Wireless is the best way to go for field use, link the sensors in wirelessly to allow adjustment of physical location, then a wireless network to a central hub/data collector/controller.

Field uses would be controlling irrigation and chemical applications for crops, watering and feeding for animals.

Tracking of individual animals through RFID's, recording feed history and health would be another step.

An automated milking machine is already in production, this could be used for similiar operations.

Many of the uses I see are already in place for large operations, this would allow their extension to smaller operations, commercial and hobby.