In this paper, a Wireless Sensor Network (WSN) solution is proposed for soil's condition measurement to monitor oil palm plantations (PalmNET) according to agricultural meteorological practices. The PalmNET monitoring system is composed by a WSN used for in-field soil's condition measurement and a web-server interface for data visualization. PalmNET can automatically collect soil moisture data and transmit field data through a ZigBee network to a web-server. The PalmNET proof-of-concept is a WSN built upon open-source hardware and software, which includes two sensor nodes, a sink and a Gateway with a GPRS module. The WSN was deployed in Palmar de la Vizcaína Experimental Field Station having the following proof of concept objectives: (i) collect and centralize soil moisture data and (ii) post data to a web application interface. Results have revealed PalmNET as a feasible, automated and solar powered application for oil palm plantations in Colombia.