Silicon, the forgotten nutrient

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Silicon, the forgotten nutrient

For generations farmers and growers have simply ignored Silicon as a plant nutrient even though research has shown that it is equally important as Calcium, Phosphorous, Magnesium, Sulphur and believe it or not, Nitrogen.

As we watch the farmer lead revolution on reducing inputs of fertilisers and chemicals Silicon will once again become known as an essential nutrient because of its ability, amongst others, of strengthening plant cell walls so that they can resist pest and disease attack plus they allow the plant to grow in high salinity situations which is a world-wide issue. Pest attack is further resisted because evidence suggests that Silicon reduces the amount of soluble Nitrogen available in the sap which attracts aphids.

Although Silicon is the second most abundant element found in the soil, it is more often than not, unavailable in the plant available form (Monosilicic or orthosilicic acid). Many agronomists now see Si as part of a trio of nutrients much needed by the plant, Calcium-Silicon-Boron. Each act as a synergist to the others. The Calcium and Silicon strengthen the cell walls and the Boron allows them to work correctly. It is the Boron that allows the Silicon to form Monosilicic acid. It is this that makes a late winter application of Boron essential to trigger Calcium uptake and the conversion of Silicon.

It is important to note right from the start that Silicon is very immobile within the plant which means regular applications are needed; which also means you need a product that can be tank-mixed into the normal foliar programme. To explain this immobility, you need to understand that if Silicon as Monosilicic acid passes a cell that is low in Silicon it enters that cell and then stays there. This means that a cell available form of silicon needs to be in the Phloem as the plant grows.

Silicon benefits…

  • The increased cell strength helps increase the effects of photosynthesis therefore more sugars are produced both to improve microbe health and (as importantly) taste and shelf life of crops. Lower Nitrogen in the sap, increased Silicon and other micronutrients can vastly increase taste and shelf life.
  • Healthier biology in the soil means better uptake of nutrients and therefore even better photosynthesis.
  • Healthy cells absorb nutrients better plus the translocation system within the plant is improved.
  • Greater cell strength gives better resistance to stress (e.g. drought).
  • Greater cell strength gives better resistance to pests and diseases.
  • Once good levels of Silicon are reached, we see much less lodging in cereals.
  • Silicon helps increase Brix levels and the production of phytoalexins to help build ISR (Induced Systemic Resistance. [Rains et al 2006]).
  • Monosalicic acid increases the plants ability to absorb and translocate other minerals.
  • The target is Silicon at 100ppm plus in the leaf which can even reduce rabbit damage. Soil Silicon needs to be around 25ppm with a good rate of available Boron.
  • The strengthened cell walls can resist fungal hyphae, and where fungi do arrive Si accumulates around the wound to stop further damage.
  • Silicon bonds onto Sodium so that it is bound into the root and can’t travel up the plant.
  • Lack of Silicon can allow Manganese to become toxic.
  • In Cucurbits, Silicon drastically reduces occurrences of powdery mildews….

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