5 Steps To Certify A Biostimulant In The EU – Your Regulatory Trial Guideline

Biostimulants are regulated under the EU Fertilising Products Regulation (2019/1009). To successfully place a biostimulant on the market, producers must demonstrate its efficacy by proving a legitimate plant biostimulant effect. This article provides a detailed guide for conducting effective trials aimed at registering biostimulants. These trials are crucial, and using the right tools, such as our biostimulant trial software, can streamline the process and ensure compliance with regulatory standards.

Key Biostimulant Claims

Biostimulant producers must substantiate one of the following four claims to achieve regulatory approval:

• Improved nutrient use efficiency

• Enhanced tolerance to abiotic stress

• Better determination of quality traits

• Increased availability of confined nutrients in soil or rhizosphere

This article will outline how to set up trials to assess biostimulants based on these claims. Trials must be adapted to the relevant crop groups, including field crops (e.g., cereals, oilseeds), woody perennials (e.g., fruit and nut trees), or vegetables, ornamentals, and medicinal plants.

Objectives of Biostimulant Trials

When conducting biostimulant trials, the following key objectives should guide the process:

• Define and characterize the product's stimulatory activity

• Establish the intrinsic efficacy of the product

• Justify the biostimulant claims in line with regulatory requirements

1. Trial Implementation and Product Description

To validate the biostimulant’s effects, trials can be conducted in controlled environments or natural field conditions. Controlled settings, such as greenhouses or climate chambers, allow for the careful monitoring of variables like temperature, light, and nutrient supply, helping reveal the biostimulant’s modes of action.

Key Consideration: Thorough documentation of experimental conditions is essential, as trial data will support your biostimulant claims.

2. Experimental Conditions

The primary goal of biostimulant efficacy trials is to gather reliable data that backs the claims made. 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.

2.1 Location and Area

When trials are conducted under controlled conditions, location is flexible. However, 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.

2.2 Untreated Control Plots

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.

2.3 Experimental Design and Statistical Analysis

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.

3. Input Application

The success of a biostimulant trial hinges on proper application techniques, including dose selection and timing.

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

3.1 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.

3.2 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.

3.3 Application Methods

Application methods should align with the biostimulant's characteristics. For example:

• 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

What are the four steps involved in assessing the field effects of a biostimulant?

4.1 Preliminary Assessments

Before beginning the main assessments, verify that crop conditions are uniform across the entire experimental setup.

4.2 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.

4.3 Assessment Frequency and Timing

Assessment frequency and timing should correspond to the crop’s lifecycle and the biostimulant’s anticipated effects.

4.4 Phytotoxicity Assessments

Preliminary trials should help evaluate the risk of phytotoxicity, and additional tests may be necessary if any toxicity symptoms emerge.

5. Presenting Results

How to present the results of biostimulant registration?

5.1 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).

5.2 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

Proving that a product qualifies as a genuine biostimulant hinges on demonstrating its specific ef-fects under various conditions, but this does not guarantee efficacy in all environments. Manufacturers must design flexible trials tailored to the diverse agronomic contexts in which the product will be used. For biostimulants that enhance nutrient availability, soil type and conditions may be more important than crop type when planning trials. As biostimulants become more complex, trial design must evolve to account for synergistic or emergent effects, introducing new challenges.

At the heart of these complex trial needs, our biostimulant trial software helps simplify and streamline every stage of the process—from experimental design to data recording and analysis. Contact us to learn how we can support your biostimulant trials and help achieve successful regulatory approval.