Low-tech biostimulants

Low-tech biostimulants: the laboratory of agroecological biodistricts?

In an agroecological Biodistrict, the recovery of territorial self-sufficiency must be achieved through circularity. This statement is not and should not be considered unrealistic: it must be transformed into a technical, organizational, and economic choice.
In the agricultural sector, all this entails the need to view spontaneous biodiversity, prunings, green residues, by-products, and waste from agricultural and livestock farms not as “waste material,” but as a functional raw material.

There’s a simple way to say it: in the Biodistrict, residue is not a residue, it’s a resource. It’s a source of carbon, microbes, molecules, and signals: biological information that the land continually produces.

If we want to truly sustainably manage agricultural systems as large as those of a Biodistrict, the point is not to purchase “alternative or natural fertilizers or biostimulants.”
The key, if anything, is to produce soil improvers and biostimulants within the district: tools that, on the one hand, accumulate organic matter and improve the soil, and, on the other, affect plant physiology by improving nutrient use efficiency, tolerance to abiotic stress, and the quality and availability of macro- and micronutrients (du Jardin, 2015; Yakhin et al., 2017).

Today I want to focus on the on-farm production of low-tech biostimulants; functional substances and matrices that, at very low concentrations, concretely help agricultural systems function better when under stress (Van Oosten et al., 2017; Di Sario et al., 2025).

The most interesting aspect, for a Biodistrict, is that on-farm production of biostimulants can become the driving force for a truly circular economy.
A Biodistrict is not measured solely by its surface area or specifications: it is measured by its ability to organize processes.
The biomass remains local and is transformed using low-tech techniques: difficult to standardize in the “industrial” sense of the term, but capable of expressing a physiological variability that is distinctive and representative of the local area itself. Such an approach can build skills and offer sustainable products and services to the entire district: consortium workshops, shared processes and practices, micro-supply chains.
And this, ultimately, is a paradigm shift: from dependence on external inputs to local production and resilience (Xu & Geelen, 2018).

For this production process to truly materialize, however, a shift in perspective is needed: to stop chasing “protocols” as if they were universal recipes and instead think in terms of local variability and functional modules.
Ultimately, all biostimulants seek to activate metabolic switches in crops: a kind of biochemical “switch” that helps the plant manage the redox system (ROS/antioxidants), osmoregulation, hormone production, VOCs (Volatile Organic Compounds), root architecture, and the microbiome. When you choose the right matrix, the specific functional module, and the appropriate transformation process, even a simple and inexpensive technology can become powerful (Van Oosten et al., 2017; Di Sario et al., 2025).

And this is where the low-tech approach comes in. The goal is not to “produce industrial chemistry,” but to obtain soluble fractions and produce natural products with repeatable functions. The methods most consistent with an artisanal, territorial approach are often enzymatic hydrolysis and controlled fermentation processes. The low-tech path a Biodistrict can take should therefore not lead to the pursuit of pure molecule production, but rather the artisanal (on-farm) transformation of the matrices present in the area, obtaining a mix of substances capable of positively influencing the ecology of the entire district.

These matrices carry packages of cofactors and biochemical signals that can only be standardized by class or indicator, and for this very reason, they make sense, especially within a district-based approach.
In a Biodistrict, this production method can become an economically structuring ecological service: a consortium micro-hub capable of producing substances that are not always identical, but traceable and safe; a hub of ecological, impact-neutral technology that engages and trains operators from local communities.

If we learn to transform methodically, without pursuing industrial purity, the district’s resources, currently considered waste, can be returned to crops in the form of biostimulants. Thus, agroecology also becomes technology: simple, replicable, and above all non-exportable, because it lives within the specificity of the territory.

Within this framework, a Biodistrict can work with a variety of biostimulants and functional matrices.
Among the most interesting are the plant growth regulators and bioactive compounds present in plant matrices: abscisic acid, jasmonic acid, melatonin, polyphenols, alginates, enzymes, and many other substances central to plant stress responses. Recent literature highlights the enormous variety of mechanisms these substances can activate, from modulation of the redox system to transcriptional and metabolic changes (Di Sario et al., 2025).

Another solid pillar in the literature is protein hydrolysates. These are mixtures of amino acids and peptides that can improve growth, nutritional efficiency, and stress tolerance, even indirectly, through interactions with the microbiota (Colla et al., 2015; Colla et al., 2017). In a Biodistrict, many supply chain byproducts considered waste biomass can be transformed into generators of high-value inputs: here, the concept of a circular economy is extremely concrete.

