On Ungolden Pond
Well, I have finally gotten rid of the mosquito-larva-laden pond in our front yard. It had a pump in it that got clogged up every two weeks, which meant it was continually clogged because I was too lazy to clean it that often. So, it got algae and scum and was not very pleasant. Though I was probably providing habitat for many creatures, I think it was not so healthy for the human creatures that lived nearby. (ie. us!)
So I pumped out all the water onto the front lawn — why let it go down the drain? Might as well water the lawn — and ripped out the plastic pond liner that the previous owners had put in there. Rather than throw it out into the landfill, I put it up for grabs on Freecycle, and it was snapped up in no time by a grateful single mom whose son always wanted a little gurgling pond in their yard. (The son better stretch well before he starts digging, because that’s a big pond and will take a lot of digging!)
Here is a view of the old pond liner that I gave away on Freecycle.
The Compost Pit
But now I am left with a hole in the exact shape of the liner above. How to fill this hole. I need dirt. Cheap Dirt. Hmm… where can I get some dirt?
Wait! I know! Now I can kill two birds with one stone. This hole in the ground will become my new compost pit. Once the items have decomposed into compost, the compost can just stay where it is and be the dirt that fills the hole and becomes part of the lawn.
Only problem is, I have never composted before. So, I did some research.
What I found is an awesome free book on Project Gutenberg by Steve Solomon called “Organic Gardener’s Composting“. It is very detailed and illuminating.
However, it is also long, so I’ll try to summarize it here. If you are going to compost yourself, I would definitely recommend reading the whole book for a full explanation of the “why” behind everything. Otherwise, if you are merely curious about the really bare basics, just read on.
Carbon and Nitrogen
Carbon and nitrogen are two elements that form the basis for many compounds used by plants.
Carbon is used to create carbohydrates, which are sugars, starches, cellulose and lignin which form the energy storage mechanism and the structure of many plants. They are also transformed into fats and oils from there. Carbohydrates are made by plants via photosynthesis from carbon dioxide in the air, water, and light energy from the sun. Plants can make these very easily. They can also get some of their carbon from the ground.
Nitrogen is used by plants to create proteins from amino acids that are composed partly of that nitrogen. However, nitrogen cannot be “fixed” from the its gaseous form in the air (N2) into a solid form usable by plants as easily as carbon can. Instead, plants have to get their nitrogen from somewhere else. Some plants get their nitrogen from various single-celled organisms that fix nitrogen into a form that plants can use. Some plants, like beans, even create an environment for these organisms to grow around their roots. Other plants need to absorb their nitrogen from their surroundings in the form of composted materials that happen to be near their roots.
The Carbon/Nitrogen Ratio
The most important thing to think about in compost is the carbon/nitrogen ratio of the stuff you are putting in your compost heap. You want to achieve the ideal of 25 units of carbon to 1 unit of nitrogen. If you do, the compost will degrade nicely and form healthy, high-quality fertilizer for plants with enough carbon and nitrogen for the plants to thrive. The final, stable compost will have a ratio of about 12.5 to 1 because some of the carbon is “burned” off by the composting organisms to get their energy.
Most things have both carbon and nitrogen, but some are very lopsided in one way or another. For example, sawdust and wood are almost all carbon with a ratio of between 100 and 400 to 1. Urine is almost all the way on the other side of the scale with a ratio of 3 or 5 to 1. To balance it out, you need to mix a little of both to achieve the 25 to 1 ideal.
Finding the carbon/nitrogen ratio of any particular piece of material is impossible without taking it to a lab for analysis. Even within a particular type of material, it depends on how that material was grown and what happened to it afterwards. For example, grass clippings from your lawn may have anywhere between 15 and 40 to 1 depending on the time of year and how much and which fertilizers you put on it.
Because of that, it is easier for the home composter to lump types of material into 5 general classes with average ratios that represent everything in the class:
- High Carbon Materials – these materials have a ratio of 100 to 1 or more. Certain things like hardwoods can even be as high as 400 to 1.
