4M – Software for Modelling and Analysing Cropping Systems Nándor Fodor (RISSAC of HAS, Hungary fodornandor@rissac.hu) Abstract: Models have played an important role in scientific research for a long time. The crop models try to simulate the functioning of the atmosphere-soil-plant system with the help of computers. These models can be effective tools in research, education and solving agricultural and environmental protection related problems. The 4M package includes a crop model and several accessories that help to operate the model. The 4M crop model is a daily-step, deterministic model that simulates the water and nutrient balance of the soil, the soil-plant interactions and the plant development and growth. To mention some examples: (1) The package can be used in education to carry out ‘zero-cost’ virtual agricultural experiments and to challenge and enhance the system oriented thinking of the students. (2) In research it can be used for designing experiments and estimating the present and future characteristics of the investigated system. (3) In practical applications the package can be used to prepare agro- technological advise (fertilization, irrigation, etc.) for farmers, and to carry out economical analyses on farm level. Keywords: crop model, estimation method, education Categories: H.5.2, J.2, J.3 1 Introduction For a long time models have played a very important role in scientific research. The primary purpose of crop models is to describe the processes of the very complex atmosphere–soil–plant system using mathematical tools (functions, differential equations, etc.) and to simulate them with the help of computers. The ultimate aim of using crop models however is to answer such questions that otherwise could only be answered by carrying out expensive and time-consuming experiments. In the 1970’s developments in information technology enabled scientists to create the first crop model software using the accumulated scientific knowledge. Since then crop models have been used in numerous educational and scientific projects. Even though, many well-developed, user friendly crop model softwares are already available such us WOFOST [Boogaard (98)], STICS [Brisson 98], DSSAT [Jones 03], CropSyst [Stöckle 03]; their source code is usually not open, therefore they can not be modified or improved by the users. Furthermore, certain required input data might only be characteristic of the area where the model was developed making it difficult or impossible to provide this data at different places. Despite the fact that there is a great emphasis on creating a single common software toolkit to facilitate the comparison and integration of the many different models in existence Journal of Universal Computer Science, vol. 12, no. 9 (2006), 1196-1207 submitted: 31/12/05, accepted: 12/5/06, appeared: 28/9/06  J.UCS