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Predicting nitrogen mineralization from soil organic matter - a chimera?

Herrmann, Anke (2003). Predicting nitrogen mineralization from soil organic matter - a chimera? Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 429
ISBN 91-576-6468-4
[Doctoral thesis]

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Predicting nitrogen (N) mineralization from soil organic matter is difficult because N mineralization is affected by several environmental factors, while being the net outcome of concurrent N processes that produce and consume mineral N. One aim of the present thesis was to study the effects of freezing and thawing on carbon (C) and N mineralization. A second aim was to elucidate if, and how, the quantity and quality of organic matter inputs affect N mineralization from the pool of soil organic matter. C and net N mineralization were determined in soils from the Ultuna Long-Term Soil Organic Matter Experiment exposed to repeated freezing and thawing (temperatures ranging from –5 °C to +5 °C). C, gross and net N mineralization in relation to quantity and quality of organic matter inputs were determined during long-term laboratory incubations at 20 °C. Gross N mineralization rates were estimated using the 15N isotope dilution technique, which is based on several assumptions. The assumption of ‘equilibrium between added and native N’ was tested by using a published data set in a dynamic compartmental model. Freezing and thawing of soils resulted in a flush in C and N mineralization, but the effect was only short-lived. It was concluded that freezing and thawing of soils during late winter and early spring is unlikely to be of importance to crop N availability in spring. Both quantity and quality of organic matter were major determinants of C and gross N mineralization, and these were proportional suggesting that C mineralization may be used as a predictor for gross N mineralization. Preferential use of added N may be a more common occurrence in 15N isotope dilution studies than hitherto thought and the assumption of ‘equilibrium between added and native N’ needs therefore critical evaluation. The data analysis presented in this thesis offers a way to estimate the potential effects of preferential use on gross N mineralization rate estimates. This thesis indicates that studies based on the mechanisms underlying N processes may improve our understanding of the relation between soil organic matter and N mineralization. Further mechanistic studies should therefore be considered in future N research.

Authors/Creators:Herrmann, Anke
Title:Predicting nitrogen mineralization from soil organic matter - a chimera?
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :November 2003
Number of Pages:42
ALLI. Herrmann, A. & Witter, E. 2002. Sources of C and N contributing to the flush in mineralization upon freeze-thaw cycles in soils. Soil Biology and Biochemistry 34, 1495-1505. II. Herrmann, A. & Witter, E. Gross and net N mineralization from soil organic matter after 45 years of addition of different organic amendments. Manuscript. III. Herrmann, A., Witter. E. & Kätterer T. An attempt to quantify ‘preferential use’ in the 15N isotope dilution technique and its impact on gross N mineralization rates. Submitted to Soil Biology and Biochemistry.
Place of Publication:Uppsala
ISBN for printed version:91-576-6468-4
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:P Natural resources > P33 Soil chemistry and physics
Subjects:Not in use, please see Agris categories
Agrovoc terms:degradation, agricultural soils, soil thermal regimes, soil organic matter, mineralization, tracer technique, nitrogen cycle
Keywords:Decomposition, agricultural soil, microbial biomass, mechanistic approach, freeze-thaw cycle, quantity and quality of soil organic matter, gross N mineralization, 15N isotope dilution technique, preferential use of added N
Permanent URL:
ID Code:386
Department:(NL, NJ) > Dept. of Soil Sciences (until 081001)
Deposited By: Anke Herrmann
Deposited On:10 Nov 2003 00:00
Metadata Last Modified:02 Dec 2014 10:04

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