Engineers at the University of Wisconsin–Madison have made a breakthrough in agricultural technology with the development of low-cost sensors designed for real-time, continuous monitoring of nitrate levels in various soil types. These innovative printed electrochemical sensors stand to revolutionize nutrient management in farming, offering significant economic benefits by enabling more precise fertilizer application.
Current methods for monitoring nitrate levels are both laborious and expensive, often failing to provide the timely data that farmers need to make informed decisions. The new sensors developed at UW–Madison, however, promise to change that by delivering a more efficient and cost-effective solution. “Our sensors could give farmers a greater understanding of the nutrient profile of their soil and how much nitrate is available for the plants, helping them to make more precise decisions on how much fertilizer they really need,” explains Joseph Andrews, assistant professor of mechanical engineering at UW–Madison and the lead researcher on the project.
The sensors are produced using an inkjet printing process to create potentiometric sensors, which are further enhanced with a layer of polyvinylidene fluoride. This material is crucial for the sensor’s functionality, as its tiny pores allow nitrate ions to pass through while blocking soil particles. Additionally, its hydrophilic properties attract and absorb nitrate-laden water. “So, any nitrate-laden water gets preferentially soaked into our sensor,” Andrews elaborates. “This is really important because soil also acts like a sponge, and you’re going to have a losing battle for getting moisture to come to your sensor unless you can match the water absorption potential of soil.”
The practical implications for farmers are substantial. While specific pricing details have not been disclosed, the expected cost savings from reduced fertilizer use alone make these sensors an attractive investment. By providing accurate measurements of nitrate levels, farmers can apply fertilizer more precisely, potentially lowering costs and mitigating environmental impacts.
The sensors have already demonstrated accurate results in tests conducted in sandy and silt loam soils in Wisconsin. The research team is now working on integrating these sensors into a multifunctional system called a “sensing sticker,” which will also include moisture and temperature sensors. These stickers, affixed to a rod and buried at various soil depths, will allow for comprehensive monitoring of nitrate leaching and movement. “By measuring the nitrate, moisture, and temperature at different depths, we can now quantify the process of nitrate leaching and capture how nitrate is moving through the soil, which hasn’t been possible before,” Andrews notes.
Looking ahead, further testing with 30 sensing rods is planned for the summer of 2024 at UW–Madison’s Hancock and Arlington Agricultural Research Stations. The technology is also in the process of being patented through the Wisconsin Alumni Research Foundation, ensuring that this pioneering development is protected and can be brought to market effectively.
This advancement in nitrate monitoring technology not only promises to enhance the economic viability of farming but also addresses critical environmental concerns. By enabling more precise fertilizer application, these sensors can help reduce the runoff of excess nutrients into water bodies, a significant factor in water pollution. As the sensors move closer to widespread deployment, they could represent a significant step forward in sustainable agriculture, offering a practical tool for farmers to optimize their practices and contribute to a healthier environment.