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Organic Agriculture: Microbial Activity and Soil Health

Organic Agriculture: Microbial Activity and Soil Health. Warren Roberts Jim Shrefler Merritt Taylor Lane Agricultural Center OSU. We All Want Food that is. Plentiful Nutritious Safe. Why Have Organic Food?. Public Concern about Food Safety

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Organic Agriculture: Microbial Activity and Soil Health

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  1. Organic Agriculture: Microbial Activity and Soil Health Warren Roberts Jim Shrefler Merritt Taylor Lane Agricultural Center OSU

  2. We All Want Food that is PlentifulNutritiousSafe

  3. Why Have Organic Food? • Public Concern about Food Safety • Perception that Organically Grown Foods are Safer & More Nutritious

  4. It’s a Matter of Life and?

  5. Microbial Activity and Soil Health • Define Microbial • Micro-organisms • Define Activity • Growth, Reproduction, Function • Define Soil Health • Ability of a Soil to Function • Chemistry, Physics, Biology • Define Biology • Study of Life and Life Processes

  6. Purpose of Soil Health • Promote Plant and Animal Systems • Promote Clean Water • Prevent Soil Erosion • Promote Human Health • Promote Life !

  7. Soil Microorganisms • Larger Animals • Bacteria (Often Single Cell) • Fungi (Often Long Filaments or Hyphae) • Actinomycetes (Properties of Both)

  8. Microorganisms • Affected by • Moisture • Temperature • Aeration • Food Supply (Organic Matter) • Acidity

  9. Location in Soil • Mostly in top inch • Almost all in top 6 inches • Rhizosphere • Adjacent to plant roots • High microbial activity • Contains root exudates

  10. Soil Animals • Earthworms • Mites • Nematodes • Protozoa • Beetles • Termites

  11. Bacteria • Mostly Single Cell • Millions per Gram • Millions of Billions per Acre

  12. Roles of Bacteria • Nitrogen Fixation • Mineralization • Organic Matter Decomposition • Soil Stabilization • Aeration • Tilth

  13. Nitrogen Fixation • Bacteria (Rhizobium and others) • Symbiotic • Bacteria gets carbon from plants • Bacteria supplies Nitrogen to plants • Usually with Legumes

  14. Mineralization • Conversion from Organic Substance to Molecular Level Minerals • Decay • Physical and Chemical

  15. Organic Matter Decomposition • Physical changes • Organisms eat, crunch, rip, tear • Earthworms, mites, ants, etc • Chemical changes • Digestion with enzymes

  16. What Controls Rate of Decay • Temperature • Moisture • Food Supply • Oxygen • C:N Ratio

  17. C:N Ratio • Microbes Need Carbon • Microbes Need Nitrogen • Nitrogen is Often the Limiting Factor

  18. C:N Ratio Slow Stinky

  19. Soil Stabilization • Soil Aggregation • Clumps of Particles • Organic Matter • Bacterial Residues • Fungal Hyphae

  20. Aeration & Tilth • High Organic Matter • Low Compaction • High Aggregation

  21. Raised Bed Gardening – Noble Foundation

  22. Fungi • Hundreds of Thousands per Gram • Perform Functions Similar to Bacteria • Decomposition • Important in Plant Nutrition • Mycorrhizae (fungus root)

  23. Mycorrhizae • Mutualism or Synergism • Benefits Plant and Fungus • Ectomycorrhizal • Hyphae do not penetrate root cells • Endomycorrhizal • Hyphae do enter root cells • Arbuscular • Very Common • 90+ % of plant families

  24. Ectomycorrhizae • Ecto- (outer) • Hyphae form sheath around root tip • Promotes nutrient absorption • Promotes nutrient translocation

  25. Endomycorrhizae • Endo – (inner) • Hyphae Penetrates Cell Wall • Promote Nutrient Uptake and Exchange • Increase Surface Contact Area

  26. To Your Good Health (Soil) • Keep pH near neutral • Avoid Compaction • Maintain Good Moisture • Promote Drainage • Good Temperature • Organic Matter

  27. A Noble Soil

  28. ProBiotics • Cultures of Beneficial Microorganisms • Compost Teas • Inoculants • Organism Food • Sugar • Molasses • Nitrogen

  29. Where We Are • 50 + years of Chemical Research • What If ? • 50 + Years of Biological Research ?

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