Enterprise information systems in agriculture and environment are becoming more complex and difficult to design and implement. This paper aims to show our vision on using model-based approaches to design complex and flexible agricultural and environmental information systems. At the center of this modeling approach is the Unified Modeling Language that facilitates expressing visually concepts of a problem domain and their relationships. UML has a core of notations that are generic and that can be used to model problems in any domain but can be extended to create profiles in order to take into consideration modeling concerns in a particular problem domain. UML profiles are created to use UML in designing spatial systems, ontologies, model driven architecture-based systems and Web-based systems and a recent profile makes it possible to us UML for business modeling purposes. UML is used to present design patterns; their use is crucial in designing complex and flexible information systems. Recently, UML is enriched with Object Constraint Language that is used to express constraints on modeling artifacts. The paper presents the state of the art in modelling agricultural and environmental systems and provides discussions for future directions.