Let's explore the composting process and the different factors that play a role in this magical method of biological breakdown. To create some high-quality compost, there are 5 main areas of "control" that need to be considered:
Feedstock and Nutrient Balance
Composting requires a proper balance of “green” organic materials and “brown” organic materials. “Green” organic material includes grass clippings, food scraps, and manure, which contain large amounts of nitrogen. “Brown” organic materials includes dry leaves, wood chips, and branches, which contain large amounts of carbon but little nitrogen. You'll typically need a higher ratio of "brown" elements (carbon) to "green" elements (nitrogen). Obtaining the right nutrient mix requires experimentation and patience. It's part of the art and science of composting.
Grinding, chipping, and shredding materials increases the surface area on which microorganisms (microbes) can feed. Smaller particles also produce a more homogeneous compost mixture and improve pile insulation to help keep up optimum temperatures (see more below). But if the particles are too small, they might prevent air from flowing freely through the pile. Again, it's all about balance.
Microbes living in a compost pile need enough moisture to survive. Water is the key element that helps transports substances within the compost pile and makes the nutrients in organic material accessible to the microbes. Organic material contains some moisture naturally, but moisture also might come from rainfall or intentional watering.
Turning the pile, placing the pile on a series of pipes, or including bulking agents such as wood chips and shredded newspaper all help aerate the pile (i.e. provide oxygen flow). Aerating the pile allows decomposition to occur at a faster rate than anaerobic conditions (i.e. the lack of oxygen). But once again: balance. Too much air can dry out the pile and impede the composting process.
Microbes require a certain temperature range for optimal activity. Certain temperatures promote rapid composting and destroy pathogens and weed seeds. Microbial activity can raise the temperature of the pile’s core to at least 140° F. If the temperature does not increase, anaerobic conditions (i.e. rotting) occur. Controlling the first four factors mentioned above are key to keeping the pile at the proper temperature. For more information on the various temperature stages in a compost pile's life cycle, and the microbes that thrive in those stages, see here.
Stay tuned for some of the different composting methods that can be used to cycle food scrap nutrients into stupendous black gold!