| soil pore | An area within soil occupied by either air or water, resulting from the arrangement of individual soil particles. (09 Oct 1997) |
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| soil profile | A vertical section of the soil through all its horizons and extending into the parent material. (09 Oct 1997) |
| soil series | A group of soils having horizons similar in differentiating characteristics and arrangements in the soil profile, except for texture of the surface layer. (09 Oct 1997) |
| soil structure | The combination or arrangement of primary soil particles into secondary particles, units or peds. (09 Oct 1997) |
| soil suborder | Second highest taxonomic level of the current U.S. Soil classification system. (09 Oct 1997) |
| soil surface | The upper limits of the soil profile, for mineral soils, the upper limits of the highest mineral horizon (A-horizon), for organic soils, the upper limit of undecomposed organic matter. (09 Oct 1997) |
| soil texture | The relative proportions of the various sizes of particles (silt, sand and clay) in a soil. (09 Oct 1997) |
| soil value | The relative lightness or intensity of colour, approximately a function of the square root of the total amount of light, one of the three variables of colour. (09 Oct 1997) |
| somewhat poorly drained soil | <botany> A condition in which water is removed slowly enough that the soil is wet for significant periods during the growing season. (04 Mar 1998) |
| expansive soil | Soils that swell when they absorb water and shrink as they dry. (09 Oct 1997) |
| air plant | <botany> A plant deriving its sustenance from the air alone; an aerophyte. The "Florida moss" (Tillandsia), many tropical orchids, and most mosses and lichens are air plants. Those which are lodged upon trees, but not parasitic on them, are epiphytes. Source: Websters Dictionary (01 Mar 1998) |
| aquatic plant | <botany> Plants that must grow in water whether rooted in the mud or floating without anchorage, plants that must complete part or all of their life cycle in or near the water. (09 Oct 1997) |
| C3 plant | <plant biology> Plants that fix carbon dioxide in photosynthesis by the Calvin Benson cycle. The enzyme responsible for carbon dioxide fixation is RuDP carboxylase, whose products are compounds containing three carbon atoms. C3 plants are typical of temperate climates. Photorespiration in these plants is high. (07 Nov 1997) |
| C4 plant | <plant biology> Plants found principally in hot climates whose initial fixation of carbon dioxide in photosynthesis is by the HSK pathway. The enzyme responsible is PEP carboxylase, whose products contain four carbon atoms. Subsequently the carbon dioxide is released and re fixed by the Calvin Benson cycle. The presence of the HSK pathway permits efficient photosynthesis at high light intensities and low carbon dioxide concentrations. most species of this type have little or no photorespiration. (21 Mar 1998) |
| vascular plant | A plant which possesses a well-developed system of conducting tissue to transport water, mineral salts and sugars. (09 Oct 1997) |