dynamics of soil carbon sequestration under oil palm plantations of different ages

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Dynamics of soil carbon sequestration under oil palm plantations of different ages

Dynamics of soil carbon sequestration under oil palm plantations of different agesByBrahene Sebastian Wisdom

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyPresentation outlineIntroductionBackground informationProblem statementJustificationObjectivesMaterials and MethodsResults and discussionSummary, conclusion and recommendations

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyIntroductionBackground informationTackling climate change demands special attention to agriculture (Smith et al. 2008).

Oil palm cultivation in GhanaBOPP, GOPDC, TOPP, SmallholdersConversion of forests and C losses

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyIntroduction contdOil palm cultivation and activitiespruning and heaping of palm fronds in between the rows of plants.

Beneficial effects of prunning and heapingEnsure clean farms to undertake other farm operations such as harvesting, rodents control, etc.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyIntroduction contdProblem statement

Evidence is thin on soil carbon studies under pruned palm frond heaps on smallholder oil palm plantations in Ghana.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyIntroduction contdJustification

There is therefore the need to quantify the soil carbon dynamics in a false chrono-sequence under pruned fronds heaped on smallholder farms in Ghana.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyIntroduction contdObjectives

To assess soil C content and stocks under pruned heaps in already established oil palm plantations of different maturity ages;

To examine the dynamics (changes) in soil C stocks over time under pruned heaps in these oil palm plantations.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyMaterials and MethodsStudy sites: private smallholder farms within the same agro-ecological zone

Site selectionfive clusters according to age of oil palm plantationQuestionnaireMulti-stage sampling for further groupingTop, Middle and Bottom slopesModal instance samplingBottom slopeEight farms were targetedsnow balling Random samplingSampling costs and locations

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

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Materials and methods contdSampled plots

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyMaterials and methods contdSample collection and preparationSampling area: 25X25mSampling depth: 0-10, 10-20 cmUniform depth increments rather than by pedogenic horizonsSampling spots1. Alleys between rows of palm trees 2. Under pruned heaps of palm branchesSampling was preceded by grid marking72 samplesCore samplers for undisturbed samplesComposite sampleSoils air dried , crushed and sieved through a 2 mm sieve for laboratory analyses

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyMaterials and methods contdCalculating for C stocks

Carbon stocks were determined on the fine earth fraction after bulk density and C content had been determined on the soils using the formular below:

C stocks (Mg ha-1) = b (Mg/m3) C content (kg/kg) a (m2) d (m)

Where b- Bulk densitya- Area of a hectard- Sampling depth

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyMaterials and methods contdCalculating carbon saturation deficitAdopted from van Noordwijk et al. (1997)Carbon saturation deficit was calculated from stocks using the formular below:Csatdef = [(Cref-Corg)/ Cref] 100%Where Cref- Carbon stock in reference soilCorg -Current carbon stock in soil

Data AnalysesGenstats (12th edition) and Minitab (16th edition) were used for computer analysis.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

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Results and Discussion

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

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Results and Discussion ContdA notable drop in OC within the first 5 years upon cultivation was seen as has been reported by by Guo and Gifford (2002).

The subsequent drop in OC beyond 10 years was gradual (Lamade et al., 2005) when compared to the 5-10 years group but less than 15 % of that for previous years as was observed under alleys with age.

Soils under these heaps had termites, beetles and other organisms except earthworms due to the vertical migration of these organisms to areas of more moisture and so affected C turnover in deeper layers instead (Briones et al. 1998a, 2010).

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyResults and Discussion ContdC stocks followed a similar trend as OC values with the 20-25 year group under pruned fronds obtaining a maximum of 25.2 Mg C/ha.

The value of 59.6 Mg C/ha calculated for the 0-20 cm layer under forest conditions (uncultivated) in this work falls within the range 5-180 t/ha for the 0-30 cm layer as put out for humid tropical forests (IPCC, 1997).

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyResults and Discussions Contd

Relationship between C stock and management optionsCarbon in soils within alleys was lower than that under pruned heaps.Cultural practices, C removal, erosion, flooding

The system of adding pruned materials as residue to soil seems to improve the storage of carbon particularly in the 0-10 cm layer.

Management system seen as the main factor affecting stocks.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyResults and Discussion ContdRelationship between C stock and management options

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyResults and Discussion ContdRelationship between C stock and management optionsInitial additions to soil were small but possibility of reaching equilibrium and exceeding is attainable beyond 25 year period.

In addition to the annual increases in stocks under prunnings, some organic materials are still present on the farm at various stages of decomposition.

Undecomposed materials serve as a means to trap and hold C and other gases (released via decomposition) which otherwise would have been emitted into the atmosphere contributing to greenhouse gases.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyConclusion and RecommendationThe basic criteria for increasing SOC is that the amount of C added in residues, including plant roots, exceeds the amount of C lost in decomposition.

Thus quantifying the effects of individual management practices such as prunning and heaping of fronds and their combinations on C sequestration is vital for improving the potential of farming systems to sequester C.

The practical implications of this research would be to encourage prunning and heaping of palm fronds within rows of palm trees at well designated spots continually. This action would not only provide nutrients to the crops but would with time contribute to building C levels in the soils in addition to the pruned materials that would remain on top of the soil.

The study recommends research into how to improve decomposition of oil palm residue to enhance the fertility of the mineral soil as infiltration through the fronds becomes limiting with increasing height of heaps.

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, ItalyThank you

GSOC17 -Global Symposium on Soil Organic Carbon21-23 March 2017 - FAO HQ - Rome, Italy

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