November 18, 2022
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BY Lila Levinson • 5:00 AM on Jul 18, 2023 CDT
To know if your soil is healthy, you need to dig in and get dirty — literally.
That’s why Dr. Shalini Prasad, a professor of bioengineering at UT Dallas, makes cutting-edge soil health technology that is buried in the ground.
Healthy soil doesn’t only put food on our plates. It can also foster ecosystems, sustain agriculture for generations and fight climate change by trapping carbon that would otherwise be in the atmosphere.
Prasad and her team, in work funded by the public benefit corporation Soil in Formation, make soil health sensors. Buried in the soil, the sensors can collect data to show farmers how practices like fertilization and irrigation are affecting soil health.
Climate change is already putting pressure on agriculture, so this data is needed more than ever. “[We need] to provide meaningful, actionable data to a global community,” said Prasad. “Change has to be coming … from everybody.”
Prasad said the sensors can be used from “community gardening all the way [to] organized commercial agriculture” to make healthy soil an achievable goal. Soil in Formation plans to market Prasad’s sensors as tools for governments and other organizations to incentivize sustainable agriculture, making the sensors free to most farmers.
Soil health, like human health, is multifaceted and can be measured in many ways. Measures of soil health include availability of nutrients for plants, risk of pesticides and other contaminants leaching into nearby freshwater, and how many earthworms are in the ground.
Context is also important when defining what “healthy” looks like, according to Dr. Jingyi Huang, a professor of soil science at the University of Wisconsin-Madison.
Huang, who is not involved in Prasad’s soil sensor project, explained, “Not all soils are created equal.” Soils with different makeups and from different climates may need different things to stay healthy.
Farmers need frequent check-ups to define optimal health for their particular soil, in their particular climate. Soil is also constantly changing, and farmers need data to help them understand how practices like fertilization and watering are impacting soil health.
Currently, that data isn’t widely available. Traditional testing requires sending a sample to a lab for expensive analysis.
“Measurements are taken, if you’re lucky, once a year,” said Prasad.
Prasad’s sensors and others like them change the game by taking data straight from the fields.
“If you want to get affordable, reliable and [frequent] information about your soil health … you should use sensors,” Huang said.
Prasad’s sensors each have unique chemical coatings. When a small electrical shock is applied, soil reacts with the coatings in a way that allows each to measure different facets of soil health.
Prasad says that testing the coatings is similar to tuning a radio. Her group works to make sure that each sensor is measuring only one variable and not picking up other channels of information.
So far, the team has developed coatings that can measure how tightly soil is packed, as well as soil moisture, acidity and nutrient content.
The sensors fit into a protective column that houses a data storage chip, a battery and wiring. After being planted in the ground, the sensors wake up every eight hours to log a measurement on the chip.
In the current design, users need to download the data directly from the chip, but Prasad hopes to develop a wireless version to streamline the process. Soil in Formation is working on a dashboard to contextualize the data and help farmers understand how to act on it.
As well as being affordable, the sensor system will have the advantage of taking soil in context. “You’re actually measuring the soil as it is,” said Dr. Vikram Dhamu, Prasad’s former student.
Dhamu works for EcoMetric Services, another private company working with Soil in Formation on the soil sensor project, and remains a close collaborator of Prasad’s.
Other collaborators at Texas A&M AgriLife have tested the sensors for accuracy against standard lab test results.
According to Prasad and Dhamu, sensors on the UTD campus, as well as in eastern Texas and Costa Rica, have performed very well, demonstrating that they can work across climates and soil types.
In their protective columns, the sensors have also survived extreme weather and interactions with wild hogs and coyotes.
In addition to helping farmers practice sustainable agriculture, soil sensors can help us work towards a carbon neutral future, said Henry Rowlands, climate advocate and CEO of Soil in Formation.
Healthy soil traps and stores carbon dioxide from the atmosphere. Historically, agriculture has disrupted soil, releasing the carbon back into the atmosphere in the form of greenhouse gases, contributing to climate change.
Practicing sustainable agriculture can reverse some of these effects. But according to Huang, who also designs soil sensors, existing sensor technology can’t easily and accurately measure how much carbon is stored in the soil.
This makes it difficult to know how well different practices work. Rowlands says UTD’s sensor innovations will make this technology possible.
With the new sensors, governments and other organizations will be able to offer incentives to farmers based on how much carbon their soil holds. Corporations will also be able to collect data to back up their claims of carbon neutrality.
Rowlands expects these groups to buy the technology and distribute it to farmers and land managers for calculating incentives. This should mean that most farmers will not need to pay for soil health monitoring.
According to Rowlands, UTD has developed the sensors faster than expected. Soil in Formation, which owns the sensor intellectual property, is looking toward manufacturing and distributing the technology to agriculture technology companies.
Those companies will then be able to use the sensors to build and market devices for measuring soil health.
For Prasad and the sensor team, the work is never done. “Soil has a lot going on,” Dhamu said.
Prasad, Dhamu, and other UTD researchers plan to add more sensors to their suite to measure more attributes of soil health and put more data into the hands of the farmers who need it.
Lila Levinson reports on science for The Dallas Morning News as part of a fellowship with the American Association for the Advancement of Science.
