Modeling soil genesis at pedon and landscape scales: Achievements and problems
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Date
2015
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Publisher
Quaternary International
Abstract
Modeling soil evolution is an important step towards understanding the complexity of the soil system
and its interaction with the other systems. The major challenge confronted by pedologists until now is
the ability to develop models capable of describing the complete complexity of the soil system. This
paper presents the state of art overview of such a soil evolution model, SoilGen, its applications and
limitations. In addition, the paper gives an overview of how the SoilGen model may be linked to landscape
evolution models to model soilscape development. SoilGen is a mechanistic pedogenetic model in
which soil forming processes such as clay migration, decalcification, carbon cycling, bioturbation,
physical and chemical weathering coupled with water flow are simulated at multi-millennium time
scale. The model has been calibrated and undergone extensive field testing, giving reasonable results at
both pedon and landscape scales. However discrepancies between observed and simulated soil properties
such as base saturation (BS), cation exchange capacity (CEC) and pH have been reported. These
have been attributed partly to simplification of soil forming processes particularly in the weathering and
chemical systems. There is therefore a need to extend the description of chemical and weathering
systems in the SoilGen model. These extensions will not only improve model performance but will also
enlarge its application range in simulating the genesis of typical features of more than half of the WRBReference
Soil Groups. We also note here that although landscape evolution models have been successfully
applied to model soil production and distribution, simplified and/or incomplete description of
soil forming processes remain major limitations. We therefore add to the voices in scientific literature
calling for integration of pedon and landscape scale models. In addition there is critical need for high
quality chronosequence, climosequence, and toposequence profile datasets to enhance calibration and
validation of soil evolution models.
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Keywords
Soil genesis, Landscape scales
Citation
Opolot, E., et al., Modeling soil genesis at pedon and landscape scales: Achievements and problems, Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.02.017