HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Liu, C. Articles by Zhou, J. M. Search for Related Content PubMed Articles by Liu, C. Articles by Zhou, J. M. GeoRef GeoRef Citation Agricola Articles by Liu, C. Articles by Zhou, J. M. Related Collections Soil Chemistry Soil Mineralogy

DIVISION S-2 - SOIL CHEMISTRY

Residence Time Effect on Iron Perturbation of Taranakite Formation

^a Dep. of Soil Science, Univ. of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8 Canada
^b The Institute of Soil Science, Academia Sinica, P.O. Box 821, 71 East Beijing Road, Nanjing 210008, China

* Corresponding author (huangp{at}sask.usask.ca)

Taranakite is an important reaction product in the immediate vicinity of phosphate fertilizer bands. The residence time effect on taranakite formation at pH 4.0 and on the iron perturbation of its formation at a Fe(II)/Al molar ratio of 1.2 (Al = 1 x 10^-2 M and NH₄H₂PO₄ = 1 M) was investigated in this study. The crystallization of NH₄-taranakite involved a phase transformation from irregularly shaped x-ray noncrystalline materials to taranakite. The incorporation of NH⁺₄ ions into taranakite structure was a relatively slow process. The presence of Fe(II) in the solution of the reaction system perturbed the incorporation of NH⁺₄ ions into taranakite structure, especially in the early aging period. Furthermore, the coating or coprecipitation of x-ray noncrystalline iron phosphates with aluminum phosphates appeared to reduce the dissolution of aluminum phosphates, thus, affecting the phase transformation to taranakite. The presence of Fe(II) greatly decreased the rate of taranakite formation and retarded its formation. This is attributed to iron phosphate coatings as impurities on taranakite particles and the subsequent retardation of its crystal growth by interfering the integration of growth units. The impact of the residence time of Fe perturbation of the formation of taranakite in the immediate vicinity of fertilizer zones in soils, especially under reduced conditions, on the transformation and dynamics of P and N in the terrestrial system merits close attention.

Abbreviations: AFM, atomic force microscopy • IR, infrared • SEM, scanning electron microscope • XRD, x-ray diffraction