Measuring Soil Health Easily and Reliably

Oct 18, 2021

By Adityarup "Rup" Chakravorty

Healthy soils are a precious resource. They are vital for protecting ecosystems, maintaining water quality, producing crops, and mitigating climate change.

There are numerous indicators to measure soil health. However, these indicators don’t always provide consistent results. In a new study, researchers report evaluating a rapid and inexpensive indicator of soil health, especially for dryland farming.

This study was recently published in the Soil Science Society of America Journal, a publication of the Soil Science Society of America.

A view of the experimental site in dryland farming in eastern Montana where soil sample

A view of the experimental site in dryland farming in eastern Montana where soil sample was collected to measure carbon dioxide flush. The research team determined that the easier and faster method of measuring carbon dioxide flush also resulted in a more reliable and useful indicator of soil health.

The researchers measured bursts of carbon dioxide gas emitted when dried soil samples are rewetted. These bursts of carbon dioxide – called carbon dioxide flush – is an indicator of soil microbial activity.

“Measuring carbon dioxide flush is simple and inexpensive,” says Upendra Sainju, lead author of the study. “We also found that carbon dioxide flush is related to several soil properties and long-term crop yields.”

Sainju believes carbon dioxide flush can be used to measure soil health and relate crop yields reliably. Currently, this method is evaluating to estimate dryland crop yields in arid and semiarid regions.

There are several advantages to using carbon dioxide flush as an indicator of soil health. For one, no chemicals are needed. Researchers can measure carbon dioxide flush from soil samples using devices called infrared analyzers.

“Not needing chemicals means carbon dioxide flush can easily be used to measure soil health directly from the field,” says Sainju. “No chemicals being used also makes this process quick and economical.”

That’s important because several existing ways to measure soil health can be expensive and take a long time to analyze. Also, “they provide mixed results when measuring soil health,” says Sainju. Having a single reliable measure of soil health will help farmers, ecologists, policy makers and various other stakeholders to evaluate the sustainability of agroecosystems for crop production, according to Sainju.

Measurement of carbon dioxide flush

Measurement of carbon dioxide flush in one-day incubation following rewetting of dry soil in a glass jar. The carbon dioxide flush is absorbed by an infrared analyzer attached to the cover of the jar (inset, upper left) and read in a laptop computer downloaded with the appropriate software.

In addition to measuring soil health, measuring carbon dioxide flush can also help farmers reduce nitrogen fertilizer use. “We can use carbon dioxide flush to estimate how much nitrogen will be available from the soil to crops during a growing season,” says Sainju. That means farmers can be strategic with fertilizer use. That can lead to lower costs of farming while enhancing environmental benefits.

To test carbon dioxide flush as a soil health indicator, the researchers collected soil samples from two dryland study sites, both in northeastern Montana. For each soil sample, Sainju and colleagues measured carbon dioxide flush in two different ways.

One was the traditional way – add water to air-dried soil samples and let them sit for four days. Then the researchers used chemicals to measure carbon dioxide flush.

They also tested a faster method; one where the wetted soils sat for just one day. Then, the researchers used an infrared gas analyzer to detect the carbon dioxide flush from the samples.

Click here to see more...

Video: Why Your Food Future Could be Trapped in a Seed Morgue

In a world of PowerPoint overload, Rex Bernardo stands out. No bullet points. No charts. No jargon. Just stories and photographs. At this year’s National Association for Plant Breeding conference on the Big Island of Hawaii, he stood before a room of peers — all experts in the science of seeds — and did something radical: he showed them images. He told them stories. And he asked them to remember not what they saw, but how they felt.

Bernardo, recipient of the 2025 Lifetime Achievement Award, has spent his career searching for the genetic treasures tucked inside what plant breeders call exotic germplasm — ancient, often wild genetic lines that hold secrets to resilience, taste, and traits we've forgotten to value.

But Bernardo didn’t always think this way.

“I worked in private industry for nearly a decade,” he recalls. “I remember one breeder saying, ‘We’re making new hybrids, but they’re basically the same genetics.’ That stuck with me. Where is the new diversity going to come from?”

For Bernardo, part of the answer lies in the world’s gene banks — vast vaults of seed samples collected from every corner of the globe. Yet, he says, many of these vaults have quietly become “seed morgues.” “Something goes in, but it never comes out,” he explains. “We need to start treating these collections like living investments, not museums of dead potential.”

That potential — and the barriers to unlocking it — are deeply personal for Bernardo. He’s wrestled with international policies that prevent access to valuable lines (like North Korean corn) and with the slow, painstaking science of transferring useful traits from wild relatives into elite lines that farmers can actually grow. Sometimes it works. Sometimes it doesn’t. But he’s convinced that success starts not in the lab, but in the way we communicate.

“The fact sheet model isn’t cutting it anymore,” he says. “We hand out a paper about a new variety and think that’s enough. But stories? Plants you can see and touch? That’s what stays with people.”

Bernardo practices what he preaches. At the University of Minnesota, he helped launch a student-led breeding program that’s working to adapt leafy African vegetables for the Twin Cities’ African diaspora. The goal? Culturally relevant crops that mature in Minnesota’s shorter growing season — and can be regrown year after year.

“That’s real impact,” he says. “Helping people grow food that’s meaningful to them, not just what's commercially viable.”

He’s also brewed plant breeding into something more relatable — literally. Coffee and beer have become unexpected tools in his mission to make science accessible. His undergraduate course on coffee, for instance, connects the dots between genetics, geography, and culture. “Everyone drinks coffee,” he says. “It’s a conversation starter. It’s a gateway into plant science.”