It is calculated by integrating the water retention curve, soil water potential \ psi ( \ theta ) with respect to \ theta:
2.
Abscisic acid is also produced in the roots in response to decreased soil water potential and other situations in which the plant may be under stress.
3.
Soil water potentials below wilting point occurred in the forest during dry season, but the driest points were not necessarily near the edge and no evidence of prolonged drought was found.
4.
Another class of sensors measure another property of moisture in soils called water potential; these sensors are usually referred to as soil water potential sensors and include tensiometers and gypsum blocks.