Soil Organisms and Roles

Power point taken and modified from Tuesday Desaulnier’s Soil Bio. PPt

Soil BiologySoil Biology

Who is down Who is down there and what there and what do they dodo they do

Sun

Humus

Producers

ConsumersDecomposers

air water

soil

Important Groups of Soil OrganismsImportant Groups of Soil Organisms

• MacrofloraMacroflora

• MicrofloraMicroflora

• MacrofaunaMacrofauna

Vascular plantsVascular plants, mosses, mosses

algae, bacteria, and fungialgae, bacteria, and fungi

Vertebrates, arthropods, earthworms, Vertebrates, arthropods, earthworms, snails… snails…

• MesofaunaMesofauna

• MicrofaunaMicrofauna

smaller arthropods and wormssmaller arthropods and worms

Nematodes, protzoaNematodes, protzoa

Size/type classSize/type class e.g. and functional group/energy acquisitione.g. and functional group/energy acquisition

Soil Animals – micro, meso, macro

BacteriaMicroflora

Microflora

Nematodes

Protozoa

Microfauna

20-200 kg/ha!20-200 kg/ha!

Mites

Springtails

Mesofauna

Other invertebrates

Mesofauna

Worms

Voles!

Macrofauna

A cup of soil containsA cup of soil contains......

BacteriaBacteria

Fungi*Fungi*

ProtozoaProtozoa

NematodesNematodes

ArthropodsArthropods

EarthwormsEarthworms

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microfaunamicrofauna

macro- and macro- and mesofaunamesofauna

200 billion200 billion

100,000 meters

20 million20 million

100,000100,000

50,00050,000<1<1

Microflora, Microflora, or “microbes”or “microbes”

B – BacteriaA – ActinomycetesMy – MycorrhizaeH – Saprophitic fungusN – NematodeCP – Ciliate protozoaFP – Flagellate protozoaM – Mite

< 1mm

1/10 mm

Aggregates held together by:

1. Fungal hyphae2. Bacterial “glues”3. Organic matter

sand

silt

hyphaeclay

bacteria

Complex, mutually beneficial Complex, mutually beneficial relationshipsrelationships

fungi

bacteria

Earthworm middenEarthworm midden

Earthworms Earthworms – (have gizzards!)– (have gizzards!)

• Probably the most important component of Probably the most important component of soil fauna (not in acid soils, not in very dry soil fauna (not in acid soils, not in very dry soils)soils)

• Eat OM & pass as much as 30 tons/ha of Eat OM & pass as much as 30 tons/ha of soil through their bodies (mixing horizons) soil through their bodies (mixing horizons) each yeareach year

• Promote good soil structure and aerationPromote good soil structure and aeration

Sun

Humus

Producers

ConsumersDecomposers

air water

soil