ACIDIC SOIL - A soil with a pH below 7. The lower the pH, the more acidic the soil.
AFFORESTATION - Planting forests on land that has not contained forests for at least 50 years.
AGGREGATES - The structures, crumbs, or clumps formed when soil minerals and organic matter are bound together with the help of organic molecules, plant roots, fungi, and clays.
AGROECOLOGY - Agroecology is a whole systems approach to agriculture that applies ecology to the design and management of sustainable production systems.
ALKALINE SOIL - A soil with a pH above 7, containing more base than acid.
ALLELOPATHIC EFFECT - Suppression of the germination or growth of one plant by another. The chemicals responsible for this effect are produced during the growth of a plant or during its decomposition.
ALLEY CROPPING - Growing annual crops in tilled strips between rows of a tree or shrub crop.
ALLOWED SYNTHETIC - A substance that is included on the National List of synthetic substances allowed for use in organic production or handling.
AMMONIFICATION - The biological process by which ammonium is released from nitrogen-containing organic matter. Ammonification is nitrogen mineralization.
AMMONIUM - A form of nitrogen (NH4+) that is avail- able to plants and is produced in the early stage of organic matter decomposition.
ANION - A negatively charged element or molecule such as chloride (Cl-) or nitrate (NO3-).
ANNUAL SEEDLING - A plant grown from seed that will complete its life cycle or produce a harvestable yield within the same crop year or season in which it was planted.
AQUIFER - A source of groundwater below the land surface.
AUDIT TRAIL - Documentation that is sufficient to determine the source, transfer of ownership, and transportation of any agricultural product labeled as "100 percent organic," the organic ingredients of any agricultural product labeled as "organic" or "made with organic (specified ingredients)" or the organic ingredients of any agricultural product containing less than 70 percent organic ingredients identified as organic in an ingredients statement.