Composting artificially accelerates the decomposition of crude organic matter and its recombination into humus. What in nature might take years we can make happen in weeks or months. But compost that seems ready to work into soil may not have quite yet become humus. Though brown and crumbly and good-smelling and well decomposed, it may only have partially rotted. – Steve Solomon from Organic Gardener’s Composting
My Mother’s expression, “life is best left as a mystery”, is the way I’m tempted to feel about composting. It’s the type of thing I want someone to give me a recipe for and just like that I have rich, sweet smelling compost that will make my beans ready for Jack to climb to the sky on. There are countless articles, books and videos on the subject and countless methods and contraptions marketed for making it. I won’t act like I fully understand it, nor will I go into the details about how it’s made. All I do know is it’s all good, but like dirt, some composts are much better than others and making it right is no easy task. Steve Solomon compares making it to making beer as it involves fermentation and careful attention to ingredients, temperature, mixing as well as many other factors.
With so much overwhelming and many times conflicting information about it, I can only say to the first time composter that unlike fertilizer (which can turn into a disaster if it’s not made right) making compost is almost always good for the environment and the garden. Another way I like to think of it is, it’s basically the poop of many tiny animals all around us and this poop is something that actually smells good and makes things grow. What a beautiful concept.
So how is it made? Not sure I want to go there but what the heck. Plainly speaking, there are all these tiny animals all around us we can’t see whose mission in life is to break things down into something I mentioned earlier, called humus. As I’ve said, anything will break down, but some things break down in a few months especially if they are mixed with the right ingredients and under the right conditions. Generally those conditions require heat, air, moisture and the perfect blend of “browns” (or carbon sources) and “greens” (nitrogen sources). “Greens” are generally fresh organic material like grass and leaves (that are still green). “Browns” are older and dryer organic materials such as straw and dried leaves (that have turned brown). A good source for examples is here . I have lots of the “greens” but not so much of the “browns”. Actually, I take that back. I have lots of “browns” like paper and cardboard but “browns” with too much carbon break down very slowly. For example, sawdust has an extremely high carbon to nitrogen ratio (or C/N ratio). The higher that ratio is, the longer it will take to turn into compost which poses a problem if you’re trying to speed up the decomposing process. So I’ve come to the conclusion that for my small composting operations, I may want to stay away from using material, such as cardboard and paper with a C/N ratio that will take longer than my particular situation requires. Anyway, from what I’m gathering, unless you’re Vermicomposting (or composting with worms) it’s best to have a C/N ratio of around 25:1.
So you have your kitchen scraps like egg shells, coffee grounds, lettuce and apple cores, etc. You throw them in something like for me, a bowl. When it fills up you add it to the compost pile. If you do nothing but continue to add your kitchen scraps, you can come back in a year, turn your pile and find some nice worms and sweet smelling, crumbly stuff at the bottom. This method is called Cool or Passive composting because the pile doesn’t heat up. It works but takes about a year and can be faster if the pile is turned twice a year.
A quicker method that generally produces better results is Hot or Active composting. This method requires the pile to sit for a period of time without the addition of new materials. When the right combinations of air, heat, water, “greens” and “browns” are mixed together, it triggers bacteria to reproduce and rapidly feed on the pile causing the temperature to raise to around 130 – 170 degrees F. Once these bacteria finish eating, the pile will cool down and enter a new phase of decomposition. This link explains the process.
How in the world do you adjust for that perfect “green” and “brown” ratio? Math wizard I am, I must confess I do nothing of the sort. Steve Solomon has a more practical alternative.
It is far more sensible to learn from experience. Gauge the proportions of materials going into a heap by the result. If the pile gets really hot and stays that way for a few weeks before gradually cooling down then the C/N was more or less right. If, after several turnings and reheatings, the material has not thoroughly decomposed, then the initial C/N was probably too high. The words “thoroughly decomposed” mean here that there are no recognizable traces of the original materials in the heap and the compost is dark brown to black, crumbly, sweet smelling and most importantly, when worked into soil it provokes a marked growth response, similar to fertilizer. If the pile did not initially heat very much or the heating stage was very brief, then the pile probably lacked nitrogen. The solution for a nitrogen-deficient pile is to turn it, simultaneously blending in more nutrient-rich materials and probably a bit of water too. After a few piles have been made novice composters will begin to get the same feel for their materials as bakers have for their flour, shortening, and yeast.It is also possible to err on the opposite end of the scale and make a pile with too much nitrogen. This heap will heat very rapidly, become as hot as the microbial population can tolerate, lose moisture very quickly, and probably smell of ammonia, indicating that valuable fixed nitrogen is escaping into the atmosphere. When proteins decompose their nitrogen content is normally released as ammonia gas. Most people have smelled small piles of spring grass clippings doing this very thing. Ammonia is always created when proteins decompose in any heap at any C/N. But a properly made compost pile does not permit this valuable nitrogen source to escape. – Seve Solomon from Organic Gardener’s Composting
As you’ve probably already discovered there are countless contraptions marketed to the gardener for composting. Here are just a few. As much as I would love to make an open air pile of compost, unless I want to thoroughly irritate my neighbors or invite unwanted critters, I’ve decided against it. Gracious family members have endowed me with two bin composters known as “tumblers”. The idea behind them is the contents can get air while the drum is being turned therefore speeding up the process. The compost is also contained from critters. Tumbler bins aren’t cheap (no less than $100.00) and up until now I haven’t had the best success which I can attribute to ignorance and neglegence but it’s high time I turned over a new “leaf”. This is serious.
Seriously, tumbler bins work by Hot composting. It’s a little tricky to get everything right as there is only a small opening in which to get at the contents but I’m going to give it my best shot. The University of Maryland Extension explained it to me this way:
Your ‘urban’ setting does provide you with some composting challenges. Elevated tumblers are a good idea to prevent rodents. On the one hand, tumblers are designed for ‘hot’ composting, i.e., filling the bin with the proper mix of materials and not adding additional materials until the finished compost is harvested. What you may try is keeping a ready supply of shredded dry leaves, sawdust, or straw next to your tumblers. Use one of the tumblers for your daily addition of kitchen scraps and add an equal amount of the dry carbonaceous material. Check the moisture content and add water only if needed. Give the tumbler a half turn. When the tumbler is filled, continue turning it each time you go to the other tumbler. Continue the process until the second tumbler is filled, then harvest the first tumbler. and continue the process. You can store finished or nearly finished compost in a metal or plastic trash can until you’re ready to use it.
As I mentioned earlier, I have a hard time finding the “browns”. Keeping the environment and expenses in mind, I don’t want to have to haul in materials especially ones that may have been sprayed with pesticides, I’d like to find good carbon sources nearby and I can think of a very good and abundant one except I’ll have to wait until Fall to get it. We’ve got huge trees all over my neighborhood. So in the Fall I’ll be going around to curbsides collecting leaves. As many as I can manage. I’ll put them in a pile and run over it with a mower a few times to shred them. One man’s trash is another man’s treasure or woman’s in this case. Since I don’t have access to these leaves now, I’ll be using whatever I can find. When finished vegetable plants dry out, I’ll use them and if nothing else, I’ll use cardboard (which I have loads of).
But there is another method much to my husband’s horror I’m willing to try called Vermicomposting. That will be in another post.
Oh yeah, and one more thing about composting. There are some things not recommended to put in the compost pile.
Some good links about composting:
Organic Gardener’s Composting by Steve Solomon
University of Illinois Extension
Compost Info Guide
Maryland University Extension