This presentation was presented during the 1 Parallel session on Theme 2, Maintaining and/or increasing SOC stocks for climate change mitigation and adaptation and Land Degradation Neutrality, of the Global Symposium on Soil Organic Carbon that took place in Rome 21-23 March 2017. The presentation was made by Mr. Miguel Taboada, from INTA - Argentina, in FAO Hq, Rome

1. Global Symposium on Soil Organic
Carbon (GSOC17)
Co-organized by FAO, GSP/ITPS,
IPCC, UNCCD/SPI and WMO
Global management of soil organic matter
Miguel A. Taboada, INTA and CONICET, Argentina

2. Soil organic matter (SOM) declines: main threat for soil
quality in 5 over 7 GSP Regionals in the SWSR.
The ITPS tasked in March 2016 to follow up “The global
management of soil organic matter” as one of four
identified priorities of action, towards contributing to the
new version of the SWSR.
Increasing SOM levels: solution to various
environmental concerns related to climate change and
food production.

3. Objective
The “Global Management of SOM ” priority of action aims to:
list, review and/or evaluate the impact of different initiatives,
practices and actions undertaken by different stakeholders
involved in SOM management with the aim of improving soil
functions, soil fertility, structural stability and movement of
water in agroecosystems and ecosystems.

4. What was done? (1)
1. Stock-template submitted to ITPS members and GSP
Regionals.
•Geographical scope of the assessment (e.g. global,
continental, country, regional)

5. 2. Who was involved
and/or participated?
Stakeholders: public/private, type of farmer,
gender issues, type of product
4. What were the results?
Effectiveness of the practice: SOM contents,
production levels (crop yields, meet and dairy
production, etc), greenhouse emissions..
1. What was done and why?
Field and/or practices aiming at SOC
sequestration, maintanance or restoration
Policies, laws and or regulations
SOM and climate change mitigation
monitoring, remote sensing, modeling
Publications: peer reviewed, “grey”,
congress and meetings, local reports
5. How were changes
observed or measured?
3. Where and what area
(size) was covered?
Scale of implementation: global,
supra-national, national, regional
Soil types
ITPS Priority of Action: “Global Management of Soil Organic Matter (SOM)”

6. What was done? (2)
2. Expert review of scientif literature produced after the
publication of SWSR 2015.
•Main focus on review and meta-analysis articles published
after 2013.
3. Assessment of Soil C stock changes in rangelands and
grasslands, for theTechnical Advisory Group of Livestock
Environmental Assessment Performance Program, FAO.

7. Main findings

8. Drivers of SOM inputs and storage in
soils
Global scale
a) Proposed Graphic of potential
saturation curve, achievable curve
and critical curve for the amount of
organic C in agricultural soils;
b) Initial increased in SOC following a
change in management are rapid,
and then slow and reach a new
quasi-equilibrium at some point.
Stockmann et al. 2013. Agric. Ecos.
Environ. 164, 80–99.

9. • Nigeria: Predictors of SOC: soil type, climate, vegetation indices and
terrain attributes, non complexed clay (Apka et al. 2016; Merante et
la. 2017).
• Wheat systems in China: Average C input of 2.1 Mg C ha−1
yr−1
to stop
soil C loss and to maintain the cropland SOC (Wang et al. 2015,
2016).
Drivers of SOM inputs and storage in
soils

10. SOC management practices effects on soil C
storage
Reduction of soil disturbance
Increasing soil carbon input
Zero-tillage (ZT)
Reduced-tillage (RT)
Direct-drilling (DD)
Cover crops (catch crops and
green manure) (CCs)
Crop rotations (CR)
Residue
management (RM) (Review by Merante et al. 2017)

11. a) Soil C is not necesarily increased, but can be redistributed in the
profile: surface stratification;
b) SOC increases by ZT and DD of 0,04 to 0,45 Mg C ha-1
yr-1
in
different countries and regions, as a function of crop rotation, cover
crops and residue returns.
c) SOC increases by RT of 0,04 to 0,18 Mg C ha-1
yr-1
.
(Merante et al. 2017)
Reduction of soil disturbance (ZT, RT,
DD)

12. a) Positive effects:
NT alone: 24.3% mitigationCombined with restoring degraded pasture
and livestock intensification (31.0% and integrated crop-livestock-
forestry system (25.6%).
South America: de Moraes Sá et al. 2017; Steinbach and Alvarez
2006.
China: Du et al. 2015.
Climate change mitigation by no tillage
is still in discussion
C sequestration vs GHG emissions

13. b) Overestimated impact of NT farming on climate change
mitigation
•No-till is beneficial for soil quality and adaptation of agriculture to
climate change, but its role in mitigation is widely overstated.
•Limited C inputs, ranging between 0.1 and 1 g C kg-1
soil yr-1
, are likely
to be the major bottleneck for C increase
Powlson et al. 2014. VandenBygaart. 2016. Cheesman et al. 2016.
Climate change mitigation by no tillage
is still in discussion

14. SOC Management practices’ effects on soil C
storage
Increasing soil carbon inputs
Cover crops (catch crops and
green manure) (CCs)
Crop rotations (CR)
Energy crops
Intercropping
Grassland
management
Land use changes to forests, grasslands
and shrublands
Fertilizers, manures and
amendments
Land abandonmentAdditional practices

