Close-up of a sprayer© Tim Scrivener

There is a lack of scientific evidence that some biostimulants actually work in UK crops, according to a new AHDB report.

With more than 6m hectares of crops treated with biostimulants, the EU is the largest market in the world with sales worth an estimated £450m/year.

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And this market is growing. Sajjad Awan, who manages natural resources work at AHDB, believes the development of targeted biostimulant products by major agrochemical companies is playing an important role.

“It’s no longer just about high-value horticulture crops or organic production either – products are being targeted more and more at conventional arable crops,” he says.

A biostimulant is anything that is applied to the crop or soil that stimulates natural processes that benefit crops. This excludes fertilisation and pesticidal action.

Difficult to compare

However, the varied range of products and benefits makes comparisons difficult.

To help clear this confusion, AHDB commissioned a scientific review of the evidence, evaluating a wide variety of literature to find evidence of benefits associated with the use of biostimulants.

Although product diversity made the process of detecting significant benefits challenging, the report highlights there are some positive yield results in cereal experiments.

Those showing benefits include seaweed extracts, humic substances, phosphite and plant growth promoting bacteria.

In contrast, two of the 11 categories had no statistically significant benefits.

Preventing yield loss in ‘bad’ years

However, the authors point out that some biostimulant products do not aim to increase yield in a “good” year, they are instead designed to prevent yield loss in a “bad” year – for example, under stressed conditions.

This, therefore, makes comparisons difficult, as Kate Storer, who led the review at Adas explains.

“The nature of these products makes it hard to demonstrate significant and consistent yield effects in trials.”

Another conclusion was that there is a lack of data for oilseed rape, which meant the researchers were unable to draw any firm conclusions.