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Paddy third-dose fertilizer (pre-panicle initiation)

The third nitrogen split in the ICAR/TNAU paddy package-of-practices is applied at the panicle initiation stage, approximately 50-60 days after transplanting (DAT), to support spikelet development and grain filling. It is the final nitrogen application of the season for transplanted paddy.

Principle

Paddy reproductive development is divided into panicle initiation, booting, heading and grain filling. Adequate nitrogen at panicle initiation supports spikelet differentiation and panicle weight, while adequate potassium during the same window supports grain filling, hull formation and lodging resistance. Nitrogen applied later than this window contributes little to yield and can delay maturity.

Implementation

Standard package-of-practices:

  • Timing: 50-60 DAT, at panicle initiation; precise timing is judged from internode elongation and from the appearance of the young panicle (1-2 mm) on dissection of the main tiller.
  • Nitrogen share: approximately one-third of seasonal N, applied as Urea.
  • Potash: where K has been split, the remaining share is applied at this stage to support grain filling. Sop Water Soluble Paddy (sulphate of potash) is sometimes preferred over Muriate Of Potash in chloride-sensitive contexts.
  • Common pairings: stem-borer management at the same window, since stem-borer-induced "dead heart" damage during panicle initiation is a major yield loss source.

The dose is broadcast on the wet field at low standing-water depth, mirroring the management of the earlier splits.

Adoption context

The three-split schedule (basal, active tillering, panicle initiation) is the universal Indian recommendation for transplanted paddy. Leaf-colour-chart (LCC) refinement is increasingly used to adjust this final dose based on actual crop colour, reducing over-application on already-vigorous crops.

Limitations

Application later than the panicle initiation window pushes assimilation into vegetative tissue and delays maturity, increasing exposure to late-season pests and weather. Underdosing at this stage caps grain weight and final yield. Variety duration must be considered: short-duration varieties may need the dose earlier, long-duration varieties later, with district-specific RDFs as the reference.

See also: Paddy First Dose Fertilizer, Paddy Tillering Top Dressing, Urea, Muriate Of Potash, Sop Water Soluble Paddy, Complex 20 20 0 13.

References

  1. Paddy Nutrient Management. TNAU Expert System.
  2. Rice Nutrient Calculator. IRRI Rice Knowledge Bank.