Question

Available moisture is the difference in water content of soil between field capacity and______.

• A. Gravitational water
• B. Permanent wilting point
• C. Saturation capacity
• D. Ultimate wilting point

Answer 1

The correct option is B Permanent wilting point

Available moisture is the difference in water content of soil between field capacity and permanent wilting point.
The soil moisture in the rootzone can vary between field capacity (upper limit) and wilting point moisture content (lower limit) as shown below:

Note: Field Capacity : It is maximum water holding capacity of soil against gravity.

$\text{Field Capacity}=\frac{\text{Weight of moisture in soil against gravity}}{\text{Field Capacity Total dry weight of soil}}$
$=\left(\frac{{\gamma }_w}{{\gamma }_d}\right)\left(n\right)$
$\text{Here,}{\gamma }_w=\text{Unit weight of water}$
${\gamma }_d=\text{Dry unit weight of soil.}$
$n=\text{Porosity}$