Biostimulants are a relatively new category of plant products that has been developing rapidly over the past ten years, helping improve plant nutrition and increase tolerance to various stresses.
Long regarded as little more than “snake oil”, they are now widely adopted by many farmers who see them as a genuine and natural alternative to chemical inputs.
However, these products are still poorly understood, and it is necessary to provide some definitions and clarifications in order to make them easier to understand and use.
- What is a biostimulant, in the scientific and practical sense of the term?
- How can biostimulants be distinguished from other products such as fertilisers or biocontrol products, with which they are often confused?
- In which situations should a biostimulant be used, and for what types of issues?
What is a biostimulant?
In the past, the term biostimulant was vague and covered a wide range of products, without clearly defining what it referred to. Clarifying this definition therefore became essential, so that distributors and users could better understand these products and their potential benefits.
Definition of biostimulants
The definition of biostimulants was established by the European Commission and published in the Official Journal of the European Union in June 2019.
“A plant biostimulant is a product that stimulates plant nutrition processes independently of the product’s nutrient content, with the sole aim of improving one or more of the following characteristics of the plant or the plant rhizosphere:
a) nutrient use efficiency;
b) tolerance to abiotic stress;
c) quality traits;
d) availability of nutrients confined in the soil or the rhizosphere.”
What are the different types of biostimulants?
This definition nevertheless remains broad and covers a wide range of products with very different formulations and modes of action.
First, it is useful to distinguish two main types of products:
- Soil activators, whose objective is to improve soil structure and fertility, independently of any input of amendments or mineral elements. Through their interactions with the soil via roots and the rhizosphere, plants directly benefit from these improvements in soil quality, particularly in terms of water and nutrient uptake.
- Foliar biostimulants, used to stimulate plant nutrition, photosynthetic activity and plant immunity against the various stresses they may encounter.
These products are therefore composed of a wide range of ingredients of natural origin: plant-based (such as plant extracts or essential oils), mineral (for example humic substances), microbial (mineralising bacteria, mycorrhizae, etc.) or even animal-derived.
A growing and increasingly structured market
As shown above, the number of products falling under the definition of biostimulants is broad, and many suppliers have taken an interest in their development in recent years, particularly within the context of the agroecological transition. The number of public and private research projects dedicated to biostimulants has increased sharply, with the aim of better understanding their modes of action and providing greater reassurance to users regarding their effectiveness.
This growing recognition has been accompanied by a significant increase in biostimulant sales over recent years. The :contentReference[oaicite:0]{index=0} (European Biostimulants Industry Council) estimated that the European biostimulant market represented €578 million in revenue in 2015, with projected annual growth of around 10% in France and across Europe.
Regulations governing the marketing of biostimulants are also becoming more stringent, both at European and French levels, in line with this clearer definition of their function. Biostimulants are now classified as Fertilising Products and Growing Media and approved as such. This regulatory framework makes it possible to clearly distinguish them from biocontrol products, with which they were often previously confused.
Biostimulants: not to be confused with other types of products!
Biostimulants and biocontrol products are two categories of products derived from natural constituents and designed to mimic natural processes in order to address agricultural challenges. However, the fundamental difference between a biostimulant and a biocontrol product lies in the distinct responses they provide, as they operate through different modes of action.
Biostimulant or biocontrol?
A biocontrol product is regulatorily classified as a crop protection product, with a direct action on phytosanitary issues (disease outbreaks, pests, weed control, etc.).
Biostimulant products, on the other hand, act by stimulating plant immunity, notably through optimised nutrition and photosynthetic activity. They therefore act on abiotic stresses (drought, climatic conditions, frost, etc.) and have an indirect effect on biotic stresses, as healthier plants are better able to withstand pests and diseases.
Biostimulants and fertilisers
It is also common to confuse biostimulants and fertilisers, which is understandable, as both aim to improve plant nutrition.
