# How do scientists measure the porosity of soil?

Soils are made of particles of different types and sizes. The space between particles is called pore space. Pore space determines the amount of water that a given volume of soil can hold. Porosity is nothing but the pores present in the spoil.

The porosity of a soil is expressed as a percentage of the total volume of the soil material. Porosity is an important measurement in areas where drinking water is provided by groundwater reserves.

Steps to find the porosity:

1. Fill one measuring cup to 200 ml with sand, the second cup with 200 ml of clay and the third with 200 ml with small pebbles.
2. Fill a graduated cylinder to 100 ml with water.
3. Slowly and carefully pour the water into the first cup until the water just reaches the top of the sand.
4. Pour slowly so no water spills out of the measuring cup. Record exactly how much water was used.
5. Use the formula below to calculate the percent porosity for the sand:

Porosity = (Amount of water added to sample ÷ Total sample volume) x 100

1. Repeat the same procedure with the clay and the pebbles.