Farming systems have to be well adapted to site specific climatic conditions and soil properties to reach a high productivity level and ensure a low risk of N exports into the environment at the same time. In the past, main efforts were made to find solutions that would increase the productivity of agroecosystems, primarily based on field experiments. Now it is necessary to find an optimal relation between biomass production and nutrient release into the environment. Simulation models of C-N dynamics seem to be able to provide useful information to reach this objective, To do this, the model has to describe turnover and transport processes in a soil as well as the development of the crop. This study reports about the integration of the crop growth model AGROSIM-ZR [AGROecosystem SIMulation-sugarbeet (ZR)] for sugarbeet (Beta vulgaris L,) with the CANDY (CArbon and Nitrogen DYnamics) model for soil-based processes in agriculturally used landscapes.