In the face of contemporary developments such as globalization, worldwide population growth and changes in climate, maintaining a stable agricultural economy as a fundamental supply system is becoming an ongoing challenge. To meet this, technological progress, in many ways, is necessary. IoT in particular is a facilitating factor in this context, as it connects and enables the usage of other emerging, innovative fields, such as Big Data or AI, in a joined manner We approach IoT in agriculture from different perspectives, outlining various goals of Ag IoT and approaches to solve them by outlining the state of the art. In addition, we implemented our own scalable solution for Smart Irrigation and evaluated it in an experiment on growing barley from seeds. In this way, we were able to conclude that our IoT system has the potential to replace humans in irrigation without compromising growth.