The development of smart farming has drawn the attention of the uses of information and communication technology in the agriculture field. There are many productive ways in IoT for cultivating the soil and raising the livestock in the agricultural sector. This paper explores various IoT applications in remote crop monitoring systems. It is a challenging task of analyzing massive amounts of unstructured data acquired from the sensor devices. This paper aims at developing an agricultural Internet system. The three layers in the system of IoT in agriculture are perception layer, transportation layer and application layer and each layer is investigated separately. Three-layer architecture is proposed in the applications of precision farming. For processing and analyzing, this design collects the data and sends it to the cloud-based back-end. After examining the data can be directed to front-end nodes again.