We’re always banging on about soil being the foundation of your entire food growing system, and how important it is to be constantly improving it.

So one of the common questions we’re asked, is “how?”

There are lots of techniques available to help you improve soil, like adding aged chicken manure, and compost and worm castings (and we’re big fans of them). Planting a diverse understorey is another really useful technique for rapid soil improvement, and you can learn more about that here.

Another useful technique is brewing your own compost tea. We brew it on a big scale (as you can see in the photo below), but it’s also easy to make on a home garden scale.

Our 1,000 L compost tea brewer set up for demonstration at a workshop
Our 1,000 L compost tea brewer set up for demonstration at a workshop

So, what is it? It’s probably easiest to start with what it’s NOT, which is compost extract.

Compost extract is made by putting compost in water and swishing it around or leaving it to soak. You can do a similar thing with weeds to make a weed tea or weed extract. They’re both fantastic things to do, but all they do is to put the nutrients and any microbes present into solution.

This method doesn’t increase the number of microbes in the brew, and that’s the point of compost tea.

Hugh showing off his bathtub full of rich worm castings, which will be used to make compost tea
Hugh showing off his bathtub full of rich worm castings, which will be used to make compost tea

To brew compost tea we start with a small amount of something that’s rich in microbes, e.g., good compost, worm castings, or leaf litter from under a mature gum tree are all perfect for this. Then we put the source material in water, agitate it to knock the microbes off, then add microbe food and oxygen for 24-48 hours and voila! The microbes breed like…well, like microbes (that is, REALLY fast when conditions are right).

Components for the compost tea brewer
Components for the compost tea brewer

This turns a small amount of healthy microbes (bacteria, fungi, nematodes, and protozoa) into a huge number in a very short time.

On the farm we always check the brew to make sure we’ve actually got the right kind of microbes, but that’s not necessary in a home-brew situation, as long as you follow the guidelines.

Hugh checking the compost tea to make sure it's full of microbes (and not just brown water!)
Hugh checking the compost tea to make sure it’s full of microbes (and not just brown water!)

Then we just put the tea on the soil under our fruit trees, and let the microbes go to work. 

There are a couple of drawbacks about making compost tea, which are that it’s a bit fiddly to make and needs some specialised eqipment, and also that the microbes are a bit like Goldilocks and won’t be happy in the soil if the temperature is too hot or too cold.

If you want to know more about this simple and effective method of quickly building healthy soil, we’ve designed a short course just for you! It’s called The Art of Compost Tea, it includes plans for making a home-sized brewer, and you can download it here.