Summary
Loading biochar with beneficial microorganisms could help crops grow better while also benefiting the environment.
Interest in using biochar as an agricultural amendment is growing due to its potential to increase soil carbon, improve soil fertility, and boost crop yields. Making biochar from waste materials also helps reduce greenhouse gas emissions from decomposing organic matter and supports a circular economy by turning waste into a useful product.
Forest biochar is made from leftover forest materials such as branches, wood shavings, and sawdust. These materials are heated without oxygen – a process called pyrolysis – producing a stable, carbon-rich material with many tiny pores.
In its raw form, biochar does not contain living organisms. New research is exploring ways to “load” biochar with beneficial microorganisms. The porous structure of biochar provides protected microhabitats where these microorganisms can live and survive longer, even under stressful environmental conditions, allowing them to support plant growth more effectively.
Bacteria from the genus Bacillus are commonly used in agriculture and make good candidates for biochar loading. Some species help plants access nutrients more easily, while others strengthen plant defenses against stresses such as disease and drought.
As part of Organic Science Cluster 4, researchers at Université Laval are testing forest biochar loaded with Bacillus and Priestia species in commercial greenhouse trials. Early results suggest that biochar treatments may indeed improve crop productivity. Further analyses are underway to measure greenhouse gas emissions, microbial activity, nutrient availability, and crop quality.
Future studies will examine whether forest biochar can improve the availability of nutrients from organic fertilizers and whether it is a cost-effective option for organic greenhouse production.
Interested in learning more? Read the full article below.
Organic-Greenhouse Forest Biochar: Effects of Microorganism-Loaded Biochar on Crop Performance and Sustainability
Olivier Dumont St-Louis, master’s student in agronomy1; Annie Bégard, Ph.D., Research Professional1; Thi Thuy An Nguyen, Ph.D., Research Professional1; Jacynthe Dessureault-Rompré, Ph.D., Professor1; Martine Dorais, Ph.D., Professor1.
1Université Laval
There is growing interest in the use of biochar as an agricultural amendment due to its potential to reduce greenhouse gas (GHG) emissions, improve soil fertility, decrease nutrient losses through leaching, increase crop productivity, and contribute to the circular economy (Marin et al., 2025; Schmidt et al., 2021). Forest biochar transforms otherwise undervalued residues into a stable soil amendment, reducing the amount of waste sent to unprofitable channels or incineration. By capturing and storing carbon sustainably, it contributes to the decarbonization of forest value chains and can generate, depending on the context, income via carbon credits or organic amendment markets (Marin et al., 2025). Local biochar production creates jobs and stabilizes outlets for sawmills and processing plants, transforming chips and residues into higher value-added raw materials. Integrated into circular economy logic, biochar is part of an approach aimed at improving soil fertility, reducing certain chemical inputs and prolonging the value of Canada’s forest resources (Schmidt et al., 2021).
Biochar is a carbonaceous material derived from the pyrolysis of plant or residual biomass and characterized by a porous structure, a generally high specific surface area, and the presence of surface functional groups that may interact with nutrients and microorganisms (e.g., carboxyl, hydroxyl, carbonyl groups) (Marin et al. 2025; Piscitelli et al., 2015). Forest biochar is produced from forest residues (i.e., branches, shavings, sawdust). Forest biochar has a large internal surface area that is conducive to the establishment of microbial communities (Piscitelli et al., 2015). Due to its high chemical stability, it does not decompose quickly, making it a component of soil or sustainable growing media. These physicochemical properties give it an increased capacity to hold water and nutrients, which can reduce leaching losses (Dorais et al., 2017; Messiga et al., 2020; Schmidt et al., 2021). By adsorbing certain nutrients and modulating their mobility, biochar can influence nutrient availability by making them available to beneficial plants and microorganisms in a controlled manner (Hale, 2014; Piscitelli et al., 2015; Lévesque et al.2020a).
What is “loaded” biochar?
In its raw state, biochar is biologically inactive when it is initially incorporated into soil or a growing medium. This is why “loading” (enriching) it, in particular through preinoculation with beneficial microorganisms, is a strategy that is increasingly being studied in agricultural production (Ajeng et al., 2023; Schommer et al., 2023). This approach aims to transform biochar into a real biological support capable of hosting, protecting and disseminating microorganisms favourable to soil activity (Nakahara et al., 2025; Schommer et al., 2023). These microorganisms contribute in particular to optimizing the mineralization of organic amendments, the main source of nitrogen for organic crops, to improving phosphorus solubilization and to stimulating plant growth and resilience to biotic and abiotic stresses (Dorais et al., 2017; Messiga et al., 2020; Sun et al., 2025).
