Transformations of phosphorus during incubation of beech leaf litter in the presence of oxides

Some minerals have large PO43- sorption capacities. However, we do not know how these mineral phases influence the speciation of organic P when organic matter decomposes. To characterize the interactions between mineral phases and organic P species, we incubated mixtures of beech leaf Litter and Fe oxide, Al hydroxide, birnessite, and quartz sand. The samples were extracted with NaOH-NaF and analysed by P-31 nuclear magnetic resonance (NMR) spectroscopy. Phosphate mono- and diesters gave the most prominent signals in the P-31 NMR spectra. During incubation, the proportion of the monoester P decreased, whereas that of the diester P increased. Since NMR intensities assigned to teichoic acids increased, it seems that microbial P accumulated during incubation. The synthesis of microbial compounds was strongest in the presence of Fe oxide. All mineral phases investigated gave rise to a resonance in the P-31 NMR spectra which was not present in the control treatment to which the mineral phases had not been added. The resonance was tentatively assigned to sugar diesters, which probably originated from organo-mineral interactions.