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Potassium nitrate (13-0-45) flowering spray

Potassium nitrate (KNO3) is a fully water-soluble compound fertiliser supplying 13% nitrate-nitrogen and 45% K2O. It is widely used as a foliar spray during the flowering and fruit-development phase of high-value crops, particularly in mango orchards, and is notified under the FCO water-soluble fertiliser schedule.

Composition

  • Grade: 13-0-45 (N-P2O5-K2O)
  • N form: nitrate (NO3-), 13%
  • K form: K2O equivalent, 45%
  • Solubility: 100% water soluble at field temperatures
  • Form: white crystalline solid or pre-dissolved liquid

Indian formulations are produced by IFFCO and several SQM-derived importers under the FCO water-soluble schedule.

Mode of action

Potassium nitrate combines the rapid plant uptake of nitrate nitrogen with a concentrated potassium dose and contains no chloride, making it suitable for foliar use even on chloride-sensitive crops. Foliar-applied K supports flower-bud differentiation, reduces flower drop and improves fruit set in mango, pomegranate and similar crops, while the nitrate fraction supports the energy demands of reproductive development. Soil-applied KNO3 is also a standard fertigation salt for protected cultivation.

Target use and dose

  • Mango orchard: 1-1.5% spray (10-15 g per litre of water), timed shortly after irrigation, applied at flowering and during early fruit development.
  • Pomegranate, grapes, vegetables: 0.5-1.5% foliar at flowering and fruit-set windows.
  • Fertigation: dissolved in irrigation water at crop-specific rates as one of the standard tank-A salts in protected-cultivation nutrient programmes.

Should not be tank-mixed in concentrate with calcium-containing solutions, which precipitate as calcium sulphate or carbonate.

Safety and regulatory status

FCO-notified water-soluble fertiliser. Non-toxic at field rates. Like all nitrate salts, it should be stored away from strong reducing agents and combustible organic materials to avoid oxidiser hazards.

See also: Muriate Of Potash, Sop Water Soluble Paddy, Water Soluble Fertilizers, Gromor Fitsol Fertigation, Calcium Magnesium Foliar.

References

  1. Potassium Nitrate Water-Soluble. Indian Farmers Fertiliser Cooperative.
  2. Potassium Nitrate 13:00:45. Fissionbiotech product profile.