Composting is the natural process of recycling organic matter, such as food scraps and yard waste, into a rich, dark material known as humus or compost. This finished product is a beneficial soil amendment created by the controlled decomposition activity of microorganisms. Home composting significantly reduces the volume of household refuse sent to landfills, where anaerobic decomposition releases methane gas. The resulting compost improves soil health by enhancing its structure, increasing its capacity to retain water and nutrients, and reducing the need for synthetic fertilizers.
Preparing Your Composting System
The success of a home composting system begins with careful planning of the location. The composting site should offer easy year-round access and feature good drainage to prevent the pile from becoming waterlogged. While compost will break down in either sun or shade, intense, direct sun may cause the pile to dry out quickly, slowing the process.
Containment options range from a simple open pile to purchased plastic bins, wire cages, or rotating tumblers. Simple wire enclosures or repurposed containers with drilled holes are inexpensive and effective. A pile measuring at least three feet wide and high is recommended to generate sufficient heat for optimal decomposition. The process depends on a proper balance of two material types: “Greens” and “Browns.”
Greens are nitrogen-rich materials, which serve as the protein source for the composting microorganisms, and include fresh grass clippings, fruit and vegetable scraps, and coffee grounds. Browns are carbon-rich materials, providing energy and bulk, and consist of dried leaves, straw, shredded paper, and wood chips.
Building the Initial Compost Pile
Starting the compost pile requires layering the collected materials in specific proportions to create an ideal environment for the microbes. The base layer should consist of four to six inches of coarse, bulky brown material, such as wood chips or twigs. This foundational layer ensures adequate air circulation at the bottom of the pile and helps absorb any excess liquid.
The ideal composition for rapid decomposition is a carbon-to-nitrogen (C:N) ratio of approximately 25:1 to 35:1. This is roughly equivalent to using two to three parts of brown material for every one part of green material by volume. Alternating thin layers of browns and greens helps distribute the nutrients and bulk evenly throughout the pile. Chopping or shredding larger ingredients before adding them increases the total surface area available for microbial action, speeding up the breakdown process.
Once materials have been added, the pile must be moistened to initiate biological activity. The goal is to achieve a moisture level similar to that of a sponge that has been thoroughly wrung out—damp but not dripping wet. If using food scraps, they should be buried deep within the center of the pile and covered with dry browns to discourage pests.
Monitoring and Maintaining the Compost
Maintaining the pile involves regularly managing the moisture level, aeration, and material balance to sustain the microbial population. The moisture content must remain consistently at the “wrung-out sponge” level, as extremes will slow the decomposition process. If the pile feels dry, water should be added slowly, ensuring the moisture penetrates the entire mass.
Aeration is accomplished by turning the pile with a pitchfork or by using a compost tumbler, which introduces oxygen necessary for aerobic decomposition. A lack of oxygen can cause the pile to become anaerobic, leading to foul smells. Regular turning, perhaps once a week, helps distribute heat, moisture, and microbes, significantly accelerating the composting time.
If a strong ammonia or rotten odor is detected, it signals that the C:N ratio is too low, meaning there is an excess of nitrogen. Add dry brown materials, such as shredded paper or sawdust, and mix them thoroughly into the pile to absorb excess moisture and rebalance the ratio. Conversely, a pile that is not heating up and decomposing slowly is often too dry or has too many browns, which requires adding water and more nitrogen-rich greens to reactivate the microbes. Avoid adding meat, dairy products, or oily foods to prevent attracting pests.
Knowing When the Compost is Ready
The composting process is complete when the material no longer resembles its original ingredients and exhibits specific physical characteristics. Finished compost should have a dark brown or black color and a fine, crumbly texture, similar to rich soil. Ready compost will have a pleasant, earthy aroma, and any sour or ammonia-like odors will be gone.
A reduction in temperature is another sign, as the active decomposition phase, where microbes generate heat, has ended. If the pile feels cool to the touch, the process has slowed significantly. The final stage, known as curing, involves allowing the finished product to sit for a period, often a month or longer, to stabilize its compounds before use. The compost can be spread as a top dressing, mixed directly into garden soil to improve structure, or steeped in water to create compost tea.