Solvay: Microplastics restriction, biologicals… How regulations and trends in seed treatment create opportunities for the development of new seed coatings?

Antoine Vielliard

Global Seed Care Director, Solvay Novecare

Agriculture is facing a major challenge: increase food production while reducing its environmental impact. The industry must accelerate its transition to sustainability without compromising performance, and gradually reduce and replace synthetic pesticides. The timeline and amplitude of this transformation is still uncertain, however, we believe that integrated pest management approach, looking holistically at the entire agricultural practice, precision farming combined with biostimulants and biocontrol solutions will be the main focus of the agrochemical industry. Bio-based solutions (biologicals, natural extracts) will be a critical pillar of a long-term roadmap to achieve pesticide reduction goals set by policymakers across the world, in particular the EU green new deal.

Solvay, as a historical leader in formulation solutions, is monitoring closely these trends and investing accordingly, both in biocontrol formulation expertise and most recently in on-seed functional coatings and enhancements.

Our strategic view is that the ability to integrate new biocontrol and biostimulant technologies directly on the seed will contribute greatly to overall pesticide reduction targets.

With the acquisition of formerly CERES seed coatings activities from Bayer, Solvay created a global player in seed coatings, with advanced on-seed formulation, biology and seed application laboratories and expertise all located in Méréville, 60 km south of Paris in France cereals’ heartland.

A near-term formulation challenge that the seed industry will face is the upcoming Restriction on Microplastics, currently in its final discussion stages in the European Union regulatory instances. Under its current scope, the draft of the restriction states that no product containing intentionally-added microplastic particles shall be produced, commercialized, distributed or used in the EU market once the restriction enters in force, with phase-out periods depending on the type of use. For instance, the seed and seed treatment industries will have five years to comply after the entry in force of the restriction.

A microplastic particle is precisely defined in the current draft, and no fundamental changes are expected in the final text. It is defined as a particle (like seed) containing solid polymer (like seed coating) of certain dimensions, namely between 0.1 µm and 5mm (for the case that interests us). A polymer is defined by the European Chemicals Agency (ECHA, in charge of REACH) as a substance with a sequence of more than 3 monomers. However polymers that are from natural origin, biodegradable or soluble in water (> 2g/L/OECD TG 120) will be exempted from the microplastic restriction. The different protocols and requirements to pass follow the OECD guidelines for biodegradation testing such as OECD 301 (B, C, D, F).

The microplastics restriction is one of the most ambitious regulatory steps taken to date under REACH in the EU and a flagship of the Chemicals Strategy for Sustainability announced as part of the EU Green New Deal in October 2020. Despite delays of several months compared to the initial calendar, the draft proposal is still expected to be submitted to the next REACH Committee meeting planned in September 2022. The vote is targeted at the December 2022 meeting of the Committee, for an addition to the Annex XVII List of Restrictions and entry in force early 2023. Accordingly, all seed treatments and treated seeds will have to be microplastic-free no later than the 2028 planting season.

Solvay Seed Care experts have started re-formulation work to be able to propose microplastic-free seed coatings, as prototypes ready to test already in 2022, for all major row crops. Corn is one of the most complex seeds to tackle, due to the variety of size, morphology and surface properties of kernels. Designing the right coatings requires an intricate knowledge of seed surface science. In the case of corn, adhesion properties need to be adapted and balanced between the hydrophilic embryo and hydrophobic cuticula of the kernel. Treatment rates are also fine tuned, almost to the single seed count, as slurry volumes impact coverage, adhesion and flowability of the seeds, from the treater’s bin to the bag, from the bag to the planter box and ultimately into the increasingly precise and fast planting wheels. These application performances of the seed coating cannot be compromised. Figures 1 and 2 summarize the comparative performance of our new microplastic-free Peridiam^Ⓡ Quality 3001 for corn, versus the current standard coating in our range.

Figure 1: Comparative performance summary of microplastic-free vs. standard corn coating

Figure 2: Visual appearance of microplastic free vs standard corn seed coating

The selected class of polymeric binders in our seed-coating formulations are either of natural origin, or biodegradable, thus in line with microplastic directive expectations.

The formulation prototypes then need to be screened in rigorous seed safety tests, to make sure that the new seed coating has no negative impact on germination. Several standardized protocols on a wide range of corn varieties have been performed in Solvay Germination Laboratory. They have all concluded to the innocuousness of our new formulation.

Dust emission is an equally important criteria for evaluating our novel microplastic-free corn seed coating. Zero-dust is the cornerstone of the stewardship policy of all global maize seed companies, who usually set dust emissions targets well below the regulatory threshold. Every novel seed coating formulation designed without microplastics goes through replicated standard Heubach dust tests to offer that guarantee to our customers treating seeds with our coatings. Solvay Seed Care application labs will also test abrasion and attrition of the coated materials (figure 3) in various treating and extreme handling conditions, which are as important as dust emission control to ensure both a quality visual appearance and reduced loss of active material.

Figure 3: Treated corn kernels after standard and strong attrition conditions

The final and more complex aspect of our seed coating evaluation program is application testing. A seed coating is applied as one of many, sometimes up to 10-15, seed treatments components in a complex fluid slurry volume. Batch treatment times, stickiness, drying speeds are all important process parameters to ensure productivity and quality of the treated seeds in upstream corn seed production sites. This is the reason why Solvay has started to engage into in-depth testing, both on our pilot seed treaters and in collaboration with corn seed customers to adjust application recipes and methods to the change of seed coatings. Large scale industrial tests can only be organized during inter campaigns and need ample planning, several years before the restriction is fully enforced. While the 2027/28 corn treating season still seems far away, microplastic-free seed coating evaluation needs to start now.

Many seed companies are also trying to manage the timeline of their new on-seed treatment innovation pipeline to match the go-live date of the microplastic restriction. A new seed treatment active targeted for introduction within the next 2 to 3 seasons will certainly be paired with a microplastic free coating option in the recipe that will be tested and applied for field trials evaluation, typically over a couple of seasons. Many of the corn seed treatment portfolio strategies include the introduction of new biological actives, such as bionematicides or biostimulants for instance. We anticipate that the implementation of the microplastic restriction in the EU first and later in other jurisdictions will converge and collide with the introduction of these new seed-applied biological treatments. Some of our solutions are already being designed to be adapted and safe for upcoming mainstream classes of biologicals. We are working on new solutions, for cereals, oilseed rape, as well as soybean and pulses, to allow for instance safe application and extended life on seed of B. japonicum inoculants.

This illustrates the structuring transformative trend that the agricultural industry will start to experience. Meeting the requirement of the EU restriction to limit the release of microplastic in the environment is seen by Solvay as a broader opportunity to co-design with customers new, biodegradable seed enhancement products that can help them integrate on seed a growing suite of biological control and biostimulant options in the future.

“2022 Seed Treatment Special” magazine will come out this June. For Feature sponsoring or advertising, please contact Christina at christina@agropages.com.

Read 2021 editon of "Seed Treatment Special"