How is Compost Made?
There are numerous print and online sources of information detailing compost techniques from the simplest bin to complex commercial aeration and windrow systems. But basic residential composting requires no sophisticated recipes. It is true that skillful composting is part art and part science and that composters become expert though practice. However, just observing a few general principles for maintaining the decomposition process will produce rich, dark material from commonly available organic waste.
A wide range of organic material can be composted, including trimmings from shrubs, fall leaves, discarded plants, grass clippings, kitchen waste, and paper. Many homeowners believe that really good compost can only be made by hauling in horse, cow, or chicken manure. However, manures are not necessary and even make the process more complicated to manage. In reality, even human waste and meat can be and are composted at high temperatures with special equipment, but these ingredients should not be included in conventional home compost systems due to potential disease and odor problems.
Key factors in successful composting are controlled moisture, a balance of nitrogen- and carbon-rich materials, and adequate oxygen.
Decomposition is carried out by bacteria and fungi that require a moist, but not wet, environment with adequate nutrients. Too much or too little of any of these factors can accelerate or slow the process. For instance, strong odors are often caused when the pile is wet and lacks oxygen. Under these conditions, aerobic bacteria are replaced by anaerobes that generate noxious gases with a sewer-like odor. The fragrance of active compost changes during decomposition and ends with a sweet, earthy smell. Intermediate stages of maturity will give off an ammonia fragrance but should never smell rotten.