By using humidity sensor to alarm the farmer as crops needed water ,we can model a automation based motor that will be started to irrigated the field if the humidity of the soil becomes below a fix threshold value....
It is a low-cost, low-power, wireless mesh networking standard. The low cost and to be widely deployed in wireless control and monitoring applications, the low power-usage allows longer life with smaller batteries, and the mesh networking provides high reliability and larger range. By use this ZigBee you design and monitoring as your reqirement