Sustainable Soil Managment
Glossary
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CALCAREOUS SOIL. Soil containing sufficient calcium carbonate (often with magnesium carbonate) to effervesce visibly when treated with cold 0.1 N hydrochloric acid.
CALCITIC LIME. Limestone consisting of calcium carbonate-based material with very low magnesium content.
CALCIIUM CARBONATE EQUIVALENT. The liming potential of a material as compared to calcium carbonate.
CAPILLARY ACTION. Movement of water in the soil through small soil pores.
CARBON CYCLE. The sequence of transformations whereby carbon dioxide is fixed in living organisms by photosynthesis or by chemosynthesis, liberated by respiration and by the death and decomposition of the fixing organism, used by heterotrophic species, and ultimately returned to its original state.
CARBON:NITOGEN RATIO. The ratio of the weight of organic carbon to the weight of total nitrogen in a soil or in organic material.
CATION EXCAHNGE CAPACITY. The amount of exchangeable cations that a soil can adsorb at a specific pH, expressed as centimoles of charge per kilogram (cmolc/kg) of soil or milliequivalents per 100 g of soil (meq/100 g soil).
CATION EXCHANGE SITES. Negative charged sites on the surfaces of clays and organic matter.
CATION. An ion that has a positive electrical charge. Common soil cations are calcium, magnesium, hydrogen, sodium, and potassium.
CHELATED MOLECULE. A large, water-soluble organic molecule that binds with a free metal ion to form a water-soluble compound. This process increases the amount of metal ion or atom dissolved in the water and the availability of that ion to plants.
CLAY: (1) The class of smallest soil particles, smaller than 0.002 millimeter in diameter. (2) The textural class with more than 40 percent clay and less than 45 percent sand, and less than 40 percent silt.
CLAY PAN. A dense, compact, slowly permeable layer in the subsoil having a much higher clay content than the overlying material, from which it is separated by a sharply defined boundary. Claypans are usually hard when dry and plastic and sticky when wet.
COLLOID. A very tiny particle capable of being suspended in water without settling out. Soil colloids have a charged surface that attracts ions.
COMPACTION (SOIL). Increasing the soil bulk density, thereby decreasing the soil porosity, by the application of mechanical forces to the soil.
COMPOSITE SOIL SAMPLE. A soil sample resulting from mixing together many individual samples.
COMPOST. Organic residues, or a mixture of organic residues and soil, that have been piled, moistened, and allowed to undergo biological decomposition. Mineral fertilizers are sometimes added. Often called artificial manure or synthetic manure if produced primarily from plant residues.
CONSERVATION TILLAGE. A general term for tillage practices that leave crop residues on the soil surface to reduce erosion.
CONTAMINANT. Any physical, chemical, biological, or radiological substance that is above background concentration but does not necessarily cause harm.
COUNTOUR STRIP-CROPPING. Layout of crops in comparatively narrow strips in which the farming operations are performed approximately on the contour. Usually strips of grass, close-growing crops, or fallow are alternated with those of cultivated crops.
CONTOUR TILLAGE. Tillage that follows the contours of a slope, rather than running up and down a slope. Helps prevent erosion and runoff.
CONTOUR. An imaginary line perpendicular to the slope that represents the same elevation.
CRITICAL VALUE. The point between sufficiency and deficiency levels for a nutrient.
CROP NUTRIENT REQUIRMENT. The amount of nutrients needed to grow a specified yield of a crop plant per unit area.
CROP REMOVAL RATE. The amount of nutrients that are removed from the field in the plant harvest, including harvested fruit, grain, forage, and crop residues that are removed from the field.
CROP ROTATION. A planned sequence of crops growing in a regularly recurring succession on the same field.
CROP SEQUENCE. The order of crops planted and harvested in a field over a period of time.
CROP UTILIZATION RATE. The total amount of nutrients required by the crop to produce both vegetation and grain, including nutrients used to produce roots, stems, crowns, and other unharvested plant parts as well as the harvested portion that is removed from the field.
CRUST. A thin layer of poorly aggregated surface soil formed by wetting and drying.
