Soil Biology

Source "www.mycorrhialfungi.info"

The life in the soil is one of my favorite topics. I think it’s importance in cropping system is grossly underestimated. After all without the soil biology there would be no soil. However complex the soil biology is I think that it is best left to mother nature to balance out this ecosystem. That is why we practice a no-till production system. Lots of benefits come with preserving this soil life that you just can’t buy from the crop inputs supplier. I strongly recommend that every person attempting to grow anything in soil find themselves as many publications about soil boilogy like this one from Univeristy of Minnesota Extension titled Soil Scientist. The more you dig into this topic the more you appriciate the value of the soil life. We will be posting great information on this topic.

The Table Below was sourced from the University of Minnesota, Extension web site.

Description	Size	Diet	Typical amt in ag soils	Action in soil
Bacteria Usually one-celled	1 um (0.001 mm)	Organic matter, especially simple carbon compounds	100 mil. to 1 bil. in a teaspoon	Decompose organic matter. Immobilize nutrients in the rooting zone. Rhizobium and other genera fix nitrogen from air. Convert ammonium to nitrate, and nitrate to nitrogen gasses. Actinomycetes, which grow as filaments, are important in decomposition at moderate-to-high pH. Create substances that help bind soil aggregates.
Fungi Grow in long filaments calleed hyphae	A few um wie, yards or miles long	Organic matter, especially simple carbon compounds. Also, living plants	Several yards in a teaspoon	Decompose organic matter. Immobilize nutrients in the rooting zone. Mycorrhizal fungi form mutually beneficial associa- tions with roots. They release acids that help make phosphorus more available to plants. Help stabilize soil aggregates.
Protozoa One-celled animals	5-500 um	Bacteria, primarily	Several thousand in a teaspoon	Stimulate and control growth of bacteria. Release ammonium.
Nematodes Roundworms. Not segmented as are earthworms	50 um wide, 1 mm long	Bacteria, fungi, protozoa, other nematodes, and roots	Ten to twenty in a teaspoon	Control many disease-causing organisms. Root-feeders may cause root diseases. Release ammonium.
Arthropods Include insects, mites, spiders, springtails, & millipedes	Microscopic to inches	All other organisms	Several hundred in a cubic foot	Shred plant residue, making it more accessible to bacteria and fungi. Enhance soil structure by creating fecal pellets, and by burrowing. Control populations of other organisms.
Earthworms	Inch or more long	Bacteria, fungi, and organic matter	Five to thirty in a cubic foot	Shred plant residue. Enhance soil structure by burrowing, mixing, and creating fecal pellets. Transport and stimulate growth of bacteria.

Description

Size

Diet

Typical amt in ag soils

Action in soil

Bacteria
Usually one-celled

1 um (0.001 mm)

Organic matter, especially simple carbon compounds

100 mil. to 1 bil. in a teaspoon

Fungi
Grow in long filaments calleed hyphae

A few um wie, yards or miles long

Organic matter, especially simple carbon compounds. Also, living plants

Several yards in a teaspoon

Decompose organic matter.
Immobilize nutrients in the rooting zone.
Mycorrhizal fungi form mutually beneficial associa- tions with roots. They release acids that help make phosphorus more available to plants.
Help stabilize soil aggregates.

Protozoa
One-celled animals

5-500 um

Bacteria, primarily

Several thousand in a teaspoon

Stimulate and control growth of bacteria.
Release ammonium.

Nematodes
Roundworms. Not segmented as are earthworms

50 um wide, 1 mm long

Bacteria, fungi, protozoa, other nematodes, and roots

Ten to twenty in a teaspoon

Control many disease-causing organisms.
Root-feeders may cause root diseases.
Release ammonium.

Arthropods
Include insects, mites, spiders, springtails, & millipedes

Microscopic to inches

All other organisms

Several hundred in a cubic foot

Shred plant residue, making it more accessible to bacteria and fungi.
Enhance soil structure by creating fecal pellets, and by burrowing.
Control populations of other organisms.

Earthworms

Inch or more long

Bacteria, fungi, and organic matter

Five to thirty in a cubic foot

Shred plant residue.
Enhance soil structure by burrowing, mixing, and creating fecal pellets.
Transport and stimulate growth of bacteria.