Furthermore, plant extracts represent perhaps the most natural form of circularity. Prunings, leaves, and processing waste can be reconverted into extracts capable of acting as biochemical signals and supporting the physiological and functional structure of the agricultural system.
And it’s not just theory: there are case studies demonstrating the use of plants and plant extracts capable of supporting physiological performance in conditions of water deficit (Abd El-Mageed et al., 2017).

Among the most studied biostimulants are macroalgae: they often contain polysaccharides and bioactive components that act as elicitors, capable of activating defense responses and improving performance even under stress (Craigie, 2011; Deolu-Ajayi et al., 2022). From a local perspective, the issue is not just “finding the algae,” but ensuring quality and traceability, because the variability of the raw material is real and can also be linked to the district (Deolu-Ajayi et al., 2022).
If the Biodistrict is coastal, local supply chains based on simple transformations (aqueous and alcoholic extractions, lactic fermentation, decoction, followed by filtration and micro-dose applications) can be considered.
If the Biodistrict is internal, a consortium supply chain with collective purchase of biomass from neighboring districts and local processing in small batches using simple, common, and traceable procedures may make more sense.

Microalgae, on the other hand, are particularly interesting because they are naturally present in company ponds and can perform multiple functions simultaneously: they contain protein and amino acid fractions, pigments, osmoprotectants, and components capable of supporting oxidative balance. The literature contains clear examples of microalgae used as biofertilizers/biostimulants (García-González & Sommerfeld, 2016) and reviews discussing their potential in sustainable agriculture (Deolu-Ajayi et al., 2022).
For many biodistricts, the most pragmatic approach is to use microalgal biomass as a raw material and work on simple extraction and application models.

Finally, if there is one biostimulant perfectly consistent with agroecology, it is the microbial one. Bacteria can improve root architecture, make nutrients available, and aid stress management (Backer et al., 2018; Orozco-Mosqueda et al., 2020; Vurukonda et al., 2016).
In a biodistrict, a poor shortcut is to purchase bacteria and fungi selected from ecological environments distant in distance and characteristics; The right path is to build simple yet codified low-tech processes, starting with mature compost and healthy soils present in the area.
Compost tea, for example, can be an interesting vehicle: the literature reports benefits in various crops regarding growth, yield, and quality, but also emphasizes the variability and importance of production procedures (Pane et al., 2016; Naidu et al., 2013).

Furthermore, an important rule that ensures results is the use of micro-doses in the field and their regular repetition, especially in the case of protein hydrolysates (Colla et al., 2015; Colla et al., 2017).
This is a way of thinking consistent with biostimulation: we work through signals and “adjustments,” rather than excesses.

When all these functional matrices are combined with low-tech extraction procedures, along with training and the participation of local communities, the system’s potential immediately emerges: the Biodistrict can build a biostimulant supply chain based on local flows of local materials and simple, traceable methods that are safe for both humans and the environment.
There’s no need to industrialize; what’s needed is a district laboratory with a few essential but well-executed elements: minimal procedures (extraction, filtration, base stabilization, traceability), application models, simple and shared measurements (field tests and indicators, etc.).

A low-tech structure is not an improvised laboratory, but a governance choice: networking resources, minimal procedures, training, and field tests to transform local variability into systemic strength. When this happens, agricultural technology returns to being “local,” rooted in the matrices, biology, and skills of the community.

In this way, circularity ceases to be an inapplicable economic principle and becomes an infrastructure.
The Biodistrict retains and produces value, reduces external purchases, recreates multifunctionality, builds skills, and fosters resilience with what is already present within it. But above all, it transforms agroecological methodologies into concrete examples of territorial technology that cannot be relocated: technology rooted in the district’s resources, skills, and local biology.
This rootedness represents a real competitive advantage.

Francesco Di Lorenzo
Agronomist

Essential Bibliography
Abd El-Mageed, T. A., Semida, W. M., & Rady, M. M. (2017). Moringa leaf extract as biostimulant improves water use efficiency, physio-biochemical attributes of squash plants under deficit irrigation.
Agricultural Water Management, 193, 46–54. https://doi.org/10.1016/j.agwat.2017.08.004

Backer, R., Rokem, J. S., Ilangumaran, G., Lamont, J., Praslickova, D., Ricci, E., Subramanian, S., & Smith, D. L. (2018). Plant growth-promoting rhizobacteria: Context, mechanisms of action, and roadmap to commercialization of biostimulants for sustainable agriculture.
Frontiers in Plant Science, 9, 1473. https://doi.org/10.3389/fpls.2018.01473

