Getting the most from biostimulants

While there is still much to learn about what biostimulants can offer, there have been some promising results in trials and on farm

Biostimulants promote plant growth and development throughout the crop cycle from seed germination to plant maturity in a number of ways. These include stimulating the natural plant processes, acting on specific aspects of plant metabolism and demonstrating the following benefits in plants, says Yara:

  • improving yield quantity and quality (e.g. sugar content, colour, etc),
  • increasing plant tolerance to abiotic stresses,
  • improving nutrient availability, uptake and assimilation into roots and shoots.

Biostimulants’ mode of action largely depends on the different bioactive compounds present in the product. For example, in seaweed extract-based biostimulants, specific polysaccharides, such as fucoidan, are priming the plant to tolerate abiotic stress while humic substances-based biostimulants can induce a hormone-like activity in plants and improve nutrient availability.

One of the main claims for many biostimulants is their positive effect on stress tolerance. The mode of action can vary depending on the biostimulant type and, in some cases, the exact mechanism which produces this effect is not yet clear.

In the case of seaweed extracts, anti-stress effects in a variety of stress situations, including temperature extremes, have been reported. Protective compounds in the seaweed extracts, such as antioxidants, could be involved.

Seaweed extracts

Research shows soil temperature and water evaporation rate are stabilised by humic substances. The insulating properties of humic substances help maintain a more uniform soil temperature, especially during periods of rapid climatic changes, such as extreme temperatures. Because water is bound in the humic substances and they reduce temperature fluctuations, soil moisture is less likely to be released into the atmosphere.

Selection of the appropriate product for a particular crop and farm situation is based on several factors, such as crop development stage, application method, environmental conditions etc.

Each product has specific claims, for example stimulation of flowering or improved nutrient uptake, based on the effect it has on plants. So consulting your local agronomist will help you choose the most suitable product for your crop based on your needs.

Biostimulants can have a synergistic effect when applied together with fertilisers. For example, the use of humic substances improves nutrient uptake by increasing the cation exchange capacity of soil. Research has shown humic and fulvic acids are excellent foliar fertiliser carriers and activators. Foliar application of humic or fulvic acids in combination with trace elements and other plant nutrients can improve the growth of plant foliage and roots.

Trial results

Yara has recently carried out two scientific field trials at Newforge and Poyntzpass, Northern Ireland, with the Agri-Food and Biosciences Institute (AFBI).

Crop: winter wheat variety, JB Diego

Fertilisation regime:

Newforge: N: 130kg/ha, P: 0, K: 115kg/ha

Poyntzpass: N: 140kg/ha, P: 40kg/ha, K: 40kg/ha


Untreated (no foliar applications)

YaraVita BioMARIS at 2.5l/ha

Spring application timings:

14 days after start of crop growth

28 days after start of crop growth

Flag leaf stage


Foliar applications of YaraVita BioMARIS increased average yield by 21.6% compared with the untreated trial.

What are biostimulants?

Biostimulants are any compound(s) or microorganisms which, when applied to crops in combination with mineral nutrients, trigger the processes which enhance nutrient uptake and efficiency, improving plant growth, tolerance to abiotic stress and yield beyond the effects of mineral nutrients alone.

Source: Yara

Case study: Optimising crop potential to overcome soil health deficiencies

In recent years, James Walgate, who farms at Hall Farm, Cuxwold, Lincolnshire, has introduced biostimulants into his growing programmes.

Mr Walgate says: “We are using biostimulants to optimise the growth of crops which are presently compromised by our increasingly dysfunctional soils caused through a deterioration in soil health.

“Our emphasis is on improving root growth and development, enabling roots to scavenge for nutrients and water more efficiently.”

With current nutrient use efficiency being down at 10-30% for phosphate, and 50-70% for nitrogen, there is huge scope to improve this. Improvements bring both crop economic and environmental benefits.

Biostimulants have also been linked to minimising the effects of stress, such as drought and waterlogging, on crop performance. These are often referred to as ‘stress busters’ and Mr Walgate is looking to exploit them.

“If health is optimised, then plants are better equipped to cope with pest and disease attacks, thereby expressing the full potential of the crop or variety. As we experience extreme weather events on a more regular basis, such as this year’s drought, building resilience into our crops can only be beneficial.”

Concerning cost, Mr Walgate says: “I do not see these products as adding cost, but more as a change in cost distribution, switching some of our plant protection investment into biostimulants and micronutrients, building the plant’s own defence mechanism.”

At Hall Farm some large investments are being made as it develops controlled traffic farming, reduced tillage systems and introduces new rotations including cover crops, as part of a long-term strategy to improve soil health.

Content sourced from our sister publication Farmers Guardian

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