AOAC SPADA Meeting

Habitat for Soil Organisms

Organisms Microflora Bacteria

Number per m 2

Number per gram soil

10 13 ‐10 14 10 12 ‐10 13 10 10 ‐10 11 10 9 ‐10 10 10 9 ‐10 10 10 6 ‐10 7 10 3 ‐10 6 10 3 ‐10 6 10‐10 3 10 2 ‐10 4

10 8 ‐10 9 10 7 ‐10 8 10 5 ‐10 6 10 4 ‐10 5

Actinomycetes Fungi Algae

Fauna

Protozoa Nematodes Mites Collembola Earthworms Other fauna

10 4 ‐10 5 10‐10 2

1‐10 1‐10

KSU image

Soil porosity and soil drainage

• Soil porosity impacts:

• Water flow and therefore  drainage • Gas exchange • Mineral weathering • Root growth

Anaerobic microbial  processes, reduced iron

Oxic conditions,  oxidation of iron to iron  oxides