4M-software package for modelling cropping systems

4M is an easy-to-handle software that has been designed for both educational and scientific purposes. Our main goal in developing 4M was to preserve the features of CERES in a user-friendly software that can be easily extended with additional modules. The package has several characteristics that make it more than a simple crop model. 4M offers optional routines for several processes of the described soil-plant-atmosphere system. The users can build different system models, according to specific purposes. 4M includes input data generators for estimating soil and weather input data that are difficult to measure. 4M is able to simulate crop rotations by using the final conditions of the system after crop harvest as initial conditions for the following crop.