Silicon and potassium silicate
Not an essential nutrient for most plants, but one of the better-evidenced stress and defence amendments in agriculture.
What is silicon and potassium silicate?
Silicon is the second most abundant element in the earth's crust but is available to plants only as soluble silicic acid. Potassium silicate is the usual soluble source in crop inputs, supplying both silicon and potassium in a strongly alkaline solution — a formulation constraint worth knowing, since it limits what silicate can be tank-mixed with.
Silicon is classified as essential for very few plant species, but as beneficial for many. Accumulation varies enormously: rice, sugarcane and cereals accumulate a great deal, while most dicots accumulate little.
How does silicon and potassium silicate work?
Two mechanisms, both well supported. Physically, silicon is deposited as amorphous silica in cell walls and beneath the cuticle, stiffening tissue. That improves resistance to lodging, reduces penetration by fungal hyphae and piercing insect mouthparts, and reduces water loss.
Biochemically, silicon primes defence responses: silicon-treated plants respond faster and more strongly to pathogen attack, with increased phenolic and phytoalexin production. This appears to be a genuine priming effect rather than a consequence of the physical barrier.
Silicon also alleviates several abiotic stresses — salinity, drought, and metal toxicity — partly by reducing uptake or by sequestration.
What does silicon and potassium silicate not do?
It is not a fertiliser in the growth-promoting sense and will not increase yield in unstressed, disease-free conditions. It does not cure established disease; the benefit is preventive priming and structural. Uptake requires soluble silicic acid, so the source and its solubility matter more than total silicon content. And in low-accumulating dicot crops the benefits are smaller and less consistent than in grasses.
Formulation and handling note
Potassium silicate solutions are strongly alkaline, typically pH 11 or above. They are incompatible with acidic products and with many calcium and magnesium sources, which precipitate. Tank-mix order and jar testing matter here more than for most inputs, and this is a common source of field failures and blocked nozzles.
Where does silicon and potassium silicate appear in the range?
Armour Boost (soluble silica and potassium silicate, K 6% and Si 15%, positioned for cell-wall rigidity, frost and insect resistance and lodging prevention) and Rigid Boost (silicon with potassium, phosphorus, nitrogen and calcium chloride). Note the data issue flagged elsewhere: Rigid Boost's active row omits calcium although the guaranteed analysis lists Ca 2%, and its positioning is inconsistent between the heading and the body copy.