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Biochar Properties. is biochar a nutrient?. is biochar a fertilizer?. In soil, charcoal breaks down very slowly. – not in months, but decades, even centuries. Compost. Pyrolysis. not affected by weathering, oxidation & digestion. 500+°C. 100. Biochar isn ’ t consumed by soil life. - PowerPoint PPT Presentation
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Ca
rbo
n r
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ain
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(%
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100
1 2 3 4 5Years
Biochar
Uncharred Biomass
Centuries?Millennia?
CompostCompost500+°C
Dr. Johannes LehmanDr. Johannes Lehman
– – and and hydrophobichydrophobic – it repels water – it repels waterwith no biological activity with no biological activity –– no microbes no microbesFresh from a burner, biochar is sterile,Fresh from a burner, biochar is sterile,
Biochar isn’t consumed by soil lifeBiochar isn’t consumed by soil life
not affected by weathering, oxidation & digestionnot affected by weathering, oxidation & digestion– – not in months, but decades, even centuriesnot in months, but decades, even centuries
In soil, charcoal breaks down very slowlyIn soil, charcoal breaks down very slowly
: Habitat and housing for microbes: Habitat and housing for microbes
SubstrateSubstrate: Adsorp nutrient ions (C.E.C. & A.E.C.): Adsorp nutrient ions (C.E.C. & A.E.C.)StorehouseStorehouse
: Absorb, hold & conserve soil water: Absorb, hold & conserve soil waterSpongeSpongeBiochar supplies three important soil services:Biochar supplies three important soil services:
Adding only raw charcoal to soilAdding only raw charcoal to soil
Fertilizers must be added with charcoalFertilizers must be added with charcoalretards plant growth 1 or 2 yearsretards plant growth 1 or 2 years
is biochar a fertilizer?is biochar a fertilizer?is biochar a nutrient?is biochar a nutrient?Biochar PropertiesBiochar Properties
50
PyrolysisPyrolysis
10 Humus
Particle sizeParticle size Surface areaSurface area Residence TimeResidence Time Structural densityStructural density Micropore densityMicropore density Moisture contentMoisture content Water AbsorptionWater Absorption Ion AdsorptionIon Adsorption CECCEC pHpH Microbial ActivityMicrobial Activity
Physical PropertiesPhysical Properties
& & AECAEC
Biochar PropertiesBiochar Properties
Particle sizeParticle size
Micropore densityMicropore density
Water AbsorptionWater Absorption
CECCEC & & AECAEC
Microbial ActivityMicrobial Activity
PHOTO: Bob Cirino, University of DelawarePHOTO: Bob Cirino, University of Delaware
Surface areaSurface areaExternal:External: square inches vs. square milessquare inches vs. square milesInternal: Internal: microporesmicropores
Varied sizesVaried sizes varied purposes: varied purposes: broadcast, seed drill, potting mix, hydroponicsbroadcast, seed drill, potting mix, hydroponicsGravelGravelRice grainRice grainPowder & DustPowder & DustWater soluble: Water soluble: lowest molecular weightlowest molecular weight
Micronize:Micronize: Nature’s nanotechnology Nature’s nanotechnologyBrittle:Brittle: easy to crush easy to crushDusty:Dusty: easily blows away easily blows awayVariable:Variable: with feedstock with feedstockWoody vs. WeedyWoody vs. WeedyScreen:Screen: separate sizes separate sizesIntimate mix:Intimate mix: at cellular and molecular scales at cellular and molecular scales
Particle Conversion ChartParticle Size Diameter
(microns)Mesh
(screen size)
Fine Sand 250 - 100 50 - 125Very Fine Sand 100 - 50 125 - 250
Silt 50 - 2 250 - 6000Clay 2 or less 6000 or more
Particle SizeParticle SizeBiochar PropertiesBiochar Properties
RecalcitrantRecalcitrantResists chemical & weathering actionResists chemical & weathering action
Resists microbial digestion & decayResists microbial digestion & decay
Sequestration = at least 100 yearsSequestration = at least 100 years
Dr. David Laird, USDA Tilth Lab: 1600 year half-lifeDr. David Laird, USDA Tilth Lab: 1600 year half-life1 to 5% loss1 to 5% lossTar & Resins Residues Tar & Resins Residues (VOC & PAH)(VOC & PAH)
HydrophobicHydrophobic (oily hydrocarbons) (oily hydrocarbons)
Vary with production processVary with production processTemperature: 500-700°CTemperature: 500-700°C (energy only: up to 1500°C) (energy only: up to 1500°C)
Pressure, Length of Time, SteamPressure, Length of Time, Steam
Gasification vs. Pyrolysis Gasification vs. Pyrolysis (burning vs. baking) (burning vs. baking)
Torrefication, Fast Pyrolysis, Flash Pyrolysis, MicrowaveTorrefication, Fast Pyrolysis, Flash Pyrolysis, Microwave
Residence TimeResidence TimeBiochar PropertiesBiochar Properties
Ca
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51 2 3 4Years
50
10
100
PyrolysisPyrolysis
Composted Biomass
Humus
Biochar1−5%
10−15%
35−50%
