From scepticism to scrutiny, the biostimulant market has changed markedly over the past 10-15 years. As products and priorities have evolved, growers are increasingly demanding clear evidence, defined roles and measurable returns. CPM finds out more.
“Where we see people using biostimulants successfully, they are usually paying attention to the whole system.” DR SYED SHAH
By Charlotte Cunningham
Fifteen years ago, the conversation around biostimulants often sat in an uneasy space between curiosity and scepticism, with products entering a market that lacked clear definition, consistent evidence – and in many cases, a coherent explanation of how or why they worked. For growers, that created uncertainty, not only around performance, but regarding where these products fitted within an already well-established agronomy programme.
In the years that have followed, that position has shifted considerably. Biostimulants are now more frequently discussed within the broader context of input efficiency, abiotic stress management, soil function, carbon accountability and the wider question of how resilient arable systems can be built in the face of rising cost pressure and regulatory change. Yet as that conversation has evolved, so too has the scrutiny applied to the category, with a growing emphasis on whether products can deliver measurable, repeatable and commercially relevant outcomes under UK conditions.
For Rob Cannings, founder of AB Consultants, that transition reflects more than a simple shift in perception. Having worked across fertilisers, pesticides, biologicals and regulatory development, he describes a market that’s matured from one built on broad claims, to one increasingly defined by system-level thinking and the demand for demonstrable value.
“Back in 2012, everybody was saying, ‘It’s rubbish, isn’t it? Why should we use it?’,” he recalls. “At that point, the challenge was to show that there was something in it, but also to explain that both timing and product choice matter, and that you can’t treat these products in the same way as conventional chemistry.”
The early market was dominated by seaweed extracts, humic substances and amino acids – materials that had long been associated with positive crop responses, but weren’t always well understood in terms of their mode of action, he believes.
Since then, developments in processing and formulation have enabled a more precise understanding of the bioactive compounds involved, as well as a broader range of source materials and combinations. “What’s changed is that the proposition has become much more scientific,” says Rob. “We understand more about what’s in these products and how they behave, and that allows them to be used in a more targeted way.”
That increasing precision has also reshaped how biostimulants are positioned within the crop. Where they were once often associated with boosting yield in a general sense, Rob suggests their role is better understood as supporting nutrient use, improving tolerance to abiotic stress and contributing to overall system resilience.
“We have to get away from thinking of them simply as yield boosters,” he stresses. “This is about managing the crop in a different way, particularly earlier in the season, where you’re making decisions without knowing exactly how the year will unfold.”
In that sense, biostimulants occupy a very different space to inputs such as fungicides, which are typically applied in response to an identifiable threat. Instead, they’re often used as part of a forward-looking strategy, where the aim is to reduce risk and improve the crop’s ability to cope with variability in weather, nutrient availability or other pressures. “If the season is normal, growers want to get their money back,” he explains. “But if conditions become more challenging, they want to be in a position where they’re ahead rather than trying to recover.”
That framing has become increasingly important as growers gain access to more detailed data on field performance and input use. With GPS tracking, satellite imagery and farm management software now commonplace, it’s possible to assess the performance of individual fields with a level of precision that simply wasn’t available a decade ago.
“Farmers can now track everything they do, from what’s applied to each field through to how that field performs,” says Rob. “So the question is no longer whether a product might do something, but what it does in a specific situation and whether that delivers a return.”
That shift towards measurable outcomes is echoed by Dr Syed Shah of Niab, who’s seen a clear change in how products are assessed both in trials and on farm. Where previously products could be marketed with relatively little supporting evidence, he says growers are now far more likely to question both the data and the claims being made.
“In the past, people could sell products without producing good quality data,” he explains. “Now there’s much more focus on evidence, and farmers are increasingly setting up their own tramline trials to see whether a product actually delivers what it says it will.”
Central to that is a clearer understanding of what constitutes a biostimulant. Many products in the market contain nutritional elements such as nitrogen, manganese or silicon, which can have a direct effect on crop performance, but that doesn’t necessarily mean the response is due to a biostimulant mode of action, warns Syed.
“If a product claims to improve rooting, nutrient use efficiency or water use efficiency, then those effects have to be demonstrated,” he adds. “And importantly, they shouldn’t simply be the result of the nutrients within the product.”
Regulation has also played a role in driving that distinction. While the UK market has remained relatively loosely defined in the years following Brexit, European frameworks have moved towards clearer criteria, requiring evidence to support specific claims before products can be registered.
