• Agricultural drainage is the removal of excess water known as free water or gravitational water from the surface or below the surface of farmland so as to create favourable soil conditions for plant growth.
• Agricultural drainage is of two types:

1) Surface drainage system

• The process of removing the excess water from the land surface is known as surface drainage.
• Surface drainage is the orderly removal of excess water from the surface of the land through improved lateral channels or constructed ditches through shaping of the land surface.
• Surface drainage applies primarily to flat land with slow infiltration, low permeability or a restricting layer in the soil profile.
• includes:

a) Collection ditches

b) Disposal ditches.

2) Sub surface drainage

• If excess water saturates the pore space of soil, the process of its removal by downward flow through the soil is known as sub surface drainage.
• Sub surface drains are underground artificial channels through which excess water may flow to a suitable outlet.