Earth Rover Program seeks to track the world’s soil health

With a synchronized tap from run-of-the-mill hammers on metal plates resting on the ground, researchers kneeling in nine fields across four continents believe they’ve hit upon more than just the earth beneath their feet.

“Waiting for it,” someone said. And then, “Waveforms!”

“Excellent, waveforms!” another said, as the tiles on screen reveal EKG-like sets of squiggles on laptops and smartphones from each of the locations.

The video promotes the Earth Rover Program, a new effort to glean critical details about the soil from the way that a hammer tap tickles a set of sensors. It’s early days for the project. But its global team is working to bring the tools of seismology — known affectionately as “the science of the squiggle,” said co-founder Simon Jeffery — to bear on teasing apart the global puzzle of soil health.

Jeffery and his fellow founders, geophysicist Tarje Nissen-Meyer and journalist George Monbiot, have staked out a far-reaching ambition to map soils with a cost-effective technology. They say they hope the program will equip farmers the world over with a better set of tools to grow crops and ensure that soils will remain healthy long into the future.

“If we don’t have soil, then we don’t have the wonderful aboveground ecosystems that the vast majority of us enjoy so much,” Jeffery, a professor of soil ecology at Harper Adams University in the U.K., told Mongabay in an interview.

He’s quick to point out that soil — the accumulated minerals, organic matter, droplets of liquid and tiny pockets of gases underfoot — holds more carbon than the combination of what’s in the atmosphere and in those Earthbound ecosystems closer to eye level. What’s more, nearly all of the food we eat depends on it.

In short, life on Earth is fiercely dependent on the functioning of the shrouded ecosystem operating below us. But its health is tenuous. Soils are exhausted by overuse, vulnerable to a changing climate and eroding away in parts of the world. And scientists are still sorting out the complex array of interactions necessary for the knife’s-edge balance required for it to function as life’s literal foundation.

The tools available today don’t often provide the detailed information that individual farmers need. They’re typically time-consuming, expensive or invasive — or all three. They also have yet to provide a global view of how soils are faring.

Soil scientists who aren’t part of Earth Rover, like Leigh Ann Winowiecki, say filling in the data gap is critical.

“If we are going to understand the state of soil health, including tracking changes over time, monitoring approaches must be robust, cost-effective, accurate, and systematically applied and scaled across diverse ecosystems,” Winowiecki, global research lead for soil and land health at the research organization CIFOR-ICRAF based in Nairobi, said in an email to Mongabay.

‘Soilsmology’

Understanding soil health often begins with a key indicator called bulk density. Bulk density measures the amount of soil packed into a given volume, Jeffery said. Regardless of the type of soil, there’s an “optimum … happy zone,” he added.

Information gleaned from that cross section can reveal if the soil is compacted, a pervasive problem for farmers and overall soil health.

“That’s a bad thing, because plant roots can’t penetrate. You don’t get gas exchange. Water doesn’t flow through. It’s that squashing, that compaction that we can pick up,” Jeffery said.

But even this fundamental barometer of soil health “is just a real pain to measure, especially when you have to go deep down the soil profile,” said Franciska de Vries. De Vries, a professor of Earth surface science at the University of Amsterdam in the Netherlands, is not involved in the program, but joined the Dec. 5 webinar that the Earth Rover team arranged. “You generally just dig one pit in a field, and it takes a whole day.”

By contrast, “a method that would allow high-resolution, quick and easy and cheap assessment of those parameters … would be brilliant,” she added.

With current techniques, scientists also struggle to measure something as simple as the depth of the soil across large areas, Jeffery said. Maps of the organic carbon stocks in soil from 2016 relied on samples of topsoil down to 20 centimeters (8 inches) across Europe, for instance — a blanket estimate for topsoil depth that’s “just bonkers,” he added.

“That’s the best they could do, because, on average, it’s something like that,” Jeffery said. “But there are areas where it’s 5 centimeters [2 in], if you’re lucky. There are areas in the Eurasian Steppe where it’s up to a meter [40 in].”

To address these types of gaps in the knowledge that, scant and incomplete as it may be, ultimately guides how we grow nearly all of our food, the multinational team has developed a new technique drawing on seismology. Its aim: to provide a window into what’s happening in the critical top layer of soil that nourishes the roots of row crops and siphons carbon from the air above.

That’s where the tweaked version of seismology — the Earth Rover team calls it “soilsmology” — comes in.

