Seaweeds 'n Soils - World Soil Day 2020
Although one of the benefits of farming seaweed is that we don't need soil, soil-science is still high on our agenda at PhycoHealth.
Why? Because seaweed can contribute a lot to the quality of soil and plants that we grow on land.
I knew that, you say - because you already buy seaweed fertilisers, or harvest some from the beaches, for your own plants right?!?!? Because seaweed are full of minerals that can break down and provide food for the plant, right?
Well yes you are right, but the story doesn't end there. There are many ways that seaweeds can benefit plants,
In a weird sort of analogy, the roots of plants are actually just an inside out version of our own gut system. The region from the root cells and out into the soil is the microbiome of plants, and seaweed can play a role in feeding that microbiome just like it does in our research on the human gut microbiome. In this way it can help to promote the good bacteria and fungi that plants needs to extract minerals from the soil more effectively, and it can also help to suppress bacteria and fungi that are otherwise a disease on the plants.
Then there are biologically signalling molecules in seaweed that turn on and off different defences in the plant itself. It is a bit like strengthening our own immune system from within our guts. Some of the plants that we love to eat can be grown organically and without pesticides by using seaweed, for example strawberries, wine grapes, the humble carrot, and locally we showed that a Jervis Bay wild seaweed bloom could be used to grow bigger radishes.
There are so many publications now showing how different seaweeds affect different crops and soils that it is hard to get the total picture, but in 2015 we published a small review generalising some of the benefits (picture below).
The importance of the benefits of seaweed to plants should not be underestimated, as we face increasing pressures on our land food production systems from more drought, higher soil salinity, depleted soil nutrients. The adaptation and tolerance of land crops to the climate stressors of drought and increasing soil salinity can be addressed in part by adding seaweed to soils. It is often best however to compost your seaweed at about 5% of the total compost. Just like for us, about 5% seaweed in our diets is just about right. Also make sure you only take what is allowed from your beach according to your local regulations. In NSW, Australia, it is 20kg per person and day. In Australia, the USA and Canada there are lots of commercial wild harvests for commercial seaweed soil additives which makes it easier for you.
So PhycoHealth says: Seaweed everyday, inside and out and in your soil.