May 27, 2024

UT-Dallas researchers tackle soil health

To find out if your soil is healthy, you need to dig in and get dirty – literally.

That’s why Dr. Shalini Prasad, professor of bioengineering at UT Dallas, pioneered soil health technology buried in the ground.

Healthy soil doesn’t just put food on our plates. It can also sustain ecosystems, sustain agriculture for generations and fight climate change by sequestering carbon that would otherwise be in the atmosphere.

Prasad and her team, in work funded by the public interest corporation Soil in Formation, make soil health sensors. When embedded in the soil, the sensors can collect data to show farmers how practices such as fertilization and irrigation affect soil health.

A health probe measures a bucket of soil in a lab at UT Dallas. The UTD team developed the sensors in the probe to record various aspects of soil health, including pH, moisture and nutrient availability.(Elias Valverde II / Staff Photographer)

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 come from everyone.”

Prasad said the sensors can be used from “community gardening all the way [to] organized commercial agriculture” to make healthy soil an achievable goal.

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Forming Soil plans to market Prasad’s sensors as tools for governments and other organizations to encourage sustainable agriculture, making the sensors inexpensive for most farmers.

‘Not all soil is created equal’

Soil health, like human health, is multifaceted and can be measured in many ways. Measures of soil health include availability of nutrients to plants, risk of pesticides and other contaminants leaching into nearby freshwater, and how many earthworms are in the ground.

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Context is also important when defining what “healthy” looks like, according to Dr. Jingyi Huang, professor of soil science at the University of Wisconsin-Madison.

Huang, who is not involved with Prasad’s soil sensing project, explained, “Not all soils are created equal.” Soils of different composition and climates may need different things to stay healthy.

Farmers need regular checks to define the optimum health for their particular soil, in their particular climate. Soil is also constantly changing, and farmers need data to help them understand how practices such as fertilization and watering affect soil health.

Sensors to measure soil health

Currently, that data is not widely available. Traditional testing requires sending a sample to a laboratory for expensive analysis.

“Movements are made, if you’re lucky, once a year,” Prasad said.

Prasad’s sensors and others like them change the game by taking data directly from the fields.

“If you want to get a reasonable price, reliable and [frequent] information about your soil health … you should use sensors,” Huang said.

All Prasad sensors have unique chemical coatings. When a small electric shock is applied, soil reacts with the coatings in a way that allows each to measure different aspects of soil health.

One of the sensors developed at UT Dallas to measure soil health. The sensors are built to fit into a custom probe.(Elias Valverde II / Staff Photographer)

Prasad says testing the coatings is like tuning a radio. Her group works to ensure that each sensor is only measuring one variable and not picking up other channels of information.

So far, the team has developed coatings that can measure how tightly packed the soil is, as well as soil moisture, acidity and nutrient content.

The sensors fit into a protective column containing a data storage chip, 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 must download the data directly from the chip, but Prasad hopes to develop a wireless version to streamline the process. Soil in Formation is working hard to put the data into context and help farmers understand how to act on it.

As well as being affordable, the sensor system will have the advantage of putting the soil in context. “You are measuring the soil as it is,” said Dr. Vikram Dhamu, Prasad’s former student.

The bottom of the soil health probe, where the sensors are located. The sensors make direct contact with the soil, where they measure aspects of soil health.(Elias Valverde II / Staff Photographer)

Dhamu works for EcoMetric Services, another private company working with Soil in Formation on the soil sensing project, and remains a close collaborator of Prasad’s.

Other collaborators at Texas A&M AgriLife have tested the sensors for accuracy against standard laboratory test results.

According to Prasad and Dhamu, sensors on the UTD campus, as well as in east Texas and Costa Rica, performed very well, showing that they can work across climates and soil types.

In their protective pillars, the sensors have also survived extreme weather and interactions with feral hogs and coyotes.

Towards carbon neutrality

In addition to helping farmers practice sustainable agriculture, soil sensors can help us work toward a carbon-neutral future, said Henry Rowlands, climate advocate and CEO of Soil in Formation.

Healthy soil captures and stores carbon dioxide from the atmosphere. Historically, agriculture has disturbed the soil, releasing the carbon back into the atmosphere in the form of greenhouse gases, contributing to climate change.

Some of these effects can be reversed by practicing sustainable agriculture. But according to Huang, who also designs soil sensors, existing sensor technology cannot easily and accurately measure how much carbon is stored in the soil.

During a field test in Costa Rica, Vikram Dhamu examines a probe containing six soil health sensors developed at UT Dallas.(courtesy of Soil in Formation)

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 the amount of carbon in their soil. Corporations will also be able to collect data to support their carbon neutrality claims.

Rowlands expects these groups to buy the technology and distribute it to farmers and land managers to calculate incentives. This should mean that most farmers will not have to pay for soil health monitoring.

According to Rowlands, UTD developed the sensors faster than expected. Soil in Formation, which owns the intellectual property detector, wants to manufacture and distribute the technology to agricultural technology companies.

Those companies will then be able to use the sensors to build and market devices to measure soil health.

For Prasad and the team of sensors, the work is never done. “There’s a lot going on in the soil,” said Dhamu.

Prasad, Dhamu, and other UTD researchers plan to add more sensors to their array to measure more soil health characteristics and put more data in the hands of 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.

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