However, a fertiliser is designed to supply mineral nutrients to the soil or directly to the plant, providing the nutrients required for proper plant growth and functioning.
Biostimulants, on the other hand, act on the plant’s ability to assimilate these nutrients, either at soil level, by making mineral elements more available to roots, or at foliar level, by strengthening plant metabolic processes.
Biostimulants should also not be confused with soil amendments, as amendments supply mineral elements to adjust soil pH.
A biostimulant may, however, be formulated with one or more mineral elements, whether naturally present or added, in order to enhance its benefits for the plant.
How should a biostimulant be used?
Now that the term biostimulant has been clearly defined, it is important, in order to better understand these products, to review their potential uses, which are numerous and varied but all share a common objective: to provide farmers with solutions to address new challenges, particularly regulatory and environmental ones.
A wide range of modes of action depending on the products used
The range of modes of action of biostimulants is as broad as the number of products available on the market, with many agronomic claims, which can lead to confusion for users. As mentioned earlier, it is therefore essential to distinguish between soil-activating products and foliar products.
In the case of soil-activating products, these include products that enhance soil biological activity, either by directly supplying microorganisms to the soil or by providing them with the nutrients they need to develop. These microorganisms can then act on the amount of humified organic matter, the mineralisation of essential nutrients for plants such as nitrogen or phosphorus, as well as on the physico-chemical characteristics of the soil (notably pH–Eh, porosity and compaction potential).
Foliar products, on the other hand, can act by intervening in plant biochemical reactions, thereby promoting plant metabolism. The complexity of the mechanisms involved is such that it is not possible to detail all potential modes of action here. As an example, a photosynthesis-activating product can lead to increased sugar production within the plant—sugars that form the basis of vegetative growth, flower and fruit formation, as well as plant immunity.
Clear benefits for plant nutrition and health
The final benefits of using biostimulants are therefore clear for farmers. Overall, plant water and nutrient uptake and metabolic activity, as outlined above, are optimised. With an internal “factory” operating at full capacity, plants are better able to defend themselves against a wide range of stresses, both biotic and abiotic. Overall plant health is improved.
What does this mean in practical terms for farmers?
Crops will develop more rapidly and will be less susceptible to climatic hazards and diseases. Nutrient deficiencies and water stress will be reduced thanks to an efficient root system and good soil quality. Flowering and the formation of seeds or fruits will also be secured.
Ultimately, farmers can benefit from yield increases and improved crop quality. They therefore have every interest in using these types of products, which are generally applied using fertiliser spreaders for solid forms or sprayers for liquid forms, in the same way as the chemical or biological inputs they already use.
A new tool to address emerging agricultural challenges
In conclusion, it is important to understand that biostimulants are not a miracle solution to emerging agricultural challenges, such as protection against pests and diseases or climate change.
A biostimulant cannot protect a crop in the same way as a conventional crop protection product, nor can it prevent yield losses in the event of drought.
However, they represent an additional tool which, alongside other levers such as varietal selection, technological innovation, etc., can provide farmers with solutions to address these challenges.
This is all the more relevant in a context where chemical inputs, such as fertilisers or plant protection products, are increasingly questioned and their use increasingly restricted due to environmental and societal pressures.
Biostimulants are a relatively new category of plant products that has been developing rapidly over the past ten years, helping improve plant nutrition and increase tolerance to various stresses. Long regarded as little more than “snake oil”, they are now widely adopted by many farmers who see them as a genuine and natural alternative to […]
...Biostimulants are a relatively new category of plant products that has been developing rapidly over the past ten years, helping improve plant nutrition and increase tolerance to various stresses. Long regarded as little more than “snake oil”, they are now widely adopted by many farmers who see them as a genuine and natural alternative to […]
...Biostimulants are a relatively new category of plant products that has been developing rapidly over the past ten years, helping improve plant nutrition and increase tolerance to various stresses. Long regarded as little more than “snake oil”, they are now widely adopted by many farmers who see them as a genuine and natural alternative to […]
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