Using an underground composting bin is my favorite way to compost “normally” (by normally I mean not a vermicomposting bin, which is also a great way to compost and I think both is the best way to go).
Composting is an art and using an underground composting bin is no different. There is sometimes a learning curve, but once you figure it out it is simple and easy to get extra nutrients for your garden.
Here is a list of items that you should not compost to help you get started. You can follow a specific percentage of greens and browns to make composting faster, but for the most part, put compost-able things together and it will turn into compost. The closer you follow a perfect ratio, the faster you will get a final product. On the other hand, if you try to follow a perfect ratio you may end up with one group or the other (browns or greens) sitting out waiting to go in a bin.
The Many Ways to Compost
I have tried many ways of composting. Here are some of the things that I have tried:
- a pen made of chicken wire
- composting bins purchased online
- red-wiggler worm systems, otherwise known as vermicomposting
- underground composting bins.
A chicken wire pen works great for leaves and brown waste, but if you put food waste in them then they become critter magnets. Composting bins that you purchase are wonderful, but tend to be expensive. Vermicomposting is my favorite compost because it is quick, but you are limited to the amount you can make. I think it is best used as a way to get small amounts of compost quickly rather than your primary means of composting. That leaves underground composting bins. You can put anything in them, the temperature holds true a little better than above ground bins, and are more critter-proof than other composting bins.
Carnivore manure should be avoided in compost at all costs. You can buy special composting bins that can handle it if you are interested, but do not put it in your regular underground composting bin (or even in an above ground one made for normal compost). Chicken manure and bedding can go straight in an underground composting bin. In fact, it helps speed up the process tremendously. If you raise mealworms for your chickens then the mealworm frass can also go in a compost bin.
DIY Underground Composting Bins
I especially like my DIY underground composting bins and that is what I am using currently.
- It holds temperature well
- It stays moist (especially important in the dry Arizona climate)
- It is not torn apart by animals since they have to jump into it to get to the goodies and I can put a lid on it. I found that few animals are willing to jump into a dark 150+ degree hole to get foodstuff unless they are desperate. In my year of composting at this location I have never had things taken out of the underground bins (unlike my above ground bins and chicken wire pen that were raided almost every night).
Another bonus to this type of a compost is that your neighbors (and you) don't even see it. The flip-side to that is you have to use a long-handed shovel to get the compost out when you are done.
Making your own DIY Underground Composting Bin
- STEP ONE: Get a container. A large underground composting bin is best (a smaller container will not hold the heat the same way as a larger one). Typically you want a compost bin to be 3 foot x 3 foot to keep in the heat, but a slightly smaller bin works fine when you are using an underground composting bin. Both of my containers are 35-45gallons (like this one at Amazon) and both HAD a lid. The Rubbermaid container held up very nicely (and is still going strong more than 2 years later), however, the lid of the off-brand container cracked in the sun within a few months.
- STEP TWO: Drill holes in the bottom and side of your underground composting bin. I drilled about every 4 inches in the bottom. I then drilled one row about 3″ up from the bottom (spaced those about 4″ apart each) and a second row about 3″ down from the top. The holes will allow your bin to drain and provide a place for earthworms to find your compost (although Arizona is one of the few places in the world that does not have earthworms. There are a few Arizona locations that do so if you see them count yourself lucky!)
- STEP THREE: Dig your hole. I dug it so the container is flush with the ground, but you can have it sit a little above the ground if you want.
- STEP FOUR: Drop your container in the hole and fill in the sides with soil.
That's it, you are done making your DIY underground composting bin!
Other Underground Composting Bin Tips
I put two underground composting bins next to each other. I fill one then start turning it (once a week) and letting it compost while I am filling the other. By the time the second bin is full I am ready to take out the compost from the first bin and start over. I get about 3 bins a year from this method (although most of that time is filling the bins, once I start turning it it takes about 8 weeks to compost and then I let it cure for 4 weeks).
Once cured I filter my compost. Anything that didn't compost all the way (the big stuff) goes into the other bin. This speeds up the composting time for the second bin (because it adds the composting microbes that were in the other bin). This is the sieve I use and it works great or you can look for a good sieve in a garden store. I have seen some people use hardware cloth to filter the compost and that can work too, but for less than $20 an actual garden sieve was worth it to me.
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