Field Server (FS) is a multi-functional sensor node, which consists of CPU (Web server), A/D converter, D/A converter, Photo-MOS relay, Ethernet controller, Wi-Fi card, high intensity LED lighting, Network camera and sensors such as air temperature, relative humidity, solar radiation, soil moisture, CO2 etc. FSs are interconnected by Wireless LAN. High-resolution pictures of fields are transferred through Wi-Fi broadband networks, and stored on Web servers. Data sets of FSs are transformed into XML database. In this study, we will show the results of soil moisture monitoring test using some soil moisture sensors, and discuss the availability and the possibility of FS in the agricultural field related to the Global Earth Observation System of Systems (GEOSS) 10-Year Implementation Plan.