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Scaling up soil carbon enhancement contributing to mitigate climate change

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Rolf Sommer (CIAT/WLE)

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Scaling up soil carbon enhancement contributing to mitigate climate change

  1. 1. SESSION 3 – THE FOUR PILLARS: IV. CONTRIBUTION TO GLOBAL MITIGATION Scaling up soil carbon enhancement contributing to mitigate climate change Rolf Sommer, Kristin Piikki, Mats Söderström, Sylvia Nyawira, Mayesse da Silva, Wuletawu Abera and Job Kihara r.sommer@cgiar.org The 4 per 1000 Africa Symposium - Building synergies across Africa to advance on soils for food security and climate, Johannesburg, South Africa 24-26 October 2018
  2. 2. "If you torture the data long enough, it will confess to anything!“ Ronald Coase, Economist, Nobel Price laureate 1991 (Economics) 2
  3. 3. 3 CGIAR Centers
  4. 4. 4 CIAT around the world
  5. 5. Connected thinking, compelling solutions WLE is a global research-for-development program connecting partners to deliver agriculture solutions that enhance natural resources – and the lives of people who rely on them 5
  6. 6. Significant support from BMZ and GIZ! 6 https://www.giz.de/en/worldwide/ 32181.html
  7. 7. Soil organic carbon sequestration – rationale Agriculture is a major contributor to climate change! • Ag production : ~12 % • Land use change: ~12 % 7 Agriculture, Forestry and Other Land Use (AFOLU) Greenhouse gas emissions by economic sector (IPCC AR5) Total emissions worldwide (2012) 14.14 Gt C Source: EcoFys 2016
  8. 8. Soils contain massive amounts of carbon, i.e. little changes can make a big difference! 9 Carbon pool Amount (billion tons C) Ocean ~39,000 Atmosphere 785 Biotic 466 – 835 Geologic (coal, gas oil) 4,000 – 5,000 Soil, organic carbon 1,220 – 1,550 Soil, inorganic carbon 750 – 950 Soil, total (1 m depth) 2,000 – 2,500 Soil organic carbon sequestration – rationale
  9. 9. 1. Large losses of soil organic matter have occurred in agricultural soils 2. These losses provide an opportunity 3. The recoverable carbon reserve capacity of the world’s agricultural and degraded soils is estimated to be between 21 to 51 Gt of carbon (FAO, 2017) 10 (Sommer et al. 2018) Soil organic carbon sequestration – rationale
  10. 10. Enhancing soil carbon improves soil fertility, soil health and helps increasing agricultural productivity and resilience! Soil organic carbon sequestration – rationale
  11. 11. Scaling up soil carbon enhancement contributing to mitigate climate change 1. What could be achieved in terms of climate change mitigation? 2. What practices? 3. Where? 4. What is required to make it happen? 12
  12. 12. 1. What could be achieved in terms of climate change mitigation? 13
  13. 13. Dynamics and climate change mitigation potential of SOC sequestration (Sommer & Bossio, 2014) SOC sequestration follows a saturation curve + Uptake of improved practices does take time 14 • The projected 87-year (2014-2100) global SOC seq. potential of agricultural land ranged between 31 and 64 Gt. (0.36 to 0.74 Gt/yr) • Global climate change mitigation potential: • 1.9-3.9 % of the SRES-A2 projected 87-year anthropogenic emissions • 10-21 % of 4p1000 target =
  14. 14. Zomer, Bossio, Sommer, Verchot (2017) Nature Scientific Reports, doi:10.1038/s41598-017-15794-8 15 Geospatial estimation of the global sequestration potential of increased organic carbon in cropland Worldwide croplands could sequester between 0.90 and 1.85 Gt C/yr, = 26–53 % of the target of 4p1000 But, unlikely to happen that way…!
  15. 15. CIAT-GIZ Infographic Tropical soils can help us make agriculture carbon neutral and meet climate targets! 16
  16. 16. 2. What practices? 17
  17. 17. The impact of Conservation Agriculture • Significant differences between CA and business- as-usual (BAU) in the top 20 cm: ~7.5 t C/ha • CA practiced between 8-15 years, i.e. avoided SOC loss or sequestration rates: ~0-5 – 0.9 t C/ha/yr 18 Topsoil (0 - 20 cm) Subsoil (20 - 40 cm) 0-40 cm CA BAU CA BAU CA BAU 25 50 75 100 10 20 30 40 50 10 20 30 40 50 Land management SOC(Mg/ha) lulc BAU CA a b a a a b * ** Western Kenya, Bungoma County Different letters indicate statistically significant differences: * at P < 0.05; ** at P < 0.10 (Sommer et al. 2018)
  18. 18. Avoiding C-losses but failing to sequester…! 2. Land use history seems the major driver of losses! 19 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 CIAT long-term trials, Western Kenya – observed SOC changes over time under improved land use 1. Instead of C-sequestration, we detect losses! Source: Sommer et al. 2018 Avoided losses: ~0.1-0.7 t C/ha/yr
  19. 19. 3. Where? 20
  20. 20. Developing the predictive capacity to quantify the impact of improved land management • Pedotransfer function to predict SOC under CA using: clay, silt, sand; relative slope; valley depth; elevation; wetness index; cross- sectional curvature; aspect (Sommer et al. 2018) 21 SOCCA [g/kg] = - 4.033 + 0.0141*clay - 8.571*rel. slope pos. - 0.0018*valley depth + 0.0049*elev. - 0.227*w. index • A boundary plane approach to map hotspots for soil carbon seq. potential (Piikki et al. submitted): Ƹ𝑧 = a + 𝑏 𝑥 + 𝑐 𝑦 + 𝑑 𝑥𝑦
  21. 21. SOC sequestration hotspot mapping • Digital soil mapping of actual and potential SOC 22 Western Kenya, Murugusi Watershed (Sommer et al. 2018)
  22. 22. Potential changes in SOC in response to an adoption of CA • Wide variation in estimated gains • Coarse-textured soils and soils with high SOC may lose carbon • Total SOC seq. on all cropland (6582 ha): 131,000 t C (~20 t C/ha) 23 (Sommer et al. 2018)
  23. 23. 4. What is required to make it happen? 24
  24. 24. Impact pathway • Stakeholder engagement, stakeholder engagement, stakeholder engagement…! • Agreed-upon priority intervention regions, and scientific/institutional alignment • Assessment of tradeoffs, as well as PES to endorse SOC-seq in smallholder farming systems and rangelands • Do we need thorough biophysical monitoring, or can PES be implemented based only on the adoption of good agricultural practices? 25
  25. 25. • The Kenya Agricultural Carbon Project (KACP) • Aim: • The project promotes Sustainable Agricultural Land Management (SALM) practices for implementation on smallholder farms for livelihood improvement and generation of GHG removals through soil and tree carbon sequestration. • BioCarbon fund payments from WB • The resulting carbon credit is considered a co-benefit and paid to farmer groups as rewards Achievements: 2009 to date • 29,497 farmers in 1730 farmer groups • 21,966 ha under SALM, • 30-50 % higher maize yields, • more months of food self-sufficiency • higher level of monthly savings Carbon: 184,447 t CO2e (verified and farmers paid carbon) Source: Miriam Nalianya, Vi Agroforestry
  26. 26. 27 Thank you! Photo © A. Notenbaert
  27. 27. CIAT Team Rolf Sommer, Mayesse da Silva, Mats Söderström, Kristin Piikki, Job Kihara, Birthe Paul, Andrew Margenot, John Mukalama, John Mutua, Wuletawu Abera, Lulseged Tamene, Tesfaye Yaekob, Evan Girvetz

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