Actinomycetes: A group of microorganisms, part bacteria and part fungus, that operate in the moderate heat zones of the compost pile.
Activator: An accelerator that can expedite the natural decomposition process. Their purpose is to increase microbial activity.
Aeration: The process of introducing air into the compost pile. This can be accomplished by turning the pile or using a compost aerator.
Aerobic: Describes organisms living or occurring only when oxygen is present.
Anaerobic: Describes organisms living or occurring where no oxygen is present.
Bacteria: A group of one-celled microorganisms that break down organic materials in the first stages of composting.
Batch Composting: A single pile is built and composted at one time without adding additional materials.
Biodegradable: Capable of being broken down into simpler compounds by microorganisms. Organic materials are biodegradable.
Bokashi Composting: Anaerobic fermentation process developed in Japan which does not generate compost but fermented organic matter.
Bushel: Many composting equipment manufacturer advertise their capacity in bushels. A bushel is an imperial and U.S. customary unit of dry volume and 1 bushel equals 8 gallons of dry matter.
Cold “Passive” Pile: A compost pile that receives little or no turning, allowing some anaerobic decomposition to occur. Cold piles compost at lower temperatures over a longer period of time.
Compost: Completely decayed organic matter used for conditioning soil. It is dark, odorless and rich in nutrients.
Composting: The art and science of combining unwanted yard waste, food scraps, and other organic materials under controlled conditions so that the original raw ingredients are transformed into compost.
Compost Tea: Made by soaking or steeping compost in water. The resulting compost tea is used for either a foliar application (sprayed on the leaves) or applied to the soil.
C/N Ratio: The ratio of carbon to nitrogen. Microbes thrive in the compost pile when their food source provides a C:N ratio between 15:1 and 30:1 — meaning that for every 15-30 parts of carbon (brown materials), 1 part of nitrogen (green materials) must be added to the pile.
Decomposition: The breakdown of organic materials into smaller particles by microorganisms.
Enzymes: Substances produced by bacteria that assist in breaking down complex carbohydrates into simpler forms.
Hot “Active” Pile: A compost pile that is turned or aerated frequently, creating high temperatures and finished compost in a relatively short time.
Humus: A dark, loamy organic material resulting from the decay of plants and animal refuse. Healthy soil will consist of about 3.5-5% of this soft, sweet-smelling and crumbly organic matter.
Inoculant: A powder or tablet made up of live bacteria and enzymes which may be added to the compost pile to speed decomposition. Also called activators.
Leachate: Any liquid draining from a source. Leachate from the compost pile contains nutrients generated during the composting process.
Lime: Often used to increase pH. Lime is especially useful when added to compost piles made up of acidic materials, such as pine needles.
Mesophiles: A general category of bacteria species that break down organic matter and thrive in the compost pile at medium temperatures (70-90 degrees).
Microorganism: Microscopic plants and animals that exist in the soil to break down organic matter
Mulch: Any organic material, such as wood chips, grass clippings, compost, straw, or leaves that is spread over the soil surface (around plants) to hold in moisture and help control weeds.
N-P-K: An abbreviation for the three main nutrients that have been identified as absolutely necessary for plants are nitrogen (N), phosphorus (P) and potassium (K). These three are also known as “macronutrients,” and are the source of the three numbers commonly found on organic fertilizer labels.
Organic: Refers to something derived from living organisms and is made up of carbon-based compounds. It is also a general term used for a type of gardening using no chemical or synthetic fertilizers or pesticides.
pH: A scale from 0-14 which expresses the degree of acidity or alkalinity of the water or soil. A pH of 7 is neutral (below 7 is acidic – above 7 is alkaline). Soil pH is important because it affects the availability of nutrients to plants and the activity of microorganisms in the soil.
Psychrophiles: A group of bacteria species that break down organic matter and thrive at low temperatures (0-55 degrees). Generally, they are the first wave of microbes to invade a compost pile.
Sheet Composting: Spreading undecomposed organic matter over the soil’s surface, then working it into the soil to decompose. Sheet composting is done at the end of the gardening season because the materials need time to break down in the soil.
Soil Amendment: Any material added to a soil to improve its physical properties, such as water retention, permeability, water infiltration, drainage, aeration and structure. They contain mostly organic matter or very slow release minerals and are often worked into the top 6 inches of the soil.
Thermophiles: A group of bacteria that work to break down organic matter under “hot” conditions (104-170 degrees). Thermophiles work hard in the compost pile performing the greatest decomposition in the shortest amount of time.
Vermicomposting: Using redworms to convert food scraps and other organic materials into rich, dark worm castings.
Windrow System: A long, low, broad compost pile often used in commercial composting operations; dimensions are limited only by the space and equipment available.
Worm Castings: The rich digested organic waste that redworms leave behind. Gardeners know them to be the most nutrient dense organic compost available.