SOIL ALIVE!

1. Land, then, is not merely soil; it is a foundation of energy flowing through a circuit of soils, plants and animals”. Aldo Leopold SOIL ALIVE!

2. “ 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

3. 5% Organic • Living, dead, decomposing, decomposed

4. Organic portion composed of: 5% 10% 85%

5. “organic” • What is special about Organic compounds? They have ENERGY • Food chain passes energy along through photosynthesis and respiration

6. Green plants can directly use sun Photosynthesis: CO2 + H2O + solar energy C6H12O6 + O2 organic !

7. Rest of us are only indirectly solar-powered Respiration: C6H12O6 + O2 ENERGY + CO2 + H2O

8. Food Chain Concept Energy is passed from one trophic level to the next.

10. What is an organic compound? • Bank of energy

11. Organic materials in soil: • 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

12. fungi Springtails earthworms Beetles bacteria mites actinomycetes: geosmin, antibiotics nematodes pseudoscorpion

13. Springtails • Arthropods • Invertebrates with external skeleton • Spring or hop • Detrivores • 100,000 / m3 topsoil

14. Beetles Arthropods; order Coleoptera 400,000 species (40% of all known insect species) Some omnivores, some eat plants, fungi, some are carnivores Larvae (grubs)

15. pseudoscorpons • Arachnid • Joint-legged invertebrate • Carnivorous: eat larvae, ants, mites, flies

16. earthworms • Annelids • Some 2700 different types • 3 categories: • Epigeic (leaf litter/compost dwelling ) • Endogeic (topsoil or subsoil dwelling ) • Anecic (deep burrow drillers)

17. Giant • Benefits to soil • Move air in and out of soil • Castings are rich in available nutrients • Produce 10 lbs / yr

18. Nematodes • Roundworms • Occupy many positions in soil food web • > 28,000 species • Most microscopic • Can be predatory or parasitic

20. Mites arachnids

21. Extracted from one ft2 of top two inches of forest litter and soil

22. Bacteria • Abundant; most important decomposers • Adaptable • Specialized: • Non-photosynthetic • Photosynthetic • Oxidize ammonium, nitrite, iron, manganese • Oxidize sulfur • Nitrogen-fixing • Aerobic, anaerobic

23. bacteria • 1 ton / acre

24. Bacteria and fungal hyphae

25. Fungi • Break down OM, esp important where bacteria are less active • branched hyphaeform mycelium: bears spores • attack any organic residue

27. 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

29. Higher fungi have basidium : club-shaped structure , bearing fruiting body • toadstools, mushrooms, puffballs, bracket fungi

30. Actinomycetes • Filamentous • morphology varies • adaptable to drought • neutral pH • usually aerobic heterotrophs • break down wide range of organic compounds

31. Decomposition A respiration process: Organic matter + O2

32. Products of decomposition… • Energy for decomposers • CO2 + H2O • Nutrients, that were in the original organic tissue, for plants • Carbon, nitrogen, etc. for the decomposers • HUMUS !

33. What is HUMUS? Ultimate decay product of decomposition “Amorphous, colloidal mixture of complex organic substances, not identifiable as tissue”.

34. Colloidal in size: tiny! • < 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

35. Sand0.05 – 2.0 mm • Silt0.05 – 0.002 • Clay<0.002 • Humus<0.00001 mm • Tremendous ability to hold water and nutrients

36. Functions of humus: • A supply of N, P, S for plants • Holds water • Provides structure • Glue that allows soil to have spaces • Prevents erosion

37. About structure…

38. Humus sequesters carbon!!! • Carbon : organic compounds • stores energy • Cycled back and forth from atmosphere to biosphere • photosynthesis and respiration

39. sequestration • Take carbon from atmosphere and move it into long-lived soil pools where it is securely stored for very, very long time SOIL CARBON POOLS: Fast 1-2 yrs Slow 15-100 years Passive (stable) 500-5000

40. CARBON OUT CARBON IN Plant residues Harvesting plants SOIL Respiration Manure Erosion Compost

41. Two Main Causes of Increased CO2 Emissions: 1. Fossil Fuel Burning 2. Net Loss of Soil Organic Carbon • Soil Carbon Sequestration: • Potential to offset fossil fuel emissions by 0.4 to 1.2 gigatons of carbon per year, 5-15% of global fossil-fuel emissions

42. How? • Restore the humus portion!!!! • Organic farming • Non-chemical no-till • Manage trees and forests • Keep green manure • Diversify crops • Compost • Mulch

43. COMPOSTING • Speeding up decomposition by making breeding grounds for decomposers

44. Composting is creating habitat for decomposers to make humus! • Making soil • Need to pay attention to amounts of carbon relative to nitrogen in the organic waste you throw into the compost. • This is the C:N ratio

45. Amount of N is more critical than amount of C : • Carbon usually makes up 45 – 55% of dry weight of tissue • Nitrogen can vary from 0.5% - 6.0% For a residue with: 50% carbon and 0.5% N, C:N ratio would be ? 100:1 (wide/high C:N) 50% carbon and 3.0% N, C:N ratio would be ? 16:1 (narrow/low C:N)

46. Carbon : Nitrogen ratio • C:N ratio • High C:N means not much nitrogen (“BROWN”) • Slow to decompose • Sawdust 600:1 ; straw 80:1 ; newspaper 120:1 • Low C:N means plenty of nitrogen (“GREEN”) • Fast to decompose • Rotted manure 20:1 ; household compost 15:1 • Break-point between high and low = 25:1 • WHY?

47. …because microbes have needs too! • Soil microbes’ cells need 8C: 1N • Only 1/3 of C from compost is taken into the cells • Therefore they need compost with 24 : 1

48. If C:N is > 24:1 • Intense competition for N • Microbes will build their bodies first, then give up N for plants; N deficiency

49. If C:N < 24:1 • Plenty of N to be released for plants

50. 1 compost 4”green” 1 compost 8 “brown”