Nutrient Cycling in Agroecosystems

, Volume 79, Issue 3, pp 291–302 | Cite as

Temporal and spatial trends in soil organic carbon stocks following maize cultivation in semi-arid Tanzania, East Africa

  • Torben Birch-Thomsen
  • Bo Elberling
  • Bjarne Fog
  • Jakob Magid
Research Article


Conversion of native ecosystems to agro-ecosystems influences the amount, quality and turnover of soil organic carbon (SOC). As most agro-ecosystems are not in a steady state in terms of the content of SOC, the time scale and feedback mechanisms of changes in SOC are highly relevant for predicting future soil fertility and potential rates of soil carbon losses or sequestration. This paper focuses on changes in land use linked to measured changes in the distribution of total stocks of SOC and the δ13C signature in the upper 0.5 m of cultivated soils in the semi-arid parts of Tanzania. Based on documented land use changes since 1950s using remote sensing data, 12 sampling sites along two transects were selected to represent semi-natural/natural savannah and maize fields cultivated for up to five decades. Comparisons between sites representing a chronosequence of well-drained soils showed that soils cultivated the last 50 years have in average less than 50% SOC compared to soils which have never been cultivated. Variations between sites were significant and a reduction in SOC could not be established at sites near present or former villages which have received substantial manure despite a long cultivation history or along a chronosequence representing wetter and more fine-grained soils. Spatial variations in land use changes were parameterized based on remote sensing data and successfully validated against sampling sites. Site-specific rates of soil element loss following cultivation were extrapolated to the study area and uncertainties related to scaling up were discussed.


Soil organic carbon Tanzania Land use changes Agriculture 



This research was conducted as an extension of the Sustainable Agriculture in Semi-Arid Africa (SASA) programme of research originally funded by the Danish Environmental Research Programme. We would like to thank the people of Ilambilole Village for their hospitality and indispensable assistance.


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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Torben Birch-Thomsen
    • 1
  • Bo Elberling
    • 1
  • Bjarne Fog
    • 1
  • Jakob Magid
    • 2
  1. 1.Department of Geography and GeologyUniversity of CopenhagenCopenhagen KDenmark
  2. 2.Department of Agricultural Sciences, Faculty of Life SciencesUniversity of CopenhagenFrederiksberg CDenmark

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