Disciplines play a major role in agricultural education and extension. Biology, chemistry and physics are all essential to understand nature and to improve the quality of agricultural production. During the past centuries, disciplines have evolved, and a multitude of specialisations emerged, like cell biology, colloid chemistry and geophysics. The development of specialisations went so far that one can speak of overspecialisation in areas, the problem of which is that there is too little communication and cooperation between subspecialisations. It is surprising that the pedagogy of interdisciplinary education is underdeveloped. Given the importance of interdisciplinary education, it is absolutely necessary to develop an interdisciplinary field of Pedagogical Content Knowledge (PCK). This can best be taught to future teachers by introducing them to different fields that are included in solving practical problems, or trying to attain certain goals. In a situation in which there are no, or hardly any, guidelines for implementing interdisciplinary education beyond the generic recommendations of educational research, how can educators make progress with the creation of a PCK for interdisciplinary education? To answer this question, this article describes six characteristics of interdisciplinary thinking that can serve as a foundation of a taxonomy of educational objects in the field of interdisciplinary education. It also presents principles that can be used in the implementation of interdisciplinary education.