Modelling of soil organic matter turnover requires special approaches according to the available data base. CCB is a simplification of the CANDY Model. It works in annual time steps and simulates the turnover of organic matter in the topsoil considering soil texture, air temperature and rainfall as environmental drivers and cropping, organic amendments irrigation and tillage as management related drivers. Model provides data about SOM dynamics and nitrogen fluxes from organic sources. For local applications it is recommended to provide annual management information. This is in most cases not feasible for regional application at large scales. Therefore the model can accept structured cropping data containing the share of each management activity in one subregional element for single time slices that will be automatically repeated until the next time slice.
The model was used to simulate the land use on arable field in the Federal State Saxony (Germany) that was divided into about 30000 subplots.
Results were first analyzed concerning the development of carbon storage in top soil and its relation to the nitrogen flux from organic sources. It can be shown that the SOM reproduction alone has only a poor relation to the nitrogen balance. If related to the environmental conditions that are expressed as biologic active time (BAT) these values are usable as an indicator for the assessment of agricultural management in order to optimize the SOM reproduction and control nitrogen surplus.
The results indicate a continuous increase of carbon storage that is accompanied by the nitrogen fixation in soil organic matter. This is mainly a result of the growing application of conservation tillage and of the steadily growing crop yields.