Permanent wilting point

Permanent Wilting Point (PWP)

In Permanent Wilting Point (PWP) plants can be no longer obtains enough moisture to meet their requirements and remained wilted until water is added into the soil.

 It is a soil characteristic.

It is the lower limit of available water to plant.

Soil moisture tension at PWP is about -15 bars or 15 atmospheres.

SC = Saturation capacity, FC = Field capacity, OMC = Optimum moisture content, PWP = Permanent welting point and UWP = Ultimate welting point

Field capacity is the water that cannot be easily drained under the action of gravity and having its presence in the root zone.

The permanent Wilting point is the water content in the root zone below which the roots can no longer extract water for their growth and dries up.

Readily available moisture is that portion of available moisture that can be most readily extracted by plants.

In general, readily available moisture is approx 75 % of the available moisture.

The difference in water content of soil between field capacity and the permanent wilting point is called available moisture.