Skip to content

Water-Soluble Fertilizers (13-0-45, 19-19-19, 0-52-34)

Water-soluble fertilisers (WSFs) are fully dissolving fertiliser salts notified under the FCO water-soluble schedule and used for fertigation through drip irrigation and for foliar sprays. They are the standard nutrient delivery format in protected cultivation and intensive horticulture, where they enable precise dose control matched to crop phenology.

Composition

The most common Indian grades include:

  • Potassium nitrate (13-0-45): 13% nitrate-N + 45% K2O; the standard high-K foliar/fertigation salt; see Potassium Nitrate 13 0 45 Flowering.
  • Balanced NPK 19-19-19: 19% N + 19% P2O5 + 19% K2O; the all-purpose vegetative-stage fertigation grade.
  • Mono-potassium phosphate (0-52-34, MKP): 52% P2O5 + 34% K2O; the flowering and fruit-set boost grade.
  • Calcium nitrate (15.5-0-0-19Ca): 15.5% nitrate-N + 19% Ca; the Ca-N source in fertigation.
  • Urea phosphate (17-44-0), mono-ammonium phosphate (12-61-0), sulphate of potash (0-0-50, see Sop Water Soluble Paddy) and others.

Major suppliers include IFFCO, SQM (imported), Haifa, Coromandel, Yara and GSFC.

Mode of action

WSFs dissolve completely in irrigation water and deliver nutrients directly to the active root zone. Compared with broadcast granular fertiliser, fertigation typically achieves nutrient-use efficiency of 70-90% (vs 30-50% for broadcast), by avoiding leaching, volatilisation and fixation losses and by matching the timing of supply to crop demand.

Target use and dose

  • Drip fertigation: typical dose of 1.5-2.5 g per litre of irrigation water depending on crop and stage.
  • Foliar spray: 5-15 g per litre for soluble flowering-stage salts (potassium nitrate at 10-15 g/L on mango is a representative use).
  • Stage-matched programmes: 19-19-19 in the vegetative phase, 0-52-34 at flowering, 13-0-45 during fruit fill, with calcium nitrate and magnesium sulphate as separate (incompatible) tank salts.

A critical compatibility rule: calcium-containing salts must not be combined in concentrate with sulphate or phosphate-containing salts, since they precipitate as calcium sulphate or calcium phosphate.

Safety and regulatory status

All listed grades are FCO-notified water-soluble fertilisers. Storage requires dry, cool conditions to prevent caking. Like all nitrate salts, products with nitrate-N must be kept away from strong reducing agents.

See also: Potassium Nitrate 13 0 45 Flowering, Sop Water Soluble Paddy, Gromor Fitsol Fertigation, Calcium Magnesium Foliar, Multi Nutrient Fertilizer Blends.

References

  1. Potassium Nitrate Water-Soluble. Indian Farmers Fertiliser Cooperative.
  2. Fertigation Nutrient Management. TNAU Agritech Portal.