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Silicon Liquid D15

15% liquid organic silicon


Label Silicon liquid 15D
Product form Liquid
Packaging IBC - 1000 liters
Silicon dioxide SiO2
pH 9.7 - 10.5
Specific weight 1.2
Color Transparant
Storage temperature: 5 - 35 ° C (41-95 ° F)
Shelf life: Unlimited in unopened container. After opening of IBC: 50 months

Silicon Liquid 15D is a liquid silicon product based on 15% silicon dioxide SiO2. This liquid silicon product is very well absorbed by plants.


The product is available in 1,000-litre IBCs.

What is Silicon Liquid 15D?

Silicon Liquid 15D is a liquid silicon product based on 15% hydrolysed silicic acid (silicon dioxide SiO2) which is free of particulate matter, making this liquid silicon product easy to absorb. This makes it also mixable with other liquid fertilizers. Of course, each mixture is different, so it must first be tested on a small scale.

What is the difference between silicon dioxide (SiO2) and silicic acid (Si(OH)4)?

The two hydrogen atoms make the difference between SiO2 and Si(OH)4 or silicon dioxide and silicic acid (also called orthosilicic acid). Silicon dioxide even consists of particles in colloidal form. With two H-atoms added, you have a solution. You can force this by, for example, bringing the pH-value to 14 (or reversed acid). Unfortunately, most of it becomes silicon dioxide again when you dilute it with water.


The so-called synthetic silicon dioxide products have a pH value of 14 as a result of treatment with caustic soda. At this pH value, everything dissolves, after which the product is blown through a flame with force. In this way, silicon dioxide is produced in nanoparticles, which have less trouble taking a few hydrogen atoms.


This is only possible if there is not too much other silicic acid nearby. When there are too many particles, you get regression to the original material. This is also observed in nature.

Silicon: most frequently asked question

There are silicon-containing products on the market that have been stabilised with choline and that are claimed to have a high absorbability. Is that true? Are these products actually better?


It doesn't matter whether these types of silicon products are bound to sodium or carbon or mixed with choline or caustic soda. There is no stability in water above 9 mmol/litre. In other words, as soon as you dilute it with water, most of it becomes dioxide again. The absorption of Silicon Liquid 15D is therefore just as good. Moreover, you need relatively little of it.

Silicon: what is silicon?

Silicon is the second most common element on earth after oxygen. The earth consists of approximately 28% to 40% silicon. Soil is therefore rich in silicon. Plants feed on minerals, including silicon. Cereals containing much silicon are wheat, barley, oats, potato and millet. Rice, hops (think of beer!), beetroot and red onion also contain silicon.

Silicon: what is the role of silicon in nature?

Silicon is an important mineral. Research has shown that certain crops thrive much better in silicon-rich soil than crops in a silicon-poor environment. Where a lot of silicon was absorbed by the plants, this resulted in healthier, larger and stronger crops and, consequently, in a better harvest.

Silicon: agriculture and silicon

That the mineral silicon is essential for a good harvest has been known for many years. Silicon is often used in agriculture, for example to fertilise the soil, enabling plants to absorb silicon more easily and in greater quantities.

Silicon: can plants absorb silicon products through the leaf surface?

Yes, almost exclusively through the leaf surface. Silicon in an easily absorbable form often has a direct positive effect on the resilience of plants. This is usually achieved by one or more additional leaf sprays. Rapidly absorbed silicon makes leaves and plant regain their natural resistance. After one or more leaf sprays, the silicon accumulates and is then incorporated as part of the cell walls in plants.

Silicon: what sources of silicon are there?

Silicon is also used in organic farming, usually in the form of SiO2 and Si(OH)4). Particularly in non-organic agriculture very different forms of silicon are used, e.g. calcium, sodium and potassium silicates (Na2SiO3 and K2SiO3), siliforce, slag with calcium silicate, silicates, thomas slag, stone meal, converter lime, hut lime, etc. This shows that many forms of silicon can be used as fertilizer in agriculture.


  • Silica gel can be used if it is sufficiently dissolved in water. It contains sodium and is therefore not suitable for use as foliar feed in high doses. Silicaforce is said to contain silicic acid. Moreover, some minerals have been added. This can disturb the delicate equilibrium of silicic acid Si(OH)4 in solution. It is not possible to keep more than 9 mmol/litre of silicic acid in solution; it automatically becomes SiO2 (silicon dioxide) again.
  • Calcium silicate: a natural form of calcium with silicon. It is extracted from limestone.
  • Potassium silicate is a synthetic potassium-silicon compound that can be used as a fertilizer.
  • Thomas slag meal (thomas meal, converter lime) is a phosphate fertilizer made from finely ground blast furnace slag from pig iron or phosphate-rich iron ore.
  • Stone meal, also known as hut lime or limestone – is finely ground rock that is used as a fertilizer and soil improver. For stone meal to have a proper effect on soil, the grain size must not exceed 0.100 mm. Stone grit is more coarsely ground rock and is less effective in the soil. The finer the grind, the faster the effect in the soil. Stone meal from the British coast contains more calcium (chalk cliffs) and is also called calcium silicate.
  • Diatomaceous earth (kieselgur) is a clay mineral with a high silicon dioxide content (80-90%). It can also contain some aluminium and iron. If small particles of it are sieved out, these (if properly treated) can partially dissolve and be used as foliar feed. Using silicon in any form via the soil serves no purpose at all.
  • Sodium silicate - water glass - has a very high pH value and is therefore unsuitable for agricultural applications. The high pH value is also a stumbling block for customer-friendly applications.


Stone meal is used to provide the soil with extra calcium (lime). Often stone meal types come from volcanic rock (slag from iron ore). Slag is a by-product of the iron-making process. Pure iron is extracted by adding calcium to iron ore. The residue, also called slag, consists of calcium bound to the minerals from the iron ore, such as magnesium, sodium, lime and iron, but also heavy metals. This slag often contains more than 10% silicon but also other (toxic) substances.


Little is known about the purity and fineness of this slag, but these qualities largely influence its effectivity. There are almost no quantitative data on the effects of stone meal. The availability of Si in stone meal is generally considered to be low. If a better availability of Si is to be achieved, the harvesting process must first be refined as it were. Stone meal is applied in tonnes per hectare, but there are almost no data available that show that Si in stone meal has any effect.


The particle size of a silicon product and the environment determine how much can be absorbed. The silicon in potassium silicate, calcium silicate, stone meal, hut lime, limestone, thomas slag meal/thomas meal or converter lime cannot be absorbed through the leaf surface. As there is more than enough silicon in soil, it is of little use to treat the soil with silicon as plants already extract silicon from the soil wherever they can.


So when silicon is talked about in agriculture, the crucial question is: which silicon types and which particle sizes are we talking about? There are very large differences between silicon products. Particle size determines how much can go into solution. The larger the particles, the lower the silicic acid content and, consequently, the lower the absorbability.

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Silicon SiO2 Stone meal Biostimulant Silicon dioxide Silicic acid Soil improvers Hut lime Converter lime Crops Plant stress Skal Thomas lime Calcium silicates Sodium silicates Microorganism Organic matter Potassium silicates Silica gel Siliforce
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