Universität Bonn

INRES Pflanzenbau

Representation of N dynamics and its relation to simulating photosynthesis and grain yield in crop models

Master Thesis

Research area

Crop science

Motivation / State of the art / Relevance

Nitrogen is one of the most important nutrients that strongly influences crop productivity. In addition to experimental trials, current crop models with an inclusion of N dynamic simulation could be used to test and understand crop response to N variations and N stress from field to large scales. Adequate simulations of N stress on crop yield replies on both an accurate estimates of N availability in the soil (supply) and dynamic N distribution within the canopy and its relations to crop growth processes (leaf growth, photosynthesis, and senescence) (demand). The latter often varies across crop models from simple (e.g. a simple lump-sum nitrogen stress index or a complex and dynamics of N within canopy and N stress imposing on the mentioned crop processes). However, advantages and disadvantages of such simple and complex models are not known.


The aim of the study are to (i) to get an overview how current crop models consider and simulate nitrogen stress and N dynamics in their models (ii) to understand which soil-plant processes considered such N dynamics and N deficiency and in which mechanisms; and (iii) to analyze impacts of different representation of N stress and dynamics on photosynthesis and grain yield.

Methodology / Procedure / Workscope / external cooperation

Students will have an opportunities to learn and work an active team with strong expertise in field trials and agro-ecosystem models. Students are expecting to learn SIMPLACE modeling framework and performing theoretical simulations with different N stress scenarios and N dynamics.

Expected results

Overview/disadvantages/disadvantages of different N modeling approaches


6 Months



Previous knowledge

Interests in crop modeling, N application, crop physiology


Dr. Thuy Nguyen, Dr. Thomas Gaiser



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