humus

(noun)

a large group of natural organic compounds found in the soil composed of decaying plants and dead and living microorganisms

Related Terms

Examples of humus in the following topics:

  • Soil Composition

    • The organic material of soil, called humus, is made up of microorganisms (dead and alive), and dead animals and plants in varying stages of decay.
    • Humus improves soil structure, providing plants with water and minerals.
    • Some soils have no dominant particle size, containing a mixture of sand, silt, and humus; these soils are called loams.

  • Physical Properties of Soil

    • The O horizon has freshly-decomposing organic matter, humus, at its surface, with decomposed vegetation at its base.
    • Humus enriches the soil with nutrients, enhancing soil moisture retention.

  • Overview of Gram-Positive Bacteria and Actinobacteria

    • This replenishes the supply of nutrients in the soil and is an important part of humus formation.

  • Actinobacteria (High G + C Gram-Positive Bacteria)

    • This replenishes the supply of nutrients in the soil and is an important part of humus formation.

  • The Role of Prokaryotes in Ecosystems

    • Related to this, one very significant source of carbon compounds is humus, which is a mixture of organic materials from dead plants and prokaryotes that have resisted decomposition.
    • The most important contributor of carbon dioxide to the atmosphere is microbial decomposition of dead material (dead animals, plants, and humus).

  • Second Declension

  • Temperate Grasslands

    • The vegetation is very dense and the soils are fertile because the subsurface of the soil is packed with the roots and rhizomes (underground stems) of these grasses, which anchor plants into the ground and replenish the organic material (humus) in the soil when they die and decay.

  • Wetland Soils

    • In low redox conditions the deposition of ferrous iron (Fe2+) will increase with decreasing decomposition rates, thus preserving organic remains and depositing humus.

  • Nutrients from Other Sources

    • Epiphytes have two types of roots: clinging aerial roots (which absorb nutrients from humus that accumulates in the crevices of trees) and aerial roots (which absorb moisture from the atmosphere).