Reference
Glossary
Plain-language definitions of the terms used in this manual, in alphabetical order, each with the chapter that teaches it.
| Term | Meaning |
|---|---|
| Add-as-you-go | A way of running a bin in which you add scraps as they come, cover each with browns, and do not build a batch. Also called cold composting. See The slow pile. The slow pile |
| Aerobic | Needing oxygen. Most decomposers in a compost pile are aerobic, which is why a packed or soaked pile smells. Choose your system |
| Aminopyralid | One of three herbicides (with clopyralid and picloram) that can survive composting and damage vegetables at very low levels. See persistent herbicide. Leaves, grass and yard |
| Anaerobic | Without oxygen. When a pile runs out of air, anaerobic microbes take over and the pile smells sour or like rotten eggs. Bokashi is deliberately anaerobic. Choose your system |
| Aspergillus | A common mold whose spores are in soil, dust and compost. It is a concern mainly for people with weakened immune systems or lung disease. See Finished compost. Finished compost |
| Batch | A hot pile built all at once from a collected supply of material, as opposed to adding a little at a time. The hot pile |
| Bedding | Damp shredded paper, cardboard, coir or leaves that a worm bin holds the worms in. Worm bins |
| Bioassay | A test that uses living plants to find out whether a material harms them. The pea or bean pot test is a bioassay. Leaves, grass and yard |
| Biodegradable | Able to be broken down by living things, over any length of time. The word on a label says little about how fast or in what conditions. What goes in |
| Bokashi | A method of fermenting food scraps, including meat and dairy, in a sealed bucket with inoculated bran. It is fermentation, not composting; the result is buried in soil or finished in a pile. Bokashi and burying |
| Bokashi bran | Bran inoculated with microbes, layered with scraps in a bokashi bucket. Bokashi and burying |
| BPI | The Biodegradable Products Institute, a certifier of compostable products. Its home-compostable mark is separate from its industrial-compostable mark. What goes in |
| Brown | A dry, carbon-rich material such as dry leaves, shredded plain cardboard or straw. See greens. Choose your system |
| Bulking agent | A coarse, dry material (wood chips, straw) mixed in to hold air spaces open. The hot pile |
| Carbon-to-nitrogen ratio (C:N) | The weight of carbon in a material compared with the weight of nitrogen. Browns have high ratios and greens low ones. Cornell gives about 30 to 1 as the usual target for the start of composting. What goes in |
| Castings | Worm droppings. They are the main part of vermicompost. Worm bins |
| Clopyralid | One of the persistent herbicides. See aminopyralid. Leaves, grass and yard |
| Cold composting | Composting that does not aim for or reach high temperatures: add, cover and wait. It does not reliably reduce weed seeds or pathogens. The slow pile |
| Compost | The dark, crumbly, soil-smelling material that remains when organic matter has decomposed under managed conditions. Choose your system |
| Compost notebook | This manual's name for the exported set of your setup, plan, logs, notes and progress. Your compost system |
| Compost tea | A liquid made by soaking compost in water. This manual does not teach it, because the evidence for its benefits is thin and mixed. See Finished compost. Finished compost |
| Compost thermometer | A thermometer with a long probe that is pushed into the center of a pile to read its temperature. The hot pile |
| Compostable | A label claim that a product breaks down in a composting test. It describes a test, often at industrial conditions, not what happens in a backyard pile. See industrially compostable and home compostable. What goes in |
| Composting | The controlled breakdown of plant and food material by microbes and small animals, steered by supplying carbon, nitrogen, water and air. Choose your system |
| Curbside collection | A program in which a city or hauler collects food scraps from households, usually in a separate cart. Kitchen and collection |
| Curing | The resting period after the active stage, when compost stops heating and matures. EPA gives at least four weeks. Finished compost |
| Decomposition | The breakdown of organic material by microbes and small animals. It happens with or without help; composting steers it. Choose your system |
| Dehydrator | A device that dries food waste with heat. Electric kitchen units sold as composters are dehydrators. See food recycler. Kitchen and collection |
| Drop-off site | A place, such as a market or community garden, where residents bring food scraps for someone else to compost. Kitchen and collection |
| Eisenia fetida | The red wiggler, the worm species used in worm bins. Garden earthworms and nightcrawlers do not do well in a bin. Worm bins |
| Enclosed bin | A bin with a lid and solid or mesh sides that holds scraps and browns and keeps animals out better than an open pile. Site and bin |
| Fermentation | The breakdown of food by microbes without oxygen, producing acids. It pickles scraps rather than rotting them. Bokashi relies on it. Bokashi and burying |
| Finished compost | Compost that is dark, crumbly, smells like soil, shows no recognizable food and no longer heats after mixing. See maturity. Finished compost |
| Food recycler | An electric countertop appliance that heats and grinds food scraps. Its output is dried food, not compost. Kitchen and collection |
| Food scrap program | A service, such as a drop-off site or curbside collection, that takes food scraps for composting. Kitchen and collection |
| Food scraps | Kitchen waste from food: peels, cores, coffee grounds, leftovers. Programs differ on which they accept. Kitchen and collection |
| Food-soiled paper | Paper such as napkins, paper towels or pizza boxes with food on them. Whether a program accepts it varies. Kitchen and collection |
| Germination test | A test of finished compost: seeds such as radish or cress are sprouted on paper towels wetted with compost water and with plain water, and the two are compared after about a week. Finished compost |
| Grasscycling | Leaving grass clippings on the lawn when you mow, so they break down there. Leaves, grass and yard |
