Agricultural Informatics is integrated with agricultural systems with informatics dedicated for the best practices using ICT. For doing best Agro Informatics practice various allied technologies are employed for healthy agricultural activities required for best computation and information management. Information Technology powered with various sub-technologies such as Software Technologies, Network Technologies, Multimedia Technologies, Web Technologies, Database Technologies, and all these impacting Agricultural Systems and it is also leads the development of new-age and advanced Agricultural Systems. Additionally, emerging technologies are proving benefits in promoting healthy agricultural practices and among these Internet of Things (IoT) is considered as important for advancing traditional agricultural systems into smart and digital agricultural systems. There are ample benefits and opportunities offered by the IoT based agricultural systems which include the flexibility, productivity, advancement of agricultural systems with quality and quantty, environmental monitoring systems, remote agricultural systems, and so on. This paper highlights basics of Agricultural Informatics emphasizing IoT applications in advancing agricultural systems. This paper reveals the existing works of IoT applications in agriculture and allied fields including the issues and challenges in contemporary context.