Assessing the potential of soil organic carbon sequestration in African soils Razafimbelo T. M*., Bernoux M., Badiane Ndour N.Y., Sabir M., Aholoukpe H., Amadji G., Balarabe O., Hien E., Koné A., Taisso M., Gallali T., Sall S., Andriamananjara A., Razakamanarivo H., Blanchart E., Barthès B., Rakotovao N., Masse D., Albrecht A., Abgassi A., Guibert H., Brossard M. University of Antananarivo, Laboratoire des RadioIsotopes Madagascar March, 22 nd 2017, Red Room,FAO, Rome, It
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Assessing the potential of soil organic carbon sequestration in African soils
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Assessing the potential of soil organic carbon sequestration in African soils
Razafimbelo T. M*., Bernoux M., Badiane Ndour N.Y., Sabir M., Aholoukpe H., Amadji G., Balarabe O., Hien E., Koné A., Taisso M., Gallali T., Sall S., Andriamananjara A.,
Razakamanarivo H., Blanchart E., Barthès B., Rakotovao N., Masse D., Albrecht A., Abgassi A., Guibert H., Brossard M.
University of Antananarivo, Laboratoire des RadioIsotopesMadagascar
March, 22nd 2017, Red Room,FAO, Rome, Italy
FAO-UNESCO, 1978
African soil main constraints
FerralsolsAcrisols, Cambisol
Regosols, Arenosols and Podzols
Ferric and Plinthic Luvisol
Fluvisols, Gleysols, Histosols
Low nutrient content, weathered, Al and Mn toxicity, High P-fixation, low nutrients and water retention, susceptible to erosion
Mainly quartz, low water and nutrient holding capacity, wind erosion, poor soils with nutrient leaching
Low nutrient content
Poor to moderate drainage
o Restauration of degraded soils
o Mantaining soil fertility and productivity of agricultural soils
o Limitation or preservation from erosion
o Safety of ecosystemic services provided by soils
Importance of soil carbon sequestration in Africa
Factors controlling soil C sequestration
C INPUTResidues, Mulch,Compost, Amendment,Deposition
C OUTPUTErosionDecompositionLeaching Harvest
Soil carbon
f [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Landscape position]
f [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Topography]
Climate
Altitude
Soil properties
Topography
Oladimeji I. Oladele, Ademola K. Braimoh, 2015
Factors controlling the maximum of soil C sequestration
f [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Topography]
Climate
Altitude
Soil properties
TopographySoil Carbon (Mg/ha)
Soil 0-100 cm
Altit
ude
Rakotonarivo, 2010
SO= South WesternNE= North East
Factors controlling the maximum of soil C sequestration
Factors controlling the maximum of soil C sequestration
f [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Topography]
Agroforestry systemsSome C sequestration values ... Madagascar
0
10
20
30
40
50
60
70
80
90
100
SOC
(Mg.
ha-1)
20
DC = 200 ‰
DC = 0.631 MgC/ha/yr
Cloves + Rice vs Rice Slash and burn
- Simple: less than 200 cloves / ha- Complex : 200 to 400 cloves / ha
24 years0-40 cm depthNitisol, sandy loam textured
* *
*
Agroforestry systems
Some C sequestration values ...
Madagascar
Andriamananjara et al., 2016
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Conclusions …
• Amount of C sequestration is/will be different according :
systems, but also climate and soil type and topography => main factors controlling carbon sequestration
• Values are affected by great variability. => Need of appropriate method for SOC changes measurement.
• Sustainable practices will be efficient for SOC sequestration by the way that carbon content will be maintained => all increases will be considered as fully positive ...
• Sustainable practices exist, but they have to be adopted by farmers and developed with them…
http://reseau-carbone-sol-afrique.org
Thank you for your attentionMerci de votre attention