| Greens | Wet, nitrogen-rich materials such as fruit and vegetable scraps, coffee grounds and fresh grass. See browns. Choose your system |
| Grit | Small hard particles, such as ground eggshell or a little soil, that a worm bin gets so the worms can grind their food. Worm bins |
| Hardware cloth | Welded wire mesh, with openings of 1/4 to 1/2 inch, used for bin floors and sides to keep rodents out. Site and bin |
| Herbivore manure | Manure from plant-eating animals such as horses, cows, rabbits and chickens. This manual uses only this kind, after composting. Leaves, grass and yard |
| Holding unit | A bin that stores material while it breaks down, with no way to turn it, as distinct from a turning unit. Site and bin |
| Home compostable | A certification (such as BPI's home mark or TÜV's OK compost HOME) that a product was tested at home-compost temperatures. Not every compostable product has it. What goes in |
| Hot composting | Composting that aims to heat to roughly 130 to 160°F by building a large enough batch and turning it. The hot pile |
| In-ground digester | A product, sometimes a cone over a buried basket, that takes cooked food and meat and lets the soil absorb it. It is not a composter and does not take garden waste. Bokashi and burying |
| Industrially compostable | Certified to break down in a commercial composting facility, in conditions a home pile does not reach. Standards include ASTM D6400. What goes in |
| Jar test | A check of finished compost: a jar of wet compost is sealed for about a week and then smelled. A sour or rotten smell means the compost is not mature. Finished compost |
| Kitchen container | The lidded container where scraps wait before they go to a bin, a bucket, the freezer or a drop-off. Kitchen and collection |
| Lasagna composting | Building a bed from layers of compostable material, such as cardboard, greens and browns. See sheet composting. Bokashi and burying |
| Leachate | Liquid that drains from a compost or worm bin. NC State advises against using it on food crops. Worm bins |
| Leaf mold | Leaves that have decayed, mostly by fungi, over months to a couple of years. It is low in nutrients and used as mulch or a soil amendment. Leaves, grass and yard |
| Legionella | Bacteria that can cause Legionnaires' disease, linked in the cited public health sources to potting mix and compost. See Finished compost for what those sources say and where. Finished compost |
| Liner | A bag or sheet of paper that lines the kitchen container. Programs differ on which liners they accept. Kitchen and collection |
| Materials inventory | The list, kept on the materials sheet, of what you have or can get, green or brown, with when it arrives and where it is stored. What goes in |
| Maturity | The state in which compost is stable enough to use around plants. The signs and the germination test check it. Finished compost |
| Mesophilic | Working at moderate temperatures, below roughly 40°C (104°F). The first stage of composting is mesophilic. Choose your system |
| Moisture | The amount of water in the pile. The target is as damp as a wrung-out sponge. Choose your system |
| Organic matter | Material that comes from living things. In soil, it is the decayed material that holds water and nutrients. Finished compost |
| Particle size | How small the pieces are. Smaller pieces break down faster, up to the point where the pile packs and air cannot enter. The hot pile |
| Pathogen | A microbe that can cause disease. A hot pile reduces many pathogens; a cool pile does not reliably. Choose your system |
| Persistent herbicide | A weed killer that survives composting and can damage vegetables at very low levels: aminopyralid, clopyralid and picloram. Leaves, grass and yard |
| PFAS | A group of long-lasting chemicals used in some molded-fiber food packaging. See What goes in. What goes in |
| Phosphorus buildup | Excess phosphorus in a soil from repeated heavy compost or manure use. A soil test shows it. Finished compost |
| Picloram | One of the persistent herbicides. See aminopyralid. Leaves, grass and yard |
| Raw manure | Manure that has not been composted. See herbivore manure. Leaves, grass and yard |
| Red wiggler | The common name of Eisenia fetida. Worm bins |
| Review | A set date on which you compare your system with your plan, using your own records. Your compost system |
| Scrap log | A record of the volume of food scraps that go into the kitchen container each day for one week. What goes in |
| Screening | Sifting finished compost to take out pieces that did not break down, which go back into the bin. Finished compost |
| Seal of Testing Assurance | A disclosure program that has compost producers publish test results. It is not a quality threshold. Finished compost |
| Sheet composting | Spreading layers of compostable material on the soil surface, usually over cardboard, to build or feed a bed. Bokashi and burying |
| Soil factory | A lidded bin of soil in which bokashi is buried, for balconies and containers. Bokashi and burying |
| Squeeze test | Picking up a handful of compost and squeezing it. A few drops of water means the moisture is about right. The slow pile |
| Thatch | A layer of grass stems, shoots and roots at the soil surface. Clippings do not cause it. Leaves, grass and yard |
| Thermophilic | Heat-loving. The stage at roughly 40°C (104°F) and above when thermophilic bacteria dominate. Choose your system |
| Trench composting | Burying food scraps in a hole or trench in the garden and covering them with soil, where they break down in place. Bokashi and burying |
| Tumbler | A sealed drum on a stand that you rotate to mix its contents. Site and bin |
| Turning | Mixing or restacking a pile to add air. A hot pile is turned when its center cools. The hot pile |
| Turning unit | A bin or bay arranged so you can move material from one section to the next, as in a three-bay system. Site and bin |
| Vermicompost | Worm castings and partly decomposed bedding harvested from a worm bin. Worm bins |
| Vermicomposting | Composting with worms in a bin. Worm bins |
| Wasted food | Food that was not eaten, including inedible parts such as peels, as EPA counts it. Choose your system |
Limits
These are working definitions for this manual. A product label, a program's rules or a regulation may use the same word to mean something narrower, and in those cases the label, the program or the regulation decides.