Bioaccessibility and bioavailability of subsoil P

• Applicants: Professor Dr. Wulf Amelung; Professor Dr. Roland Bol; Professor Dr. Jan Vanderborght
• Subject Area: Soil Sciences
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 259474743

In our current studies we found that P is enriched in subsoil biopore systems but not bioaccessible in the bulk subsoil. Evidence for the latter conclusions was derived by missing isotope equilibria between subsoil phosphates and soil water. This project was no designed to test the hypotheses that (i) the delta18O signature of phosphates indicate higher bioaccessibility of P in biopore walls than in the bulk soil, (ii) subsoil roots may readily acquire P from minerals, (iii) plant phosphates reflect at least partly the delta18O signature of soil phosphates, (iv) the degree of subsoil P uptake increases when the surface soil is deficient in nutrients and water, and that (v) higher P-accessibility in hotspots can be implemented in R-SWMS, allowing for estimating P uptake from the subsoil more precisely. To achieve these goals we will apply 18O isotope exchange experiments between soil phosphates and water, perform radioactive and stable isotope tracing experiments with soil and triple-labeled apatite (44Ca, 33P, 18O) as well as a numerical modeling of nutrient acquisition by the roots.

• DFG Programme: Research Grants
• Participating Person: Professorin Dr. Andrea Schnepf