Missouri farm sensors could rescue Gulf of Mexico

SQUEEZING THE MOST OUT A process is what it is all about these days in manufacturing, so why should growing corn be any different? Now there is a sensor called a light emitting diode (LED) that can accurately measure the color of young corn and apply the proper amount of nitrogen the plant will need.

Using the correct amount of nitrogen fertilizer to gain the best possible corn yields is a challenge for economic and environmental reasons. Applying too much nitrogen is costly and can contribute to water quality problems. Applying too little can result in sub-par crop yields.

"The key is that all fields will have an in-field variability, which is illustrated by the color of the corn itself," said Harlan Palm, research assistant professor of agronomy in the University of Missouri's (MU) College of Agriculture, Food and Natural Resources.

This is the second year researchers are testing this new technology on farms across Missouri. They hope this LED approach will not only increase profits for producers but also create a healthier environment.

The environmental question comes in because in areas like the Gulf of Mexico there is a nitrogen runoff carried by the Mississippi River that created a "dead zone." Dead zones happen when nutrients such as nitrates and organic nitrogen promote rapid growth of tiny plankton in coastal waters, which then decay and consume oxygen. The low oxygen level in the water, called hypoxia, stresses or kills bottom-dwelling creatures on which the region's seafood industry depends.

"Past research has shown that many fields in Missouri can make full yields with less nitrogen than they are receiving," said Peter Scharf, MU nutrient management specialist.

In the study, researchers applied an ample amount of nitrogen in early spring to only one area of the field. LED devices mounted on a fertilizer applicator measure light reflected from small (12- to 15-inch) corn plants in this area, providing a reference or baseline point. The computer-equipped applicator then applies nitrogen fertilizer to the rest of the field. Variable rates of nitrogen then go on the crop depending on the color or reflective value of corn leaves detected by the LEDs.

"The idea is to cut back in smart places," Scharf said. "This technology allows us to diagnose how much fertilizer is needed better than we could with a previously used method."