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Managing What You Can't See

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Powerpoint by Prof. Edward Rayburn. 2012 Soil Science presentation

Powerpoint by Prof. Edward Rayburn. 2012 Soil Science presentation


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  • 1. Pasture Ecology - ManagingThings That We Cannot See. Ed Rayburn Extension Specialist West Virginia University erayburn@wvu.edu
  • 2. Pasture-Based Livestock Producers• In business harvesting solar energy.• Converting solar energy into food and fiber products for people.• Manage – plants to optimize harvest of solar energy, – animals to transfer that energy into livestock products, – cycling of mineral nutrients in the landscape – to make business socially, economically, and environmentally sustainable.• Are pasture ecosystem managers.
  • 3. Energy Flow and Nutrient Cycles
  • 4. Generalized Nutrient Cycle
  • 5. Soil Organic Matter• Plant residues (dead plant material, course OM)• Active organic matter (rapid decomposition)• Slow organic matter (slow decomposition)• Passive organic matter (stable OM)
  • 6. Citizens of the Soil Community• Plant roots and root nodules• Earthworms• Slugs and snails• Nematodes• Woodlice• Spiders and Mites• Centipedes and Millipedes• Spring tails• Beetles• Ants and Termites• Bacteria and Actinomycetes• Protozoa• Fungus
  • 7. Soil Citizens Provide Community Services• Nitrogen fixation• Nutrient cycling – shredders – decomposers – predators• Soil structure and aeration – water infiltration, holding capacity• Soil moisture affects microbial activity• Each has an optimum environment• Redundancy of functional species with different optima• Each has a niches• All participate in the soil food web
  • 8. Photos FromNRCS Soil Biology Web Site http://soils.usda.gov/sqi/concepts/ soil_biology/biology.html
  • 9. Earthworms (3 niches)
  • 10. Earthworms
  • 11. Arthropods (Insects and Relatives)
  • 12. Dung Beetles (3 niches)Dung Beetles of Central and Eastern North Carolina Cattle Pastures http://www.cals.ncsu.edu/entomology/guidetoncdungbeetles.pdf
  • 13. http://www.cals.ncsu.edu/entomology/guidetoncdungbeetles.pdf
  • 14. Slugs and Snails• Primary consumers• Shredders• Predators http://www.backyardnature.net/snail_sl.htm
  • 15. Bacteria• Decomposers – immobilize nutrients in cells – make energy and nutrients available• Mutualists partner with plants – nitrogen-fixing bacteria• Pathogens• Chemoautotrophs – obtains energy from nitrogen, sulfur, iron or hydrogen not carbon compounds
  • 16. Bacteria Services• Nutrient cycling – decomposition – hold nutrients• Disease suppression – compete with disease-causing organisms below and above ground• Water movement – substances bind soil particles into stable aggregates – water infiltration – water-holding capacity• Symbiotic bacteria with legumes – convert nitrogen from air to form plant can use• Nitrifying bacteria – change ammonium (NH4+) to nitrite (NO2-) then to nitrate (NO3-)• Denitrifying bacteria – convert nitrate to nitrogen (N2) or nitrous oxide (N2O) gas• Actinomycetes – decompose hard-to-decompose compounds, chitin and cellulose
  • 17. Protozoa Help With Nutrient Cycling By Feeding on Bacteria
  • 18. Protozoa Come in Three Forms, Amoeba, Flagellates, Ciliates
  • 19. Free-Living Nematodes (4-types)• Bacterial-feeders consume bacteria.• Fungal-feeders puncture cell wall of fungi and suck out the internal contents.• Predatory eat other nematodes and protozoa.• Omnivores eat a variety of organisms or may have a different diet at each life stage.• (Root-feeding nematodes are plant parasites, and are not free-living in the soil)
  • 20. Nematodes• Fungal-feeding • Bacterial-feeding
  • 21. Fungi • Decompose OM • Glomalin secretion develops soil structure • Extract nutrients • Hold nutrients
  • 22. Fungi Help Plants Extract Nutrients From Soil
  • 23. Arbuscular Mycorrhizal Fungus (AM)
  • 24. Ectomycorrhizae Important To Trees
  • 25. Basic Nutrient Cycling• Plant, bacteria and fungus – extract N from air or soil – extract macro and micro minerals from soil• Plant consumed by herbivore or dies• Herbivores deposit manure and urine• Shredders break large material into small bits• Bacteria consume rapidly degraded CHOs (sugars etc.)• Bacteria consume less degradable CHOs (fiber)• Fungi and actinomycetes consume even less degradable CHOs (fiber and lignin)• Macro and micro minerals released for plants• Organic forms of P and micro minerals more available to plants
  • 26. Community Interactions• Legume, bacteria• Legume, bacteria, and grass• Legume, bacteria, fungus, and grass
  • 27. N Transfer From Legume (Clover & Bacteria) to Grass In a New Seeding. 25 20 Ryegrass w/Ryegrass CP% 15 ladino clover Ryegrass w/o ladino clover 10 5 0 1-Feb 2-Apr 1-Jun 31-Jul 29-Sep 28-Nov 27-Jan
  • 28. Transfers Between Legumes, Grasses, and Soil By Way of Mycorrhizae.
  • 29. Community Interactions• Bacteria and nematodes• Bacteria, mites, and nematodes
  • 30. Interactions • Nematodes eat bacteria • Mites eat nematode • Nematodes eat fungus • Fungi eat nematodes
  • 31. Healthy Soil Ecology Balance of• Food supply (organic matter with adequate macro- and micro mineral nutrients)• Physical environment above and below ground (cover and habitat at all scales)• Healthy consumers, omnivores, predators, and predators of predators (diversity)• Chemical environment (soil oxygen, pH, fertility)• Thermal and moisture environment
  • 32. Management Needed to Help the System (a)• Soil pH 6.0-7.0 depending on the legume• Adequate not excessive soil P and K• Inoculate legume seed with proper bacteria• Manage nutrients on the farm – (recycle manure, urine, and organic residues)• Proper grazing management – timing and intensity suitable for the forage mixture• Proper fall grazing – develop tillers in grasses and stolons of white clovers – reduce adult clover root curculio activity
  • 33. Management Needed to Help the System (b)• Rest pastures to get cover for night crawlers• Legumes for livestock and earthworms – they prefer legumes over grasses• Fly control friendly to dung beetles• Weed control friendly to legumes and soil micro organisms• Co-graze livestock – convert “weeds” to animal feed and manure
  • 34. Take Home• Above ground we manage plants with animals to capture solar energy, convert it into marketable livestock products, cycle nutrients so that our pasture system can be sustainable.• This management influences soil organic matter to feed macro- and microorganisms in the soil.• This affects the soil’s physical condition, availability of macro- and micronutrients and soil moisture to plants.• Understanding how management affects the soil community assists us in our management of the entire pasture ecosystem.
  • 35. NRCS Soil Biology Web Sitehttp://soils.usda.gov/sqi/concepts/ soil_biology/biology.html
  • 36. Dung BeetlesDung Beetles of Central and Eastern North Carolina Cattle Pastures http://www.cals.ncsu.edu/entomology/guidetoncdungbeetles.pdf
  • 37. • http://www.soilfoodweb.com/