Land, then, is not merely soil; it is a foundation of energy flowing through a circuit of soils,...
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Transcript of Land, then, is not merely soil; it is a foundation of energy flowing through a circuit of soils,...
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- Land, then, is not merely soil; it is a foundation of energy flowing through a circuit of soils, plants and animals. Aldo Leopold
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- Soil is the hidden, secret friend, which is the root domain of lively darkness and silence Francis Hole Soil by parts: 5% organic, 50% space, 45% mineral
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- Living, dead, decomposing, decomposed
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- 85% 5% 10%
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- What is special about Organic compounds? They have ENERGY Food chain passes energy along through photosynthesis and respiration
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- Photosynthesis: CO 2 + H 2 O + solar energy C 6 H 12 O 6 + O 2 organic !
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- Respiration: C 6 H 12 O 6 + O 2 ENERGY + CO 2 + H 2 O
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- Energy is passed from one trophic level to the next.
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- What is an organic compound? Bank of energy
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- More living biomass below ground than above! Beneath 1 acre: equivalent to 12 horses 1 cubic meter of soil: 50,000 earthworms 50,000 insects and mites 12 million roundworms 1 pea-size bit of soil: 30,000 protozoa 50,000 algae 400,000 fungi Billions of bacteria
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- Springtails Beetles pseudoscorpion earthworms nematodes mites actinomycetes: geosmin, antibiotics bacteria fungi
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- Arthropods Invertebrates with external skeleton Spring or hop Detrivores 100,000 / m 3 topsoil
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- Arthropods; order Coleoptera 400,000 species (40% of all known insect species) Some omnivores, some eat plants, fungi, some are carnivores Larvae (grubs)
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- Arachnid Joint-legged invertebrate Carnivorous: eat larvae, ants, mites, flies
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- Annelids Some 2700 different types 3 categories: Epigeic (leaf litter/compost dwelling ) Endogeic (topsoil or subsoil dwelling ) Anecic (deep burrow drillers)
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- Giant Giant Benefits to soil Move air in and out of soil Castings are rich in available nutrients Produce 10 lbs / yr
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- Roundworms Occupy many positions in soil food web > 28,000 species Most microscopic Can be predatory or parasitic
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- arachnids
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- Extracted from one ft 2 of top two inches of forest litter and soil
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- Abundant; most important decomposers Adaptable Specialized: Non-photosynthetic Photosynthetic Oxidize ammonium, nitrite, iron, manganese Oxidize sulfur Nitrogen-fixing Aerobic, anaerobic
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- 1 ton / acre
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- Bacteria and fungal hyphae
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- Break down OM, esp important where bacteria are less active branched hyphae form mycelium: bears spores attack any organic residue
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- Mycorrhizae: s Symbiotic ; infecting plant roots, formed by some fungi normal feature of root systems, esp. trees increase nutrient availability in return for energy supply plants native to an area have well-developed relationship with mycorrhizal fungi
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- Higher fungi have basidium : club-shaped structure, bearing fruiting body toadstools, mushrooms, puffballs, bracket fungi
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- Filamentous morphology varies adaptable to drought neutral pH usually aerobic heterotrophs break down wide range of organic compounds
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- A respiration process: Organic matter + O2
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- Energy for decomposers CO2 + H2O Nutrients, that were in the original organic tissue, for plants Carbon, nitrogen, etc. for the decomposers HUMUS !
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- Ultimate decay product of decomposition Amorphous, colloidal mixture of complex organic substances, not identifiable as tissue.
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- < 0.00001 mm in diameter Nutrients and water attach to surface area of soil particles Smaller the particle, the greater the surface area per unit volume
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- Sand 0.05 2.0 mm Silt 0.05 0.002 Clay