Modelling cropping systems—highlights of the symposium and preface to the special issues

Science has developed and applied models for centuries, but automated calculations based on program instructions have emerged only during the last few decades. Agronomic models condense assumptions about biological process interacting with the physical and chemical environment through mathematical equations. The process of developing models to simulate the crop-soil interactions driven by weather and agricultural management has been ongoing for more than three decades. The goal to evaluate agriculture and the associated impact on economic, environmental and human health related aspects has lead to the development of models that simulate the behaviour of complex cropping systems. After great scientific progress and expectations in the first two decades, there now is a new widespread feeling that we face new challenges and prospects, both in terms of science, simulation techniques and application. The 2nd International Symposium on Modelling Cropping Systems, held in Florence, Italy, from 16 to 18 July 2001 (Bindi et al., 2001), addressed questions concerning agricultural modelling such as (i) are we making progress in crop modelling? Can we do better? (ii) when is a model adequate? (iii) why are you modelling? Applications and user interaction, and (iv) which software designs are needed for evolution? These essential questions reflecting the awareness of the sketched dilemma in agronomic science were addressed in four sessions that all contained a start-up panel discussion, a series of oral and poster presentations with short discussions and a final plenary discussion. Some highlights raised during the symposium are discussed below.