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Uwe Franko, Burkhard Oelschlägel, Stefan Schenk, Martina Puhlmann, Katrin Kuka, Janine Mallast née Krüger, Enrico Thiel, Nadia Prays, Katharina Meurer, Eric Bönecke

Helmholtz-Centre for Environmental Research - UFZ





The agro-ecosystem model CANDY (Carbon And Nitrogen DYnamics) has been developed to describe carbon and nitrogen dynamics in mineral soils.

CANDY started its history as an integrated simulation tool for carbon and nitrogen dynamics in soils providing a user interface for input and output data. Over time more and more adjustments have been introduced to make the model usable for the specific task. By now CANDY is a system consisting of a number of modules; some of them are mandatory for ecosystem modelling because they provide the infrastructure, while others. Others may be switched on or off depending on the objective and the available data. It consists of a modular system of sub models and a database for model parameters and results.


Model specific input data comprises soil and plant properties as well as initial soil values, weather data, agricultural soil management data, and measurement values. The user interface of the model provides geographic information system facilities that are designed to organize regional scenario simulations.



The model results consist of soil and crop related state variables and fluxes connected to soil organic matter, nitrogen, and water in daily time steps.

Special features:

1. CANDY calculates a biologic active time (BAT) which allows the assessment of organic matter turnover conditions for different sites.

2. A weather generator provides the possibility to simulate long term scenarios.

3. An optional auto fertilizer scheme implements good farming practices for nitrogen application.

4. The optional CIPS approach describes the relevance of soil structure for the long term stabilization of soil organic matter.


Scientific articles

Franko, U., Oelschlägel. B., Schenk, S. (1995): Simulation of Temperature-, Water- and Nitrogen dynamics using the Model CANDY. Ecol. Model., 81, S. 213-222

Franko,U., Crocker, G.J., Grace, P.R., Klir, J., Körschens, M., Poulton, P.R., Richter, D.D. (1997): Simulating trends in soil organic carbon in long-term experiments using the CANDY model. Geoderma, 81, 109-120

Franko, U., Schenk, S. (2001): Modelling of Carbon Dynamics in a Rural Area of Central Germany. In: Rees, R.M., Ball, B.C., Campbell, C.D., Watson, C.A. (eds): Sustainable Management of Soil Organic Matter

Franko, U., Mirschel, W. (2001): Integration of a Crop Growth Model with a Model of Soil Dynamics. Agronomy Journal, 93, S. 60-66

Franko,U. and Puhlmann,M., (2002). Potential for optimisation of Carbon and Nitrogen dynamics on Black Earth in Central Germany - and N-turnover. Arch. Acker-Pfl. . Boden., 48: 1-6.

Franko, U., Kuka, K., Romanenko, I. A., Romanenkov, V. A. (2007): Validation of the CANDY model with Russian long-term experiments. Regional Environmental Change 7 (2), 79-91

Hesser, F.B., Franko, U. and M. Rode (2010):
Spatially distributed lateral nitrate transport at the catchment scale.
J. Environ. Qual. 39, 193-210

Krüger, J., Franko, U., Fank, J., Stelzl, E., Dietrich, P., Pohle, M., Werban, U., (2013):
Linking geophysics and soil function modeling — an application study for biomass production
Vadose Zone J. 12 (4), 10.2136/vzj2013.01.0015

Kuka, K., Franko, U., Rühlmann, J. (2007): Modelling the impact of pore space distribution on carbon turnover. Ecol.Modell. 208 (2-4), 295-306

Puhlmann, M., Kuka, K., Franko, U. (2006): Comparison of methods for the estimation of inert carbon suitable for initialisation of the CANDY model Nutr.Cycl.Agroecosys. 74 (3), 295-304

Richter, G.M., Schmidt, T., and Franko,U. (2004): Using long-term experiments to evaluate models for assessing climatic impacts on future crop production. Archives of Agronomy and Soil Science 50 (6), 553-562

Rode, M., Thiel, E., Franko, U. Wenk, G., Hesser, F. (2009).
Impact of selected agricultural management options on the reduction of nitrogen loads in three representative meso scale catchments in Central Germany.
Science of the Total Environment,407, 3459-3472

Ludwig, B., Kuka, K., Franko, U., von Lützow, M. (2008): Comparison of two quantitative soil organic carbon models with a conceptual model using data from an agricultural long term experiments.
J. Plant Nutr. Soil Sci. 171, 83-90

Smith, P., Smith, J.U., Powlson, D.S., McGill, W.B., Arah, J.R.M., Chertov, O.G., Coleman, K., Franko, U. et al. (1997): A comparison of the performance of nine soil organic matter models using datasets from seven long-term experiments. Geoderma, 81, S. 153-225

Smith, P., Smith, J. U., Franko, U., Kuka, K., Romanenkov, V. A., Shevtsova, L. K., Wattenbach, M., Gottschalk, P., Sirotenko, O. D., Rukhovich, D. I., Koroleva, P. V., Romanenko, I. A., Lisovoi, N. V. (2007): Changes in mineral soil organic carbon stocks in the croplands of European Russia and the Ukraine, 1990-2070; comparison of three models and implications for climate mitigation Regional Environmental Change 7 (2), 105-119

Schmidt, T.; Franko, U., Meissner, R. (2008): Uncertainties in large-scale analysis of agricultural land use-A case study for simulation of nitrate leaching Ecological Modelling 217, 174-180



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