However, biochar loading is not limited to microbial inoculation. Effective loading also requires contact with a nutrient source to saturate its adsorption sites primarily with NH₄⁺, Ca2+, Mg2+, K+ (Marin et al. 2025; Piscitelli et al., 2015). This source can be minerals for conventional crops or organic (compost, compost tea, liquid or solid organic fertilizers) for organic crops. In the absence of nutrient input, microbial inoculation is mainly biological colonization and biochar may adsorb nutrients from the substrate, to the detriment of plants and microorganisms.
Inoculation Methods
Physical adsorption is the most commonly reported method, characterized by a mixture of bacterial cultures with biochar (Ajeng et al., 2023; Nakahara et al., 2025). This approach relies on the porous structure of biochar to provide shelter for bacteria and uses physical forces to attach microorganisms to the surface of biochar. Another approach is based on the bio-encapsulation of microorganisms on the surface of biochar (Schommer et al., 2023). This strategy involves the initial adhesion of bacterial cells to the porous surfaces of the biochar, followed by the development of a biofilm to ensure their attachment and protection (Ajeng et al., 2023; Schommer et al., 2023). This phenomenon was demonstrated by scanning electron microscopy, revealing the presence of biofilms on the internal surfaces of the biochar. Finally, chemical coating methods can be used to trap microorganisms in sodium alginate beads, coexisting with biochar, allowing for their protection, gradual release, and easier transport (Lu et al., 2021; Schommer et al., 2023).
The porous structure of biochar provides stable microhabitats that protect these microorganisms from environmental stresses such as desiccation, UV radiation, or microbial predation (Nakahara et al., 2025; Schommer et al., 2023). This protection promotes the long-term survival of microorganisms, which may increase their agronomic efficiency compared to microbial application alone (Nakahara et al. 2025). In the presence of organic fertilizers, they can accelerate the transformation of organic matter into nutrients that can be assimilated by plants (Dorais et al., 2017; Messiga et al., 2020).
Bacillus enrichment
Among the beneficial microorganisms used, Bacillus species are of particular interest because they produce resistant spores and have many PGPR (Plant Growth-Promoting Rhizobacteria) properties (Hale, 2014; Hashem et al., 2019; Vlajkov et al., 2023). True microbial allies, bacteria of the genus Bacillus are widely used in agriculture for their beneficial effects. Some species promote the decomposition of organic matter by accelerating the mineralization of nitrogen contained in organic fertilizers (Dorais et al., 2017; Messiga et al., 2020). By producing enzymes and metabolites, they make nutrients more available to plants (Hashem et al., 2019). Several species of Bacillus, such as B. megaterium or B. subtilis, are capable of solubilizing phosphorus, mobilizing potassium, and producing enzymes involved in nutrient mineralization (Hashem et al., 2019; Jia et al., 2022; Joly et al., 2021). Bacillus can produce phytohormones (auxins, cytokinins, gibberellins) as well as siderophores that facilitate iron absorption (Hashem et al., 2019). Some species are also known to induce a state of “pre-conditioning” of plant defense responses (induced systemic resistance), allowing for faster and more efficient activation of defense mechanisms during exposure to biotic or abiotic stresses (diseases, drought, salinity) (Hashem et al., 2019; Sun et al., 2025). The combination of biochar and Bacillus can thus contribute to improving the mineral nutrition of crops and their resilience to stress (Ajeng et al., 2023; Vlajkov et al., 2023). This synergy is likely to increase the efficiency of fertilizer use, while limiting losses to the environment (Lévesque et al., 2020a; Messiga et al., 2020). Biochar inoculated with Bacillus is found in reducing the incidence of diseases of land-borne origin (Gravel et al., 2013; Jia et al., 2022; Joly et al., 2021). Some species produce naturally occurring antimicrobial compounds, such as lipopeptides (iturine, surfactin), and can induce systemic resistance mechanisms in plants (Hashem et al., 2019; Joly et al., 2021). At the same time, biochar is thought to promote the establishment of beneficial microbial communities and may alter soil physicochemical conditions in a manner that is detrimental to pathogens, thereby helping to reduce pressure from organisms such as Fusarium, Rhizoctonia or Pythium (Gravel et al., 2013; Jia et al., 2022; Lévesque et al., 2020a). In combination with the improved soil structure, water retention and root aeration provided by biochar, these mechanisms can result in increased root development and improved overall crop vigour (Messiga et al., 2020). From an environmental point of view, the use of biochar inoculated with Bacillus is part of a more sustainable agricultural production approach. This combination can influence the efficiency of the nitrogen cycle in soil or growing media and thus affect emissions of nitrous oxide (N₂O), an important greenhouse gas (Lévesque et al., 2020b; Lévesque et al., 2018). By modulating microbial processes and nitrogen biogeochemical cycles, loaded biochar could contribute, under certain conditions, to a reduction in the environmental footprint of agricultural systems (Lévesque et al., 2020a, 2020b; Marin et al. 2025).
