Integrating biologicals with biocompatible adjuvants for holistic soil health management in agriculture

An article coordinated by Sarah Harding, PhD, on behalf of the speakers at the World Bioprotection Forum’s Use of Adjuvants with Biologicals and Soil Health Management in Agriculture, taking place on 12th October 2021.

The stewardship of soil health is integral to maintaining planetary wellbeing, and it is essential for plant health and yield. Therefore, it is ironic that current agricultural practices – which grew out of 20th century concerns over food security – have damaged the soils we rely on to feed the world.

Owing to their very nature, conventional pesticides are toxic to living organisms. Therefore, it is not surprising that pesticide‐contaminated soils are reported to see inactivation of nitrogen‐fixing and phosphorus‐solubilizing micro-organisms. Disturbances in molecular interactions between plants and nitrogen‐fixing rhizobacteria are also evident, along with reduced biochemical reactions, such as the mineralization of organic matter, nitrification, denitrification, ammonification, redox reactions or methanogenesis. Even chemicals in soil fertilizers, which are intended to nourish the soil, pollute ground water sources, and affect the health of soil micro-organisms by changing soil pH. 

As a result of these concerns, and others pertaining to human and environmental safety, the past decade has seen an increasing number of chemicals withdrawn from the market. According to the Pesticide Action Network (PAN), more than 225 pesticides are currently banned in the UK and EU. The UK government’s 25 Year Environment Plan states that soils must be managed sustainably by 2030, and the EU has committed to a 50% reduction in pesticide use by 2030 to protect soil health, the ecosystem and wildlife. 

Harnessing nature

The problem with banning chemicals is that, too often, there seem to be no alternatives. Yet novel technologies offer new approaches to providing 21st century solutions to 21st century. As of the end of 2020, there were over 200 biopesticides available in the US market. For example, Bacillus thuringiensis (Bt) is a naturally occurring soil bacteria that has been proven effective against a range of insect pests. Since the banning of the pesticide chlorpyrifos in 2016, turf managers have increasingly turned to beneficial nematodes to control leatherjacket populations. And in a novel approach to ‘vaccinate’ tomato plants against the Pepino Mosaic Virus, success has been found by applying beneficial viruses to tomato crops. 

“Globally, we spend US$60 billion a year on chemicals, in our quest to protect crops from pests and diseases,” says Dr Minshad Ansari, CEO and Founder of Bionema, who is speaking at the WBF Summit in October. “Yet nature provides solutions that could protect our crops, in the form of microorganisms (nematodes, fungi and bacteria).”

Nature offers a huge untapped resource for ‘bioprotectants’ (still called ‘biopesticides’ in some parts of the world). Of the billions of microbes found in a handful of soil, we are yet to identify and characterise 99% of the species that might increase crop productivity, maintain plant health, or protect against crop pests and diseases. 

“Soil is nature’s most powerful technology, and should be prized in the same way we celebrate the role of wind and solar power of reshaping emissions and tackling climate change,” says Jonatas Bredow Alves, Global Portfolio Lead – Soil and Seed Health at UPL Ltd, and a speaker at WBF summit. “UPL’s wide portfolio of biological, climate-smart, and technology solutions has been designed to enhance the strength, resilience and sustainability of the natural world, ensuring healthier soils means a healthier planet.”

Adjuvants

Any product developed for pest control must be formulated with the goal of better targeting, penetrating or protecting the plant at risk of pestilence or disease. Adjuvants such as wetting agents, dispersants, detergents, emulsifiers and foaming agents, are commonly added to pesticide products or spray mixtures to enhance their performance and/or physical properties. Through enhanced application, they optimise the efficacy of the active ingredient. Biocompatible adjuvant formulations can help increase the efficacy of bioprotectants by 20-30%, while protecting soil health.

Nature has thousands of solutions to offer, but those solutions need to be packaged and applied in a way that makes them practical to use. In fact, one of the biggest challenges for producers of bioprotection products is not identifying new solutions – it is formulating those solutions in a way that allows practical storage, application and utility. 

It could be argued that this is no different to synthetic pesticides. However, as Dr Ansari explains, “Not all adjuvants are biocompatible – even if they claim to be – end users really have to know their compatibility before tank mixing.”

Most adjuvants are not required to be listed on pesticide product labels because of less toxic than pesticides. However, in a recent study, researchers found that 10–20% of marketed adjuvants (wetting agents, surfactants, soil conditioners) can have negative impacts on microorganisms. 

Formulation challenges for biologicals

Finding the right adjuvants for BioProtection products can be a particular challenge. As well as providing the required support, adjuvants must be compatible with the active organism and suited to its application technique. 

“The selection of the right formulation to meet the chemical needs of the active ingredient is critical,” advises Dr Martin Shaw, Team Leader – R&D at Croda. “It ensures your material remains stable for the desired shelf-life period prior to application and is also suitably incorporated into a system that can be applied effectively to the target area.”

