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Potassium release and fixation in Ferralsols (Oxisols) from Southern Togo
Author(s) -
POSS R.,
FARDEAU J. C.,
SARAGONIT H.,
QUANTIN P.
Publication year - 1991
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1991.tb00111.x
Subject(s) - chemistry , subsoil , fertilizer , potassium , oxisol , ammonium , cation exchange capacity , soil water , soil test , ion exchange , wetting , agronomy , soil science , environmental chemistry , zoology , environmental science , ion , materials science , biology , organic chemistry , composite material
SUMMARY Potassium release and fixation were studied on Ferralsols (typic Eutrustox) of Southern Togo both by isotopic exchange with 42 K+ ions and by exchange with 1 M ammonium acetate. Experiments were conducted on soil samples taken from surface (0–30 cm) and subsoil (80–100 cm) layers of four plots. These plats, with the same soil type, were subjected to various kinds of use: forest and crops, with or without fertilizers. A single wetting and drying of the soil samples increased the amounts of exchangeable K. This exchangeable K release could stem from clay protonation during drying. However, the K release is insufficient to allow permanent intensive agriculture without K fertilizer addition. Soil samples were therefore treated with KCI in order to study K fixation. About 20% of the applied K was fixed and the percentage increased with wetting and drying. The fixation can be explained by the presence of about 2% of interstratified clay minerals in these kaolinitic soils. Comparison of the kinetic characteristics of the isotopically exchangeable K with the amounts of ammonium exchangeable K revealed the existence of several kinds of exchange site for K ions.