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Single Super Phosphate (SSP)

Single Super Phosphate (SSP) is the oldest commercial phosphatic fertiliser, manufactured by acidulating rock phosphate with sulphuric acid. The reaction yields a granular product carrying water-soluble phosphate, calcium and sulphate-sulphur, making SSP unique among Indian phosphatic fertilisers in supplying both secondary and primary nutrients in a single low-cost product.

Composition

  • Phosphate: 16% water-soluble P2O5
  • Sulphur: 11-12% S (as sulphate)
  • Calcium: 19-21% Ca
  • Magnesium: trace
  • Boronated SSP: additionally carries 0.15-0.20% B
  • Form: dark-grey granular or powder, FCO-notified

Major Indian suppliers include Coromandel (Gromor SSP), GSFC, Indian Phosphate Limited (Ankur), Mahadhan and Rama Phosphates.

Mode of action

SSP dissolves slowly in soil moisture and releases water-soluble monocalcium phosphate near the granule. The slightly acidic reaction zone keeps phosphate plant-available in alkaline soils, where Dap is less effective. The simultaneous release of calcium and sulphate makes SSP a preferred basal P source for sulphur-loving and calcium-loving crops including oilseeds, pulses, alliums, brassicas and sugarcane. The lower P density compared with DAP (16% vs 46%) means SSP needs about three times the physical quantity for the same P dose, increasing transport and application labour.

Target use and dose

Applied as a basal P source at sowing or land preparation, with the dose set to meet seasonal P2O5 demand at the product's 16% P concentration. SSP is the standard basal P source in rainfed oilseeds and pulses on sulphur-deficient soils, where the combined P and S supply addresses two deficiencies in one application. It is also preferred over DAP in alkaline calcareous soils. For groundnut, SSP at sowing is complemented by gypsum at pegging (see Gypsum In Groundnut).

Subsidy and regulation

Notified under the FCO phosphatic-fertiliser schedule. Subsidy is paid under the Nutrient-Based Subsidy regime, with per-tonne nutrient subsidy notified twice a year.

See also: Dap, Gypsum In Groundnut, Sulphur Fertilizer, Boron Fertilizer, Complex 20 20 0 13.

References

  1. Bharat SSP Product Page. Suvarna Bhoomi.
  2. Ramban SSP Product Page. JACPL.