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Biostimulants are inherently multidimensional
Biostimulant are versatile: they can be classified along complementary dimensions - origin, active ingredient, mode of action, application.
But their multiplicity doesn’t stop there: a single product may combine several active ingredients with distinct and synergistic modes of action, while a single active ingredient may originate from various sources.
Consider for example, amino acids that can be extracted from animal protein hydrolysates or synthesized from plant materials; phytohormones that can be extracted from seaweed or chemically synthesized; or even humic acids that can be found in vermicompost or in the leonardite rock.
The biostimulants offer a diverse and versatile panel of solutions! Understanding these dimensions is essential for evaluating biostimulants and enabling more targeted and effective use in modern agriculture.
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Origin
Biostimulants can be divided into two main categories: microbial and non-microbial. Microbial biostimulants consist of living organisms such as beneficial bacteria or fungi. Non-microbial biostimulants include organic substances derived from plants or animals, as well as mineral compounds.
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Mode of action
Biostimulants are characterized by the physiological effects they produce. These include enhancing nutrient uptake, stimulating root or shoot development, improving tolerance to abiotic stress, or promoting soil microbial activity and structure.
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Active ingredient
Amino acids, humic and fulvic acids, polysaccharides, mycorrhizal fungi, beneficial bacteria, phytohormones… the list continues but each of these compounds has specific modes of interaction with the plant or the soil microbiome, and their classification helps guide appropriate use cases.
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Application method
Biostimulants can be applied using various methods, including foliar spraying, soil incorporation, seed treatment, fertigation systems, or even in combination with conventional fertilizers. The application affects the overall effectiveness of the active ingredients.
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For better readability, we have structured our mapping based on the two primary categories defined by EU Regulation: non-microbial biostimulants and microbial-based biostimulants.
Non-microbial biostimulants comprise naturally derived substances - primarily extracted from plants, animals, composted materials, or minerals - that stimulate key metabolic and physiological processes in plants. These substances often act by mimicking plant hormones or enhancing enzymatic pathways.
| Example of biostimulants (non exhaustive) | Main modes of action (non exhaustive) |
|---|---|
| Phytohormones (cytokinin, auxin, gibberellin, etc.), and other macro and micro nutrients (e.g., betaine, oligosaccharides, mannitol) from seaweed extracts (Ascophyllum nodosum, Laminaria, Ulva, etc.) | Stimulate root development, modulate hormonal pathways, improve tolerance to abiotic stress |
| Chitosan and chitin derivatives from crustaceans (e.g. shrimp, crab), insects or fungi (e.g. Aspergillus niger, Mucor rouxii) | Elicit plant immune responses, provide antimicrobial properties, enhances water regulation, improve micronutrient availability (chelating agent) |
| Amino acids derived from enzymatic or chemical hydrolysis of plant (e.g., soybean, corn, algae) or animal proteins | Boost enzymatic activity, allow energy savings under stress |
| Fulvic acids and humic acids from decomposed organic matter (e.g. vermicompost extracts), or more mineral-rich materials (e.g. leonardite, peat) | Improve nutrient mobility and transport across cell membranes (fulvic acids); enhance soil properties (aggregation, microbial activity, micronutrient availability) (humic acids) |
| Synthetic compounds like hormone precursors and lignosulfonates | Modulate plant hormonal pathways, improve micronutrient availability, improve tolerance to abiotic stress |
| Inorganic compound (e.g. silice) | Strengthens cell walls, induces systemic resistance |
This list is non exhaustive
The start-up ecosystem is active in this space, with a strong focus on solutions derived from seaweeds extracts and amino acids. These products are already well known in the market and easy to use, but they present a lower barrier to entry compared to microbial solutions.
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What about soil-enhancing amendments?
While soil-enhancing amendments are sometimes grouped with non-microbial biostimulants, they are more appropriately positioned within the broader framework of nature-based solutions. One of the most promising of these is enhanced rock weathering - a process that not only contributes to carbon sequestration, but also improves soil fertility by gradually releasing essential trace minerals and helping regulate soil pH. These solutions are excluded from our mapping.
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Microbial biostimulants consist of beneficial microorganisms that interact with plant roots or internal tissues to promote growth. Under the EU Fertilising Products Regulation (EU) 2019/1009, microbial biostimulants fall under Product Function Category 6(A). The regulation currently operates under a restrictive positive list of authorized microorganisms defined in Component Material Category 7: