Making Compost – The Basics
Compost can range from passive – allowing the materials to sit and rot on their own – to highly managed. Whenever you intervene in the process, you’re managing the compost. How you compost is determined by your goal. If you’re eager to produce as much compost as possible to use regularly in your garden, you may opt for a more hands-on method of composting. If your goal is to dispose of yard waste, a passive method is your answer.
Passive composting involves the least amount of time and energy on your part. This is done by collecting organic materials in a freestanding pile. It might take a long time (a year or two), but eventually organic materials in any type of a pile will break down into finished compost. More attractive than a big pile of materials sitting in your yard is a 3-sided enclosure made of fencing, wire, or concrete blocks, which keeps the pile neater and less unsightly. Add grass clippings, leaves, and kitchen scraps (always cover these with 8″ of other material). The pile will shrink quickly as the materials compress and decompose. Wait a year or two before checking the bottom of the bin for finished compost. When it’s ready, shovel the bottom section into a wheelbarrow and add it to your garden beds. Continue to add greens and browns to have a good supply of finished compost at the ready. After the first few years, most simple piles produce a few cubic feet of finished compost yearly.
Managed composting involves active participation, ranging from turning the pile occasionally to a major commitment of time and energy. If you use all the techniques of managing the pile, you can get finished compost in 3-4 weeks. Choose the techniques that reflect how much you want to intervene in the decomposition process and that will be a function of how fast you want to produce compost.
The speed with which you produce finished compost will be determined by how you collect materials, whether you chop them up, how you mix them together, and so on. Achieving a good balance of carbon and nitrogen is easier if you build the pile all at once. Layering is traditional, but mixing the materials works as well.
Shredded organic materials heat up rapidly, decompose quickly, and produce a uniform compost. The decomposition rate increases with the size of the composting materials. If you want the pile to decay faster, chop up large fibrous materials.
You can add new materials on an ongoing basis to an already established pile. Most single-bin gardeners build an initial pile and add more ingredients on top as they become available.
The temperature of the managed pile is important – it indicates the activity of the decomposition process. The easiest way to track the temperature inside the pile is by feeling it. If it is warm or hot, everything is fine. If it is the same temperature as the outside air, the microbial activity has slowed down and you need to add more nitrogen (green) materials such as grass clippings, kitchen waste, or manure.
Use a compost thermometer to easily see how well your compost is doing. They are inexpensive, and quite convenient to have.
If the pile becomes too dry, the decay process will slow down. Organic waste needs water to decompose. The rule of thumb is to keep the pile as moist as a wrung-out sponge.
If you’re building your pile with very wet materials, mix them with dry materials as you build. If all the material is very dry, soak it with a hose as you build. Whenever you turn the pile, check it for moisture and add water as necessary.
Too much water is just as detrimental as the lack of water. In an overly wet pile, water replaces the air, creating an anaerobic environment, slowing decomposition.
Air circulation is an important element in a compost pile. Most of the organisms that decompose organic matter are aerobic – they need air to survive. There are several ways to keep your pile breathing. Try not to use materials that are easily compacted such as ashes or sawdust, without mixing them with a coarser material first. People who build large piles often add tree branches or even ventilation tubes vertically into different parts of the pile, to be shaken occasionally, to maximize air circulation.
A more labor-intensive way to re-oxygenate the pile is to turn the pile by hand, using a large garden or compost fork. The simplest way is to move the material from the pile and restack it alongside. A multiple-bin system makes this efficient, in that you only handle the material once. Otherwise, you can put the material back into the same pile. The object is to end up with the material that was on the outside of the original pile, resting in the middle of the restacked pile. This procedure aerates the pile and will promote uniform decomposition.
The following information is for the highly managed pile and the optimum finished compost in the shortest amount of time. Decomposition occurs most efficiently when the temperature inside the pile is between 104 degrees F and 131 degrees F. Compost thermometers are available at garden shops and nurseries. It is best not to turn the pile while it is between these temperatures, but rather when the temperature is below 104 degrees F or above 131 degrees F. This keeps the pile operating at its peak. Most disease pathogens die when exposed to 131 degrees for 10-15 minutes, though some weed seeds are killed only when they’re heated to between 140 degrees and 150 degrees. If weed seeds are a problem, let the pile reach 150 degrees during the first heating period, then drop back down to the original temperature range. Maintaining temperatures above 131 degrees can kill the decomposing microbes.