AbstractAgricultural fertilization and irrigation are closely related to the problems of agricultural yield, product quality, and environmental pollution. Precision fertilization and irrigation is an effective method to solve this problem. In order to precisely control plant fertilization and irrigation, a monitoring system is designed and implemented using open-source software, loose communication structure, industrial control computer (IPC), programmable logic controller (PLC), and control and monitoring devices. The control command management subsystem of the system’s upper computer is built using GoWin IPC, cloud server, mobile devices, and 4G wireless network. Each application running in the upper computer is developed using open-source software such as PostgreSQL, Smobiler, etc. The fertilization and irrigation monitoring subsystem of the lower computer was built using HollySys PLC model LE5107L and different sensors for various data parameters as control units. The system allows real-time remote monitoring and control of agricultural precision fertilization and irrigation through mobile applications, with an average communication delay of 1.45 s between the upper and lower units, and less than 3 s overall, allowing for long-term stable communication. The current system can adapt to the variable environment in the field and has been operating stably in the field for 2 months. This paper provides a convenient system construction solution for field farmland where network wiring is not possible, and it has low construction and maintenance costs, reliable operation, and a flexible structure for agricultural applications.