Is the answer to land-based agriculture found in the ocean?

For almost a hundred years, conventional agriculture has been using industrial fertilisers and pesticides to enhance crop production and growth. We now understand that overusing chemical fertilisers is terrible for the planet. Fertilisers leave soil, water, air and food polluted with harmful toxins. They cause greenhouse gas emissions and eutrophication of lakes and oceans.

Macroalgae (or seaweed), meanwhile, possess biologically active compounds, which also positively influence plant development and soil fertility. In fact, research is finding that many of the concerns raised over fertiliser use can be answered with seaweed alternatives. Developing these products on a commercial scale could offer a real opportunity for food systems and the fight against climate change.

Land-based agriculture generates billions of tons of produce, far outstripping aquaculture, with our oceans potential remaining largely untapped.

There are over 9,000 species of marine algae, divided into three main types: brown, red and green. Kelp is the most common and grows in huge underwater forests stretching across the vast coastlines of most continents. Kelp forests effectively regulate climate change, growing by up to 60cm a day and sequestering 10-times more carbon dioxide than land-living trees or plants.

Seaweed helps improve marine biodiversity, water quality, reduces ocean acidification, and enhances coastal communities' livelihoods. Unfortunately, current method for farming seaweed is labour intensive, costly, and primarily wild-harvested in small amounts. If solutions are found to farm, cultivate and process at scale, seaweed could offer the world a renewable resource that may massively change the face of land-based farming while fighting climate change.

Seaweed-based solutions offer farmers a nature-based alternative to today's chemically-intensive methods. Seaweed can produce a wide variety of products for agriculture and horticulture. Without damaging side effects, its practical uses include being a bio-fertiliser, bio-stimulant, and plant protection product.

Here are some of the ways seaweed benefits agriculture:

- Seaweed is rich in minerals and nutrients, promotes higher seed germination and plant protection.

- It decomposes faster than other types of organic manure, is a great compost full of minerals and enzymes which improves soil structure and quality.

- As a bio-stimulant, it improves root strength, crop yields and water retention.

- It has a positive impact on abiotic and biotic stress results, minimises agricultural loss, and is particularly useful in arid and desert climates.

- If mixed with animal feed, it reduces methane emissions from cattle and provides the animals with healthy micro-minerals.

- It enables farmers to switch from hazardous chemical fertilisers to organic farming methods.

Macroalgae contain a diversity of macro and micro-nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, etc.) and significant amounts of vitamins that help plant development. Phycocolloids (a kind of seaweed gum) and enzymes affect soil's physical, chemical, and biological properties. This improves seed germination, plant establishment, water retention and soil aeration.

Brown algae, meanwhile, are amazing bio-stimulants. They improve the natural health of plants, boosting their abiotic tolerance and resistance to pests and diseases.

Seaweeds are hormone-containing products with identifiable amounts of active plant growth substances. Seaweed-based bio-stimulants can accelerate and perfect the natural processes of plants, helping them absorb nutrients at a molecular level which increases growth. This helps plants grow, improves their natural defences and stress resistance levels.

While seaweed bio-stimulants are reasonably easy to produce, they are challenging to bring to market due to complex regulations and lack of widely accepted standards. Similarly, there is little empirical data available to effectively compare the positive carbon impact of the seaweed supply chain with their industrial counterparts.

Seaweed's potential to offer solutions to the climate crisis and the burden of feeding the world's population deserves further investigation. Scientists are hard at work to better understand the value of seaweed as a bio-resource. As agriculture shifts toward responsible offshore marine aquaculture at scale, seaweed can offer transformative solutions for the industry.