Abstract

Mechanistic models are often used to predict N mineralisation from soil organic matter. Such models usually estimate N mineratisation from C mineralisation, often necessitating assumptions about the C:N ratio of the decomposing organic matter. We tested, in a Laboratory experiment, whether the latter was reflected in the C:N ratio of bulk soil organic matter. Soils that, since 1956, had received organic amendments of widely different C:N ratios were sampled in May 2001, approximately 18 months after the last applications of the amendments. Carbon and gross N minerahsation were determined consecutively over a 17-week incubation period at 20degreesC. Gross N mineralisation rates were estimated using equations based on first-order kinetics for NH4+ consumption. Despite differences in C:N of the bulk soil organic matter, across the soils gross N mineratisation was approximately proportional to C mineratisation. The proportionality factor between C and gross N mineralisation was approximately 5 (gross N mineratisation in relation to C mineralisation), suggesting that C:N of the decomposing organic matter of ca. 9 in all soils.

Keywords

C : N ratio; mechanistic models; minerahsation; soil organic matter

Published in

Title: Controlling nitrogen flows and losses
ISBN: 978-90-76998-43-5
Publisher: Wageningen Academic Publishers

SLU Authors

• Herrmann, Anke

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

• Witter, Ernst

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

• Kätterer, Thomas

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Soil Science
Agricultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/2863