NPOTATO is a SUCROS type of crop growth simulation model which can simulate crop growth under potential, water limited and nitrogen limited conditions. The main simulated processes are: photosynthesis, phenological development, assimilate distribution over crop organs, soil evaporation, crop transpiration, crop's nitrogen uptake, soil water fluxes, soil organic matter decomposition, soil nitrogen mineralization and other soil nitrogen processes.
NPOTATO model is mainly based on the NWHEAT model. See there for further information about the model approaches.