Organic Framing

Provision of Sub-Surface Drainage

In the areas of high salinity, it is essential to bring down the salinity by leaching the salts. It is also necessary to lower the water table if it is shallow and saline and maintain it below the critical depth to prevent resalinisation. Drainage of agricultural lands can be achieved through a package of the following measures,

• Intercept the flood and seepage water from above by opening sufficiently large drain (called interceptor drain) and divert the same from affecting the holding.
• Construct a good feeder drain (called vertical disposal drain) in the field, along the slope and connect it with the common drain or natural drains such as nallas.
• Construct adequate drains in the plots and crop fields and connect them to the vertical disposal drain.
• Provide drop pits and stone pitching in erodable spots.
• If the soils are alkali in nature, apply sufficient quantities of chemical and organic amendments, based on soil test results.
• Traditionally drainage is provided by means of open ditches, dug out either by human labour or by earth moving equipment.
• The width and depth depends on the quantity of water to be removed and root system of the crop. Though, they can be opened without much skills, they have several limitations such as,
  • The sides collapse and silt up fast.
  • Weeds and grasses grow up and clog the drain and also spread weed seed.
  • Harbor pests like rats.
  • Become water-logging and breed mosquitoes.
  • Occupy 15-20 % of land area.
  • Obstruct cultivation and movement of machinery.
  • All lateral drains have to be ploughed up and re-laid after each cropping.
• Out of the various methods of drainage systems and reclamation of saline soils, subsurface drainage system will be most effective and long lasting particularly in heavy soils. This system includes laying of perforated PVC pipes under ground and draining the accumulated salts along with water to a common outlets/well.
• The drained water will be tested for its quality and if found suitable, the same water will be recycled to the crop.
• There are different dimensions of perforated and unperforated pipes (blind pipes) available with reputed plastic manufacturing companies , with BIS specification. It is an excellent system for all irrigated agriculture crops like sugarcane, yielding orchards, plantations and sensitive crops like turmeric.