water takes place.