University of Illinois (UI) researchers have developed a liquid nitrogen applicator that can read the needs of a corn crop and adjust rates on the go.

Using “off-the-shelf” technology, UI scientists built an applicator that uses a multi-spectral camera mounted 1' in front of the machine to detect nitrogen stress. It's accurate enough to provide analysis similar to leaf tests using a SPAD meter. That data is then sent to a computer that controls a variable-rate applicator.

The 25-row applicator uses individual row drops, and each nozzle is controlled based on the reading taken by the high-tech eye mounted in the camera.

“We can infinitely vary liquid nitrogen application rates from 0% to 100%,” says Qin Zhang, UI ag engineer. “In our tests, we're using 28% N, but you could use any blend you wanted.

“In our plots, we preplant-applied fertilizer rates that ranged from 0% to 100% of the corn crop's predicted needs,” he says. “At harvest, the yields from the different plots showed little variation.”

Adjusting nitrogen rates on corn is just the beginning for this technology, according to Zhang. “With different sensors we can use the same technology to recognize weeds and adjust herbicide applications,” he says.