What is Biostimulant Testing for Registration?

Biostimulant testing for registration is the process of evaluating plant biostimulants to ensure compliance with regulatory frameworks in the European Union and United States. This involves proving efficacy in enhancing plant growth, nutrient uptake, and crop quality through field trials, laboratory testing, and regulatory assessments.

Why Biostimulant Testing is Critical for Registration

Biostimulants are regulated under the EU Fertilising Products Regulation (2019/1009) and various registration processes in the United States. To gain approval, manufacturers must demonstrate biostimulant efficacy by proving measurable benefits such as:

• Improved nutrient uptake
• Enhanced tolerance to abiotic stress
• Increased crop quality and yield
• Stimulation of natural processes in plants

The following sections outline the biostimulant testing process to support these claims and achieve regulatory compliance.

Key Steps in Biostimulant Testing for Registration

1. In-House Biostimulant Testing: From Discovery to Field Validation

Before submitting a biostimulant for regulatory approval, companies conduct extensive in-house testing to refine formulations and select the most promising products. Manufacturers start by searching for active ingredients with positive plant effects, testing them under controlled conditions before combining them into multi-component formulations. Once a product is formulated, laboratory screenings are conducted to determine its initial efficacy.

Steps in the In-House Biostimulant Testing Process:

1. Active Ingredient Research – Identifying compounds with beneficial effects on plant growth and stress tolerance.
2. Formulation Development – Combining active ingredients with excipients to create a viable product.
3. Laboratory Screening – Evaluating efficacy in controlled conditions to select top-performing formulations.
4. Greenhouse and Field Testing – Assessing product performance under diverse environmental conditions.

The most promising formulations are then tested in greenhouses then in field trials to simulate real growing conditions. Typically, trials are staged, starting in controlled environments and progressing to full-field conditions. This approach enables producers to fine-tune application methods, dosage, and formulations. Learn more on bioproduct field testing in our article: Biosolution Research To Maximize Crop Performance: An Agronomic Approach.

Greenhouse and field trials enable researchers to determine:

• Active ingredient interactions
• Optimal dose-response relationships
• Potential phytotoxicity risks

This step is particularly important for microbial plant biostimulant products, as soil health enhancement and microbial viability depend on precise application conditions.

During the final stage, field trials are conducted in a limited capacity to validate early findings under various environmental conditions, such as different soil types, climates, and stress factors. Advanced software solutions like Bloomeo Biosolutions help analyze data from these tests, enabling companies to determine precise conditions where the biostimulant is most effective. For example, software analytics might reveal that "this biostimulant enhances nutrient uptake in dry conditions with acidic soil and low salt concentration."

Only the most efficient products, that have a commercial potential, proceed to the regulatory testing are completed do companies proceed with regulatory testing to meet compliance standards.

2. Understanding Biostimulant Claims and Regulatory Requirements

Once a promising product has been identified, the next step is regulatory testing to validate at least one of the following official claims:

• Nutrient use efficiency improvement
• Tolerance to abiotic stresses (e.g., drought, salinity)
• Better determination of quality traits
• Increased availability of confined nutrients in soil or rhizosphere

Each biostimulant industry trial should align with a defined regulatory framework, ensuring that data collection meets product label requirements.

3. Setting Up Effective Biostimulant Field Trials

Field trials play a crucial role in biostimulant testing, as they provide real-world data on product efficacy. These trials should be conducted under conditions that highlight the biostimulant's mode of action and active ingredients. Here are the key aspects of biostimulant field trials:

Location selection: Choose test sites with relevant abiotic stresses

Field trials must be conducted in regions where the soil and climate conditions accentuate the biostimulant’s benefits. The selected crop must represent the intended use of the product, and deviations should be explained.

Untreated control plots: Compare results against control groups

All trials require an untreated control group to compare the effects of the biostimulant. If the biostimulant contains nutrients, ensure that the control group receives equivalent nutrient inputs to isolate the specific effects of the biostimulant. In stress-resistance studies, the same stress conditions should apply to control plots, and a non-stressed, non-treated group should be included when appropriate.