Finally, the pre-inoculation of biochar accelerates the appearance of the agronomic benefits associated with its use. While the effects of biochar applied alone may require several years to fully manifest, the targeted addition of microorganisms such as Bacillus could act as a “biological starter”, facilitating faster integration of biochar into the soil food web or growing media (Dorais et al., 2017; Vlajkov et al., 2023).
Ongoing Organic Science Cluster 4 Trials
An experiment led by Olivier Dumont St-Louis, a master’s student in the Dorais and Dessureault-Rompré teams at Université Laval, aims to evaluate the combined effects of biochar and a consortium of microorganisms on various agronomic and environmental indicators in a commercial environment (Gen V crops). In addition, two other trials aim to evaluate the effects of different doses of biochar and the impact of enriched biochar on the in vitro mineralization of organic fertilizers, however these aspects are not addressed in this article. The biochar used comes from the company Airex Énergie and is produced from fir and spruce bark residues pyrolyzed at temperatures between 450 and 600 °C, while the biostimulant used is the product Éra Boost Pro, a consortium of Bacillus licheniformis, Priestia megaterium [formerly Bacillus megaterium], Bacillus velezensis and Bacillus subtilis of the company Ulysse Biotech.
Thus, an experiment was set up at the Gen V greenhouse complex to evaluate the impact of biochar enrichment with Era Boost Pro on greenhouse gas (GHG) emissions, microbial communities, nutrient dynamics (availability and uptake by the plant), crop productivity, fruit quality and economic profitability in the context of the production of cucumbers fertilized with organic fertilizers. The combined effects of biochar (0 and 10% v/v) and biostimulant (absence or presence of Era Boost Pro) on different agronomic and environmental indicators were evaluated under two fertilization regimes (100% animal or mixed, 50% animal – 50% plant), thus making it possible to compare eight treatments according to a factorial design in random complete blocks repeated three times. Biochar was inoculated directly into the substrate at planting by the application of Boost Pro Era, and subsequent applications are made every three weeks throughout the crop cycles. Each replicate includes four tanks as subunits, for a total of 96 experimental 75 L tanks. The substrate used is a mixture of 75% organic peat and 25% wood fibre (Berger).
Preliminary results indicate that no significant difference in yield was observed during the first crop cycle. In contrast, in the second crop cycle, for mixed fertilization, forest biochar treatment was associated with a significant increase in yields, with an increase from 64 to 69 fruits per m2 (P=0.017). The trial is underway for a third crop cycle. Data analyses of GHG emissions, microbial activity of growing media and their microbial communities, nutrient content, as well as mineral analyses of plants and fruit quality are ongoing.
Outlook
More broadly, other trials conducted by the Dorais and Dessureault-Rompré teams (e.g., different doses, cultures and microorganisms), in addition to the one presented here, will determine whether forest biochar can improve the mineralization of organic fertilizers, as well as the productivity and quality of organic crops in greenhouses. It will also be evaluated whether a PGPR-enriched forest biochar is able to modify bacterial communities in such a way as to accelerate the mineralization of organic fertilizers. For organic growing media receiving various fertilizer sources, the ability of forest biochar to reduce greenhouse gas emissions, limit nutrient leaching and increase carbon sequestration will be evaluated. Finally, it will be examined whether the use of forest biochar, enriched or not with beneficial microorganisms, represents an economically viable option for cucumber growers in organic greenhouses.
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Published February 19, 2026
Organic Science Cluster 4 is an industry-led research and development endeavour co-managed by the Organic Federation of Canada and the Organic Agriculture Centre of Canada at Dalhousie University and supported by the AgriScience Program under Agriculture and Agri-Food Canada’s Sustainable Canadian Agricultural Partnership together with over 80 funding partners.
