CIAT Soil Carbon Sequestration Research by Rolf Sommer, CGIAR Research Program on Water, Land and Ecosystems. Presentation made at Soil Carbon Sequestration: Supporting NDCs and donor action. A CGIAR-wide workshop held 12 Nov 2017 at ZEF Center for Development Research, University of Bonn. Workshop organized jointly by: CGIAR Research Programs on Climate Change, Agriculture and Food Security (CCAFS); Water, Land and Ecosystems (WLE) and Forests, Trees and Agroforestry (FTA)

1. CIAT Soil Carbon Sequestration Research
Rolf Sommer, Mayesse da Silva, Mats Söderström, Kristin Piikki, John
Mukalama, John Mutua, Job Kihara, Lulseged Desta, Evan Girvetz, Lou Verchot
Soil Carbon Sequestration: Supporting NDCs and donor action
- A CGIAR-wide workshop to coordinate outputs and plan joint
funding proposals,
Bonn, 12 Nov 2017
r.sommer@cgiar.org

2. 2
How carbon seq.
in soils relates to
CIAT’s agenda?
• Soil C as a driver of soil fertility,
as a driver of landscape health
and entry point for land
restoration
• Soil C sequestration as a triple
CSA win (addressing
productivity resilience and
mitigation)
• Soil carbon and soil health is a
cluster of activity in WLE-RDL

3. • WLE: Sommer & Bossio study (2014)
à global; desktop study; scenarios;
mitigation potential
• GIZ commissioned: Winowiecki (2015)
"Landscape-scale Assessments of Soil
Health: Local Determinants of Soil
Organic Carbon in Ethiopia" (link)
• WLE/GIZ: CIAT SOC APP (2016)
à online tool to calculate SOC sequestration
amounts on ag. land (link)
• SOC-seq. estimates as part of the
CCAFS publication: Wollenberg et al.
(2016) "Reducing emissions from
agriculture to meet the 2°C target".
Global Change Biology (link)
3
Past research

4. Dynamics of SOC sequestration
SOC sequestration follows a
saturation curve
+
Uptake of improved practices
does take time
=
4

5. • GIZ-commissioned study Model-based assessment of soil organic carbon dynamics and potentials for carbon
sequestration under integrated soil fertility management and conservation agriculture in Western Kenya by R.
Sommer June 2017 (link)
• Various blogs:
• Soil Organic Carbon and the 4‰ Initiative: Soils for food security and climate by Deborah Bossio | Nov 27, 2015 (link)
• Shifting sands: putting carbon back into soils by Rolf Sommer | May 9, 2016 (link)
• Trees on agricultural land sink four times more carbon by Georgina Smith | Aug 10, 2016 (link)
• Sink more carbon in the soil? It’s not that easy by Georgina Smith | Dec 5, 2016 (link)
• Sink it or lose it: the carbon trade-off by Georgina Smith | Mar 17, 2017 (link)
• What is CGIAR doing on soil carbon and climate change? by Lini Wollenberg, Christopher Martius, Keith Shepherd and Rolf Sommer | Jun
28, 2017 (link)
• Not so dirt-cheap: how soils could save the day at climate talks, by Rolf Sommer, WLE Thrive Blog. | Nov. 2017 (link)
• Presentation at the FAO Global Symposium SOC 2017, Rome Enhancing SOC sequestration: myth or reality in Africa?
by R. Sommer (link)
• Presentation at the EGU 2017, Vienna: "The soil carbon dilemma in the humid tropics: cannot hoard it!?" by R.
Sommer, B. Paul and J. Kihara (link)
• CarbonBrief - WLE Opinion piece for Earth Overshoot Day; Improving Africa’s soils to cut emissions and boost food
security by Shepherd & Sommer (link)
• HuffPost – CGIAR gets serious about soil carbon as home of
4p1000 initiative" - Aug 2017 (link)
5
Publications, blogs and media releases

6. CIAT-GIZ Infographic
• focus: mitigation
• simplifying the message
6

7. Sommer, Paul, Mukalama, Kihara (2017). Reducing losses but failing to sequester carbon in soils
– the case of Conservation Agriculture and Integrated Soil Fertility Management in the humid
tropical agro-ecosystem of Western Kenya; AGEE in print.
7
Recent research
ISFM
17
19
21
23
25
1/Jan/05 1/Jan/08 1/Jan/11 1/Jan/14
SOC (g/kg)
FYM+ R+
FYM+ R-
FYM- R+
FYM- R-
LSD
Conservation Agriculture
17
19
21
23
25
1/Jan/05 1/Jan/08 1/Jan/11 1/Jan/14
0T R+
CT R+
CT R-
0T R-
LSDs, same
level of tillage

8. 8
-2.0
14.0
-2
2
6
10
14
R- R+ R- R+
FYM- FYM+
Losses of SOC over 12 yrs. (t C/ha/15cm)
-2.0
2.0
6.0
10.0
14.0
-2
2
6
10
14
N0 P60
N30 P60
N60 P60
N90 P60
N0 P60
N0 P0
N0 P60
N30 P60
N0 P0
N0 P60
N30 P60
N0 P60
N30 P60
N60 P60
N90 P60
N0 P60
N0 P0
N0 P60
N30 P60
N0 P0
N0 P60
N30 P60
N0 P60
N30 P60
N60 P60
N90 P60
N0 P60
N0 P0
N0 P60
N30 P60
N0 P0
N0 P60
N30 P60
N0 P60
N30 P60
N60 P60
N90 P60
N0 P60
N0 P0
N0 P60
N30 P60
N0 P0
N0 P60
N30 P60
M-M MS M-T T-M M-M MS M-T T-M M-M MS M-T T-M M-M MS M-T T-M
R- R+ R- R+
FYM- FYM+
Losses of SOC over 12 yrs. (t C/ha/15cm)
D = ~8.7 t C/ha
725 kg C/ha/yr
Avoided losses in response to manure application
(INM3)

