By, Bill Krasean
Sven Bohm and Kevin Kahmark are standing in the middle of the Great Lakes Bioenergy Research Center (GLBRC) field site in Hickory Corners, MI, where researchers study the sustainability of different crops grown for use as liquid transportation fuel.
Each is holding a small remote control box similar to one used in video games. On the ground nearby are two small black unmanned aerial vehicles, a.k.a. drones.
Soon both drones are airborne, humming quietly above the ground and zipping off in selected directions under the eye of the two drone pilots.
While both drones in this demonstration look like off-the-shelf UAV’s, both are equipped with specialized scientific instruments that will help KBS researchers study, close-up, factors in helping farmers best manage their crops over the growing season.
Bohm, information manager for the KBS LTER program, said the drones are the latest advancement in monitoring soil, water and other factors in crop health. Information gained during flights is an improvement over data that has been collected from satellite measurements and has a higher resolution than the data collected through the use of airplanes similarly equipped.
“Satellite data is useful but with the UAV’s we can get so much closer, even closer than with airplanes,” Bohm said. “Flexibility is the key with drones. They are smaller, much cheaper and more specific to our needs.”
The drone flown by Kahmark, technician and researcher at the LTER, has a small Micasense RedEdge multispectral sensing camera that simultaneously captures five discrete bands in visible and near infrared electromagnetic spectrum, enabling the creation of tailored indices for customized applications.
Among the information that can be calculated by using the camera is what is called the Normalized Difference Vegetation Index, or NDVI. NDVI is a measure of photosynthetic activity, one of the most commonly used vegetation indices for crop health.
Kahmark said that NDVI data provides a wide variety of benefits ranging from accurate growth trends, crop vigor and health, pest outbreaks, information on optimizing the timing of crop inputs and soil moisture.
There are huge benefits both to the farmer and to the wider environment by minimizing the use of insecticides, herbicides, fertilizers, excess water and at the same time increasing the yield of crops.
The multispectral sensor technology can be used throughout the crop cycle — sowing, irrigation, fertilization or harvesting — allowing the farmer to manage his or her crops very effectively in every season.
Bohm’s smaller drone is equipped with a clever, light-weight sensor and computer that he designed and built to analyze albedo, a measure of incoming and outgoing solar energy. The albedo measurement helps scientists more accurately calculate crop energy balance—energy in equals energy out—a factor important to agronomists and ecologists.
Improvements in energy efficiencies are vital to sustainable agricultural practices, primarily because of a growing use of chemical fertilizers and pesticides that can upset the energy balance.
Bohm and Kahmark are licensed by the FAA to fly the drones. By law, any aircraft operation used commercially or for research in the national airspace requires a certificated and registered aircraft, a licensed pilot, and operational approval.
The KBS drones can be flown up to 350 feet and can collect data over 55 acres in about 35 minutes, Bohm said, adding, “The data the drones collect will help us determine which crops can provide both high yields and environmental outcomes that benefit society.”
KBS LTER research is funded by the National Science Foundation and aims to understand the ecology of Midwest cropping systems and agricultural landscapes.