African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6576

Full Length Research Paper

Soil carbon dynamics, climate, crops and soil type –calculations using introductory carbon balance model (ICBM) and agricultural field trial data from sub-Saharan Africa

  O. Andrén1,4, T. Kätterer2, J. Juston3, B. Waswa1 and Kristina Röing de Nowina1,2*        
  1Tropical Soil Biology and Fertility Institute of International Center for Tropical Agriculture (CIAT-TSBF), P. O. Box 823-00621, Nairobi, Kenya. 2Department of Soil and Environment, Swedish University of Agricultural Sciences, P. O. Box 7014, SE-750 07, Uppsala, Sweden. 3Department of Land and Water Resources Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm, Sweden. 4Björklundavägen 3, SE-756 46 Uppsala, Sweden.
Email: [email protected]

  •  Accepted: 26 July 2012
  •  Published: 30 November 2012

Abstract

 

A simple soil carbon model, the Introductory Carbon Balance Model (ICBM), is useful for projecting soil C dynamics in temperate and tropical land-use systems. A spreadsheet-based version of ICBM is presented, with an emphasis on African and short-and long term projections under variable conditions (climate, crops, soil). ICBM has two compartments, young and old soil C, and five parameters, intended to project soil C dynamics in a 30-year perspective even when detailed data are lacking. Information necessary is a rough estimate of annual carbon input to soil, a coarse measure of residue quality and some information about climate. If basic weather station data and water-related soil properties are available, more exact projections can be made. Typically, the model is used for answering questions such as: (1) If crop residues are returned to the field, how much will soil carbon increase after 30 years? (2) With limited local data available, will rough estimates (climate zone and crop yield etc) still make projections possible? Compared with more complex models, this approach is rapid and simple and yet still gives accurate results. The model is available as an Excel® spreadsheet, and which projections can be made and effects of different agricultural treatments can be compared. Here, agricultural field experiments in Africa are used to show how ICBM rapidly can be parameterized for conditions different from those it was originally calibrated for, and how projections can be made from this base parameterization. Concepts behind modeling approaches, as well as possible improvements, are also discussed.

 

Key words: Soil carbon, agriculture, modeling, carbon sequestration, Africa.