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Impact of andosolization on pedogenic Fe oxides in ferrallitic soils

(2019) GEODERMA. 347. p.244-251
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Abstract
The accumulation of soil organic matter (SOM), poorly crystalline Fe oxides and metal-humus complexes is a trait of non-allophanic Andosols. The process of andosolization, which may occur in ferrallitic soils with high organic matter content, can involve transformation from well crystallized Fe oxides to poorly crystallized Fe oxides and Fe-humus complexes. This study investigates such changes in pedogenic Fe mineral associations for a soil toposequence between 1500 and 2260 m altitude along the southern flank of the volcanic Bambouto Mountains, Western Cameroon. The soils consist of highly weathered material, dominated by kaolinite, gibbsite and Fe oxides, grading to Protoandic Umbrisols at high altitude, recording an increase in SOM content with increasing altitude. As revealed by selective extraction analysis, the relative amount of poorly crystalline Fe oxides is low in the Bt and Bo horizons of low-altitude pedons, as well as in deep subsurface horizons of the high-altitude pedons. In contrast, it is significantly higher in the A and Bw horizons of the high-altitude pedons, with a clear increase with increasing altitude. Mossbauer spectroscopy analysis of B horizon samples identifies goethite as the dominant Fe oxide phase in nearly all pedons, with higher hematite contents in a mid-altitude zone marked by lower annual rainfall than in other parts of the toposequence. The Mossbauer spectra also reveal the presence of dissolved organic matter (DOM)-ferrihydrite, whose abundance is greatest in the Bw horizon of the high-altitude pedons, with an increase in relative abundance with increasing altitude. The observed patterns are attributed to dissolution-reprecipitation of Fe oxides that initially formed through ferrallitic weathering of volcanic parent materials that were roughly uniform along the toposequence. At high altitude, coupled hematite dissolution and DOM-ferrihydrite formation are favoured by high organic matter contents and low pH, related to cool humid environmental conditions and their effect on the vegetation and organic matter cycling.
Keywords
Fe oxides, DOM-ferrihydrite, Mossbauer spectroscopy, Andic properties, Bambouto Mountains, Cameroon, ACRISOL-PODZOL SEQUENCE, HILLS SOUTHERN INDIA, MIDDLE AMAZON BASIN, IRON-OXIDES, DEFERRALITIZATION PROCESS, BRAZILIAN OXISOLS, EXTRACTABLE IRON, ORGANIC-MATTER, FERRIHYDRITE, MICROMORPHOLOGY

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Citation

Please use this url to cite or link to this publication:

MLA
Van Ranst, Eric et al. “Impact of Andosolization on Pedogenic Fe Oxides in Ferrallitic Soils.” GEODERMA 347 (2019): 244–251. Print.
APA
Van Ranst, E., Mees, F., De Grave, E., Ye, L., Cornelis, J.-T., & Delvaux, B. (2019). Impact of andosolization on pedogenic Fe oxides in ferrallitic soils. GEODERMA, 347, 244–251.
Chicago author-date
Van Ranst, Eric, Florias Mees, Eddy De Grave, Liming Ye, Jean-Thomas Cornelis, and Bruno Delvaux. 2019. “Impact of Andosolization on Pedogenic Fe Oxides in Ferrallitic Soils.” Geoderma 347: 244–251.
Chicago author-date (all authors)
Van Ranst, Eric, Florias Mees, Eddy De Grave, Liming Ye, Jean-Thomas Cornelis, and Bruno Delvaux. 2019. “Impact of Andosolization on Pedogenic Fe Oxides in Ferrallitic Soils.” Geoderma 347: 244–251.
Vancouver
1.
Van Ranst E, Mees F, De Grave E, Ye L, Cornelis J-T, Delvaux B. Impact of andosolization on pedogenic Fe oxides in ferrallitic soils. GEODERMA. 2019;347:244–51.
IEEE
[1]
E. Van Ranst, F. Mees, E. De Grave, L. Ye, J.-T. Cornelis, and B. Delvaux, “Impact of andosolization on pedogenic Fe oxides in ferrallitic soils,” GEODERMA, vol. 347, pp. 244–251, 2019.
@article{8612603,
  abstract     = {{The accumulation of soil organic matter (SOM), poorly crystalline Fe oxides and metal-humus complexes is a trait of non-allophanic Andosols. The process of andosolization, which may occur in ferrallitic soils with high organic matter content, can involve transformation from well crystallized Fe oxides to poorly crystallized Fe oxides and Fe-humus complexes. This study investigates such changes in pedogenic Fe mineral associations for a soil toposequence between 1500 and 2260 m altitude along the southern flank of the volcanic Bambouto Mountains, Western Cameroon. The soils consist of highly weathered material, dominated by kaolinite, gibbsite and Fe oxides, grading to Protoandic Umbrisols at high altitude, recording an increase in SOM content with increasing altitude. As revealed by selective extraction analysis, the relative amount of poorly crystalline Fe oxides is low in the Bt and Bo horizons of low-altitude pedons, as well as in deep subsurface horizons of the high-altitude pedons. In contrast, it is significantly higher in the A and Bw horizons of the high-altitude pedons, with a clear increase with increasing altitude. Mossbauer spectroscopy analysis of B horizon samples identifies goethite as the dominant Fe oxide phase in nearly all pedons, with higher hematite contents in a mid-altitude zone marked by lower annual rainfall than in other parts of the toposequence. The Mossbauer spectra also reveal the presence of dissolved organic matter (DOM)-ferrihydrite, whose abundance is greatest in the Bw horizon of the high-altitude pedons, with an increase in relative abundance with increasing altitude. The observed patterns are attributed to dissolution-reprecipitation of Fe oxides that initially formed through ferrallitic weathering of volcanic parent materials that were roughly uniform along the toposequence. At high altitude, coupled hematite dissolution and DOM-ferrihydrite formation are favoured by high organic matter contents and low pH, related to cool humid environmental conditions and their effect on the vegetation and organic matter cycling.}},
  author       = {{Van Ranst, Eric and Mees, Florias and De Grave, Eddy and Ye, Liming and Cornelis, Jean-Thomas and Delvaux, Bruno}},
  issn         = {{0016-7061}},
  journal      = {{GEODERMA}},
  keywords     = {{Fe oxides,DOM-ferrihydrite,Mossbauer spectroscopy,Andic properties,Bambouto Mountains,Cameroon,ACRISOL-PODZOL SEQUENCE,HILLS SOUTHERN INDIA,MIDDLE AMAZON BASIN,IRON-OXIDES,DEFERRALITIZATION PROCESS,BRAZILIAN OXISOLS,EXTRACTABLE IRON,ORGANIC-MATTER,FERRIHYDRITE,MICROMORPHOLOGY}},
  language     = {{eng}},
  pages        = {{244--251}},
  title        = {{Impact of andosolization on pedogenic Fe oxides in ferrallitic soils}},
  url          = {{http://dx.doi.org/10.1016/j.geoderma.2019.04.013}},
  volume       = {{347}},
  year         = {{2019}},
}

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