As with many domains, information retrieval and knowledge management (IR/KM) in agriculture suffers from the problems of semantic heterogeneity, making it difficult for providers to disseminate their services effectively and for users to retrieve the information they need. Based on the analysis of resources in the domain of agriculture, this paper proposes a) application profiles for dealing with the problem of heterogeneity originating from differences in terminologies, domain coverage, and domain modelling, and b) a root ontology based on the application profile which can serve as a basis for extending knowledge of the domain.