Researchers Demonstrate “Lab-on-a-Drone” System for Real-Time Nitrate Monitoring

New drone-mounted sensor platform enables mid-air water analysis to support agriculture and water quality management

Researchers have developed a new “lab-on-a-drone” system that can collect and analyze water samples in real time, according to a study reported in ACS Sensors. The system is designed to measure nitrate levels in hard-to-reach areas, including drainage ditches and swampy lowlands. The approach could help farmers better manage fertilizer use while reducing nitrate runoff into nearby waterways.

Nitrogen-based fertilizers play a central role in modern agriculture. However, much of the applied nitrogen does not remain in the field. Water drainage systems often carry it away, where it can convert into nitrate. High nitrate levels can contribute to algal blooms, low-oxygen “dead zones,” and drinking water contamination. Monitoring these levels remains difficult because runoff often occurs in remote or muddy locations, and samples usually require transport to a laboratory.

To address this challenge, Jonathan Claussen and colleagues developed a lower-cost and more efficient monitoring system that brings laboratory-style analysis directly to the sampling site. Their goal was to improve access to timely nitrate data while reducing the need for manual sampling and lab processing.

How the System Works

The research team built a compact monitoring system that includes a custom pump, low-cost electrochemical nitrate sensors, and a potentiometric device. They mounted this equipment onto a commercially available drone. A long tube extends below the drone to pull water into the onboard system during flight.

Once collected, the water sample is analyzed mid-air. Each analysis takes about seven minutes. The system stores results on an onboard memory card, allowing the drone to collect and process multiple samples before returning to the ground.

Field Testing and Accuracy

In controlled tests, the sensor system detected nitrate concentrations as low as 2.5 parts per million. The results were 95% as accurate as those from standard laboratory-based electrochemical nitrate detection systems.

The team also tested the system at an agricultural drainage ditch in Iowa. The drone measured average nitrate concentrations of 5.39 parts per million. These findings matched previous measurements from the area and remained below the U.S. Environmental Protection Agency’s maximum drinking water limit of 10 parts per million.

Broader Applications in Agriculture

The researchers say the system makes nitrate monitoring easier and more practical than existing approaches. They also note that the platform could support future “lab-on-a-drone” applications. These may include monitoring bacteria or pesticide contamination in agricultural waterways.

The authors have filed a U.S. patent related to the technology. The research received funding from the National Science Foundation, the National Institute of Food and Agriculture at the U.S. Department of Agriculture, and Iowa State University’s Digital and Precision Agriculture Applications Funding Opportunity.

The paper’s abstract is available here through the American Chemical Society.

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