: Arable farmers can't control the weather, but they can compensate for its vagaries to some degree by watering their crops. To determine the necessary amount of water, farmers need to know the temperature and humidity of their soil—and that's where new radio-based technology could help. Chuan Wang of the University of Manchester in the UK and his colleagues are developing cheap, robust sensors that can be plowed into the ground. When a tractor passes over one, radio waves transmitted by the tractor power the sensor, which then transmits its data up to the tractor, also in the form of radio waves. A similar system is being tested in the fields of Nebraska by Mehmet Can Vuran of the University of Nebraska–Lincoln and his colleagues. According to Can Vuran's estimates, data gathered by the sensors could help reduce by 40% the amount of water used to irrigate crops.