Composting bins can be made in all different shapes and sizes. This video does a review of 10 different composting bins and tumblers. They find that the bins reach the highest temperatures–about 140 to 160 degrees. The compost tumblers reach about 130 to 140 degrees. The hotter the better for making compost.
There are some drawbacks to the composting bins:
It is much easier for animal visitors to get into the compost if you are using food scraps.
In order for the composting to be quick you need to turn the pile.
It is hard, physical labor to turn the pile.
It is time-consuming to turn the pile.
They talk about air circulation which is a real plus for composting and some of the bins have a lot of holes for great air circulation. (Though these holes can be a problem if you have animal visitors because it is easy to get into the pile.) There was a complaint that the compost tumblers didn’t have so much air circulation because of a lack of air holes. I disagree because a lot of air circulation happens in the tumbling which is one thing that helps tumblers create compost faster.
Lastly they show a compost tumbler which didn’t have a proper mix of greens and browns. I was very interested in this because I did the same thing with my compost tumbler. See this post Greens and Browns in Composting. I quickly corrected the problem with the addition of browns or carbon to my compost. In my case I used peat moss. It was in the middle of the summer and I didn’t have shredded leaves around. This is indicative that composting with tumblers is not perfect and you can mis-manage them just like you can mis-manage any compost pile.
Here is the video of the review of compost bins ( http://youtu.be/-lCVcv04K5Y):
It is important to understand about the ratio of greens and browns in composting. Greens have a low carbon to nitrogen ration. So they are high in nitrogen or protein. Examples of greens are vegetable scraps from your kitchen, animal manure, green leaves and cut grass. All “greens” are not actually green with coffee grounds being an example of this. See finished compost in the picture to the right.
Greens help the bacteria and fungi grow and multiply creating a high temperature in the compost pile. The bacteria and fungi and other micro-organisms are responsible for the decomposition of the plant materials.
Browns have a higher carbon or carbohydrate content. They decompose at a slower rate and include fallen leaves, sawdust, paper and straw. Browns also supply food to soil organisms. In a compost pile browns absorb odors and function to keep the pile from getting too wet.
In order to compost successfully you need to have a combination of greens and browns. In the summer it is harder to obtain a lot of browns unless you have leaves saved up from the autumn. See this link for a chart of what you can compost or not. Also check out the whole website. It will teach you a lot about composting.
This summer my compost bin was way too wet and smelled rotten. As I was examining it one day I noticed a lot of white worm like things. I was really grossed out. After some internet research I discovered that they were maggots! Ugh! And that this can happen if your pile is too wet.
My problem was that I didn’t have enough “browns” or carbon to balance out the mix. I added more leaves and that really took care of the problem. The compost dried out a little and the maggots died. Hurray! I wouldn’t have wanted to see all the flies that would have come from those maggots! Now they will just be part of the compost and fertilize my garden. Has this happened to you? Next week I will post about a worm composting experience this week that really surprised me!