Total Soil Water Potential
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| 25.01.2010 | Author: sathya | Posted in Soil Plant and Water Relation | | Print
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‘The amount of work that must be done per unit quantity of pure water in order to transport reversibly and isothermally an infinitesimal quantity of water from a pool of pure water at a specified elevation at atmospheric pressure to the soil water’. (Difference between the energy state of soil water and that of pure water.)
Pt = Pg + Pm + Po
Pt = Total soil water potential
Pg = Gravitational potential
Pm = Matric potential
Po = Osmotic potential
Gravitational potential (Pg)
Pg = Gh
G = Acceleration of gravity.
h = Height of soil water above a reference elevation.
Osmotic potential (Po)
Attraction of ions and other solutes to water.
Matric potential (Pm)
Attraction of soil colloids to water.
Suctions and Tensions
Matric and Osmotic potential both negative.
Because both of above forces reduces free energy of soil water.
These negative forces are referred to as suctions or tensions.
Soil moisture content versus suction
Inverse relationship between the water content of soils and the suction or tension.