9. WLE: Zomer, Bossio, Sommer, Verchot (2017) Geospatial Estimation of the Global Sequestration
Potential of Increased Organic Carbon in Cropland Soil, Nature – Scientific reports in print.
9
Recent research
Worldwide croplands could sequester
between 0.90 and 1.85 Pg C/yr,
• = 26–53% of the target of 4p1000
à towards carbon neutrality of
agriculture:
emissions from agricultural
activity 1.4 – 1.6 Gt C/yr
(~12 % of total global emissions)

10. F i e l d - V i l l a g e - Re g i o n - C o u n t r y - C o n t i n e n t - G l o b e
Small data and Big data
– soil information for sustainable intensification
Mats Söderström & Kristin Piikki
Swedish University of Agricultural Sciences (SLU) / International Center for Tropical Agriculture (CIAT)
10

11. BMZ large grant project (2017-2019)
Scaling up soil carbon enhancement interventions for food security and climate
across complex landscapes in Kenya and Ethiopia
1. Improved soil carbon sequestration potential maps to identify hot-spots for increasing soil carbon;
2. An improved process-based dynamic soil carbon-vegetation model to assess policy and program
scenarios;
3. Analysis and synthesis of gender-specific constraints and opportunities to adoption of soil carbon
enhancing agriculture across the landscape;
4. Development and assessments of policy and program scenarios for impact on soil carbon across
the landscape;
5. Assessment and visualization of the multiple benefits and trade-offs of increased soil carbon at the
landscape level for policy and program scenarios; and
6. Programmatic and policy support … build awareness and enhance capacity of partners to
implement gender sensitive approaches to priority setting, planning, design and implementation of
programs.
11

12. GIZ Climate Smart Soils – SOC (hotspot) mapping
• Time series analysis – loss of SOC
in response to forest conversion
• Impact of Conservation
Agriculture on reducing losses or
sequestering carbon
• Digital soil mapping of actual and
potential SOC in a watershed in
Western Kenya (Murugusi)
• Rapid indicators of SOC /
degradation status
• POXC
• MIRS
12

13. Loss of carbon after conversion of forest (Nandi Kenya)
13
40
80
120
160
0 20 40 60
Age since conversion
SOCton/ha
Land Use
Eucalyptus
Grass
Maize/Beans
Pristine
Rotation
Sugarcane
Tea
Mean
Eucalyptus
Grass
Maize/Beans
Pristine
Rotation
Sugarcane
Tea
Topsoil
40
80
120
160
Pristine Sugarcane Rotation Tea Maize/Beans Eucalyptus Grass
Lan use
SOCton/ha
Topsoil

14. Biophysical simulation of SOC – long(er) term
• Avoided losses of SOC in response to improved land use:
0.33-0.65 t C/ha/yr
14
60
65
70
75
80
85
90
95
100
1/Jan/04 31/Dec/09 1/Jan/16 31/Dec/21 1/Jan/28 1/Jan/34
SOC (t/ha/40 cm)
FYM+ R+ T-M N30
Zero-tillage Full R+
M-M N90
FYM+ R- M-M N0
FYM- R+ M-M N90
FYM- R- M-M N0

15. Finding the holy grail
• Importance of
• climate, landscape position, geomorphology and soil properties
• land use history!?
• "base" SOC levels
Þ SOC sequestration potential = base_SOC + f[climate; landscape; soil properties; …]
• True C-sequestration vs. "avoided losses"?
SOC content
Time
Improved management
Common practice
?
15

16. What’s the challenge?
16
• Soil carbon sequestration not (yet) part of the set of options to mitigate
climate change
• Little “knowns” and lots of “unknowns” and aspirations
• confusing, nerdy discussion
• high aspirations (4p1000)
• Low visibility ( though now improving)
• Multiple ownerships (UNCCD vs. UNFCCC; WLE vs. CCAFS vs. FTA)
• MRV
• No standardization
• SOC is a slow variable

17. Precision
agriculture
Soil C sequestration
/ avoided losses
A B
AfSIS
ISRIC Soil property
maps of Africa at
250 m resolution
Biophysical
models
• point scale
• global
C emission
markets & trading
voluntary vs. compliance
Big Data
MRVAGRIS
Questions:
• how much C can be sequestered? (D)
• how much time does it take?
• what (co)benefits are there?
• what tradeoffs?
• what does it require and cost?
• farming practices
• PES
• policies and action
• how to monitor, report and verify?
Soil health and
human
nutrition
Food/yield gap
& Ag.
intensification
CSA and
mitigation
WOCAT
UNCCD - LDN
(Global
network of)
long-term trials
Digital Soil
mapping
20x20
Crowd sourced
information
AFR100
Bonn
Challenge
Social capacity
Human
capacity
Policy &
Action
UNFCCC / IPCC
Transformation
Carbon tools &
apps
17

18. 18
Thank you!
Photo © A. Notenbaert

19. Winowiecki - Creating a Decision Tree for SOC
Dynamics
19