Pulse Brain · Growing Health Evidence Index
Tier 3 — Observational / field trialPeer-reviewed

Controls on timescales of soil organic carbon persistence across <scp>sub‐Saharan</scp> Africa

Sophie F. von Fromm, Sebastian Döetterl, Benjamin Butler, Ermias Aynekulu, Asmeret Asefaw Berhe, Stephan M. Haefele, S. P. McGrath, Keith Shepherd, Johan Six, Lulseged Tamene, Jérôme Tondoh, Tor‐Gunnar Vågen, Leigh Winowiecki, Susan Trumbore, Alison M. Hoyt

Global Change Biology · 2023

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Summary

This study addresses a critical knowledge gap on soil carbon cycling in sub-Saharan Africa by presenting radiocarbon and mineral data across multiple sites and climatic zones. The findings reveal that moderately weathered soils in seasonal climates with reactive clay minerals retain organic carbon longer than highly weathered humid-zone soils, and that arid soils show carbon persistence similar to seasonal zones despite different mechanisms. These process-oriented distinctions suggest that pedo-climatic groupings may improve predictions of soil carbon dynamics under future climate change.

UK applicability

The study focuses exclusively on sub-Saharan African soils, which differ substantially from UK soil conditions in climate (temperate versus tropical/arid), weathering stage, and dominant mineralogy. Whilst the methodological approach (radiocarbon dating of soil carbon) is transferable, the specific timescale estimates and climate–mineralogy relationships are not directly applicable to UK farming or carbon sequestration policy.

Key measures

Radiocarbon ages (Δ14C or equivalent), soil mineralogy (clay mineral reactivity and crystallinity), organic carbon persistence timescales (mean ± SD in years) stratified by topsoil and subsoil depth, climate zone (arid, seasonal, humid), and soil weathering stage

Outcomes reported

The study measured radiocarbon ages and mineral composition of soil organic carbon across sub-Saharan Africa to quantify how long carbon persists in topsoils and subsoils under different climatic and weathering conditions. It reported mean persistence timescales ranging from 140–396 years in topsoil and 454–963 years in subsoil, depending on soil weathering stage, mineralogy, and climate zone.

Theme
Farming systems, soils & land use
Subject
Soil carbon & organic matter
Study type
Research
Study design
Field survey with broad-scale radiocarbon and mineralogical analysis
Source type
Peer-reviewed study
Status
Published
Geography
Sub-Saharan Africa
System type
Other
DOI
10.1111/gcb.17089
Catalogue ID
BFmou2m5p8-2g4u7y

Topic tags

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