Sugar kelp extract boosts wheat yield and farmers' profits

Lead partner Algapelago Marine, a farming-led seaweed biotech business operating an offshore seaweed farm, has collaborated with Herts-based Rothamsted Research and the UK Agri-Tech Centre to demonstrate the efficacy of these products under abiotic stress conditions.

The project, called ‘Optimising low energy extraction of kelp for soil and livestock nutrition’ (or Low Energy Kelp), is funded by Innovate UK, the UK’s innovation agency.

Interest is growing in the use of seaweed-derived biostimulants in agriculture due to their potential to enhance crop growth, promote stress tolerance and increase nutrient use efficiency, and because they are derived from a sustainable source with positive environment impacts.

Current agri-seaweed products are dominated by seaweed sourced from wild harvest and the demand for seaweed-derived soil and animal supplements is expected to grow exponentially as policy drives a reduction in chemical inputs. However, the biochemical mechanisms involved in their beneficial impacts on crops remain poorly understood.

Algapelago Marine has developed a low energy method for extracting biostimulants from farmed seaweed that provides a biostimulant product of consistent quality with potentially significant commercial value.

To establish optimal application methods and rates for Algapelago’s TD65 biostimulant, two experiments were conducted in controlled environment facilities.

The first investigated the impact of four different rates of foliar applications on wheat and field bean yields under both well-watered and drought-stressed conditions; the second probed whether foliar application or soil application had the greatest impact on yields of wheat.

The aims of the first experiment were to determine the optimal application rate of TD65 under ambient conditions, and also to see if there were any yield benefits when plants were drought stressed.

The second experiment was conducted to try to identify if the benefits of the biostimulant were due to direct plant physiological impacts, or if any benefits were due to stimulation of soil microbial activity and consequent increases in nutrient availability and uptake efficiency.

For the application rate experiment, wheat and field beans were grown in 10cm diameter x 90cm deep intact clay-loam soil cores, deemed appropriate for both ambient and drought-stress experiments.

For the application method trial, plants were grown in 2L pots in a substrate of either sieved soil or glass beads (simulating a hydroponic system), providing a comparison between a crop grown in either the presence or absence of soil microbes.

Three application methods were applied: foliar only, soil only and foliar plus soil microbes, and in all experiments, results were compared against controls grown in identical ways but minus biostimulant applications.

In the application rate experiment, an optimal application rate was identified, resulting in enhanced plant growth and a 24 per cent increase in wheat grain yield, as well as a 45% increase in grain number, compared to the control values. No benefit of the biostimulant application was observed in the drought-stressed plants.

In the application method experiment, the application method didn’t affect the yields of wheat in either growing medium, although the plants grown in the hydroponic system significantly outperformed those grown in soil.

Further experiments investigating the timings of applications relative to growth stage, and applications under different drought stress scenarios (only one was tested here), are recommended to further understand and optimise the use of Algapelago’s TD65 biostimulant product.

In addition, experiments using different rates of fertiliser application are recommended, as the biostimulant potentially could perform better under more nutrient-limited conditions than those that were used in the study.

Overall, there is evidence that seaweed-derived biostimulants can, under certain conditions, provide crop yield benefits.

Luke Ansell, Head of Operations at Algapelago Marine, said: “The completion of the Rothamsted crop trials is a significant milestone for the project and wider product development.

“Thanks to the Rothamsted team for all their hard work and we are thrilled to see a 24% yield increase in wheat grain due to this prototype sugar kelp extract.

“This result has validated our belief in the quality of our cultivated sugar kelp and extraction method. While we await the full analysis results from this study, a wider trial program is underway across soft fruits, field and root vegetables which will further build the evidence base for product efficacy.”

This project has established the feasibility of rope-grown kelp species to improve UK food resilience, build soil health and lower carbon emissions and nitrate usage. This directly supports the Government’s agricultural goals for the Government Food Strategy.

Cultivated kelp is a rich and sustainable source of potash, micronutrients and bioactive compounds and cultivation provides shelter and food for a range of organisms, including commercially important fish species.

Professor Adie Collins, Science Director at Rothamsted Research, said: “At a time when yields and corresponding profits are under pressure from a range of abiotic and biotic stresses, biostimulant research offers a glimmer of hope to farmers in an ever more challenging world.”

This project builds on previous feasibility studies to optimise the liquid extraction and ensiling of kelp, developing a novel two-stage extraction process which produces consistent agricultural products.

Dr. Saro Rengaraj, Innovation Associate for Soil Health at the UK Agri-Tech Centre, said: “From sea to soil, kelp builds resilience and grows results.

“Algapelago’s kelp biostimulants could boost soil resilience, nutrient cycling and microbial health - sustainably enhancing crop productivity.”