This document discusses biochar as a means of carbon sequestration in soils. It notes that soils can store carbon through organic and inorganic forms, and their ability to store additional carbon depends on factors like existing carbon levels, soil type, climate, and land management. Two strategies to improve carbon sequestration are changing management to achieve "attainable" storage levels through practices like no-till, and enhancing storage to "potential" levels by applying external carbon sources like biochar. Biochar is highlighted as an effective way to sequester carbon due to its chemical stability and long residence time in soils. The document estimates biochar could offset 12% of annual emissions from land use change if "slash and burn"

1. Muhammad Irfan
Institute of Soil & Environmental Sciences
University of Agriculture Faisalabad
Pakistan
BIOCHAR FOR CARBON SEQUESTRATION

2. BIOCHAR FOR CARBON SEQUESTRATION
 Soils play an important role in the global carbon cycle, both as sources and sinks of carbon
 Carbon exists in two forms within soils; organic and inorganic (calcite and dolomite)
 The ability of soils to store additional carbon depends on a number of factors, including existing
levels of carbon, soil type, temperature, rainfall, carbon form and how the land is managed
 Two major strategies for improving carbon sequestration within the soil profile; changing land
management practices to achieve ‘attainable’ carbon levels and enhancing carbon sequestration to
achieve ‘potential’ levels

3. Attainable Carbon Storage Levels
 Determined by soil type, plant growth rates and rates of mineralization
 Limited by rainfall, temperature and plant nutrition
 Changing management practices that increase the return of biomass to soil or slows its decomposition
 Traditional methods include no-till practices, retaining stubble and converting marginal cropping
lands into forested areas
 Associated risks (forest fires and reversion to conventional tillage practices)

4.  Determined by soil type and largely cannot be
influenced by management practices
 Practices that overcome climatic limitations to
increase potential carbon sequestration include
applying carbon to soils from external sources,
such as manure and biochar
 Biochar is means of sequestering carbon due to
its high chemical stability, carbon content and its
potential to reside in soils over a long period
‘Slash and burn’ to ‘slash and char’ can offset ~ 12% of all emissions annually from change in land use
Total emissions can be reduced to ~ 3 tonnes carbon dioxide equivalents per tonne of biochar
Potential Carbon Storage Levels

5. Soils have a great potential
to sequest carbon

6. The CO2 Problem
 Ideal level of CO2 : 280 - 350 ppm
 Present level is: 393 ppm (12% above 350)
 Disaster level is: 450 ppm (28% above high end)
 Pollutive CO2 for removal: 50 ppm
 Only 50% of anthropogenic CO2 emissions are naturally sequestered
 Anthropogenic sequestration could be applied to pick up the slack
WILL GET HOTTER?
 IPCC indicated that during the 21st century the global surface temperature is likely to rise a further
1.1 - 2.9 °C for their lowest emissions scenario and 2.4 - 6.4 °C for their highest
 For every 1 degree centigrade increase in atmospheric temp, rice yields decline by 10%

7. Pyrolyzing biomass can be used to store carbon
in soil
Half-life of biochar
is ~1400 years
The CO2 Solution

9. Timelines for Carbon Transformations &
Permanence
CO2
Biomass
(living and dead)
Natural short-term cycle of
growth and decay
(including biomass
burning) is Carbon
Neutral: C=
Fossil Fuels Bio-carbon
Biochar in Soils
Hundreds or thousands of
years as long-term carbon
sequestration:
100 million years
(C-)
Optional human activity,
creating Terra Preta
Burn it Burn it
200+ years of fossil fuel
consumption is Carbon
Positive: C+
Storing carbon is Carbon
Negative:
C-
C-

10. Timelines for Carbon Transformations &
Permanence
CO2
Biomass
(living and dead)
Natural short-term cycle of
growth and decay
(including biomass
burning) is Carbon
Neutral: C=
Fossil Fuels Bio-carbon
Biochar in Soils
Hundreds or thousands of
years as long-term carbon
sequestration:
100 million years
(C-)
Burn it Burn it
200+ years of fossil fuel
consumption is Carbon
Positive: C+
Storing carbon is Carbon
Negative:
C-
C-
Optional human activity,
creating Terra Preta

11. If all agricultural residue were charred per year and plowed into soils, the annual removal potential is 3.5 ppm
Biochar Potential to Sequest CO2
The reality is every year we add ~ 5 billion tons that add ~ 2.4 ppm of CO2 to our atmosphere
For every 1 billion ton of net CO2 addition to atmosphere, the CO2 concentration increases by 0.5 ppm