Production, reactivity, and bioavailability of dissolved organic phosphorus species in soil – indicators of the recycling efficiency of forest

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With mineral sources of phosphorus becoming increasingly scarce with progressing ecosystem development, forests start to recycle organic phosphorus. Inorganic phosphorus forms tend to be bound strongly to secondary minerals, thus, it is hardly available to plants but also not leached from soil. Instead, phosphorus leaching losses tend to be governed by mobile organic forms, whatever state the ecosystem is in. Microbial compounds such as nucleotides and nucleic acids seem to form the most mobile fraction of dissolved organic phosphorus in soils, while plant-derived compounds such as phytate are less prone to leaching. However, those potentially mobile microbial compounds are labile to enzymatic hydrolysis, thus, the phosphorus contained may be taken up by plants and microorganisms, thus, minimizing the phosphorus leaching losses from recycling ecosystems.

The proposed research aims understanding the chemical characteristics of dissolved organic phosphorus compounds controlling their mobility, the controls on the composition of dissolved organic phosphorus, and if dissolved organic phosphorus is available for plants.

We will collect forest floor seepage water and solutions from mineral soils along a gradient of phosphorus availability. These solutions will be analyzed for chemical organic phosphorus species, using spectroscopic methods (basically NMR, complemented by XPS and XANES analyses on selected samples), and for enzymatic release of the phosphorus contained (in combination with spectroscopic methods). This approach will inform on mobile and labile dissolved organic phosphorus compounds. Similar analyses will be carried out on solutions deriving from other proposed experiments on potential controls (drought, pH) on dissolved phosphorus release. These samples allow to track changes in composition, thus, in the chemical and biological reactivity of dissolved organic phosphorus. Laboratory assays will be used to address the potential mobility of organic phosphorus species (sorption experiments, in combination with spectroscopic methods) as well as experiments with labeled compounds. The latter will address the potential plant uptake of dissolved organic phosphorus, either after enzymatic hydrolysis or directly in the form of small molecules.




Principal investigators: 

Dr. Klaus Kaiser
Martin-Luther-Universität Halle-Wittenberg, Bodenwissenschaften
Von-Seckendorff-Platz 3
D-06120 Halle (Saale)
Tel.: (+49) 345 22590


Study sites


Bad Brückenau (BBR)

Conventwald (CON)

Lüss (LUE)

Mitterfels (MIT)

Vessertal (VES)


Funded by

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