Can sea urchins be used to boost plant growth and biomass?

The Norwegian Institute of Bioeconomy Research (NIBIO) is one of Rissa Citizen Science’s research partners in the Ocean Green project. At NIBIO’s Bodø office, Dr Abirami Ganesan's findings could help reduce Norway’s dependence on fertilizers while contributing to food security.

Abirami Ganesan testing sea urchins in growing experiments at NIBIO.

Hi Abirami, can you introduce yourself briefly?

I’m Abirami Ganesan, a researcher at NIBIO in Norway. My research focuses on the sustainable use of marine bioresources and how these resources can be converted into valuable products for agriculture and the circular bioeconomy.

This summer, you tested urchins as a fertilizer. Can you tell us what the experiment was and what the results were?

We investigated whether sea urchin biomass could be converted into a useful soil amendment or plant-growth-promoting product. We tested different sea urchin preparations and application rates on turf grass, bent grass, and white clover under controlled growing conditions.

We monitored plant growth and biomass, and we observed that the response was influenced by several factors, including sea urchin particle size, application concentration, soil type, and plant species. Overall, we saw differences among the treatments as well as differences in how the three plant species responded. We are now looking more closely at these interactions through statistical analysis.

Green lettuce seedlings were primed using Seaurchin (SU) biostimulant at concentrations ranging from 0.2% to 2.0% and compared with Acadian® (0.2%) as a commercial biostimulant. The photo was taken 15 days after sowing.

Urchins are essentially a shell and some soft tissues inside: what are the parts that are beneficial to plants?

Sea urchins contain both mineral-rich hard structures and nutrient-rich soft tissues, and our research explores how these different fractions can be put to use.

We separate sea urchin biomass into liquid and solid fractions. The liquid fraction is being tested as a biostimulant for lettuce, including through foliar application, while the remaining solid material and shell fractions are being evaluated for grass growth and soil health.

Rather than treating sea urchins as a single material, we are exploring how each fraction can be used for the right agricultural purpose, adding value to an underutilized marine resource.

Sea urchins sampled at one of Rissa Citizen Science's kelp forest restoration sites for NIBIO.

Did adding urchins in the soil change the nutritional values of the plants?

Yes, we observed improvements in plant biomass and density following the application of sea urchin shell powder. The response varied among turf grass, bent grass, and white clover, as well as across the different treatments.

We are also investigating whether sea urchin treatments influence nutrient uptake and mineral composition in these plants. This will help us understand whether the benefits extend beyond visible growth to changes in plant nutrient status.

Dr Abirami Ganesan inspired Rissa Citizen Science to run outreach experiments in Tromsø with ViNN and DYRK in 2026. Urchins and kittiwake guano were tested on lettuce and parsley.

If people want to use urchins in their vegetable garden, what advice would you give them?

Sea urchins have potential for garden use, but how they are processed and how much is applied really matter. Washing can reduce residual salts, while crushing and fractionation help produce materials suitable for different agricultural applications.

Our trials show that higher application rates do not automatically mean better plant growth. We are therefore working to identify the right processing method and application rate before recommending a specific concentration for home gardeners.

Sea urchins used in Rissa Citizen Science's outreach experiment at DYRK to grow lettuce and parsley in 2026.

What would be the next steps before sea urchins could be used as a fertilizer commercially?

Before sea urchins could be used commercially, we first need to identify the best processing methods and application rates, and confirm their effectiveness across different plants, soils, and growing conditions.

We are also investigating how different processing methods affect the nutrient composition of the sea urchin material, how these nutrients influence plant growth, and how they are released and become available in the soil.

The next step would be larger-scale and repeated trials to demonstrate consistent performance, environmental safety, and economic feasibility before moving toward commercial production and regulatory approval.

Sea urchins at one of Rissa Citizen Science's kelp forest restoration sites, before we started.

Is there anything else you would like to add?

What excites me most is the opportunity to turn captured sea urchins into a useful resource for agriculture, whether for greenhouse crops or turf grass.

Rather than simply asking, “Can sea urchins be used as fertilizer?”, we are asking: Which parts are most useful? How should we process them? How much should we apply? And which plants and soils benefit most?

Our goal is simple: make the best use of the whole sea urchin biomass, create agricultural value, and leave as little waste as possible.

Dr Abirami Ganesan’s research inspired Rissa Citizen Science to conduct an experiment at the DYR community garden in Tromsø, where we are growing lettuce and parsley.

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Dr Abirami Ganesan's research mentioned in this article is funded by the Ocean Green project, led by Ava Ocean. The other research partners are NIVA (Norwegian institute for water research) and Akvaplan-niva. The industry partners are Across Nature and Hofseth Biocare. 20 Knop helps with dissemination. Rissa Citizen Science is part Ocean Green as well, leading the restoration of kelp forests with volunteers in Tromsø.