1. THE SOIL FOOD WEB

2. Soil Biology and the Landscape

3. The Soil Food Web

4. Components of Soil Organic Matter Decomposing organic matter (active fraction) 33% - 50% Stabilized organic matter (humus) 33% - 50% Fresh residue <10% Living organisms <5%

5. Rhizosphere

6. Microbial Biomass with Depth

7. Seasonal Microbial Activity

8. FOOD WEB & SOIL HEALTH

9. Biomass of Soil Organisms in Four Ecosystems

10. Typical Numbers of Soil Organisms in Healthy Ecosystems Ag LandPrairieForest Organisms per gram (teaspoon) of soil Bacteria100 mil. -1 bil. FungiSeveral yards10s – 100’s of yds1-40 miles (in conifers) Protozoa1000’s 100,000’s Nematodes10-2010’s – 100’s100’s Organisms per square foot Arthropods< 100500-200010,000-25,000 Earthworms5-3010-50 (0 in conifers)

11. Methods for Measuring the Food Web Counting Direct counts of individuals Plate counts of colonies Activity levels Respiration (CO 2 production) Nitrification rates Decomposition rates Cellular constituents Biomass C, N, or P Enzymes Phospholipids DNA and RNA

12. Bacteria with fluorescent stain for counting

13. A Complex Food Web

14. Complexity of the Soil Food Web in Several Ecosystems

16. BACTERIA

17. Bacteria

18. Nitrogen-fixing Bacteria Nodules formed where Rhizobium bacteria infected soybean roots.

19. Actinomycetes Bacterial cells that grow like fungal hyphae

20. Bacteria vs. fungi

21. FUNGI

22. Fungi and Soil Quality –Decompose carbon compounds –Improve OM accumulation –Retain nutrients in the soil –Bind soil particles –Food for the rest of the food web –Mycorrhizal fungi –Compete with plant pathogens

23. Mycorrhizae Tree root Mycorrhizal structure Fungal hyphae

24. Ectomycorrhizae

25. Arbuscular Mycorrhizae (AM)

27. Mushrooms: The fruiting body of some fungi

28. Mycorrhizal Fungi

29. PROTOZOA Ciliates Largest of the three types Move by means of hair-like cilia Eat the other protozoa and bacteria Amoebae Also large Move by means of a temporary foot (pseudopod) Include testate amoebae (with shell-like covering), and naked amoebae Flagellates Smallest of the three Move by means of a few whip-like flagella.

30. First 29 of 58 Slides On Soil Foodweb