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1.16 Miao Picture 3.JPG Guohui Feng
A student uses the GreenSeeker active canopy sensor to collect canopy reflectance data. The collected data will help determine the crop’s nitrogen status.

Researchers work to develop efficient paths to manage nitrogen

Light sensor tools help growers make sense of nitrogen

By Yuxin Miao, University of Minnesota


Too much of a good thing can be a bad thing. That’s certainly true for nitrogen fertilizers.

“Managing nitrogen is vital for global food security,” says Yuxin Miao, an agronomist at the University of Minnesota. “It is also crucial for reducing pollution and climate change.”


Miao and his colleagues have been researching ways to efficiently manage nitrogen in agriculture. They compared several approaches in their studies.

To test different nitrogen management strategies, Miao and his colleagues conducted field experiments from 2008 to 2012. The study site was in the Hebei Province in northern China. The researchers tested the different strategies on a winter wheat and summer corn rotation system.

Some of the other nitrogen management strategies tested by Miao also reduced fertilizer use. But they all had drawbacks. For example, one system required testing the soil for nitrogen levels. “However, this system had labor, time, and cost limitations,” says Miao.


The researchers found that one approach, active canopy sensor-based nitrogen management, is the most efficient.

Sensor-based nitrogen management uses light sensors to actively monitor crop health and vitality. The sensors measure different wavelengths of light coming from crop leaves. These measurements serve as proxies for crop health.

Based on field measurements, software in the sensors can calculate how much nitrogen crops need. Farmers can use these data to apply optimal amounts of nitrogen to crops.


The goal is to “match nitrogen supply with crop nitrogen demand,” says Miao. That allows crops to access nitrogen fertilizers exactly when they most need it. In turn, that could increase yields.

This approach has several benefits compared to other nitrogen management strategies. “It reduced overall nitrogen fertilizer application,” says Miao. “It also decreased nitrogen loss into the environment and lowered nitrous oxide emissions.”

Canopy sensor-based systems have several other advantages as well. “Using sensors is fast and non-destructive,” says Miao. “There are no additional costs beyond purchasing the sensors.”

Also, the latest models of sensors are not influenced by environmental light. That means growers can get an accurate measurement no matter the weather—no need for clouds to clear.

There may also be monetary benefits. “This technology can reduce the use of nitrogen fertilizers,” says Miao. “Farmers can lower production costs and increase economic returns.”

Miao is now working to make improvements. Some of the new systems will be more suitable for high-yield cropping systems. Others may be more efficient than the current hand-held ones.

Working as a team

Miao thinks that farmers can’t do it alone working relationships have to be made between farmers, researchers and service providers.

Miao presented these results at the November 2018 meeting of the American Society of Agronomy and Crop Science Society of America in Baltimore, MD.

Source: American Society of Agronomy, Soil Science Society of America, Crop Science Society of America, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.

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