Subsurface drainage
Subsurface drainage removes
the excess water which has infiltrated into the soil and that can be held there
by capillary forces even against the gravitational force. This type of drainage
is typically needed for the soils that contained impervious or slowly permeable
rocks or a layer below the soil surface. This impervious layer does not allow
the water to move deeper into the soil so that the crop production does not
hamper. Subsurface runoff systems include pipe/ tile drainage, mole drainage
and drainage wells. The subsurface drainage system of 20 m spacing and 1.5 m depth
can increase the cotton, wheat, and rice yield upto a great extent. The cost of
making a subsurface drainage system is 2-2.5 times higher than the surface
drainage system.