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Short note: Sub-surface irrigation

Short answer

Sub-surface irrigation supplies water to the root zone from below via a raised water table (natural) or buried perforated pipes (artificial). It suits permeable surface soil over an impervious layer 2-3 m down, flat land and low-salinity water. Advantages: low evaporation, no farm disruption; disadvantages: high cost, salt build-up and waterlogging risk.

Write a short note on sub-surface irrigation.

Sub-surface irrigation supplies water to the root zone from below the ground surface. The water table is raised or water is released below the surface so that it reaches the roots by capillary action.

Types

  1. Natural sub-irrigation: the water table is naturally high, or seepage from canals or rivers keeps the root zone moist (e.g. low-lying river-bank lands).
  2. Artificial sub-irrigation: water is fed through open ditches or buried perforated/porous pipes below the root zone; the water table is controlled by a gate or pump.
  ground ----------------------------
  root zone
  ~~~~~~~ raised water table ~~~~~~~~
  o=o=o perforated pipe
  ===== impervious layer ===========

Conditions for success

  • Permeable surface soil with an impervious layer 2-3 m below.
  • Flat land and a good drainage outlet.
  • Low-salinity water.

Merits

Little evaporation loss, no interruption of farm operations, no erosion, very efficient use of water.

Demerits

Costly installation, risk of salt build-up in the root zone, waterlogging if drainage is poor, and difficulty in maintenance.

✓ Answer checked by Claude Opus 5.5 (high effort)

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