15. Cover crops (catch crops and green
manure)
No-till cover crops can sequester between 0.10 and 1 Mg ha−1
per
year of SOC relative to no-till without cover crops, depending on
cover crop species, soil type, and precipitation input.
Argentina: Rimski et al. 2015.
Europe: Merante et al. 2017 Soil Tillage Res.165, 95–106.
Poeplau and Don. 2015.
Brazil: Raphael et al. 2016.
Blanco-Canqui. 2013. Bioenergy Research 6, 358

16. a)Positive effects of intercropping with respect sole crops on C (184 +/-
86 kg C ha-1
) and N (45 +/- 10 kg N ha-1
) sequestration rates;
b) Total root biomass in intercrops was on average 23% greater than the
average root biomass in sole crops.
Cong et al. 2015.
Crop rotations
Merante et al. 2017
a) Crop rotation including legumes (e.g. vetch) and meadow
grasses can increase SOC by 0.17 Mg C ha-1
yr-1
;
b) Total SOC increases 10-17 Mg C ha-1
Intercropping

17. Grassland management
England grasslands: Ward et al. 2016.
a) Total stocks of soil carbon (t ha- 1) to 1 m depth 10.7% greater at
intermediate relative to intensive management, which equates to
10.1 t ha-1
in surface soils (0–30 cm), and 13.7 t ha-1
in soils from 30
to 100 cm depth.

18. Case 1 (b). Roth-C Model
Estimations Flooding Pampa
Argentina
LEAP: Peralta and Taboada 2017

19. Land use changes to forests, grasslands and
shrublands
Grain to Green Program (GGP) in China
Deng et al. 2014. Global Change Biol. 20, 3544–3556
Liu et al. 2014. Landscape Ecol. 29, 1675–1688.
a) 135 recent publications (844 observations at 181 sites) showed an
initial decrease soil C stock (0-100 cm) changes during the early
stage (<5 years) of GGP, and then an increase to net C gains (>5
years) coincident with vegetation restoration;
b) Converted areas from croplands to forests under the GGP program
could sequester 110.45 Tg C by 2020, and 524.36 Tg C by the end
of this century.

20. Simulated increases in biomass and soil C

21. • Austria: greening of arable land by intermediate crops and by
"Evergreen" system;
• China: Grain to Green Program;
• Songliao Region (China): implementation of a regional plan for
erosion control, regulation of land use and recovery of degraded
soils.
• Uruguay, Honduras, Mexico, Senegal: laws or regulations for the
use and conservation of soils and forests, application of manures and
biosolids.
• Land Degradation Neutrality Program
• 4 pour mil initiative, commanded by France
Land policies

22. Summary
Drivers of SOC sequestration
•Soil texture: % clay, non complexed clay
•Soil type, climate
•Residues: amount, incorporation, quality (C:N)
•Minimum C inputs to maintain critical SOM levels: About 2 Mg C ha−1
yr−1

23. SOC positively affected by:
•ZT, DD and RT, with variations caused by crop rotation, N management
and soil type.
•crop rotations including legumes and meadow grasses,
•cover crops with variations caused by tillage, climate and legumes.
•manures and N fertilization
•Conversion to pastures, grasslands and afforestation
•Rangeland management, as a function of management intensity
Summary
Warning: Need to be more realistic about both the benefits and
disadvantages of no-tillage on CC mitigation.

24. Thanks!

25. Minimum C inputs to maintain critical SOM levels
Global wheat systems (Wang et al 2016. Scientific Reports)
•Critical C input rates needed to maintain existing soil C level (RothC simulations) at
0.1° × 0.1° resolution estimated to be 2.0 Mg C ha−1
yr−1
,
•large spatial variability depending on local soil and climatic conditions. Scientific
Reports).
Drivers of SOM inputs and storage in
soils

26. Europe
a) Soil potential stability (n-potential) and capacity to store organic carbon can be
inferred from the presence of non-complexed clay (NCC) in soils. b) Soils of European
regions classified on the basis of five n-potential categories (i.e. >20; 15–20; 10–15; 5–
10; <5).
Drivers of SOM inputs and storage in
soils
Merante et al. 2017. Soil Tillage Res.165, 95–106.

27. Nigeria (Akpa et al. 2016. Geoderma 271, 202 –215)
a)Potential to sequester about 0.2 to 30.8 Mg C ha−1
depending on the agroecological
zone;
b)Predictors of SOC: soil type, climate, vegetation indices and terrain attributes;
c)Highest SOC density in Forest LULC, Humid Forest and Ferralsols; lowest in Sahel
Savannah and Arenosols.
Drivers of SOM inputs and storage in
soils
China (Wang et al. 2015. Plant Soil 394, 57-71)
a)Average C input of 2.1 Mg C ha−1
yr−1
to stop soil C loss and to maintain the
cropland SOC in China;
b)Global mean of 55 Mg C ha−1
by 2050 when 5.1 Mg C ha−1
yr−1
is incorporated
into the soils.
Migue: de America no hay nada?

28. Schierhorn et al. 2013.
Kämpf et al. 2016.
•Low Carbon sequestration in the early years after abandonment, but
carbon uptake increased significantly after approximately 10 years
•high potential for carbon sequestration in areas abandoned more than 4
years ago;
•sequestration rate is 0.75 t C ha−1
yr-1
after an average of 14 years of
abandonment. Proportional sequestration is highest under semi-arid
climate or low initial SOC stock.
Land abandonment

29. Conclusions
Land policies
•Greenning programs: evergreen, GGP in China
•Land degradation neutrality
•4 x 1000 initiative
•Guidelines for Sustainable Soil Management (FAO-GSP-ITPS)
•Climate Smart Agriculture
•Laws or regulations encouraging soil conservation practices or
discouraging deforestation