Taking cyberinnovation to the farm

Ratnesh-KumarData from soil sensors gives researchers and farmers insight into sustainable agricultural practices

Maintaining soil health by protecting land suitable for growing crops continues to be a priority as the world’s population rises. Issues like managing the nitrogen cycle, which is also one of the 14 Grand Challenges identified by the National Academy of Engineering, are becoming an increasingly important part of sustainable agriculture.

Ratnesh Kumar, professor of electrical and computer engineering, says being in Iowa gave him fertile ground to expand his domain expertise beyond cyberphysical and embedded control systems (where he has earned recognition as an IEEE Fellow) and apply cyber practices to farming.

Kumar, Robert Weber, professor emeritus of electrical and computer engineering, and Ph.D. student Gunjan Pandey have developed a portable, wireless, low-cost network analyzer that can be buried beneath crop fields. The sensor measurements are intended to provide a deeper understanding of fertilizer inputs and the nitrogen cycle, both of which are a major source of water quality impairment and also result in greenhouse emissions.

The nitrogen level that has increased from things like fertilizer and certain crops that are produced, like soybeans, ought to be rebalanced, according to Kumar. He adds that plants don’t necessarily use all the fertilizer put on them, and that has been causing significant problems such as hypoxia in coastal waters. “With the data from our sensors, we want to be able to determine the adequate amounts of fertilizer to apply as well as uncover ways to improve irrigation practices.”

The sensors Kumar and his team have designed collect information about water levels and soil nutrients, gathering details at a wide range of frequencies through measurements of complex impedance. This detail includes capacitance (how an electrical charge is stored) affected by moisture and conductance (how easily an electric current passes) affected by nutrients present in their ionic forms.

A key feature to the sensors is a first-of-its-kind wireless interface. Kumar says such an interface allows the sensors to be used in-situ, so researchers can actively gather information without interfering in any agricultural operations. The design was inspired from “meta-materials” that feature electromagnetic properties not found in natural materials.

“The sensors also have an inbuilt calibration mechanism so they don’t need to be manually calibrated each time conditions, such as temperature, change,” he added.

The group is also working with agronomists, specifically soil scientists and crop scientists, to develop sensor-driven models for soil- and crop-growth dynamics. Kumar says such understanding is crucial to the management of soil nitrogen and other nutrients as well as soil health.

His research has been supported by the National Science Foundation through two prior grants and was recently awarded a $1 million, four-year grant from NSF under the CyberSEES program. Additionally, the sensors component has one pending U.S. Patent.

Kumar says he has even more advancements in his sights. “Going forward, we will be thinking about the entire system of soil, plant and air. They all must be monitored simultaneously to assess the soil, plant and air attributes relevant for soil, water and air health toward sustainable agriculture.” Electronic microchips send frequencies out in the ground to detect movement amongst other things.