Precision agriculture is nowadays getting more and more attention in Europe. Due to the common water shortage problem, precision irrigation could become a key activity to save and use water in a more sustainable way. This paper builds upon an automatic irrigation system implemented as a context-aware system in which context is acquired thanks to a wireless sensor network. In such system, ontologies are used to solve integration problem of heterogeneous data provided by different types of sensors. Moreover, ontologies enable reasoning over these data to enrich the context. The automatic irrigation system will be installed on the pilot site of Irstea called AgroTechnoPole, located in Montoldre. The main goal of this paper is to analyze the SOSA/SSN and SAREF standard ontologies in regards to the ontological requirements that arise from the AgroTechnoPole use case.