Let's Make Compost Tea

Andrew Shindyapin

November 11, 2018

This blog post describes the motivation, theory, and practical application of composting and compost tea. I also have a materials/supplies idea list on Amazon, if you want to take skip the explanation and just take a look at the materials needed.

Motivation

Why compost? There’s the very virtuous and obvious answer: to recycle kitchen waste and divert it from the landfill. That’s a great answer, but there is more to it than that. When you compost and apply it to your yard/garden, you are also producing homemade fertilizer. If you also make and use compost tea, you actually enable your plants to ward off pests. Thus the compost tea acts as a homemade natural pesticide. I find the ability to use waste as an input into a resource produced at home and consumed at home very appealing.

Theory

I understood the basis of composting and applied it for a many years now. However, I always thought that the idea of compost tea amounted to little more than hippy voodoo… that is, until I listened to a three-hour lecture by Dr. Elaine Ingham, a microbiologist and soil biology researcher, where she discussed the importance of having a diverse set of organisms in the soil.

Having a highly-diverse population (what is called the soil food web) allows plants to get all the nutrients they need to grow well. This range of organisms compete with pests, keeping their population minimal. Also, some of this biodiversity includes predators who eat the pests, actively reducing their population. This doesn’t mean you’ll never see pests among your plants, but it does mean that your plants won’t be ravaged by the pests.

For further reading on soil biology, see the link at the bottom of this blog post.

Application: Composting

There are different types of compost bins that you could purchase or make yourself. The simplest is in fact no container at all: you can just throw all your food waste into a pile in your yard somewhere. Of course, that comes with several disadvantages: the untidiness of the pile and the possibility of rodents. Next up in effort is a wire mesh rolled up in a cylinder a few feet in diameter. You can also build a box with a lid, like I did, or purchase a ready-made container.

To facilitate quick decomposition, make sure the compost has contact with the ground, so the diversity of organisms have a large surface area for transferring onto the food waste. Alternatively, if you want to make or use a compost container that has no direct contact with the soil, you can do so but you will need to add a compost accelerator/starter that has the requisite biodiversity of organisms. I initially put my compost box on pavers, and did not use compost starter. My compost decomposed very slowly, taking months to show signs of decomposition.

Then I moved the compost bin to be placed over ground, and used a pitchfork to turn the compost. Then, the decomposition process greatly accelerated. I would estimate that any given kitchen waste completely decomposed within a month. I added well-composted compost from a friend for good measure; this has the same effect as adding compost starter. Besides food waste (including napkins), I also make sure to throw wild-growing mushrooms, grass clippings, and pruned branches into the compost bin.

You can also make a worm bin to decompose your food waste, and even keep it inside (vermicomposting). (The worms will naturally find your waste in your outside compost; inside, you would have to add them intentionally.) The US Environmental Protection Agency has an excellent how-to article on making and maintaining the worm bin. See the bottom of the blog post for the link.

Application: Making Compost Tea

Here are the steps I take to make compost tea:

I start with my aquaponic pond water. You can also use tap water, but you would want to aerate it with the air pump and air stone for at least twenty-four hours to get the chlorine and/or chloramine out.
Then I place the eight-inch airstone on the bottom, and turn the pump on (see the first picture below). Next, I add well-decomposed compost into a mesh bag, zip it up, and attach it to a carabiner s-hook, which I attach to the edge of the bucket while lowering the mesh bag into the bucket. (I cut out a small notch in the lid to allow the s-hook and the tubing into the bucket with a closed lid.)
I let the pump run for at least twenty-four hours (more if it is colder outside). After twelve hours, a thick froth forms on the top of the tea, which is indicative of the bacteria and other organisms going into hyper-growth mode and multiplying quickly.
I then fill up my sprayer with the compost tea, and spray the trees, flowers, grass, and the garden veggies with it. I apply the compost from the mesh bag around one of my fruit trees.

At a minimum, it is good to repeat this process twice a year: early spring, after the last frost, and early autumn. However, because the process is so easy, I’ve done it every couple months starting in the spring. I would not recommend making and using the compost tea if the temperature dips below freezing.