Effect of residence time on the kinetics of nonexchangeable ammonium release from illite and vermiculite

Citation
D. Steffens et Dl. Sparks, Effect of residence time on the kinetics of nonexchangeable ammonium release from illite and vermiculite, J PLANT NU, 162(6), 1999, pp. 599-605
Citations number
29
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE-ZEITSCHRIFT FUR PFLANZENERNAHRUNG UND BODENKUNDE
ISSN journal
14368730 → ACNP
Volume
162
Issue
6
Year of publication
1999
Pages
599 - 605
Database
ISI
SICI code
1436-8730(199912)162:6<599:EORTOT>2.0.ZU;2-P
Abstract
The fraction of nonexchangeable ammonium (NH4+) can play an important role in N cycling of soils as a sink (fixation) or a source (release) of NH4+. R ecently fixed nonexchangeable NH4+ especially seems to be a significant sou rce for N release. The aim of our study was to determine the effect of resi dence time on the kinetics of nonexchangeable NH4+ release from illite and vermiculite. Calcium-saturated illite and vermiculite, containing NH4+ that was "fixed" for one and 60 d, were extracted with a H-resin for 0.25 to 38 4 h. Both clay minerals "fixed" significantly more NH4+ in 60 d than in 1 d , but vermiculite "fixed" more NH4+ than illite. The kinetics of nonexchang eable NH4+ release from illite and vermiculite were well described by the E lovich equation and by a heterogeneous diffusion model. In vermiculite the percentage of nonexchangeable NH4+ release decreased from 84% to 78% when t he time of fixation increased from 1 to 60 d. In illite time of residence h as not influenced the complete release of newly fixed NH4+.