A compost pile is easy to make and doesn’t require much space. In order to reach optimal temperatures, the pile should be at least 3 feet wide, 3 feet across, and 3 feet tall (one cubic yard). That is the minimum size to generate temperatures that can kill weeds and pathogens, but smaller compost piles will also work with reduced efficiency. Larger piles work even better because their size will increase the temperature in the pile, but anything taller than 8 feet is overkill. Extremely large piles of compost are at risk for spontaneous combustion, and they are also extremely difficult to aerate properly.
To build a compost pile, start by clearing off a patch of ground. Choose a spot that’s away from trees or fast growing vines – the roots from these plants can infiltrate the compost pile and suck away nutrients. It’s also important to remove any weeds or seeds from the area – if your compost pile fails to get hot enough, these seeds will get mixed into the finished product and may germinate when you use the compost as potting soil or fertilizer. The best ground for a compost pile will be slightly elevated and have excellent drainage. It is also a good idea to locate compost piles away from inhabited buildings, gardens, or silos because they can attract insects.
If you plan to build a very large pile, be sure to put footpaths every 8 feet or so that are wide enough for a wheel barrel. Then, line the ground with groundcloth or plastic liner to protect against root intrusion. If there are moles, groundhogs, or other burrowing animals in your area, you may want to put a layer of chicken coop wire or hardware cloth too. Avoid putting the compost pile against a wooden fence or deck – the compost can stain wood and may encourage rotting.
After you pick out the perfect spot, it’s a good idea to gather separate piles of ‘green’ and ‘brown’ organic matter. Green waste is high in nitrogen – it includes things such as vegetable scraps, fresh grass clippings, and manure from herbivores. Brown waste has a high concentration of carbon – it includes things such as leaves, dried grass, and twigs. There are certain things that you should NOT put in your compost pile. Before you start construction, please review our section on ingredients that don’t belong in a compost pile.
Break these components into very small pieces, but save a few sticks for building support structures. The more surface area your ingredients have, the faster they will decompose. Start with a layer of brown waste and leave plenty of airspace at the bottom of your compost pile – this will help with drainage and also create a chimney effect of airflow.
Use your piles of organic material to create alternating layers of brown and green waste. Sticks and split logs are important for building the pile because they will provide support and hold everything together. Use twigs in the compost pile the same way that you would use them to build a campfire – with alternating rows and columns that allow air to flow through easily. The center of the pile will have to support the most weight, so you may want to use the thickest sticks in that area. If you plan on turning your compost pile regularly, don’t worry so much about structure. Instead, you may want to feed your sticks through a wood chipper to get the most surface area and the fastest decomposition.
Animals and pests are often attracted to the smell of rotting garbage. If you put a lot of green waste into your compost pile, it can be a very good idea to put fresh waste near the bottom and under sticks or thorns. Such a barrier will do a good job keeping raccoons and skunks away, but insects and rodents will often be able to sneak through very small openings, and snakes may also move into the pile to feed on them. Because of this, it’s a very good idea to wear protective clothing and make plenty of noise to scare animals away when turning a compost pile.
Keep building your compost pile until you run out of materials. Each layer can be as thick or as thin as you’d like to make it. The best way is to use thin layers of green material (2-4 inches) and thicker layers of brown materials (5-7 inches). If you don’t have any green waste available when building your pile, it may be a good idea to add one of the following as a compost activator: manure from a grass eater (ie; cow, sheep, goat, llama, hamster, gerbil, rabbit, chicken), alfalfa meal, bloodmeal, bonemeal, coffee grounds, or even just soil from another part of your yard. Cat and dog droppings are not recommended because they may carry disease. Horse manure is not recommended because it has a high number of weed seeds.
Depending on your climate, it may be a good idea to cover your compost pile with a tarp. This is necessary if rainfall or snow is heavy in your area, because excess moisture can slow down the composting process. Moisture should be in the same range as a wrung out sponge – if you can extract water by pressing or squeezing the compost in your hand, then there’s too much moisture. There are other ways to protect your compost pile from the weather, such as placing it under a tree or under a roof overhang, but they have drawbacks (trees rob the compost pile of nutrients and building a compost pile against a building can attract pests inside). To get around this, you may want to take advantage of dead trees or unoccupied buildings, such as a garden shed, patio, or arbor.
The final step is waiting. Let nature take its course, and before you know it, you’ll have a pile of rich, black gold (no, not the kind that you can put in your gas tank, but the kind of natural fertilizer that plants thrive on). Finished compost has a carbon to nitrogen ratio of about 15:1. The resulting material is coarse, crumbly, and spongy – a perfect mulch for absorbing water and gradually releasing nutrients into the soil.