Soil Organisms and Roles

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Soil Organisms and Roles
Power point taken and modified from Tuesday
Desaulniers Soil Bio. PPt
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Soil Biology

• Who is down there and what do they do

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Sun
Producers
Consumers
Decomposers
Humus
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Important Groups of Soil Organisms
Size/type class
e.g. and functional group/energy acquisition

• Macroflora
• Microflora
• Macrofauna

Vascular plants, mosses
algae, bacteria, and fungi
Vertebrates, arthropods, earthworms, snails

• Mesofauna
• Microfauna

smaller arthropods and worms
Nematodes, protzoa
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Soil Animals micro, meso, macro
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Microflora
Bacteria
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Microflora
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Nematodes
Microfauna
Protozoa
20-200 kg/ha!
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Mites
Mesofauna
Springtails
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Other invertebrates
Mesofauna
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Worms
Voles!
Macrofauna
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A cup of soil contains...
Bacteria Fungi Protozoa Nematodes Arthrop
ods Earthworms
200 billion

Microflora, or microbes
100,000 meters
20 million

microfauna
100,000
50,000

macro- and mesofauna
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hyphae

• Aggregates held together by
• Fungal hyphae
• Bacterial glues
• Organic matter

clay
sand
silt
bacteria
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Complex, mutually beneficial relationships
bacteria
fungi
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Earthworm midden
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Earthworms (have gizzards!)

• Probably the most important component of soil
  fauna (not in acid soils, not in very dry soils)
• Eat OM pass as much as 30 tons/ha of soil
  through their bodies (mixing horizons) each year
• Promote good soil structure and aeration

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Sun
Producers
Consumers
Decomposers
Humus