Experimental design: Use statistical methods like Latin square or split-plot design

The experimental design must align with the trial objectives and claims. For reliable statistical analysis, trials should be designed with sufficient replication—at least four replicates per treatment is recommended. Plot sizes depend on the crop type:

• Field crops: Minimum 20 m²
• Woody perennials: Minimum 3 plants or 25 units
• Vegetables, ornamentals, medicinal crops: Minimum 10 m²

For field trials, plots should be homogeneous, or designs like the Latin square or split-plot can be employed.

Application methods: Ensure proper dose selection and timing

The success of a biostimulant trial hinges on proper application techniques, including dose selection and timing. Example: A plant growth regulator trial in corn might involve foliar application at different growth stages to determine the optimal nutrient uptake effect.

What are the main parameters to test when preparing a biostimulant formulation?

• Comparing Basis and Doses - The reference for comparison should reflect the expected effects of the biostimulant. Preliminary trials are highly recommended to determine the correct dosage. Test a range of doses to pinpoint the most effective one.

• Timing and Frequency of Application - Timing and frequency of application depend on the plant growth stage, stress exposure, and other factors. Preliminary trials should help identify the optimal application timing.

• Application Methods - Application methods should align with the biostimulant's characteristics. Here are a few examples: When testing microorganisms, special attention should be given to maintaining viability ; For spray applications, ensure nozzle and pressure settings are appropriate ; For soil applications, consider factors like soil pH and organic content to optimize incorporation.

4. Assessments and Data Recording

To strengthen registration process applications, data from trials must be:

• Standardized across multiple locations
• Consistently measured to track effects over time
• Statistically validated to support product label claims

Here are the four steps involved in assessing the field effects of a biostimulant:

1. Preliminary Assessments - Before beginning the main assessments, verify that crop conditions are uniform across the entire experimental setup.
2. Main Assessments -The variables chosen for main assessments should directly reflect the biostimulant’s effects. When conducting trials across multiple sites, it’s critical to assess the same variables in all locations to en-sure consistency.
3. Assessment Frequency and Timing -Assessment frequency and timing should correspond to the crop’s lifecycle and the biostimulant’s anticipated effects.
4. Phytotoxicity Assessments -Preliminary trials should help evaluate the risk of phytotoxicity, and additional tests may be necessary if any toxicity symptoms emerge.

Using biologicals software, like Bloomeo Biosolutions, ensures quality control in data recording and statistical analysis.

5. Submitting Results for Regulatory Approval

Present individual trial results in a way that clearly differentiates control data and treated plot data. Use absolute values for control data and relative or absolute values for treated plots (e.g., efficacy percentages).

Key Elements of a Successful Submission:

• Individual trial reports - Separate datasets for each experiment.
• Aggregated trial analysis - Combining data for statistical robustness.
• Supporting documentation - Including environmental impact assessments and industry standards compliance.

Individual Trial Results

Present individual trial results in a way that clearly differentiates control data and treated plot data. Use absolute values for control data and relative or absolute values for treated plots (e.g., efficacy percentages).

Grouping Trials

When presenting results from multiple trials, tables or graphs can highlight key information, such as:

• Assessment periods and crop stages

• Number of trials and observed organs

• Treatment applications

Ensure that both mean values and measures of variation are included to support statistical significance.

Conclusion

Successfully registering a biostimulant requires well-structured testing that follows the regulatory guidelines in the European Union and United States. By following these five key steps, manufacturers develop and introduce new biologicals to the market.

To establish that a product is a genuine biostimulant, it must demonstrate specific effects under varying conditions, though this doesn’t guarantee it will perform consistently across all environments. Biostimulant companies must design flexible trials to suit the wide range of agronomic conditions where the product will be used. For biostimulants that improve nutrient availability, soil type and conditions may be more critical than the crop type when planning trials. As biostimulants become more advanced, trial designs must evolve to account for synergistic or emerging effects, which introduces new challenges.

At Doriane, we offer biologicals software that simplifies field trials, data collection, and analysis. Reach out today to enhance your biostimulant certification trials and navigate the regulatory framework with confidence.

To go further: Agronomy Testing with varieties and other parameters

Several factors can be taken into account, like environmics, genetics, agricultural practices and inputs. Then we deal with multi-factorial testing, also called "system trials", and this can be managed in Bloomeo. The agronomy testing software supports the research department with standardized traits and automation, thus saving time and resources. In addition, data analysis in dashboards support decision-making.