Preprints
https://doi.org/10.5194/soil-2021-78
https://doi.org/10.5194/soil-2021-78

  17 Aug 2021

17 Aug 2021

Review status: this preprint is currently under review for the journal SOIL.

Modelling the effect of catena position and hydrology on soil chemical weathering

Vanesa García-Gamero1, Tom Vanwalleghem1, Adolfo Peña2, Andrea Román-Sánchez3, and Peter A. Finke4 Vanesa García-Gamero et al.
  • 1Department of Agronomy, University of Córdoba, Da Vinci building, Madrid km 396 Rd., 14071 Córdoba, Spain
  • 2Department of Rural Engineering, Civil Constructions and Engineering Projects, University of Córdoba, Da Vinci building, Madrid km 396 Rd., 14071 Córdoba, Spain
  • 3Department of Forest Ecology, The Silva Tarouca Research Institute, Lidická 25/27,602 00 Brno, Czech Republic
  • 4Department of Environment, University of Ghent, Coupure Links 653, 9000 Ghent, Belgium

Abstract. The sensitivity of chemical weathering to climatic and erosional forcing is well established at regional scales. However, soil formation is known to vary strongly along catenas where topography, hydrology, and vegetation cause differences in soil properties and possibly chemical weathering. This study applies the SoilGen model to evaluate the link between topographic position and hydrology with the chemical weathering of soil profiles on a north-south catena in southern Spain.

Pedogenesis was measured and simulated in seven selected locations over a 20000-year period. A good correspondence between simulated and measured chemical depletion fraction (CDF) was obtained (R2 = 0.47). An important variation in CDF values along the catena was observed, although the position along the catena alone, nor by the slope gradient, explained this variation well. However, the hydrological variables explained the observed trends better. A positive trend between CDF data and soil moisture and infiltration and a negative trend with water residence time was found.

The model sensitivity was evaluated with a large precipitation gradient (200–1200 mm yr−1). While a marked depth gradient was obtained for CDF with precipitation up to 800 mm yr−1, a uniform depth distribution was obtained with precipitation above 800 mm yr−1. The basic pattern for the response of chemical weathering to precipitation is a unimodal curve, with a maximum around a mean annual precipitation value of 800 mm yr−1. Interestingly, this corroborates similar findings on the relation of other soil properties to precipitation and should be explored in further research.

Vanesa García-Gamero et al.

Status: open (until 12 Oct 2021)

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Vanesa García-Gamero et al.

Vanesa García-Gamero et al.

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Short summary
Short-scale soil variability has received much less attention than regional scale. Chemical Depletion Fraction (CDF), a proxy for chemical weathering, was measured and simulated with SoilGen model along two opposite slopes in southern Spain. The results show that differences in CDF could not be explained by topography alone but by hydrological parameters. The model sensitivity test shows the maximum CDF value for intermediate precipitation as similar findings for other soil properties.