Worm Casting Tea Brewing

I’m exploring Biochar. I’m documenting progress on this thread: Biochar Biochar is not a rich nutrition source in and of itself. It is mostly a carbon structure that has a huge amount of surface area that can provide a home for microbial life. The first step in using biochar is to balance the C:N ratio just like compost. This makes it amenable to microbial life. The next step is to add the microbes. My application for worm casting tea is to introduce microbial life to biochar that I plan to experiment with on my tree seedlings. However, folks use worm casting tea for other plant applications, so I thought I’d start a new thread on my brewer.

You can buy a brewer for worm casting tea, but after watching a few videos and looking at a couple designs, I decided to build my own using a 5 gal bucket I already had and $20 in plumbing parts from lowes.

Many designs use air stones as diffusers and aquarium pumps to provide air. I already have 5 gal buckets and a regular air compressor in the garage that I use for air tools and such. I decided to use that as my air source.

I make a PVC diffuser that fits into a 5 gal bucket:

It is just 1/2" PVC pipe and some fittings with an adapter hooked to a quick connect. You will also notice the T at the top. The only reason I used a T to connect the quick connect is to provide a place to hook a bungy cord to secure the unit to the bucket.

On the bottom side I simply used a tiny drill bit and drilled holes through the PVC pipe. I didn’t thing you could see them on the picture so I used a marker and drew black lines along where I drilled the holes. If you notice I put an elbow on the ends of the cross members and a short length of pipe and endcap. These act as feet to keep the unit stable.

Here is the diffuser simply placed in the 5 gal bucket:

The final picture is the unit in the first test operation. I cranked the output pressure on the compressor down to 20 psi and connected it to the quick-connect. It fired up just fine. I’m not sure I really needed it, but you can see how the bungee goes over the T to secure the diffuser in the bucket.

The next step is to get some worm castings. I think I found a local source.

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I hope it’s in your home/yard! :wink:

No, I don’t manage my own, but I think there is a family farm not too far from mine that sells them fresh.

I’ve had many worm bin designs and found that the flow through type are the easiest to manage. Scraps in the top, harvest out the bottom. No need to dump and sort.
I simply mix with water and either soil drench or filter and foliar spray.
If I understand correctly, the purpose of aeration is to increase the aerobic population. I used to do that, but find it not necessary as the anaerobic bacteria deeper in the soil are also beneficial and the soil will balance itself with what it needs.
Some folks also will add molasses. I find that adding milk feeds important microbials to balance fungal overpopulations from wood chips and the like (which I have).

Thanks for the guidance. This will be my first go at charging biochar with it. How much milk do you use in a 5 gal batch?

One reason I was looking at maximizing the aerobic population is that the air pruning containers I’m using or only 1 to 3 gallon and have protrusions on all sides directing rots to openings. So, the container environment is more of an aerobic one.

Perhaps the non-aerated approach would be better for the field planted trees.

Why would worm casting tea be better than worm castings by themselves. When I make compost I throw all my kitchen scraps including meat into 32 gallon garbage pales with holes drilled in the bottom and cover each bucket of garbage with a bucket of horse stable waste.

After they’ve been sitting for about 6 months they are a foul mix of low oxygen rot and thousands of red worms (apparently a species that require very little oxygen- I find them in rich, soggy marsh soils but never had to transport any to my compost- they find it).

If civilization crashes they will be my most reliable protein source, meanwhile, they turn my compost into a kind of worm castings. I have to let the slop air out in a secondary composting before it is ready for my garden.

No need for tea, bring the organic matter with the rest of the meal is how I see it.

Hey Alan,
I agree with you (if you build it they will come) but there are circumstances in which folks find the worm castings tea indispensible. (1) Certainly for foliar applications to balance out fungal or other bacterial populations. One day I’ll go back through my journal and catalog all the problems this has reversed. (2) In established plantings where immediate remediation is needed. If you already have manure worked in, likely these problems don’t come up for you. (3) Access, hauling and GMO feeds are concerns with those who don’t have stables.

To forestandfarm,
I’d use about 1/4 c fresh milk/5 gal bucket. Spoiled milk has some of the bacterial food used up already. With my bin I just harvest, mix with water and apply. I use a filter bags made for paint sprayers doubled up to filter what I will foliar spray. I think keeping the castings wet is important so if you have access to fresh (vs. dried) castings they are ‘ready to use’ ;o)


The application here is to inoculate biochar prior to use. Biochar has a huge surface area that can be home to lots of microorganisms. The idea of the tea of casting is to increase population first by feeding and aerating for 24 hours. Second is that the water serves as a carrier to distribute them throughout the biochar.

Again, I’m new at this. There is no reason I could not start with compost and make compost tea the same way. My pile started with all wood chips. I did throw lawn clippings in during the summer as they were cut and used my loader to mix, but I doubt if I got nearly enough green. My guess is that there is some composting going on down at the core of the pile. I just figured fresh worm castings would be a good source for the brew.

IMO, the tea is better only when you have bare soil devoid of beneficial microorganisms. If you have a healthy soil with worms already in it, you’ll see very little difference.

[quote=“forestandfarm, post:8, topic:4399”]
Biochar has a huge surface area that can be home to lots of microorganisms. [/quote]

I don’t claim to be an expert on biochar but my thinking is it has a high cation exchange capacity. Meaning it holds onto nutrients in ionic form in the soil just like clay and organic matter. Have you read that it holds microorganisms rather than nutrients?

It holds nutrients and also changes the tilth of the clay to provide a home for microbes. Prior to adding worm tea, I’m trying to balance the C:N to about 20:1. I’m just starting with hand-on experience, but my reading suggest at this C:N you can add it as a direct soil amendment without tying up nutrients. Added without regard to C:N, my reading suggests can tie up nutrients for several years so a positive response is delayed.