competition for N in Forest Soils: Stabilization of Organic N in Recalcitrant Pools
Zusammenfassung der Projektergebnisse
The focus of our research is the elucidation of major stabilization processes for soil organic nitrogen (SON) from soils investigated in the Research Unit. Soil samples from field as well as laboratory experiments were used to characterize nitrogen (N) partitioning in different soil compartiments. Results of a physical fractionation showed that SON stabilization is mainly controlled by interaction with the mineral phase. In the studied soil (Rendzic Leptosol), about 70% of SON is stored within the fine silt and clay fraction in organo-mineral associations and 24% is found in the labile particulate organic matter fraction (POM) consisting of (partly degraded) plant residues. For the investigation of the chemical composition of SON, bulk soil samples and soil fractions were studied by 15N NMR spectroscopy and wet chemical extraction. 15N NMR spectra revealed a dominance of peptide N structures within all soil fractions. This was also confirmed by high contents of extractable α-amino N contents that reached up to 75% of 13 total N within the investigated bulk soil samples. Results from C NMR spectroscopy point towards a relative low state of decomposition of SOM, which may be an explanation for the high contents of proteineous compounds. This study clearly demonstrates that SON stabilization through organo-mineral interaction is the major process for organic nitrogen (ON) storage in the investigated forest soil type. It will thus be the main process to be investigated with respect to competitive N partitioning in the studied forest ecosystem.
Projektbezogene Publikationen (Auswahl)
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Untersuchung von Stabilisierung und Zusammensetzung von SON in verschiedenen Fraktionen eines Waldbodens mit Hilfe von stabilen Isotopen. DBG-Workshop Stable Isotopes in Soil
Naumann PS, Knicker H, Winkler JB, Kögel-Knabner I
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Molecular approaches to soil organic matter composition and origin. Soil Science Society of America Annual Meeting, Indianapolis, USA, November 2006
Kögel-Knabner I
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Competition for N in forest soils: stabilisation of organic N in recalcitrant pools. 4th international symposium on physiological processes in roots of woody plants, Bangor, UK, September 2007
Naumann PS, Knicker H, Kögel-Knabner I
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Innovation and global change - Application of modern analytical tools (NMR, MALDI-TOF, XANES) for revealing C and N sequestration mechanisms in forest soils. International Symposium on Forest Soils and Ecosystem Health 2007“Noosa, Queensland, August 2007
Knicker H, Preston C, Prietzel J, Thieme J
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Waldböden und limitierter C-Input: Auswirkungen auf die Qualität und Quantität der organischen Bodensubstanz. German Soil Science Society Biannual meeting, Dresden, Germany, September 2007
Naumann PS, Knicker H, Kögel-Knabner I
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(2008) 15N immobilization in forest soil: a sterilization experiment coupled with 15CPMAS NMR spectroscopy. European Journal of Soil Science 59, 467-475
Morier I, Schleppi P, Siegwolf R, Knicker H and Guenat C
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(2008) Climate and parent material controls on organic matter storage in surface soils: A three-pool, density-separation approach. Geoderma 147, 23-33
Wagai, R., Mayer, L.M., Kitayama, K., Knicker, H.
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(2008) Use of pyrolysis/GC–MS combined with thermal analysis to monitor C and N changes. Catena 74, 296-303
De la Rosa, J.M., Gonzaléz-Pérez, J.A., Gonzaléz-Vázquez, R. Knicker, H., López-Capel, E.,Manning, D.A.C., Gonzaléz-Via, F.J.
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A new insight into microscale soil organic matter dynamics – from single particles to aggregates. AGU Fall Meeting, San Francisco, USA, December 2008
Mueller CW, Heister K, Hillion F, Herrmann AM, Koegel-Knabner I
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Does water stress affect composition and stabilization of SON? – A 15N labelling phytotron experiment. Eurosoil 2008, Vienna, Austria, August 2008
Naumann PS, Knicker H, Winkler JB, Kögel-Knabner I
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Factors influencing SOM stability. Soils Workshop ’Knowledge gaps in soil C and N interactions, Uppsala, Sweden, June 2008
Knicker H
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Humusqualität und Standorteigenschaften. Rundgespräch der Bayerischen Akademie der Wissenschaften, Kommission für Ökologie, April 2008
Kögel-Knabner I
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Rapid vertical changes of soil organic matter composition under juvenile beech trees – a lysimeter study. Eurosoil 2008, Vienna, Austria, August 2008
Mueller CW, Stoelken G, Pritsch K, Brueggemann N, Winkler JB, Kögel-Knabner I
