Selective sorption of potassium in a weathering sequence of volcanic ash soils from Guadeloupe, French West Indies
(2004) CATENA — Vol. 56, n° 1-3, p. 185-198 (2004)
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- Volcanic ash soils are usually associated within the weathering sequence glass --> allophane --> 4 halloysite. On the eastern slopes of the volcano La Soufriere, Guadeloupe, this sequence occurs in a toposequence Molli-silicic Andosol-Humic Andosol-Haplic Andosol-Haplic Nitisol, where the average annual rainfall decreases from 4000 mm at 420 m a.s.l. to 2500 mrn at 30 m a.s.l. Of this sequence, we selected four profiles and examined the relationships between weathering stage, clay mineralogy and exchangeable K+-Ca2+ selectivity. With increasing weathering, the total content of alkaline and alkaline-earth cations of the B horizon steadily decreased from 185 cmol(c) kg(-1) soil in the Molli-silicic Andosol to 24 cmol(c), kg(-1) soil in the Nitisol. K+ selectivity was small in the Molli-silicie Andosol, but significantly increased with increasing weathering stage and increasing content of halloysite. In the Haplic Andosol and Nitisol, the very strong selectivity for K+ ions may be linked with the presence of a 2:1 clay mineral, but could not be attributed unequivocally to this mineral or to halloysite. The 2:1 mineral occurred as a discrete phase mixed with halloysite and exhibited X-ray diffraction features, suggesting its vermiculitic nature. (C) 2003 Elsevier B.V. All rights reserved.
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Ndayiragije, S., & Delvaux, B. (2004). Selective sorption of potassium in a weathering sequence of volcanic ash soils from Guadeloupe, French West Indies. CATENA, 56(1-3), 185-198. https://doi.org/10.1016/j.catena.2003.10.010 (Original work published 2004)