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Hands sift through compost ready for use


  • Aeration: Process by which the oxygen-deficient air in compost is replaced by air from the atmosphere. Aeration can be enhanced by turning.
  • Aerobic: A biochemical process or condition occurring in the presence of oxygen.
  • Anaerobic: A biochemical process or condition occurring in the absence of oxygen.
  • C:N Ratio: Carbon-to-nitrogen ratio. The proportion of carbon to nitrogen affects how quickly microorganisms work. Materials high in carbon include leaves, sawdust, wood chips, and straw. High nitrogen materials are such things as grass clippings, food scraps and manure. The optimum C:N ratio is in the range of 25:1 to 35:1.
  • Compost: Organic matter that is undergoing decomposition or has resulted from decomposition.
  • Composting: Biological decomposition of organic materials by microorganisms under controlled, aerobic conditions to a relatively stable, humus-like material called compost.
  • Corms: Compressed underground stem with bud on top, these growths tend to be very hardy.
  • Cured: Compost that has stabilized and is ready to be planted in. Also known as "finished."
  • Curing: Curing is the biological process of stabilizing compost so that it is ready to be used as a planting media. Curing takes place naturally, by setting compost to the side and letting it complete the compost process. see also Finishing in the compost tutorial.
  • Decomposition: The process by which materials chemically break down.
  • Finished: Compost that has stabilized and is ready to be planted in. Also known as "cured."
  • Humus: The end product of composting. Organic material which is completely decomposed.
  • Inoculants: Also called "activator" or "compost starter." A material rich in microorganisms which is added to the compost pile to accelerate the decomposition process. (Finished compost, manure, soil, are types of inoculants.)
  • Inorganic: Derived from a non-living source (e.g., rocks, sand, and plastic, or shells used as mulch).
  • Irrigate: To add/apply water.
  • Mesophilic: Bacteria which are active in the temperature range between 40 degrees and 110 degrees F, but thrive at 70–90 degrees F. Most of the decomposition that takes place in a compost pile is mesophilic.
  • Microbial: Relating to microorganisms (microbes).
  • Microorganisms: Microscopically small living organisms that digest decomposable materials through metabolic activity. Microorganisms – also known as microbes – are active in the composting process.
  • Mulch: Organic or inorganic materials which are spread on the soil surface. Mulch slows down the evaporation of water from the soil, moderates soil temperatures, discourages weeds and beautifies the landscape.
  • MSW Composting: Municipal Solid Waste Composting. The controlled degradation of the organic materials found in municipal solid waste. Includes some kind of preprocessing to remove non-compostable inorganic materials.
  • Organic: Derived from or produced through the biological activity of living organisms.
  • Oxygenate: To add oxygen, “aerate”
  • Pathogen: Any organism capable of producing disease or infection. Often found in waste material, pathogens are killed by the high temperatures (131°F or higher for 3 days) of the composting process.
  • pH: A measurement of the acidity or alkalinity of a material, on a scale form 0 to 14. The pH range for finished compost is 6.0–8.0, or roughly neutral.
  • Psychrophilic: Bacterial species that work in low temperature range (below 65 degrees F). Are most active around 55 degrees F.
  • Rebar: Solid, cylindrical, metal bars, approximately 1/2–3/4 inches in diameter, made in varying lengths from 4 feet long to 12-plus feet. Rebar is used in construction to reinforce the strength of poured concrete. This material may be salvaged from construction sites, or purchased at home hardware stores.
  • Rhizomes: A creeping underground stem; these growths tend to be very hardy.
  • Tea: A liquid created by taking cured/finished compost and steeping (or soaking) it in water to extract nutrients and microorganisms. Compost tea then can be added to or sprayed on indoor plants, potted plants or others to aid in growth/health.
  • Thermophilic: Heat-loving bacteria that exist in a temperature range of 104–200 degrees F. Ideal range is 122–131 degrees F.
  • Tilth: The physical condition of soil relative to the ease of plant growth.  The "fluffiness" of the soil, so roots grow easily.
  • Tubers: Thickened portions of underground stems with eyes or buds on the side (e.g. nutsedge).
  • Yard Waste: Leaves, grass clippings, yard trimmings and other organic garden debris.