Canellas, L. P., Olivares, F. L., Aguiar, N. O., Jones, D. L., Nebbioso, A., Mazzei, P., & Piccolo, A. (2015). Humic and fulvic acids as biostimulants in horticulture.
Scientia Horticulturae, 196, 15–27. https://doi.org/10.1016/j.scienta.2015.09.013

Canellas, L. P., Canellas, N. O. A., da Silva, R. M., Spaccini, R., Mota, G. P., & Olivares, F. L. (2023). Biostimulants using humic substances and plant-growth-promoting bacteria: Effects on cassava (Manihot esculentus) and okra (Abelmoschus esculentus) yield. Agronomy, 13(1), 80.
https://doi.org/10.3390/agronomy13010080

Colla, G., Nardi, S., Cardarelli, M., Ertani, A., Lucini, L., Canaguier, R., & Rouphael, Y. (2015). Protein hydrolysates as biostimulants in horticulture.
Scientia Horticulturae, 196, 28–38. https://doi.org/10.1016/j.scienta.2015.08.037

Colla, G., Hoagland, L., Ruzzi, M., Cardarelli, M., Bonini, P., Canaguier, R., & Rouphael, Y. (2017). Biostimulant action of protein hydrolysates: Unraveling their effects on plant physiology and microbiome.
Frontiers in Plant Science, 8, 2202. https://doi.org/10.3389/fpls.2017.02202

Craigie, J. S. (2011). Seaweed extract stimuli in plant science and agriculture. Journal of Applied Phycology, 23, 371–393. https://doi.org/10.1007/s10811-010-9560-4

Deolu-Ajayi, A. O., van der Meer, I. M., van der Werf, W., & Karlova, R. (2022). The power of seaweeds as plant biostimulants to boost crop production under abiotic stress.
Plant, Cell & Environment, 45(9), 2537–2553. https://doi.org/10.1111/pce.14391

Di Sario, L., Boeri, P., Matus, J. T., & Pizzio, G. A. (2025). Plant biostimulants to enhance abiotic stress resilience in crops.
International Journal of Molecular Sciences, 26(3), 1129. https://doi.org/10.3390/ijms26031129

du Jardin, P. (2015). Plant biostimulants: Definition, concept, main categories and regulation.
Scientia Horticulturae, 196, 3–14. https://doi.org/10.1016/j.scienta.2015.09.021

García-González, J., & Sommerfeld, M. (2016). Biofertilizer and biostimulant properties of the microalga Acutodesmus dimorphus.
Journal of Applied Phycology, 28(2), 1051–1061. https://doi.org/10.1007/s10811-015-0625-2

Naidu, Y., Meon, S., & Siddiqui, Y. (2013). Foliar application of microbial-enriched compost tea enhances growth, yield and quality of muskmelon (Cucumis melo L.) cultivated under fertigation system.
Scientia Horticulturae, 159, 33–40. https://doi.org/10.1016/j.scienta.2013.04.024

Orozco-Mosqueda, M. del C., Glick, B. R., & Santoyo, G. (2020). ACC deaminase in plant growth-promoting bacteria (PGPB): An efficient mechanism to counter salt stress in crops.
Microbiological Research, 235, 126439. https://doi.org/10.1016/j.micres.2020.126439

Pane, C., Palese, A. M., Spaccini, R., Piccolo, A., Celano, G., & Zaccardelli, M. (2016). Enhancing sustainability of a processing tomato cultivation system by using bioactive compost teas. Scientia Horticulturae, 202, 117–124. https://doi.org/10.1016/j.scienta.2016.02.034

Van Oosten, M. J., Pepe, O., De Pascale, S., Silletti, S., & Maggio, A. (2017). The role of biostimulants and bioeffectors as alleviators of abiotic stress in crop plants.
Chemical and Biological Technologies in Agriculture, 4, 5. https://doi.org/10.1186/s40538-017-0089-5

Vurukonda, S. S. K. P., Vardharajula, S., Shrivastava, M., & Ali, S. (2016). Enhancement of drought stress tolerance in crops by plant growth promoting rhizobacteria. Microbiological Research, 184, 13–24. https://doi.org/10.1016/j.micres.2015.12.003

Xu, L., & Geelen, D. (2018). Developing biostimulants from agro-food and industrial by-products. Frontiers in Plant Science, 9, 1567.
https://doi.org/10.3389/fpls.2018.01567

Yakhin, O. I., Lubyanov, A. A., Yakhin, I. A., & Brown, P. H. (2017). Biostimulants in plant science: A global perspective. Frontiers in Plant Science, 7, 2049. https://doi.org/10.3389/fpls.2016.02049