The surface tension = 0.728×10-6 KN/cm at 20°c

Concave meniscus will only take place if the inner walls of the tubes are initially wet. If the walls are dry, a depressed convex meniscus will be formed.

Capillary water is the soil moisture located within the interstices and voids of capillary forces.

Since surface tension is the property of the molecules on the surface of the liquid body, the coefficient depends on the chemical nature.

Since the upward force due to surface tension are balanced by downward force at the lower end there will be no water retained in the tube.

If a capillary tube is of non-uniform diameter height of capillary rise will be depending upon the direction of flow of water in the tube.

Since the soil pores always carry adsorbed water, the meniscus formation in capillary tube will always be concave.

Coarse-grained soils have relatively low hygroscopic moisture due to their limited specific surface.

The capillary force of soil moisture depends upon various factors such as surface tension of water, pressure in water relation to atmospheric pressure, and the size and conformation of soil pores.

In the sandy soil there is no significant force of attraction between the soil particles, hence it contains pore water.