Our Mariculture Program Manager, Mary Williams, on her experience using the first batch of sugar kelp grown with Metlakatla Development Corporation through the Regenerative Ocean Farming Project to make a seaweed fertilizer for local growers.
When I tell people that I’m working on a kelp farming project on Coast Ts’msyen Territory (Prince Rupert, BC), one of the first questions I’m asked is, what are you using the kelp for? After an awkward pause, my standard response is that we’re figuring that out.
Regenerative ocean farming involves creating mini-ecosystems by growing various seaweed and shellfish species that complement one another. This method enhances the surrounding ocean ecosystem health while providing food and jobs for coastal communities. Ecotrust Canada and Metlakatla First Nation are working together to provide research and innovation capacity to support regenerative ocean farm development.
We started with growing kelp for the Regenerative Ocean Farm’s pilot year (2021-2022). Kelp and its derivatives have an overwhelming number of uses, ranging from pharmaceutical supplements to beauty products to human and animal food — or, as demonstrated by the tasty latissima Gose from Wheelhouse Brewing Company, it can be used to add salt or prevent sediment separation in beer!
But kelp farming, like any other form of farming, requires you to understand your crop — its quality, quantity, ideal harvest time, nutritional value, and biofouling presence — before you can have any meaningful entry into the market.
In February 2022, the ocean farming team at Metlakatla Development Corporation, GreenWave, and Ecotrust Canada planted our first two long lines (400m) of sugar kelp on Metlakatla’s ocean tenure up toward Tuck Inlet. We were hoping to gain a better understanding of our crop, but mainly, we just wanted to see whether it would actually grow well on long lines here, and we wanted more practice working a kelp farm.
Metlakatla’s crew was able to successfully harvest over 1,560 lbs of kelp by June 2022!
Beyond rinsing and freezing the kelp, we had no additional tools to stabilize or dry the kelp, except for the sun, which isn’t particularly reliable (or commercially food safe) in Prince Rupert, especially at this quantity. So, the bulk of our kelp waited in a freezer in Seal Cove, on the coast by Tuck Inlet, until we were ready to make a fertilizer using these nutrient-rich algae. Ts’msyen peoples have long used seaweed (and fish guts) as fertilizer to enrich the soils and foods of the North Coast, so we always knew this would be a great infrastructure-lite use for this batch of kelp.
Our Food Systems Coordinator, Charles Gerein, spent some time researching the best kelp fertilizer recipes, and in February 2023, Metlakatla Development Corporation and Ecotrust Canada thawed, rinsed, and soaked around 900 lbs of kelp to reduce the salt content of the algae. After which, we transferred the kelp into six 55-gallon drums, where it’s currently fermenting in freshwater. We give the increasingly smelly fertilizer an occasional stir.
This fertilizer will be ready for local use in just under a month, and we hope locals will try it in their gardens and house plants this spring! Samples of the fertilizer are currently being analyzed by a lab, and we’ll share the nutrient content of this batch of fertilizer when it’s ready for distribution.
Why seaweed fertilizer?
- Contains beneficial nutrients such as potassium, phosphate, and magnesium.
- Used by gardeners wishing to avoid animal-derived or chemical fertilizers.
- All types of plants benefit as it provides vital nutrients while improving root nutrient intake and resistance to disease.
- Improves soil quality by promoting bacterial activity in the soil, which improves structure, aeration, and moisture retention.
- Keeps pests, particularly slugs, under control due to inherent salt content and sharp edges (if using whole).
- Sustainable, renewable fertilizer source found locally in the Pacific Northwest of BC.
How to use seaweed fertilizer?
- Dilute the fertilizer, ten parts water to 1 part fertilizer, and apply to the soil at the base of plants once every two weeks. The dilution rate can vary. Use on lawns, houseplants, flowers, and fruit and vegetable plants.
- Use the fertilizer once plants have established root growth during the gardening season, not when they are young.
How can you get it?
A few drums of the fertilizer will go directly to local communities and farms. The rest of the fertilizer will be available at a pop-up market Ecotrust Canada is organizing on Saturday, April 29th from 11am-2pm in Cow Bay, Prince Rupert, BC.
If you bring your own container, you can fill it with fertilizer for free! We recommend bringing a container that seals tight to avoid spills. We’ll also provide pre-filled containers of fertilizer, which you can get for a suggested donation of $5.
If you can’t make the market, please contact me at maryw[at]ecotrust[dot]ca if you’d like to get your hands on some fertilizer OR our next batch of fresh sugar and winged kelp that we’ll start harvesting in May and June.
We’d love to collaborate with local communities, food providers, and entrepreneurs, and we are always happy to hear from you!
[This blog was published on Apr 27, 2023]