Water in soil (Soil Water)
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| Soil water |
As by name we can understand the meaning of soil water. The water present in soil is called soil water.
Soil
water is of two types.
- Free water (Gravitational water)
- Held water
Free water
The water which is free to move through soil mass (within
the voids or pores in the soil) under the influence of gravity is called free
water. Because this water is free to move under influence of gravity that’s why
it is also known as free water.
Held water
As by name we can understand the meaning of held water we
can say held water is water which is held (not free to move).
So,
held water is the water which is not free to move through soil mass (within the
voids or pores in the soil) because of certain forces existing within the pores
is known as held water.
Held water is further classified into:
- Structural water
- Absorbed water
- Capillary water
Structural water
The water which is chemically combined within the crystal
structures of soil minerals present in the soil (like silica) is called
structural water.
Because the water is chemically combined with soil minerals
that’s why extraction of water can’t be done by the help of ordinary process
like oven drying and many more.
So, what to do for extraction of water?
For extraction of water we have to simply break the structure
of soil mass. Thus we can say that this water can’t be extracted because it is
the part of soil mass itself.
Adsorbed water
The water which is adsorbed by soil from atmosphere mainly
in humid condition due to it’ hygroscopic nature is called adsorbed water. The
water adsorbed is held within the pores of soil due to force of adhesion. This
water is also known as contact water or hygroscopic water.
Capillary water
As by name we are able to understand capillary water as the
water held due to capillary action.
So, the water which is held between the soil voids or pores
due to capillary forces is called capillary water.
