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Silicon Fertilizers and Spreaders

Silicon is a beneficial element (rather than an essential nutrient in the conventional sense) for grasses including rice, sugarcane and maize. Plants in these families accumulate silicon as phytoliths in cell walls, which strengthens stems, improves lodging resistance and confers tolerance to drought, sucking pests, blast and heavy-metal stress. Silicon spreaders (organosilicone surfactants) are a separate category, tank-mixed to improve spray coverage.

Composition

The Indian market for silicon fertilisers includes several formulations:

  • Calcium silicate (CaSiO3): granular slow-release silicon plus calcium, used as a basal in rice and sugarcane.
  • Potassium silicate (K2SiO3): water-soluble, used in fertigation and foliar applications.
  • Orthosilicic acid stabilised liquids: high-mobility soluble silicon used at low foliar rates.
  • Diatomaceous earth and silicate slags: lower-grade soil sources.

Organosilicone spreaders are a chemically distinct category of surfactants used to break leaf-surface water tension; they are not nutritional fertilisers despite the shared "silicon" descriptor.

Mode of action

Silicon is taken up as monosilicic acid (Si(OH)4), translocated through the xylem, and deposited as amorphous silica beneath the cuticle and in cell walls. The silica deposits stiffen leaf and stem tissues, improve light interception by keeping leaves erect, and form a mechanical barrier against fungal penetration and insect feeding. Independent field research reports approximately 45 kg per hectare of applied silicon improving stem strength, lodging resistance, photosynthesis and tolerance to drought, pests and heavy metals in rice.

Target use and dose

  • Rice and sugarcane: 45 kg Si per hectare as a basal calcium silicate or silicate slag application, or as a maintenance foliar with stabilised soluble silicon.
  • Foliar: 1-2 ml/L of stabilised orthosilicic acid at vegetative and pre-heading stages.
  • Spreaders (organosilicone): 0.5-1 ml/L tank-mixed with foliar sprays to improve coverage on waxy leaves.

Safety and regulatory status

Silicon-bearing fertilisers are notified under the FCO beneficial-element schedule; organosilicone spreaders are sold as adjuvants. Non-toxic at field rates.

See also: Paddy First Dose Fertilizer, Paddy Tillering Top Dressing, Calcium Magnesium Foliar, Multi Nutrient Fertilizer Blends, Sulphur Fertilizer.

References

  1. Silicon Nutrition Improves Lodging Resistance of Rice. Plants (MDPI).
  2. Silicon-Calcium Fertilizer Rice Yield. Nature Scientific Reports.