Presence Of Water In Soil
Presence Of Water In Soil

Presence Of Water In Soil

PRESENCE OF WATER IN SOIL

Water present in the soil may be classified under three heads:

  1. Hygroscopic water,
  2. Capillary water,
  3. Gravitational water.

1.Hygroscopic Water.

  • When a soil sample after having been completely dried in an oven is put in an open atmosphere,
  • It absorbs some amount of water from it.
  • The amount of water so absorbed by the oven-dried soil sample is termed as hygroscopic water.
  • This water is not capable of any movement by the action of gravity force or capillary force.
  • The amount of this water in the soil can vary only if there is a change in the moisture content in the atmosphere.
  • This water is not available for plant growth.

2. Capillary Water.

  • This water is that water content in soil excess of hygroscopic water,
  • which exists in the pore space of the soil, due to molecular attraction.
  • This water is held in the form of a thin continuous film around
  • The soil particles due to forces of surface tension.
  • It is this water that remains available for the plant growth between successive waterings to the crops. See Fig

Various forms of water

3. Gravitation Water.

  • It is that part in excess of hygroscopic and capillary water,
  • which will drain out of the soil under the action of gravity.
  • This water passes down and joins the groundwater table.
  • This water is also known as superfluous water.
  • It is also not available for the growth of plants as it readily gets drained whenever it finds conditions favorable for it.
  • Water present in the soil may be classified as unavailable, available
  • This classification is based on the availability of soil water for plant growth. See Fig.

 

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