- 行业: Earth science
- Number of terms: 26251
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An international scientific society that fosters the transfer of knowledge and practices to sustain global soils. Based in Madison, WI, and founded in 1936, SSSA is the professional home for 6,000+ members dedicated to advancing the field of soil science. It provides information about soils in ...
A term used in kinetics to indicate the amount of energy required to bring all molecules in one mole of a substance to their reactive state at a given temperature. Conceptually, this energy barrier must be overcome to get a reaction to go forward. At higher activation energies, reactions are slower if temperature and composition are constant. It is usually determined from an Arrhenius plot of the inverse of the absolute temperature vs. rates of reaction at different temperatures.
Industry:Earth science
Impure ferruginous deposits developed in bogs or swamps by the chemical or biochemical oxidation of iron carried in solution.
Industry:Earth science
Force, as with a tillage tool, acting at a right angle to the direction of movement of the tillage implement.
Industry:Earth science
A vermiculite with partially filled interlayers of hydroxy-aluminum groups. It is normally dioctahedral in both the interlayer and the octahedral sheet of the vermiculite layer. It is common in the coarse clay fraction of acid surface soil horizons. It has intermediate cation exchange properties between vermiculite and chlorite. Synonyms are "chlorite-vermiculite intergrade"; "vermiculite-chlorite intergrade. "
Industry:Earth science
Potential energy of soil water due to the weight of water (hydrostatic pressure) on the point of interest. Pressure head is expressed as energy per weight and is equal to the height of water between the point of interest and the free water surface (water table), hp, also termed the piezometric head. Pressure potential is expressed as energy per unit volume and equals the piezometric head, Hp, the water density, ρ, and the gravitations constange, g (ρghp.
Industry:Earth science
Cohesion in granular soils due to capillary forces associated with water.
Industry:Earth science
A term used in Canada to describe an intrazonal group of imperfectly to poorly-drained forested soils having dark-gray A horizons, moderately high in organic matter, underlain by mottled gray or brownish gleyed mineral horizons. They have a low degree of textural differentiation.
Industry:Earth science
Groups of capability units within classes of the land capability classification that have the same kinds of dominant limitations for agricultural use as a result of soil and climate. Some soils are subject to erosion if they are not protected, while others are naturally wet and must be drained if crops are to be grown. Some soils are shallow or droughty or have other soil deficiencies. Still other soils occur in areas where climate limits their use. The four kinds of limitations recognized at the subclass level are: risks of erosion, designated by the symbol (e); wetness, drainage, or overflow (w); other root zone limitations (s); and climatic limitations (c). The subclass provides the map user information about both the degree and kind of limitation. Capability Class I has no subclasses.
Industry:Earth science
