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., Kon A., Taisso M., Gallali T., Sall S., Andriamananjara A., Razakamanarivo H., Blanchart E., Barths B., Rakotovao N., Masse D., Albrecht A., Abgassi A., Guibert H., Brossard M.

University of Antananarivo, Laboratoire des RadioIsotopesMadagascarMarch, 22nd 2017, Red Room,FAO, Rome, Italy

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FAO-UNESCO, 1978African soil main constraintsFerralsolsAcrisols, CambisolRegosols, Arenosols and PodzolsFerric and Plinthic LuvisolFluvisols, Gleysols, HistosolsLow nutrient content, weathered, Al and Mn toxicity, High P-fixation, low nutrients and water retention, susceptible to erosionMainly quartz, low water and nutrient holding capacity, wind erosion, poor soils with nutrient leachingLow nutrient contentPoor to moderate drainage

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Restauration of degraded soils

Mantaining soil fertility and productivity of agricultural soils

Limitation or preservation from erosion

Safety of ecosystemic services provided by soils

Importance of soil carbon sequestration in Africa

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Factors controlling soil C sequestrationC INPUTResidues, Mulch,Compost, Amendment,DepositionC OUTPUTErosionDecompositionLeaching Harvest

Soil carbon

f [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Landscape position]

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f [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Topography]Climate AltitudeSoil propertiesTopography

Oladimeji I. Oladele, Ademola K. Braimoh, 2015Factors controlling the maximum of soil C sequestration

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f [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Topography]Climate AltitudeSoil propertiesTopography

Soil Carbon (Mg/ha)Soil 0-100 cm

AltitudeRakotonarivo, 2010SO= South WesternNE= North EastFactors controlling the maximum of soil C sequestration

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Factors controlling the maximum of soil C sequestrationf [Climate, Altitude, Soil properties (texture, mineralogy, mineral reserve), Topography]Climate AltitudeSoil propertiesTopographyClay + Fine silt (%)

Potential Soil Carbon sequestration (?)

020406080020406080100

Vegetao perene

Sistema melhorado

Cultura permanentePerennial vegetationImproved systems (+MO)Annual crops (-MO)Feller and Beare, 1997

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Changes in management / practicesConservation agriculture

Organic fertilizers

Improved Rice practices

Crop rotation/ associationAgroforestry

Potential techniques for soil carbon sequestration

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Use or Improvement of existing traditional practices

Zai holes

Improved fallows Half-moon holes

Potential techniques for soil carbon sequestration

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Potential C-sequestration technological options for humid and semi-arid climates

Marks et al.,2009Modified from Lal, 2004

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CaSA Network

Soil Carbon for Sustainable Agriculture in Africa

http://reseau-carbone-sol-afrique.org

21 teams, 11 african and european countries

AlgeriaBeninBurkina FasoCameroonCte dIvoireMaliMadagascarMorrocoSenegalTunisiaFranceTo replace Soil and Soil Carbon as centers of the sustainability of Agricultural Systems

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C sequestration values ...

Conservation agriculture

Photos : Husson O.Madagascar

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% Clay020406080Gleysoil (Gl)Ferralsol 1 (Fr1)Ferralsol 2 (Fr2)XHumid tropical climate (2500mm, 19C)XXSubtropical climate (1300mm, 17C)Ferralsol 3 (Fr3)XTropical climate (1200mm, 20C)Ferralic Cambisol (Cf)Fluvisol (Fl)XXSome C sequestration values ... Conservation agricultureRazafimbelo et al., 2010

Madagascar

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Some C sequestration values ... Conservation agricultureRazafimbelo et al., 2010Main cropLegume Inputs DC in kgC/ha/yrHumid tropicalTropicalSubtropRiceStylosanthes guy.0Gl. (20%)803RiceStylosanthes guy.Mineral Gl. (20%)1816*Fr1 (45%)RiceStylosanthes guy.0527Fr2 (30%)RiceStylosanthes guy.Mineral 0MaizeVigna unguic.ManureCf (20%)137RiceVigna unguic.ManureFl (15%)727*MaizeVigna unguic.Cf (20%)220ManureMineral RiceVigna unguic.Fl (15%)600ManureMineral SoybeanMaizeFr3(65%)324ManureMineral

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Roose et al., 1999To wake up earlyA microcatchment systemA local supply of organic matter

15Photos : Hien E.Zai practicesSome C sequestration values ... Hien E.Burkina Faso

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Masse et al., 2011No significant differences in 0-10cmSOC higher in Zai holes Effect of durationMore effects in holes than inbetween HolesSoil organic carbon changes in za systems

Zai practicesSome C sequestration values ... Burkina Faso

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Mucuna Pruriens Joseph G. Mureithi, KARI, Kenya*Maize + mucuna vs Maze + NPK

11 years0-40 cm depthNitisol, sandy loam textured

Mucuna cover effect*SOC (Mg.ha-1)SOC : Mucuna>Maize+NPK>Maize No fert.Barths et al., 2004 Legume useSome C sequestration values ... DC = 1.35 MgC/ha/yrBenin

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Manure

Organic urban waste

CompostManure Urban organic waste - CompostFerralsol, clayey (40%)8 years0-30cm depthMgC/ha/yrOrganic fertilizerSome C sequestration values ... DC1 = 21 DC2 = 86 DC3 = 103 MgC / haDC1 = 0.158DC2 = 0.609DC3 = 0.752MadagascarRafolisy et al., in prep

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Agroforestry systemsSome C sequestration values ...

Madagascar

SOC (Mg.ha-1)20DC = 200

DC = 0.631 MgC/ha/yrCloves + 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 systemsSome C sequestration values ... MadagascarAndriamananjara et al., 2016

Conclusions Amount of C sequestration is/will be different according :systems, but also climate and soil type and topography => main factors controlling carbon sequestrationValues 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 them21

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http://reseau-carbone-sol-afrique.orgThank you for your attentionMerci de votre attentionMisaotra tompokoThanks to :

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