Basic Soil and Water Relations

In a soil system of total volume Vtotal and total weight or mass Wtotal:

Vtotal = Vair + Vwater + Vsolid                                           ...(eqn. 1)
Vvoid = Vair + Vwater                                                         ...(eqn. 2)

Wtotal = Wair + Wwater + Wsolid                                       ...(eqn. 3)

Equations 1 and 3 state that the total volume or weight of a soil is the total of the space occupied by air, water, and solid.

Meanwhile, you can find the volume of void space by equation 2. Void space is the space that is not occupied by any solid matter.

Difference between Irrigation and Drainage

Before we start discussing the many equations surrounding Irrigation and Drainage, let us first know the basic difference between the two.

Well, the basic difference between the two lies in the method used to achieve a desired result.


From its simplest definition, irrigation is the application of water to create a condition in the soil that is favorable for plant growth.On the other hand, drainage is the removal of excess water from the soil to create a condition in the soil that is favorable for plant growth.

So...

Irrigation and Drainage have the same purpose (create a condition in the soil that is favorable for plant growth).

And...

Irrigation is the application of water

While...

Drainage is the removal of excess water.

I hope that helps. ^.^