CALCAREOUS SOIL - A soil in which finely divided lime is naturally distributed; it usually has a pH between 7 and slightly more than 8.
CAP-AND-TRADE - A mechanism of reducing overall greenhouse gas emissions (usually CO2) in which a cap is set on how much greenhouse gases any given entity can emit. To emit more than the cap allows, the entity is allowed to buy (or "trade") an emission allowance from another source that has reduced its emissions.
CARBON DIOXIDE - A naturally occurring compound that is integral for life functions on Earth, found in gaseous form at surface temperatures. All animals, plants, fungi, and microorganisms produce carbon dioxide during respiration. Plants use it during photosynthesis. Carbon dioxide is also generated as a natural by-product of the decomposition of organic matter and the combustion of fossil fuels or vegetative matter, among other chemical processes.
CARBON DIOXIDE EQUIVALENT - A universal standard of measurement against which the effects of different greenhouse gases can be evaluated in a common framework of global warming potential. For example, 1 ton of methane has a carbon dioxide equivalent or global warming potential of 21, meaning that one-ton of methane in the atmosphere has the same effect on climate change as 21 tons of carbon dioxide.
CARBON SEQUESTRATION - The removal from the atmosphere and secure storage of carbon dioxide 2 in oceans, forest, soils, or geologic materials through physical, biological processes such as photosynthesis, or man-made processes such as deep injection into geologic formations.
CARBON SINK - A reservoir for carbon dioxide removed from the atmosphere. Natural sinks include oceans; trees, plants, and other organisms that use photosynthesis to remove carbon from the atmosphere by incorporating it into biomass; soils that provide longterm storage of carbon as organic matter and humus; and rocks such as limestone.
CARBON-TO-NITROGEN RATIO (C:N) - The amount of carbon divided by the amount of nitrogen in a residue or soil. A high ratio results in low rates of decomposition and can also result in a temporary decrease in nitrogen nutrition for plants, as microorganisms use much of the available nitrogen.
CARBON TRADING - A market-based mechanism that mitigates the increase in atmospheric CO2 and other greenhouse gases. It allows carbon dioxide emitters to offset these emissions by purchasing “credits” from individuals or organizations that sequester carbon dioxide or other greenhouse gases.
CARBONACEAOUS MATTER - Organic matter with a high proportion of carbon and low proportions of otber plant nutrients. Generally having a carbon:nitrogen ratio greater than 35:1.
CATION - A positively charged ion such as calcium (Ca2+) or ammonium (NH4+).
CATION EXCHANGE CAPACITY (CEC) - The amount of negative charge that exists on humus and clays, allowing them to hold on to positively charged chemicals (cations).
CERFTIFICATION - A determination made by a certifying agent that a production or handling operation is in compliance with the Act and the regulations in this part, which is documented by a certificate of organic operation.
CERTIFIED OPERATION - A crop or livestock production, wild-crop harvesting or handling operation, or portion of such operation that is certified by an accredited certifying agent as utilizing a system of organic production or handling as described by the Act and the regulations in this part.
CHELATE - A molecule that uses more than one bond to attach strongly to certain elements such as iron (Fe2+) and zinc (Zn2+). These elements may later be released from the chelate and used by plants.
CLIMATE CHANGE- Any systematic shift in the long-term statistics of climate elements (such as temperature, rainfall, or winds) sustained over several decades or longer. This can include changes to both averages of these elements as well as measures of variability and extremes. These changes can be caused by natural external forcings (see definition for forcing(s) below), such as changes in solar emission or slow changes in the Earth’s orbital elements; by natural internal processes of the climate system; or by human activities (anthropogenic forcings).
COLLOID - A very small particle with a high surface area that can stay in a water suspension for a very long time. The colloids in soils - the clay and humus molecules - are usually found in larger aggregates and not as individual particles. These colloids are responsible for many of the chemical and physical properties of soils, including cation exchange capacity, chelation of micronutrients, and development of aggregates.
COMMINGLING - Physical contact between unpackaged organically produced and non-organically produced agricultural products during production, processing, transportation, storage or handling, other than during the manufacture of a multi-ingredient product containing both types of ingredients.
COMPANION PLANTING - A general term essentially synonymous with intercropping but often used to refer to the planting of non-crop or ornamental species with vegetables for attraction of beneficial insects.
COMPOST - The product of a managed process through which microorganisms break down plant and animal materials into more available forms suitable for application to the soil. Compost must be produced through a process that combines plant and animal materials with an initial C:N ratio of between 25:1 and 40:1.
CONSERVATION TILLAGE - Any tillage system that maintains 30 percent or more of the soil surface covered with plant residues after planting. Where soil erosion by wind is the primary concern, any system that maintains at least 1,000 pounds per acre of flat, small grain residue equivalent on the surface throughout the critical wind erosion period.
CONVENTIONAL TILLAGE - Full width tillage that disturbs all of the soil surface and is performed prior to and/or during planting. Less than 15 percent of the soil is covered with residue after planting, or less than 500 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. Generally involves inversion of a plow layer or multiple field operations with non-inversion tools. Weed control is accomplished with crop protection products and/or cultivation.
COULTER - A fluted or rippled disk mounted on the front of a planter to cut surface crop residues and perform minimal soil loosening prior to seed placement. Multiple coulters are used on zone-till planters to provide a wider band of loosened soil.
COVER CROP - A crop grown to protect the soil from erosion during the time of the year when it would otherwise be bare. Sometimes called a green manure crop.
CRITICAL EROSION PERIOD - Period of the year when most of the erosion of unprotected fields can be expected to occur.
CROP RESIDUES - The plant parts remaining in a field after the harvest of a crop, which include stalks, stems, leaves, roots, and weeds.
CROP ROTATION - The practice of alternating the annual crops grown on a specific field in a planned pattern or sequence in successive crop years so that crops of the same species or family are not grown repeatedly without interruption on the same field. Perennial cropping systems employ means such as alley cropping, intercropping, and hedgerows to introduce biological diversity in lieu of crop rotation.
CRUSTING - Surface compaction resulting from raindrop impact, particle detachment, and size sorting, leaving the finest soil particles concentrated at the surface. Impedes infiltration, gas exchange, and seedling emergence.
CULTIVATION - Shallow tillage intended to manage weeds. Can be blind (not guided by crop position) or directed (row crop cultivation - designed to minimize disruption of crop rows). Traditional cultivation equipment does not function well with high residues but high-residue options exist. Actions include undercutting, vibration, and rolling. Can be draft or PTO powered.
CULTURAL METHODS - Methods used to enhance crop health and prevent weed, pest, or disease problems without the use of substances; examples include the selection of appropriate varieties and planting sites; proper timing and density of plantings; irrigation; and extending a growing season by manipulating the microclimate with green houses, cold frames, or wind breaks.