Soil C Stocks: from climate importance to field assessment
Ciniro Costa JuniorBonn, November 10, 2017
Climate Food and Farming (CLIFF) Network Annual Workshop

Soil C Stocks:
1) Climate importance
2) Land use effects
3) Potentials
4) Soil sampling, measuring and calculations
5) Final remarks

CO2
Carbon Cycle
Soil Organic Matter
Organic
Compounds
(photosynthesis)

Atmosphere = 760 Gt
Terrestrial Carbon Pools
Soil = 2500 Gt
62% organic (1500 Gt)
Biotic = 560 Gt
EROSION (1.5 Gt)Aquatic Systems
CO2CO2
CO2

Soil = 2500 Gt
62% organic (1500 Gt)
Figure source: http://www.tulsamastergardeners.org/lawngarden/lg_soil.html

Figure source: https://www.slideshare.net/chrislake/sol-biology-andsom
Soil = 2500 Gt
62% organic (1500 Gt)

19 to 95
tCO2e ha-1
(IPCC, 2006)
LivestockAgriculture
± 0 to 2.0
t C ha-1 y-1 (IPCC, 2006)
Chapter 2: Generic Methodologies Applicable to Multiple
Land-Use Categories (t Ha-1 IN 0-30 CM DEPTH)
()

Conventional Tillage No tillage
- +
Foto: Claudia S. da C. Ribeiro Foto: Gessi Ceccon
Maia et al., 2009

Scopel et al., 2006
Replacing Tillage by No-Tillage - and Crop Succession (Brazil and Europe)

Sugihara et al., 2012
Tillage, fertilization, residues management and soil type (Africa)

Burning Without
Burning
Sugarcane harvesting
Cerri, 2010- +
Galdos, et al., 2009

Degraded Pasture Improved pasture
- +Foto: AJ Agropecuária
Maia et al., 2009

Sanderman et al., 2017
World Soil Carbon Stock

“Agricultural land uses have resulted in the loss of 133 Pg C from the soil.”
Sanderman et al., 2017
Soil = 2500 Gt
62% organic (1500 Gt)
- 9%
~ 3,5 Billion ha pastagem
~ 1,5 Billion ha pastagem
Land use has lost 9% of the global soil organic C stock

Pasture under degradation - Pará State Brazil
Photo: Ciniro Costa Junior
Global GHG emissions (2016) (including LUC) = 51.9 Gt CO2
“…with adoption of best management practices, two thirds
of lost SOC can be recovered…, then SOC sequestration has
the potential to offset 88 Pg C (322 Gt CO2) of emissions.”
Sanderman et al., 2017
Lal, 2004
UNEP
THE SOIL C STOCK OFFSET POTENTIAL IS BIG!
Agriculture contributes ~5.0–5.8 GtCO2e yr1
Agricultural non-CO2 emissions mitigation by 2030 to stay within the 2 °C
limit is about 1 GtCO2e yr-1
~50 Gt CO2e in 10 years (2020-2030) (Wollenberg et al., 2016).
Agricultural technologies = 40% (without soil C sequestration)
Soil Carbon (and other C sequestration) = 60% (30 GtCO2)

SOIL CARBON STOCK – WHAT IS THAT?
Amount of C in a given soil layer
Figure source: http://ufrr.br/museusolos/index.php?option=com_content&view=article&id=63

Est C = (SC x SD x SL)
where:
Est C = soil C stock (Mg ha-1)
SC = soil carbon content (%)
SD = soil bulk density (g cm-3)
SL = soil layer (cm)
(VELDKAMP, 1994)
SOIL CARBON STOCK – CALCULATION

Est C = (SC x SD x SL)
SC = soil carbon content (%) = 2
SD = soil bulk density (g cm-3) = 1.0
SL = soil layer (cm) = 10
Est C = 20 t C ha-1 (at the 0-10 cm soil layer)
SOIL CARBON STOCK – CALCULATION

Est C = (SC x SD x SL)
where:
Est C = soil C stock (Mg ha-1)
SC = soil carbon content (%)
SD = soil bulk density (g cm-3)
SL = soil layer (cm)
(VELDKAMP, 1994)
SOIL CARBON STOCK – CALCULATION

SOIL BULK DENSITY – SOIL SAMPLING AND ANALYSIS
Figure source:
http://ufrr.br/museus
olos/index.php?optio
n=com_content&view
=article&id=63
Figures source -
https://pt.slideshare.net/RomuloViniciusTioRominho
/06-propriedades-fisicas-ligadas-a-mecanizao
Sato, 2013

Est C = (SC x SD x SL)
where:
Est C = soil C stock (Mg ha-1)
SC = soil carbon content (%)
SD = soil bulk density (g cm-3)
SL = soil layer (cm)
(VELDKAMP, 1994)
SOIL CARBON STOCK – CALCULATION

Soil is burned at 975°C and C content is given as a %
SOIL CARBON CONTENT – SOIL SAMPLING AND ANALYSIS
0.2 mm
~10 mg
Sato, 2013
Gitirana Jr., (2007)
Figure source:
http://ufrr.br/museusolos/index.php?option
=com_content&view=article&id=63

