Small farm complex irrigation controller based on wireless communication

The subject of the present work is an irrigation controller able to satisfy the needs of a small farm for water, nutrients and pesticides having in view the consumption efficiency, as well as energy savings and cost effectiveness. In order to achieve these targets, the process is largely automated being a scheme with closed loop reaction based on the monitoring of several main parameters characterizing the soil and environment condition. The monitoring element is a multi-sensor device connected wirelessly to the central unit of the irrigation controller. For a small and medium size farm several devices are needed forming a wireless sensor network. The paper is focused on the peculiar solar supply of the wireless sensors network in order to exploit the data provided by the photovoltaic cell for a better management of the crops. Agronomists agree that crops needs are for a medium illuminance ranging from 20,000 to 50,000 lx, that corresponds to a shade illuminated by entire clear blue sky, midday. Therefore, the experiments were conducted mainly for establishing a threshold voltage for detecting 20,000 lx illuminance in order to count the days requested for proper harvesting.