composting

Composting is the biological decomposition of organic waste into a stable, nutrient-rich soil amendment known as compost. It is typically performed under aerobic conditions by communities of bacteria, fungi, and other organisms, sometimes aided by worms or insects. The process generates heat as materials break down and reduces the volume of waste.

Common inputs include green materials (kitchen scraps, fresh grass clippings) and brown materials (dried leaves, straw, shredded paper). Aiming for a carbon-to-nitrogen ratio of roughly 25 to 30:1 helps maintain microbial activity. Moisture should resemble a wrung-out sponge, and adequate aeration is essential, often achieved by turning the pile or using an aerated bin. The decomposition proceeds in stages: an initial mesophilic phase, a thermophilic phase with higher temperatures, and a curing phase as the material stabilizes.

Methods range from small-scale backyard systems (open piles, bins, or tumblers) to large-scale windrow composting in which long piles are regularly turned, or in-vessel systems that control moisture and temperature. Other approaches include vermicomposting with red worms and bokashi fermentation, which pre-ferments organic waste using anaerobic microbes.

Benefits include diversion of organic waste from landfills, reduced methane emissions, improved soil structure and fertility, increased water retention, and reduced need for chemical fertilizers. Finished compost is dark, crumbly, and earthy smelling, and can be applied to garden beds, mulch, or incorporated into potting mixes.

Limitations include odors and pests if the pile becomes too wet or compacted, inadequate heat that leaves pathogens or weed seeds viable, and contamination by plastics or metals. Cold, unmanaged composting can be slow. Users should avoid adding meat, dairy, or diseased plant material in home systems, and follow local guidelines to manage leachate.

Time to maturity ranges from several months to a year, depending on method and conditions.