Water

Water needed for plant growth is taken up by the roots from the soil. The soil water exists in three forms: hygroscopic, capillary, and gravitational or superfluous. A soil that has been saturated with water so that all pore spaces have water in them has all three types of water.

Gravitational Water is the water that is pulled downward through the soil by gravity.

Capillary Water is the water held in pore spaces of capillary size.

Hygroscopic Water is a film of water that is so tightly bound to the soil particles that it is unavailable for plant growth.

Field Capacity is a measure of the amount of water held by the soil after gravitational water has drained.