Position-specific transformation of low molecular weight organic substances in soil
2 Department of Soil Physics, University of Bayreuth
P 1.11 in Ecosystem Function
Position-specific transformation of low molecular weight organic substances in soil
Michaela Dippold1, Bruno Glaser2, Yakov Kuzyakov1
1Department of Agroecosystem Research, University of Bayreuth
2Department of Soil Physics, University of Bayreuth
Transformation of low molecular weight organic substances (LMWOS) in soil is one of the most important processes as all high molecular substances pass the stage of LMWOS during their decomposition. We suggest to use the unique feature of isotope applications – the position-specific labeling – to get a closer look on these transformations. Sugars, amino acids and carboxylic acids labeled with 14C and 13C in different positions will reveal transformation of LMWOS in soil including sorption, decomposition, utilization by microorganisms, as well as incorporation into soil organic matter (SOM). 13C enrichment of PLFA of microorganisms after application of position-specifically 13C labeled LMWOS will show utilization of individual C atoms by various microbial groups. Mean residence times and the stabilization of C from individual positions of LMWOS molecules in SOM will be estimated under field conditions. Moreover the uptake of LMWOS by plants as intact substances or as metabolites of the labeled substances will be evaluated based on differences in labeled C uptake from various molecule positions. Detailed knowledge of transformation of C from individual functional groups will allow generalization of the fate of LMWOS in soils and applications for studies on SOM, microbial biomass, sorption of LMWOS and studies based on 13C natural abundance.