Which 2 : 1 clay minerals are involved in the soil potassium reservoir? Insights from potassium addition or removal experiments on three temperate grassland soil clay assemblages - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Geoderma Année : 2008

Which 2 : 1 clay minerals are involved in the soil potassium reservoir? Insights from potassium addition or removal experiments on three temperate grassland soil clay assemblages

Résumé

Field and laboratory observations based on X-ray diffraction techniques suggest that 2:1 clay minerals behave as a K reservoir. However, 2:1 soil clay assemblages are most often composed of a mixture of different 2:1 clay mineral populations and the role of these different clay mineral populations in K absorption or K release are not fully understood. This present work addressed this question, through laboratory experiments, by using an X-ray pattern decomposition program to quantify peak area modifications of different clay mineral populations induced by K addition and K removal through plant action. This study was performed on three typical temperate grassland soil clay assemblages containing illite, interstratified illite/smectite and soil vermiculite. Our results revealed that the quantities of well crystallized illite increased at the expense of soil vermiculite as a result of K absorption whereas the opposite trend was observed following K depletion. This particular relationship between well crystallized: illite and soil vermiculite suggests that they constitute a subgroup among 2:1 clay minerals. Poorly crystallized illite and interstratified clay minerals were also significantly affected by K absorption or removal indicating that they are also involved in soil K dynamics. Moreover, we observed that these short term clay mineral modifications (occurring at the day scale) induced by root K extraction are reversible. We also observed that the linear relationship between clay K content and the centre of gravity position of X-ray diffraction patterns in the 2:1 clay mineral range seem to be a general property for soil clay assemblages dominated by illite and interstratified illite/smectite materials. Our results support the view of 2:1 clay minerals as a K reservoir and specify the role of each of the 2:1 clay mineral populations in K absorption and release. All the 2:1 clay minerals commonly found in temperate grassland soil clay assemblages take part in the soil K reservoir.
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Dates et versions

bioemco-00341616 , version 1 (25-11-2008)

Identifiants

  • HAL Id : bioemco-00341616 , version 1
  • PRODINRA : 250176

Citer

Pierre Barré, Bruce Velde, Colin Fontaine, Nicole Catel, Luc Abbadie. Which 2 : 1 clay minerals are involved in the soil potassium reservoir? Insights from potassium addition or removal experiments on three temperate grassland soil clay assemblages. Geoderma, 2008, 146, pp.216-223. ⟨bioemco-00341616⟩
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