- Medium Carbon Materials – these materials are in the range of about 50 to 1
- Balanced Materials – these materials are in the range of about 25 to 1, and are in the right range already.
- Medium Nitrogen Materials – these materials are in the range of about 12 to 1
- High Nitrogen Materials – these materials have a ratio of 6 to 1 or less
Here is a short list of materials and the classes they are in. This is not an exhaustive list! I will be making a separate page with a large list of materials as I find them.
|dried brown grass clippings
dried corn stalks
low quality hay
|green grass clippings
top quality hay
The trick then is to mix these things in the right way to generally achieve about 25 to 1.
If you do not mix them in the right way, you will still get compost that looks and smells the same as regular compost, but it will not have the right mix of nutrients or nitrogen for the plants. I found out that the municipal solid waste compost I was advocating in an earlier post comes mostly from balanced to high carbon sources, which are basically all the garden wastes from everyone’s yards. These are green and dried grass clippings, dried plants, fallen dried leaves, branches and wood clippings. Basically, it is everything you throw into the green bin when taking care of your yard and garden. All of those things are heavier on the carbon side than on the nitrogen side. This means that the compost is actually lower quality than it could be, and does not provide enough nitrogen to the plants to be a good fertilizer.
To achieve the right ratios, you should put the materials together with the following ratios:
For every unit of high or medium carbon material you put into the compost, put in 24 times as much medium nitrogen or 8 times as much high nitrogen materials to balance it out.
Alternately, you could say:
For every unit of medium nitrogen material you put in, put 4% of a unit worth of high or medium carbon material to balance it out.
For every unit of high nitrogen material you put in, put in 12% of a unit worth of high or medium carbon material to balance it out.
In terms of the balanced materials, you can put in as much as you want, as long as all the other carbon materials are balanced by the nitrogen materials.
When I say “unit” in the above sentences, I mean any type of weight unit like pounds or kilograms. The unit doesn’t matter as much as the ratio between them and that you use the same unit of measurement for everything.
The acidity level for compost should be right about neutral. (ie. pH of 7). Many foods, especially fruits, are very high in acid (pH < 7), and create an unbalanced mix. Check out the list of the acidity of various foods on the FDA web site. To combat too much acidity, you can add in alkaline foods such as lima beans, egg shells, frozen cooked corn, or even a little baking soda (not baking powder). Be careful how much!
You may have seen the NPK measures on regular inorganic fertilizer at the store. These are the measure of Nitrogen, Phosphorus, and Potassium (symbol K) in the fertilizer. These “macronutrients” are most needed for plant development, but so are a wide variety of “micronutrients” that occur in far smaller concentrations. Inorganic fertilizers have many problems that I won’t go into, but one in particular is the focus on the macronutrients. Eventually, if you only replace the macronutrients in the soil year after year, all the micronutrients will get used up by those years worth of crops, and you will eventually get a very unhealthy soil.
Compost can have all the nutrients, macro and micro. The easiest way to achieve this is to just put in a variety of foods into your compost. Mostly, it will come out right by itself. (This is also healthy for you because it means you are eating a variety of foods at home!) However, if you have a large amount of one particular food in the compost, then you will usually run into problems of too much of some nutrients and not enough of others. Variety is the spice of compost, as well as life!
The bacteria in compost need water to thrive. The compost should be somewhat wet like a damp cloth. Add in a little bit of water each time you throw in some more food, and perhaps on hot, dry summer days as well.
There are two types of composting: aerobic, and anaerobic. Both will produce a similar compost using the same feedstocks, but the aerobic compost will smell a heck of a lot better as it is composting. Don’t get me wrong, it isn’t an extremely pleasant smell until it gets near the end, but it is a lot better than the anaerobic composting. Also, aerobic composting is usually faster.
So, you need to turn the compost every few days to introduce new air and new oxygen. Various manufacturers sell “tumbling” composters that can be spun on a hinge or axis. They are expensive (like $250), but work very nicely and easily if you can afford them. I’m planning in the future to make one for myself out of recycled/reused materials. But, that’s for a future posting!
