soil as a three phase system

## Water content formula of soil

Learn water content formula in a given mass of a soil

## Water content formula .

The water content formula w, also called the moisture content, is defined as the ratio of weight of water Ww to the weight of solids (Ws or Wd) in a given mass of soil.

$w&space;=&space;\frac{W_{w}}{W_{d}}$

The water content  formula w is generally expressed as a percentage. However, when used in the formulae giving relationship between certain quantities, it may be expressed as a fraction

$w&space;=&space;\frac{W-W_{d}}{W_{d}}x100$

The usual procedure to find the natural water content is to take a mass of about 20 g to 30 g of soil sample in a container and determine its mass M very accurately. The soil sample is then kept in an oven (105°C–110°C) for about 24 hours so that it becomes perfectly dry. Its dry mass Md is then determined and the water content is calculated from the relation

In the field of geology and agriculture, water content (w’) is defined as the ratio of the weight of water to the total weight of soil mass. Thus,

In order to find relation between w and w’,

$w&space;=&space;\frac{w'}{100&space;-&space;w'}$