Soil Biology

Soil Biology

Plant roots
1. support plant
2. form interface btwn plants and soil
3. absorption of water and nutrients
4. Direct interactions
  1. Positive
    1. Mycorrhizal fungi
      1. ectotrophic
      2. endotrophic
  2. Negative
    1. Pathogens
      1. many causative organisms of plant diseases enter via soil
      2. fungi
      3. nematodes
    2. Grazing
      1. importance of nematode and arthropod grazing on root tissues now recognised
5. Alter soil env.
  1. rhizosphere
    1. region adjacent to plant roots
  2. plant exudates
    1. leak from plant root cells
    2. low molecular weight organic compounds
    3. provide readily available organic C source and nutrients for microbial growth
Soil microorganisms
1. Prokaryota
  1. Bacteria
    1. Different shapes
    2. Some motile
    3. Dominate at higher pH
    4. Some autotrophic
  2. Actinomycetes
    1. Filamentous
    2. Slow growing
    3. Heat resistant
    4. Produce powerful antibiotics
2. Eukaryota
  1. Fungi
    1. Mycellium of hyphae
    2. Dominate ate lower pH
  2. Protozoa
    1. Single celled animals
    2. Aquatic
    3. Can regulate bacterial pop'ns
3. Mineralisation
  1. release nutrients into soil
    1. decomposition of organic matter
4. Immobilisation
  1. removes nutrients from soil
  2. synthesis of organic matter
Soil animals
1. contribute less than 5% to carbon emissions from soils
2. key system regulators of soil microbial activity
3. microbes 'sleep' til animals stir up soil

Resource summary

	Created by Liv about 11 years ago