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Fertigation

Fertigation is the application of water-soluble fertilisers through a micro-irrigation system, most commonly a Drip Irrigation network. Nutrients dissolved in the irrigation water are metered to the root zone in synchrony with each irrigation event, allowing precise dose splitting through the crop cycle.

Principle

A fertiliser solution is injected into the irrigation line upstream of the lateral network using a venturi injector, fertiliser tank or dosing pump. Because the wetting bulb produced by drip emitters concentrates roots in a defined volume, the dissolved nutrients are taken up efficiently with little leaching below the active root zone. Splitting the season's fertiliser into many small applications maintains a steady supply that closely tracks crop demand.

Implementation

ICAR-IIHR Bengaluru publishes crop-wise fertigation schedules for horticultural crops. ICAR research recommends splitting fertiliser into approximately fourteen equal doses at 8-day intervals through the crop cycle for many vegetables and orchard crops. Only fully water-soluble grades such as urea, potassium nitrate, calcium nitrate, mono-ammonium phosphate, potassium sulphate and water-soluble NPK blends are suitable; conventional SSP and complex fertilisers will precipitate in laterals. PMKSY's PDMC operational guidelines list fertigation tanks and venturi or Dosatron injectors as eligible components for subsidy.

Adoption context

Trials show 20-40% reduction in total fertiliser input compared with broadcast application, with yield maintained or improved. The practice is widely used on chilli, vegetables, banana, oil palm and sugarcane. Soil-test-based recommendations from Soil Testing underpin the season dose before it is split into the fertigation schedule.

Limitations

Acidic fertilisers and incompatible salt blends accelerate emitter clogging; periodic flushing and acid washing (see Drip Emitter Clogging) is required. Cost of fully water-soluble grades is higher per unit nutrient than conventional fertilisers. Backflow-prevention check valves are essential to prevent contamination of the water source.

See also: Drip Irrigation, Automatic Drip Irrigation, Sprinkler Irrigation, Drip Emitter Clogging, Soil Testing.

References

  1. Fertigation Schedule. ICAR-Indian Institute of Horticultural Research, Bengaluru.
  2. Drip fertigation for vegetables. Indian Farming, ICAR.
  3. Operational Guidelines of Per Drop More Crop. PMKSY.