The Compost Cooking Process

The compost cooking process:

1) Air
2) Water
3) Heat
4) Organic Materials
5) Mixing
6) Structure
7) Rest

1 - A compost pile needs to breath. This allows for aerobic decomposition. If it does not breath the compost goes through an anaerobic fermentation; this causes foul odors, amongst other things. Aeration is necessary for rapid odor-free decomposition. There are two typical methods for aeration. Turning the materials is the most common or forced air systems usually for larger piles. Oxygen is needed for the soil organisms as well.

2 - All living things need water. A compost pile has a host of living things both being broken down and doing the breaking down. If the soil is too wet the air is removed causing anaerobic fermentation. If it is too dry there can be no chemical reactions to break down the materials. It needs to be moist like a sponge. The proper moisture level is about 55% to 65%. You can take a handful from the pile and squeeze it and it does not drip with water but it is still moist. You must water it when it gets too dry but turn it very frequently if it gets too wet.

3 - Heat is necessary to accomplish the cooking process. If the pile does not get hot enough certain materials do not break down enough. If it gets too hot it can cause a destruction of the nutrients in the soil. The ideal peak temperature is near the center top of the pile and is around 160 degrees Fahrenheit. This allows the organic materials to break down enough to kill any weed seeds or other undesirable materials, yet maintaining the organic nutrients needed to make it rich and nutritious to plants. If it goes above 160 degrees it may also kill the needed decomposers preventing them from doing their job.

4 - The main organic materials are carbon and nitrogen. Nitrogen is used in the structure of the soil so it does not get too compact as well as the physical structure of organisms in the soil. The carbon is the main source of the energy for the decomposers. The ideal starting ratio is 30 carbon to 1 nitrogen. So as to not worry about this ratio when building the pile, put a large variety of organic materials in the pile. The ideal blend is a minimum of five different organic materials, the more the better. Or, in other words each type of organic material should take up no more than one fifth of the volume of the pile. Some examples of what to include in the pile would be grass clippings, leaves, vegetable scraps, garden residue and yard clippings. Material not to include are diseased plants, meat scraps, fat and oils and certain manures. Just like people need a variety of foods to be properly nourished, so do plants.

5 - The pile should be mixed frequently at the beginning to allow the air to get in so it does not decompose incorrectly causing bad odors. It also allows the water to evaporate if there is too much. Mixing allows the materials on the outside to be moved to the inside to attain the proper level of heat. The items put in the pile should be small or cut up into small pieces no larger than two inch cubes but the smaller the better. This allows the air, water and organisms to move freely in the pile and increases the surface area of the materials. This increases the productivity of the organisms.

6 - The structure should be anywhere from 3'X3'X3' to 4'X4'X4' in size. The structure affects the heat and ease of turning. If the compost pile is too small the decomposition is too slow because it does not get hot enough. If the structure cannot protect against the rain it could get too wet allowing for anaerobic fermentation. Also, snow, cold temperature and wind could cool the pile and slow the decomposition process.

7 - At the beginning, the pile only needs to rest for short periods of time before mixing - a couple days at a time max. When the pile is mostly decomposed it can be left to rest to allow the organisms to finish what they started. The organisms are the ones that do the work to properly break down the nutrients into the right chemical composition making the composted soil nutritious for plants. Once they are done and the pile is decomposed you have nice dark, rich, fresh smelling soil. This is very nutritious for plants and ultimately you, eating the fruits of the plants or the roots, stems and leaves - depending on the plant - growing out of it. Finished compost should not be mixed with existing soil because existing soil contains weeds and lacks nutrition and structure. The first time creating a garden, compost should be mixed in a blend of one third compost, one third course vermiculite and one third peat moss. Every time after that, compost alone should be added to the existing mix. You will see and eat the fruits of your labors.