There are some things you should not put into the compost at home:
- Meat and fish scraps, including foods made with meat like spaghetti sauce. These make for great nitrogen materials because they contain lots of proteins. However, there are a number of problems with them. First, when they break down (ie. putrify), they smell EXTREMELY bad due to the creation of putrescine and cadaverine. Anyone who has ever smelled a decaying dead body before knows what I mean. Second, they will also attract pests such as rats and raccoons that will dig through your compost and make a complete mess in your yard. Third, the putrefying meat can be a harbour for bacteria and diseases, so you cannot put the resulting compost on any edible plants in your garden. If you have a completely secure and closed off vessel to compost the meats (concrete?), or if you live on a farm, and you are only using the compost on ornamental plants, then you can compost the meat. Otherwise, if you are composting at home, trust me. Just avoid the meat.
- Oils. Oils go rancid and smell. The smell is not as bad as the meat, but it can get bad. More importantly, oils break down very slowly and the rest of your compost will be done before the oils in it are.
- Human feces. Just don’t do it. For one thing, it stinks. This is not even good on your ornamentals because of the human diseases it can harbour such as E. Coli. If you want to compost your own wastes, there are composting toilets for that purpose which guarantee that the composting happens hot enough to kill all these diseases.
- Diseased plants. Some diseases can survive the composting process and infect your other plants when you use it as fertilizer.
- Weeds with seeds in it. This is because the seeds will survive if the compost doesn’t get hot enough, and you will be sowing a new batch of weeds in your garden when you’re done.
- The roots of underground creeper plants, unless they are thoroughly pureed somehow. These resist composting and will grow new plants. Example: bamboo. That is nasty stuff that is very difficult to kill.
- Anything that is not organic or was not alive at one time. This includes all glass, plastics and metals, except for plastics made from starches which are designed to be biodegradable.
- Solid wood, twigs, sticks, and bark. These are actually okay in the compost, but they break down by fungii so slowly that they don’t really add much to your compost. The rest of the compost will be done long before the wood is.
- Glossy magazines. The paper has too many contaminents in it. Regular paper, especially newsprint, is fine because it is usually printed with soy inks that are biodegradable, but avoid those perfume-laden glossies.
- Glossy paper plates. These are usually made with a thin layer of plastic to protect the paper from getting waterlogged and falling apart, and the plastic of course never breaks down. If you want to compost your paper plates, there are a variety of brands that advertise that they are compostable and they are made only of paper and no plastic.
How It’s Gone So Far
Well, since writing the earlier parts of this article, it has rained very heavily where we live. Unfortunately, that meant the ground got water logged, and the pit became a pool again which only drained slowly as the ground dried out again. This meant all the food was buried under a foot of water or so, which means anaerobic composting started up. YUCK-O. It smells really bad now. I have stopped adding food to the pit and covered it with leaves and dried grass from the yard. This successfully insulated us from the smell. I thought the rainwater would just absorb into the ground. I didn’t realize it would just stay there if it rained enough.
So, I have co-opted an old plastic garbage can I had lying around. Now all the food goes there. There are air holes poked in the top, and I can roll the can around on the ground to mix everything and introduce air. This has gone very well, and is a heck of a lot cheaper than one of those tumbling composters.
The smell is very light. Standing right beside the can, I can’t smell anything odd most of the time. I have to open the lid before I get the bad food smell. It looks right too. Much of the older food is turning brown and black, though it may be due to the coffee grounds. There are lots of fruit flies and other insects in there, which is good, as they are part of the process of breaking down foods.
The plan is to compost all the food, then fill the pit the rest of the way with a mix of compost and dirt. Surprisingly, after only 5 weeks of adding food to the can, it is now 1/3 full. We eat a lot at home, it seems. I think I may need more cans in the future for making compost for my garden! I also have to remember next fall to store some dried leaves and plants to use as the “carbon” for next year’s compost.