Rob believes that divergence has created both opportunity and risk within the UK. “We’ve effectively had a gap where the rules haven’t kept pace with the market,” he says. “That’s allowed a lot of products in, but it also means there’s a wide range of quality and a lack of consistency in how things are described.”
As new legislation emerges, that’s likely to change, with companies already aligned to European standards better positioned to adapt, believes Rob. In the meantime, Syed notes that products registered elsewhere in Europe can offer a degree of reassurance. “If a product has been registered in countries with stricter requirements, it gives you more confidence that there’s data behind it,” he says. “But that still has to be tested under UK conditions, because responses can vary significantly.”
That variability remains one of the defining challenges of the category. While consistent responses have been observed in certain situations, particularly in root crops such as potatoes, sugar beet and fodder beet, results in cereals have been more mixed, points out Syed.
“In root crops, we tend to see more consistent benefits, especially with amino acid-based and phosphite-based products, because they support root development. In cereals, the response is much less predictable and often linked to lower input systems.”
Niab trials have shown that some phosphite-based products can deliver yield benefits under reduced nitrogen regimes, where improved rooting and nutrient capture become more important. However, those benefits tend to disappear where fertiliser inputs are already optimised. “When nitrogen levels are high and other limiting factors are removed, there’s less opportunity for a biostimulant to make a difference,” he explains. “So their role becomes more relevant where inputs are being reduced or where the crop is under some form of stress.”
From a physiological perspective, much of that response links back to how plants allocate resources under different conditions. Where moisture or nutrient availability is limiting, crops will naturally invest more in root growth in order to access those resources, and biostimulants which enhance rooting or root efficiency can support that process, he explains.
In contrast, where nutrition is readily available, the crop prioritises above-ground biomass and yield formation, reducing the relative benefit of interventions aimed at improving resource capture.
This also helps to explain why responses can be highly seasonal, explains Syed. In years where disease pressure is low and growing conditions are favourable, there may be little opportunity for biostimulants to demonstrate an effect, whereas in more challenging seasons their role in supporting stress tolerance or nutrient uptake may become more visible.
Timing is therefore critical, particularly where the objective is to influence root development or early crop establishment. Applications made during the early vegetative phase, when the crop is actively building root mass and canopy, are more likely to deliver a response than those made later in the season once yield potential has largely been set.
“Growth stages 21-25 are important. If you apply at GS31-33, it’s too late,” suggests Syed. “But conditions matter too; if the crop is waterlogged, lacking oxygen or sitting in compacted soil, a biostimulant isn’t going to solve that.”
That practical caveat is important because the current interest in biostimulants is closely linked with regenerative and lower-input systems, where they’re often used alongside a range of other practices aimed at improving soil health and reducing reliance on synthetic inputs.
These may include changes to rotation, variety selection, drilling date and the use of organic manures, all of which can influence crop performance in their own right, says Syed. “Where we see people using biostimulants successfully, they’re usually paying attention to the whole system. It’s not just about applying a product; it’s about how that fits with everything else they are doing.”
Rob observes a similar trend, with biostimulants increasingly being integrated into broader nutrient and soil management strategies rather than used in isolation. He expects that integration to deepen over the coming years, particularly as fertiliser companies look to adapt their offering in response to changing demand. “There’s a real opportunity to combine fertiliser and biostimulant strategies in a way that improves efficiency and adds value,” he says. “That’s where I think we’ll see more development.”
At the same time, advances in digital technology are likely to support more targeted use, enabling growers to identify where specific interventions are most likely to deliver a benefit, rather than applying products across the whole farm as a default, adds Rob.
For now, both Rob and Syed return to the same underlying principle: that biostimulants must be considered within the context of a clearly defined objective, supported by evidence and applied with an understanding of how they interact with the wider system. “There isn’t an RB209-type guide for biostimulants,” comments Rob. “And that’s part of the challenge. The same product can do different things depending on crop and timing, so people require better guidance.”
But as the market continues to evolve, he believes the direction of travel is becoming clearer. “We’ve moved on from asking whether biostimulants do anything,” concludes Rob. “Now it’s about what they deliver in a real farming system – what’s the return on investment, and how does it reduce risk. If you can’t demonstrate that, growers simply won’t use it.”
This article was taken from the latest issue of CPM. Read the article in full here.
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