Universität Bonn

INRES Crop Science

Phosphate-mobilization from the subsoil in field experiments

Master Thesis

Research area

Crop science, soil science

Motivation / State of the art / Relevance

Crop roots may grow to a depth of 1m or more. However, estimates of nutrient requirements for crop production are mainly based on an analysis of only the topsoil.
In this study, the potential mobilization of phosphate by desorption will be analyzed in soil profiles up to 1m depth. Plant roots may further stimulate phosphate mobilization by excretion of citrate. The current analysis will therefore consider phosphate desorption by water alone as well as by water with added citrate.
Both analyses will be conducted on samples of field experiments in Germany with contrasting soil types (e.g., sand vs loam).


  • Determination of phosphate desorption in water and citrate solution
  • Data evaluation and interpretation

Methodology / Procedure / Workscope / external cooperation

This work will include a literature review and laboratory work including an analysis and discussion of the results.
Depending on individual interests and qualification this work may be extended to a cooperation with Prof. Schnepf (FZ Jülich), to include the obtained results on phosphate desorption into soil-root-models.

Expected results

Data analysis and interpretation (text, tables, figures)


6 Month


English or German

Previous knowledge

Interest in nutrient dynamics in agricultural systems


Sara Bauke (soil science), Dr. Sabine Seidel (crop science), Andrea Schnepf (FZJ)


sarabauke@uni-bonn.de, sabine.seidel@uni-bonn.de, a.schnepf@fzjuelich.de

Additional Information

Motivation to train or apply software like Latex/Lyx (for thesis), JabRef (for literature database) and R/Octave (for statistics and figures) is welcome and will be supported

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