Currently being tested in lab soil at the University of Manchester, UK, the sensors are cheap to produce, low-power and can be left to gather information in the soil for years without maintenance. They use radio frequency identification to communicate and harvest a small amount of power from an RFID reader mounted on a tractor that collects the data as it moves over each node, says Chuan Wang, who works on the project at the university.
Another team at the University of Nebraska-Lincoln (UNL) – based in the Midwest's Corn Belt – is already well on the way to making a large-scale version of Wang's system a reality. Nebraska is the home of the iconic center pivot irrigation system responsible for the perfect circles that decorate the fields in that part of the US. They are using wireless sensors, embedded in the soil, that transmit information about current soil conditions to a base station.
By understanding exactly how much moisture is in the soil, UNL team leader Mehmet Can Vuran says entire rotations of a pivot can be saved, along with thousands of litres of water. They are already working with one of the four major center pivot irrigation companies, TL Irrigation, to bring the system to market.
"Thirty or forty per cent water savings are possible without affecting yields," Can Vuran says. "In fact, yields can be improved by optimising water – if you provide too much water to a crop it reduces the yields."
The driving force for this kind of technology is rising population, he says. It is expected to increase by 40 per cent by 2050. Demand for food will double in developing countries. "If you look at the way we're using water, we're using 70 per cent of our freshwater resources for agriculture – most of our resources, and yet the future demands that will double. As farmers say, we basically need 'more crop for drop',"
Syndicated content: Hal Hodson - New Scientist
Image: University of Nebraska-Lincoln - Importing data from underground wireless sensor