Phosphorus turnover in forest soils: Effects of drying/rewetting and the role of dissolved organic P

P-Turnover

From 09/2014 to 11/2017

Staff: Mai Van Dinh, Marie Spohn, Egbert Matzner

Dissolved organic phosphorus (DOP) is often the major P compound in soil solutions and an important contribution to the P cycle in forest ecosystems. We will determine and compare solute fluxes of total P and DOP in experimental sites, representing P aggrading and P recycling forest ecosystems. The release of P by drying and rewetting of forest floors will be studied in laboratory experiments using both disturbed and undisturbed soil samples. Special emphasis is given to intensities of desiccation and rewetting, aiming in the identification of threshold values for P release from microbial biomass and of recovery times of the sensitive pools. Furthermore, the microbial use (net mineralization, immobilization) of DOP derived from different forest floor horizons will be studied in laboratory solute incubations with soil microbial inoculum. Quality of dissolved organic matter will be characterized by spectroscopic properties, and, in cooperation with other groups, by more sophisticated methods (like NMR) addressing organic P binding forms.