Airplane sensor reveals nitrogen levels to farmers

pte20220114015 Environment/Energy, Products/Innovations

University of Illinois’ new hyperspectral system scans fields in record time as it flies over them

Fields: Sensors determine the correct nitrogen requirement (Photo:

Urbana-Champaign (pte015/1/14/2022/11:30) – University of Illinois researchers have developed a hyperspectral sensor mounted under an airplane that tells farmers how much nitrogen fertilizer to apply to their fields to achieve optimal yields and prevent over-fertilization. While the human eye sees the primary colors green, red and blue and their mixed colors, hyperspectral sensors record data from 20 to 250 different channels, ranging from wavelengths in the UV range to long-wave infrared.

A few seconds per hectare is enough

Used over fields where plants are growing, the sensor can use the reflected light to provide information on whether leaves and other greens are supplied with sufficient nitrogen or need to be fertilized. “Measuring nitrogen in fields is very time-consuming and labor-intensive. We only need a few seconds per hectare,” says assistant professor Sheng Wang. The system also offers much higher spectral and spatial resolution than satellite imagery, which is also captured with hyperspectral sensors.

“Bridging a gap between field measurements and satellites, our approach offers a cost-effective and highly accurate approach to crop nitrogen management in environmental precision farming,” Wang adds. The aircraft, equipped with a sensor that detects wavelengths in the visible and near-IR spectrum (400 to 2400 nanometers), flew over an experimental field in Illinois three times during the 2019 growing season. At the same time, the agricultural researchers determined the nitrogen content of the plants by taking samples, which they analyzed in the laboratory. The air measurement reached 85 percent of the values ​​from the laboratory.

Soon precise information from space

Wang believes his team’s experience with the airborne measurement method can be applied to satellite crop monitoring. The US space agency NASA and other organizations are already planning new missions with satellites equipped with high-resolution hyperspectral sensors. These could scan even larger agricultural areas even faster and determine the nitrogen requirement, it is said.




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