Soil Terminology

Key terms for Soil in Ecosystems and for the Food Infrastructure Service (The Farm).

Soil: Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere, has four important functions:

  • as a medium for plant growth

  • as a means of water storage, supply and purification

  • as a modifier of Earth's atmosphere

  • as a habitat for organisms

All of these functions, in their turn, modify the soil and its properties.

Soil can be seen as a type of Ecosystem at a microbiological level.

Soil Science: is the study of soil as a natural resource on the surface of the Earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.

Pedosphere: Soil occupies the pedosphere, one of Earth's spheres that the geosciences use to organize the Earth conceptually. This is the conceptual perspective of pedology and edaphology, the two main branches of soil science. Pedology is the study of soil in its natural setting. Edaphology is the study of soil in relation to soil-dependent uses. Both branches apply a combination of soil physics, soil chemistry, and soil biology.

Soil Classification: deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.

Soil Formation: also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order (anisotropy) within soils. These alterations lead to the development of layers, termed soil horizons, distinguished by differences in color, structure, texture, and chemistry. These features occur in patterns of soil type distribution, forming in response to differences in soil forming factors.

Soil Fertility: refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.[3] It also refers to the soil's ability to supply plant / crop nutrients in the right quantities and qualities over a sustained period of time. A fertile soil has the following properties:[4]

  • The ability to supply essential plant nutrients and water in adequate amounts and proportions for plant growth and reproduction; and

  • The absence of toxic substances which may inhibit plant growth e.g Fe2+ which leads to nutrient toxicity.

Soil retrogression and degradation: are two regressive evolution processes associated with the loss of equilibrium of a stable soil. Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession reverts the land to its natural physical state. Degradation is an evolution, different from natural evolution, related to the local climate and vegetation.

Respiration (Soil): Soil respiration refers to the production of carbon dioxide when soil organisms respire. This includes respiration of plant roots, the rhizosphere, microbes and fauna.

Soil respiration is a key ecosystem process that releases carbon from the soil in the form of CO2. CO2 is acquired by plants from the atmosphere and converted into organic compounds in the process of photosynthesis.

Microorganism: A microorganism, or microbe,[a] is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.

Detritus: In biology, detritus (/dɪˈtraɪtəs/) is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts communities of microorganisms that colonize and decompose (i.e. remineralize) it.

Feces, Fecal Matter, Faeces: are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine.[1][2] Feces contain a relatively small amount of metabolic waste products such as bacterially altered bilirubin, and dead epithelial cells from the lining of the gut.[1]

Fungus: A fungus (plural: fungi[2] or funguses[3]) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. (Fungi).

Humus: humus is the dark organic matter that forms in soil when dead plant and animal matter (including aerobic compost) breaks down further, specifically through the action of anaerobic organisms. Humus has many nutrients that improve the health of soil, nitrogen being the most important.

Nutrient Cycle

Nutrients are a necessary part of soil and result from the decomposition process or other biogeochemical processes (see *).

Types of Nutrients

Nutrient (primary)

  • Nitrogen *

  • Phosphorous *

  • Potassium

MicroNutrient

  • Boron

  • Chloride

  • Copper

  • Iron

  • Magnesium

  • Molybdenum

  • Zinc

Beneficial

  • Aluminium

  • Cobalt

  • Iodine

  • Nickel

  • Selenium

  • Sodium