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Abstract

The well-established dynamical global vegetation, hydrology, and crop growth model LPJmL is extended by a terrestrial nitrogen cycle to account for nutrient limitations. In particular, processes of soil nitrogen dynamics, plant uptake, nitrogen allocation, response of photosynthesis and maintenance respiration to varying nitrogen concentrations in plant organs, and agricultural nitrogen management are included into the model. All new model features are described in full detail and results of a global simulation of the historic past (1901–2009) are presented for evaluation of the model performance. We find that implementation of nitrogen limitation significantly improves the simulation of global patterns of crop productivity. Regional differences in crop productivity, which had to be calibrated via a scaling of the maximum leaf area index can now largely be reproduced by the model, except for regions where fertilizer inputs and climate conditions are not the yield limiting factors.