Soil Organic Carbon (SOC) Equilibrium and Model Initialisation Methods: an Application to the Rothamsted Carbon (RothC) Model

Nemo, K. Klumpp, K. Coleman, M. Dondini, K. Goulding, A. Hastings, Michael B. Jones, J. Leifeld, B. Osborne, M. Saunders, T. Scott, Y. A. Teh, P. Smith

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27 Citations (Scopus)


Carbon (C) emissions from anthropogenic land use have accelerated climate change. To reduce C emissions, dynamic models can be used to assess the impact of human drivers on terrestrial C sequestration. Model accuracy requires
correct initialisation, since incorrect initialisation can influence the results obtained. Therefore, we sought to improve the initialisation of a process-based SOC model, RothC, which can estimate the effect of climate and land-use change
on SOC. The most common initialisation involves running the model until equilibrium (‘spin-up run’), when the SOC pools stabilise (method 1). However, this method does not always produce realistic results. At our experimental sites, the observed SOC was not at equilibrium after 10 years, suggesting that the commonly used spin-up initialisation method assuming equilibrium might be improved. In addition to method 1, we tested two alternative initialisations for RothC that involved adjusting the total or individual SOC pool equilibrium
values by regulating the C input during the entire spin-up initialisation period (method 2) and initialising each SOC pool with recently measured SOC values obtained by SOC fractionation (method 3). Analysis of the simulation accuracy for each model initialisation, quantified using the root mean square error (RMSE), indicated that a variant of method 2 that involved adjusting the equilibrium total SOC to observed values (method 2-T) generally showed less variation in the
individual SOC pools and total SOC. Furthermore, as total SOC is the sum of all SOC pools, and because total SOC data are more readily available than the individual SOC pool data, we conclude that method 2-T is best for initialising RothC.
Original languageEnglish
Pages (from-to)215-229
Number of pages15
JournalEnvironmental Modeling & Assessment
Issue number3
Early online date4 Nov 2016
Publication statusPublished - Jun 2017

Bibliographical note

The authors would like to thank Angus Calder and Cheryl Wood (University of St Andrews, UK) who let us use the laboratory facilities to perform the soil fractionation and their helpful support. The authors are also grateful to Olivier Darsonville, Jean- Luc Ollier, Marine Zwicke and Pierre Legoueix for their technical supports at INRA Clermont- Ferrand, UREP, France and also Alex Coad, European Commission - Joint Research Centre for advice on statistics. Funding to support this work was provided by FP7 project GHG- Europe (Grant No. 244122). Pete Smith is a Royal Society-Wolfson Research Merit Award holder.


  • SOC
  • RothC
  • model initialisation
  • agricultural management
  • ecosystem models
  • SOC fractionation


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