Under the Microscope

Why Soil Life are Important

Micro-organisms perform a multitude of roles in the soil including decomposing organic matter and in doing so release nutrients to the plant. The activity of soil micro-organisms also improves the water holding capacity and the structure of the soil. This makes the soil more porous, allowing better root penetration, which in turn means that plants have greater access to oxygen, nutrients and water.

Maintaining a healthy balance of beneficial micro-organisms can also actively keep out plant pathogens, which helps to achieve more sustainable turf care.

 Functions of Soil Organisms

Type of Soil Organism

Major Functions


Photosynthesisers
  • Plants
  • Algae
  • Bacteria
Capture Energy
  • Use solar energy to fix CO2
  • Add organic matter to soil (biomass such as dead cells, plant litter and secondary metabolites)

Decomposers
  • Bacteria
  • Fungi
Break down residue
  • Immobilise (retain) nutrients in their biomass
  • Creates new organic compounds (cell constituents, waste products) that are sources of energy and nutrients for other organisms.
  • Produce compounds that help bind soil into aggregates
  • Bind soil aggregates with fungal hyphae
  • Nitrifying and denitrifying bacteria convert forms of nitrogen
  • Competes with or inhibits disease-causing organisms

Mutualists
  • Bacteria
  • Fungi
Enhance plant growth
  • Protect plant roots from disease-causing organisms. Some bacteria fix N2
  • Some fungi form mycorrhizal associations roots and deliver nutrients (such as P) and water to the plant

Pathogens
  • Bacteria
  • Fungi
Parasites
  • Nematodes
  • Micro arthropods
Promote Disease
  • Consume roots and other plant parts, causing disease
  • Parasitise nematodes or insects, including disease-causing organisms

Root Feeders
  • Nematodes
  • Macro arthropods
    (eg cutworm, weevil, larvae & symphylans)
Consume plant roots
  • Potentially cause significant plant losses

Bacterial-feeders
  • Amoeba
  • Protozoa
  • Nematodes
Graze
  • Release plant available nitrogen (NH4+) and other nutrients when feeding on bacteria
  • Control many root-feeding or disease-causing pests
  • Stimulate and control the activity of bacterial populations

Fungal-feeders
  • Nematodes
  • Micro arthropods
Graze
  • Release plant available nitrogen (NH4+) and other nutrients when feeding on fungi
  • Control many root-feeding or disease-causing pests
  • Stimulate and control the activity of fugal populations

Shredders
  • Earth worms
  • Micro arthropods
Break down residue and enhance soil structure
  • Shred plant litter as they feed on bacteria and fungi
  • Provide habitat for bacteria in their gut and fecal pellets
  • Enhance soil structure as they produce faecal pellets and burrow through soil.

Higher-level predators
  • Nematode feeding nematodes
  • Larger arthropods, mice, voles, shrews, birds, other above ground animals
Control populations
  • Control the population of lower trophic-level predators
  • Larger organisms improve soil structure by burrowing and by-passing soil through their guts
  • Larger organisms carry smaller organisms long distances.