Just like any other living thing, soil microorganisms that damage crops die if they get too hot. Keeping this fact in mind, scientists have developed a new system that uses soil-heating microwaves to kill such pests. This technology may one day replace the use of environmentally harmful pesticides.
Developed by Dr. Sunshin Jung and colleagues at the Korea Electronics Research Institute (KERI), the device uses a proprietary antenna that emits microwaves into the soil.
By selectively increasing or decreasing the wavelength and phase of these waves, they can be spaced so that they meet and overlap at specific points underground. The amplitude of the waves increases at these points, causing the moisture in the soil to heat to temperatures of 60 to 100ºC (140 to 212ºF) - the exact temperature can be adjusted via the antenna.
In its current form, the system is capable of heating soil to a depth of 30 centimeters (11.8 inches). Jung and his team believe this should be enough to eradicate harmful microorganisms such as bacteria, fungi and nematodes that live in or near plant roots—although unfortunately, beneficial microorganisms will be affected just as well. By comparison, the weed-killing microwave device developed at the University of Melbourne only penetrates 5 to 10 centimeters (2 to 3.9 inches).
KERI technology is currently being commercialized by industry partner JooeunCareFarmCo. It could also conceivably be used in applications such as non-destructively killing termites in wooden structures, melting ice on winter roads, or cleaning oil-contaminated soil.
"We take advantage of the wave properties of microwaves, guiding them to overlap rather than diffuse, and heat the subsurface soil," Jung said. "This technology helps kill pests that live underground after harvesting without the use of pesticides, has no side effects, and does not pollute the environment. It will make a great contribution to agricultural productivity and farmers' income."