Soil Glossary

The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants. (ii) The unconsolidated mineral or organic matter on the surface of the Earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time. A product-soil differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics.

The scientific study of soils and their weathering profiles.

Process of soil formation and development by soil forming factors: climate (mainly temperature and precipitation), parent material, living organisms (plants and biota), topography, time, water and Man.

Soil with a pH value greater than 7.0.

Soil with a pH value less than 7.0.

The characteristic physical and biological activity of soils that influences productivity, capability, and resiliency, which are important for different sectors, such as agriculture, environmental protection, landscape architecture and urban planning.

Single layer in soil profile with similar properties or material but which differs at least in one property, e.g. colour or texture from adjacent horizons above or below in the profile.

A subsurface soil horizon characterised by the in-situ alteration of soil material or the accumulation of clay, iron, and other materials from the topsoil. The soil material shows substantial change relative to the parent material, and generally contains less organic matter and lower levels of biological activity than the surface topsoil.

A vertical section of soil horizons from the upper layer to the parent material, showing the arrangement of soil horizons typical for individual soil types and used as a basis for soil classification.

A recognizable soil layer with specific, measurable properties that serve as key indicators for classifying the soil.

Representative vertical section taken from vertical face of a soil profile pit or section, which represents arrangement of soil horizons; there are various methods of how to take and conserve soil monoliths.

Depth of soil profile from the top to parent material or bedrock or to the layer of obstacles for roots. It differs significantly for different soil types. It is one of basic criterions used in soil classification. Soils can be very shallow (less than 25 cm), shallow (25 cm-50 cm), moderately deep (50 cm-90 cm), deep (90cm-150 cm) and very deep (more than 150 cm).

Mineral or rock material on and/or from which soils are formed during pedogenesis (soil formation process); parent material is one of the five major soil forming factors.

The unconsolidated mantle of weathered rock and soil material on the Earth’s surface, sometimes considered to be loose earth materials above solid rock.

Soil particles between 0.002 mm and 0.05 mm (in some countries 0.06 mm is the upper size limit), with high or medium-high specific area influencing stability of soil structure; also used as a texture class name for medium and medium-fine soil materials.

Material transported and deposited by wind and consisting of predominantly silt-sized particles, forming important fertile soils.

The combination or arrangement of primary soil particles into secondary units or peds. The secondary units are characterized on the basis grade (degree of distinctness), size, and type (shape; degree of distinctness).

Volume of water and air that can be held in a soil; ratio of the volume of voids to the total volume of the soil.

Soil size fraction larger than 2 mm.

Numerical proportion (% by wt.) of sand, silt and clay in a soil. Sand, silt and clay content are estimated in the field, and/or quantitatively in the laboratory, and then placed within the texture triangle to determine soil texture class.

Represented by protozoa, viruses, bacteria, fungi and algae. The most prevalent are bacteria and fungi, and depending on conditions (water and nutrients content, temperature, etc.) they can be in an active or non-active state. According to nutrient (and oxygen) demand, micro-organisms are divided to autotropic and heterotrophic, (aerobic and anaerobic) groups. Micro-organisms are a good indicator of soil status and quality.

Soil biodiversity has been defined as the variety of life below ground, from genes and species to the communities they form, as well as the ecological complexes to which they contribute and to which they belong, from soil micro-habitats to landscape.

Substances released from plant root system in drops or small quantities of carbohydrates, organic acids, vitamins and many other substances essential for life of soil micro-organisms.

Consists of organic debris that accumulates at the surface under either wet or dry conditions and in which any mineral component present does not significantly affect the soil properties. Organic soil material must have organic carbon (organic matter) contents as follows: (1) if saturated with water for long periods (unless artificially drained), and excluding live roots, either: 18 % organic carbon (30 % organic matter) or more if the mineral fraction comprise 60 % or more clay; or 12 % organic carbon (20 % organic matter) or more if the mineral fraction has no clay.

A process, whereby the carbon of organic residues is transformed and converted to humic substances through biochemical and abiotic processes.

The amount of soil nutrients in chemical forms, accessible to plant roots or compounds likely to be convertible to such forms during the growing season.

The conversion of an element from an organic form to an inorganic state as a result of microbial activity.

Groundwater is that portion of the water below the surface of the ground at a pressure equal to, or greater than, that of the atmosphere.

Infiltration is the process by which water on the ground surface enters the soil.

The wearing away of the land surface by water, wind, ice, gravity or other natural or anthropogenic agents that abrade, detach and remove soil particles or rock material from one point on the earth’s surface, for deposition elsewhere, including gravitational creep and so-called tillage erosion.

Negative process often accelerated by human activities (improper soil use and cultivation practices, building areas) that leads to deterioration of soil properties and functions or destruction of soil as a whole, e.g. compaction, erosion, salinization.

Soil ecosystem services are a benefit to society, derived from a healthy ecosystem property or processes.

The characteristic physical and biological activity of soils that influences productivity, capability, and resiliency, which are important for different sectors, such as agriculture, environmental protection, landscape architecture and urban planning.

Podzolic soil is typically found in coniferous forests and heaths and is characterised by strong leaching, which leads to an accumulation of iron, aluminium and organic matter in the deep B horizons. These materials have been transported (eluviated) from the overlying soil horizons (eluvial horizons) by water. Podzolic soils may have B horizons cemented by iron, aluminium and organic matter.

Organic soil material with more than 50% of organic matter derived from plant residues with not fully destroyed structure.

A zonal great soil group consisting of soils with a thick, nearly black or black, organic matter– rich A horizon high in exchangeable calcium, underlain by a lighter-colored transitional horizon above a zone of calcium carbonate accumulation; occurs in a cool subhumid climate under a vegetation of tail and midgrass prairie.