Volodymyr Krut, Chief Microbiologist at BTU-Center, agrees: “The effect of a safe and organic bioprotector must not be hindered by adding a non-compatible adjuvant to the mixture. The ideal solution would be biological adjuvants, and there are a number of these in development, as we try to develop fully natural solutions for agriculture.”

One example is BTU Center’s biological adjuvant that enhances adherence to the target plant. “The bacterium Paenibacillus polymyxa produces exopolysaccharides that – when mixed with biological products – help to retain their active agents on the leaf and in the upper layer of the soil,” explains Volodymyr Krut. “This means that combining a biopesticide with an exopolysacharides-based adjuvant can prevent active agents from washing off and prolong their effects. Exopolysaccharides have also demonstrated an ability to retain moisture and protect plants from a number of stress factors, including freezing, drought and heat.”

“Getting biologicals to where they need to be on a crop is key to performance,” added Dr Benjamin Langendorf from Momentive.  “Many biologicals use excessive amounts of water, leading to run-off and loss of the active ingredient. However, as one example, Momentive’s Silwet adjuvants can facilitate enhanced spray coverage, while potentially allowing for a reduction in spray volume (up to 75% of spray to run-off rates).  This means more hectares can be sprayed per tank, as well as keeping more spray on the plant and less on the ground. Additionally, because of their unique superspreading properties, Silwet adjuvants can get spray into those hard-to-reach places on the crop, where pests hide.”

According to Croda’s Dr Martin Shaw, a common approach to formulating with bioprotectants is to look at water free systems. This minimises exposure to elements which can have a negative impact on the viability of the active. This could also be true of adjuvants used within formulations. For this reason, OD (oil dispersions) or WDG/WP (water dispersible granule/wettable powder) formulations might be the preferred choice of formulation type. Developing chassis systems, where there is confidence of little antagonism from adjuvants, into which bioprotectants can be added is a great way to speed up developments.  

“Seed coating could also be a very interesting delivery system to unlock the full potential of biological solutions, but it comes with its own technical challenges”, explains Renaud Perrin, Formulation Specialist at Stepan Europe. “When applying a microorganism on a seed for example, the coating formulation should not only be compatible with the microbe but also counteracts destructive phenomena such as dehydration. Those are problems we’re tackling at Stepan, combining effort in surfactant and polymer development with application expertise on seeds.”

Collaborate to innovate

Applying biologicals with adjuvants could improve the cost-effectiveness of biological products and enhance their persistence and efficacy in the soil environment, making them a more attractive biocontrol option for different cropping systems.  Assessing the compatibility of a range of biologicals with many adjuvants has not yet been studied in detail, therefore comprehensive research on how adjuvants can improve efficacy of biological products, if applied together, is required.

In order to bring bioprotection products to market in a commercial-ready, usable form, collaborations between different specialists are required. For example, an innovator with a novel bioprotection agent could work with a company specialising in formulation development to develop viable solutions, and support in testing a range of adjuvants for their compatibility with a test microorganism could provide vital insights into appropriate integration. 

Many of the companies taking part in the WBF Summit on Adjuvants offer support with testing, formulating and developing novel bioprotectants. Collaboration for innovation is key. If we can connect the bioprotection sector, we can help advance the industry by providing products that are practical to use, and work in the field as well as in the lab. 

“We believe that unique innovation in science and technology can be established through collaboration,” says Dr Ansari. “As well as developing our own range of products, we are working with exceptional researchers around the world, promoting a culture of open and collaborative communication.”

Similarly, Croda has developed a number of solutions for customers in the bioprotection sector, utilising a robust portfolio of high-performance adjuvants. Dr Martin Shaw explains: “Across a range of materials this can include low moisture, demineralised or super refined variants. All of this builds towards developing improved delivery systems for new classes of agrochemical active ingredients.”   

Meanwhile, with the opening of its Agricultural Centre in Winder, GA, Stepan is adding to its 50 + years knowledge in microbiology and agricultural formulations new in-house capabilities in efficacy assessment.  “We believe that the development of efficient biological solutions, and hence their wider adoption, needs an integrated product development approach by leveraging agronomic, biological and formulation expertise. Achieving the immense task to change our agricultural practices will require more in-depth collaboration of the different experts in those fields and across the value chain” says Renaud Perrin. 

Want to know more?

We have damaged and polluted the planet, and we have ruined the soils on which we depend to grow our crops. These are 21st century problems, but innovation in AgriTech can provide the 21st century solutions that we need to address those challenges. 

On 12 October 2021, the WBF is hosting a free webinar to discuss the use of adjuvants with biologicals and soil health management in agriculture. A key goal is to connect those looking to develop biorational products with industry partners who may support the realisation of these products into commercial materials. For more information, visit https://www.worldbioprotectionforum.com/events/use-of-adjuvants-soil-health-in-agriculture/#