THE LIVING SOIL

1. THELIVINGSOIL

2. Functions of soil • Support plant growth • Regulate water flow • Absorb and transform pollutants • Habitat for living organisms  Soil Quality

3. Objective: Soil organisms: • Who are they and what do they do? • How do they contribute to soil quality?

4. VEGETATION • Vegetation - Additon of Organic Matter (OM). • Prairie ~ OM added to upper 2 ft. of soil due to fibrous root system of grass plants. Ap A AB Bg

5. VEGETATION • Forest ~ OM added to upper 4 “ due to yearly leaf fall to surface of soil. A

6. Prairie - Border Biotic Factor • Prairie - Border soils (oak savannahs) have the influence of the prairie and forest ~ due to changes in vegetation over the past 8000 years the soils have been both under prairie and forest.

7. Soil Organisms: sizes and abundances

8. Size classification of soil fauna • Microfauna (<0.1mm diameter) • Occupy water films and existing water-filled pores • Protozoa, nematodes

9. Mesofauna (0.1 – 2mm diameter) • Occupy existing water- and air-filled pore spaces • Able to break free from surface tension of soil water • Potworms, microarthropods

10. Macrofauna (2-20mm diameter) • Able to alter soil structure • Earthworms, macroarthropods

11. Bacteria • Microscopic, single-celled • Up to 3 billion/g • Autotrophs, decomposers, plant symbionts, pathogens

12. Fungi • Thread-like hyphae; some form visible fruiting bodies (mushrooms, bracket fungi) • Up to 50 meters/g • Decomposers, plant symbionts, pathogens, predators

13. Protozoa • Single-celled animals • 10,000 - 100,000/g • Feed on bacteria, fungi, decaying organic matter, other protozoa

17. Nematodes • 1 - 4.5 mm • Up to 7 million /m2 • Bacteria feeders, fungus feeders, predators, plant roots, parasites

18. Isopods • Crustaceans • Feed on decaying plant residues

19. Myriapods • Centipedes – predators • Millipedes – decaying plant residues • Symphylans, pauropods

20. Springtails • 1 - 7 mm • Up to 100,000/m2 • Fungus feeders, decaying OM, some plant feeders

21. Mites • 0.1 - 3mm • Up to 250,000/m2 • Decomposers, predators, parasites, plant feeders

22. Earthworms • 2 - 20 cm • 10 - 950/m2 • Many introduced species • Decaying organic matter • Different ecological types

23. Anecic Earthworms • Medium to large size • Dorsal, anterior pigment • Permanent vertical burrows • Forage for plant residues on the soil surface • e.g. Lumbricus terrestris

24. Endogeic Earthworms • Small to medium size • Unpigmented • Horizontal burrows in topsoil • Feed on dead plant roots and other buried organic matter • e.g. Octolasion tyrtaeum

25. Epigeic Earthworms • Small in size • Red-brown pigment • Weak burrowers; do not inhabit mineral soils • Forest litter, compost • e.g. Eisenia fetida

26. Role in Soil Processes • Soil formation and soil structuring • Nutrient recycling and retention • Population regulation

27. Role in Soil Formation • Fragment and humify organic residues and mix into mineral soil

28. Soil formation • Formation and stabilization of aggregates • Formation of pore spaces

29. Nutrient Availability • Symbiotic associations • Rhizobium and legumes • Mycorrhizae and most plants

30. Nutrient Availability • Nutrient mineralization from organic matter pools • Biological nutrient pool

34. Population regulation