| soil | Unconsolidated material on the earth's surface that supports or is capable of supporting plants out-of-doors. (09 Oct 1997) |
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| soil horizon | A distinct layer of soil, more or less parallel with the soil surface, having similar properties such as colour, texture and permeability, the soil profile is subdivided into the following major horizons: A-horizon, characterised by an accumulation of organic material. B-horizon, characterised by relative accumulation of clay iron, organic matter or aluminum. C-horizon, the undisturbed and unaltered parent material. (Some soils have an E-horizon, characterised by leaching of organic and other material.) (09 Oct 1997) |
| soil hue | A characteristic of colour related to one of the main spectral colours (red, yellow, green, blue or purple), or various combinations of these principle colours, one of the three variables of colour, each colour chart in the Munsell Soil Colour Charts (Kollmorgen Corporation 1975) represents a specific hue. (09 Oct 1997) |
| soil matrix | The portion of a given soil having the dominant colour, in most cases, the matrix will be the portion of the soil having more than 50 percent of the same colour. (09 Oct 1997) |
| soil microbiology | The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms. (12 Dec 1998) |
| soil permeability | The ease with which gases, liquids or plant roots penetrate or pass through a layer of soil. (09 Oct 1997) |
| soil phase | A subdivision of a soil series having features (for example, slope, surface texture, thickness and stoniness) that affect the use and management of the soil, but which do not vary sufficiently to differentiate it as a separate series. (09 Oct 1997) |
| soil pollutants | Substances which pollute the soil. Use for soil pollutants in general or for which there is no specific heading. (12 Dec 1998) |
| soil pollutants, radioactive | Pollutants, present in soil, which exhibit radioactivity. (12 Dec 1998) |
| soil pore | An area within soil occupied by either air or water, resulting from the arrangement of individual soil particles. (09 Oct 1997) |
| 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) |