Position-specific transformation of low molecular weight organic substances in soil

DFG KU 1184/19

From 03/2010 to 02/2013

Principal Investigator: Bruno Glaser, Yakov Kuzyakov
Staff: Michaela Dippold

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. Based on the unique feature of isotope applications, we will reveal position-specific transformation of LMWOS in soil for representatives of sugars, amino acids and carboxylic acids. These LMWOS will be labeled with 14C and 13C in different positions of the molecules and their fate in soil will be investigated 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 the use efficiency by various microbial groups. Mean residence times of C from individual positions of LMWOS molecules in SOM will be estimated under field conditions and the stabilization of C from various positions will be compared. 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. The results will allow specification and generalization of the fate of LMWOS in soils and are relevant for studies on SOM, microbial biomass, sorption of LMWOS and studies based on 13C natural abundance.