When organic materials are separated from trash and allowed to decompose aerobically, with an adequate amount of oxygen, they can be turned into compost, a valuable resource. Used in garden beds, compost helps to loosen soil and improve drainage, provides plants with valuable nutrients, feeds life-sustaining microorganisms, protects soil from erosion and compaction, and conserves water and other resources. What more could one ask of a product that can be made almost anywhere in a simple process from ingredients that are available in abundance and for free?
Hot or Cold?
Brooklyn College Garden maintains two compost systems, one hot and one cold. Hot, or kitchen, compost happens in this three-bin system. It is fed a balanced diet of greens and browns. You can read more about the chemistry of greens and browns here. In our hot compost system, greens are vegetable scraps supplied by gardeners. Browns are fall leaves supplied by the trees on campus, supplemented with occasional infusions of sawdust from untreated lumber. The well aerated and judiciously watered mix of nitrogen-rich vegetable matter and carbon-rich fall leaves and sawdust is turned weekly to bi-weekly. It heats up quickly and breaks down fast, yielding about a cubic yard of nutritious compost in two to three months. To find out how the compost process works and who the main players are go to this link. Once the hot compost has cooled down and is ready for application, it is sifted and used to replenish the soil in our 28 vegetable plots with organic matter.
Cold compost, also known as yard or orchard compost, happens slowly and quietly in wire bins. Prunings from perennial flowers, herbs, and shrubs as well as healthy weeds (without seeds!) are chopped up and piled up together with the (pest and disease-free) vegetable plant residues gathered from the 28 garden plots at the end of the summer growing season. These materials are generally much lower in nitrogen than the vegetable scraps and break down much more slowly. After decomposing for about four to six months with little intervention, the piles are aerated and turned. After another two or three months, the material is sifted. Finer materials are used to enrich the soil around the trees, fruiting shrubs, flowers, and herbs in the common areas of the garden. Coarser, woody materials are either returned to the pile where they are allowed to break down further or they are used as the basis for new raised beds, in the spirit of the thrifty processes known as hugelkultur or grow heaps, and lasagna gardening or sheet mulching.
Become a Compost Member
If you’d like to contribute your vegetable scraps to the garden’s hot compost, go here to find out what materials are acceptable and how to join the garden as a kitchen compost member.