From top 25% of effective root zone depth how much quantity of total water extraction take place by roots

From the top 25% of effective root zone depth, 40% of total water extraction takes place by roots.
The amount of water that a crop can extract from its root zone and its magnitude depending on the type of soil and the rooting depth.
As a rule of thumb about 70% of the moisture extracted by the root is obtained in the top half of the root zone, about 20% from the third quarter and about 10% from the soil in the deepest quarter of the root zone.