∆ Est C = (SC x SD x SL) (t2, situation 1,…) - (SC x SD x SL) (t2, situation 1) / y
SC = soil carbon content (%)
SD = soil bulk density (g cm-3)
SL = soil layer (cm)
y = years
SOIL CARBON ASSESSMENT – SOIL C STOCK RATE CALCULATION

∆ Est C = (SC x SD x SL) (t2, situation 1,…) - (SC x SD x SL) (t2, situation 1) / y
SC = soil carbon content (%) = 2 (t1) | 2.5 (t2)
SD = soil bulk density (g cm-3) = 1.0 (t1) | 2.0 (t2)
SL = soil layer (cm) = 10
y = years = 10
∆ Est C = [50.0 (t2) – 20 (t1)] / (10) = 3 t C ha-1 y-1 (at the 0-10 cm soil layer)
SOIL CARBON ASSESSMENT – SOIL C STOCK RATE CALCULATION

Approaches For Assessing Soil Carbon Stock Change
Diachronic Synchronic
(chronossequence)

Year 1
Diachronic Approach
Year 2
At least 2 Soil
Samples
Overtime at
the same area

Corbeels et al, 2016
Diachronic approach – C stock variation rate

Year 1
Chronosequence Approach

Year 1Year 2
Chronosequence Approach

Year 3Year 2Year 1
Chronosequence Approach
Soil SampleSoil SampleSoil Sample
1 Soil Sample batch at the same moment

Year 3Year 2Year 1
Chronosequence Approach (additionality)
Soil SampleSoil SampleSoil Sample
1 Soil Sample batch at the same moment

Corbeels et al, 2016
Chronosequence (synchronic) approach – C stock variation rate

Corbeels et al, 2016
Chronosequence x Diachronic Approaches

Costa Junior et al., 2013
Chronosequence x Diachronic Approaches

If soil bulk density is diffenrent, fixed soil layer compare different soil masses!
May lead to wrong interpretation about the soil management effect on Soil C Stocks
Situation 1
Soil Density (0-10 cm) = 1.5 g cm-3
Soil Mass (0-10 cm) = 1.500 Mg.ha-1
Situation 2
Soil Density (0-10 cm) = 2.0 g cm-3
Soil Mass (0-10 cm) = 1.600 Mg.ha-1.
0-10 cm 0-10 cm
Soil C = 2 % Soil C = 1.5 %
Soil C Stock = 30 Mg ha-1 Soil C Stock = 30 Mg ha-1
SOIL CARBON STOCK CALCULATION – MASS CORRECTION

Est C = (SC x SD [(SDref / SD) x SL)])
where:
Est C = soil C stock (Mg ha-1)
SC = soil carbon content (%)
SD = soil bulk density (g cm-3)
SL = soil layer (cm)
SDref = soil bulk density (g cm-3)
SOIL CARBON STOCK CALCULATION – MASS CORRECTION

SOIL CARBON STOCK CALCULATION – MASS CORRECTION
Fernandes & Fernandes, 2013

SOIL CARBON STOCK CALCULATION – MASS CORRECTION
Fernandes & Fernandes, 2013

SOIL CARBON STOCK CALCULATION – MASS CORRECTION
Fernandes & Fernandes, 2013

“Stratifying the area in terms of factors that influence carbon stocks will normally
reduce errors associated with project-scale estimates of carbon stocks”
Aynekulu et al., 2011
SOIL CARBON STOCK – SAMPLING DESIGN

Aynekulu et al., 2011
SOIL CARBON STOCK – SAMPLE SIZE

No sistema plantio direto, o revolvimento do solo
a cada quatro anos não ocasionou mudanças no teor
de carbono orgânico total em relação ao plantio direto
contínuo por mais tempo (Figura 6), indicando que
um eventual revolvimento, seguido de um retorno
ao sistema plantio direto, não ocasionaria grande
prejuízo à matéria orgânica.
Marcolan & Anghinoni, 2006
Permanence
“O revolvimento do solo a cada quatro anos
não ocasionou mudanças no teor de C em
relação ao plantio direto contínuo, indicando
que um eventual revolvimento não ocasionaria
grande prejuízo à matéria orgânica”

degraded pasture
Well managed (0–20 cm depth)
Time-dependence

0
50
100
150
200
250
-1000
1000
3000
5000
7000
1 2 3 4 5
kg CO2e ha-1 (+ soil C sequestration)
kg CO2e ha-1
tCO2 kg carcaça produzida
Soil carbon sequestration impact on GHG balance of pasture
restoration and intensification
Based on Cardoso et al. (2016) and Maia et al. (2009)
Extensive
degraded pasture
Increasing levels of pasture restoration and intensification
GHG emissions
(t CO2e ha-1 y-1)
Beef production
(kg carcass ha-1 y-1)
kg carcass ha-1
Net
Emissions

Final Remarks
- Soil C stocks is the biggest terrestrial C pool
- Soil management affects soil C stocks, but there is many dependences
- Soil mass correction is a good practice in calculating soil C stock
variation
- Recovering degraded land can significantly offset GHG emissions
- Checking soil C stocks diachronically is desirable and may be pursued

Ciniro Costa Junior
ciniro@imaflora.org
CLIFF Network