Reading between the squiggles

The most common technique for assessing soil health involves cutting into the soil you’re examining. “But of course, by digging hole in the soil, you’re destroying the structure you’re trying to look at,” Jeffery explained in the team’s Dec. 5 webinar launching the program.

And the technique often doesn’t provide the level of detail needed to make critical decisions. With limited or incomplete information about soil, a farmer often has to make their best guess about what the land needs — in terms of plowing, or additions of water or fertilizer, for example. If they believe that the soil has become too compacted for the roots of their crops to break through, they might choose to till the whole field with a technique farmers call “subsoiling” to break up that hard layer below the surface. But tractor fuel is expensive, and the process takes valuable time.

The assumption may be that the entire field is compacted, but that’s often not the case, Peter Semba Mosongo, a soil scientist at the Centre for Ecosystem Restoration Kenya in Limuru, which partners with the Earth Rover Program, told Mongabay.

“What you find is that there are sections,” Mosongo said. “With our technology, we are going to pinpoint and tell you, ‘This is the section that needs subsoiling.’” Another section, he added, might not need such treatment.

“It’s going to save you time. It’s going to save you money,” he said. And he said that such prescriptive targeting can also help avoid unnecessarily harming soil productivity and health.

As Jeffery noted, disrupting the soil destabilizes the very structure that’s responsible for its critical functions, like the carbon found in organic material. Churning up the earth injects oxygen into the system, stoking the decomposition process that can lead to the formation of carbon dioxide.

In addition to keeping climate-warming carbon locked away, soil relies on its organic contents to stick together, Mosongo explained.

“Soil organic matter is what holds the soil,” he said. “It’s like the glue of the soil particles, and it controls also the amount of moisture that soil can hold.”

Without that structure in place, the soil is more apt to get washed or blown away by storms, Mosongo added.

Until now, though, the kinds of testing available to diagnose these sorts of issues at a granular level haven’t been feasible.

“The farmers [can’t] do the soil health analysis because they are already financially pressed,” Mosongo said in the group’s webinar.

“It’s simply out of the question,” Mosongo added. “It’s a luxury they can’t afford.”

In Kenya, farmers already face high costs of seed and fertilizer, along with dips in soil fertility and erratic weather — while mostly relying on rain-fed agriculture.

The Earth Rover technology is complex, if somewhat familiar, and the team is working on streamlining it further. A set of MEMS accelerometers, similar to the ones that track your step count or flip the screen orientation from portrait to landscape on your smartphone, record the distortions of high-frequency waves generated by those hammer taps through the first few tenths of a meter of the soil.

“As those seismic waves pass through a medium, they pick up information,” Jeffery said. The resulting distortions appear on a phone or laptop as a set of interpretable “squiggles” — the foundation of seismological analysis.

The higher-frequency waves the Earth Rover team uses don’t travel as far into the soil as the longer waveforms traditionally used in seismology. But they provide more detailed information on the substrate they’re passing through.

“[Seismologists] basically look at those squiggles and interpret them,” Jeffery said, “and can draw conclusions about the structure.”

The relatively simple setup, the Earth Rover team said, can give farmers an unprecedentedly detailed look into the ground beneath their feet.

“Soil degradation is undoubtedly one of the great challenges of our time, and if we don’t do something about it, it is going to massively negatively affect people and the environment moving forward,” Jeffery said. “I think we have a moral imperative to help where we can.”

‘Soilcast’-ing

Program scientists are also working to leverage giant data sets that pull together information about soils. They’re using artificial intelligence — instead of ChatGPT, an “ERP-GPT” engine — that aims to interpret the collected raw information in a way that’s accessible to farmers on the ground. The team envisions the development of what it calls “soilcasts” that provide actionable information. The problems that soilcasts could help to solve may extend beyond the compaction of soil, such as high salt concentrations or too little organic material.

Ultimately, the goal is to make this technology available to farmers across the world and provide them with critical feedback. This information could guide their decision-making in near real time about how best to manage soil health and minimize the damage that’s so often caused when humans grow food.

“Imagine being a farmer that has a ‘soilcast’ app on their phone, and getting a suggestion … to irrigate a certain part of the plot in their land, or anticipate weather patterns for upcoming climate extremes, perhaps to anticipate how to change to a different crop rotation if you know that a really extreme El Niño is coming,” co-founder Tarje Nissen-Meyer, a professor in environmental intelligence at the University of Exeter in the U.K., said during the webinar.

He noted the importance of collaboration in integrating both the data and what farmers already know after a lifetime of working the earth. “That’s really at the heart of what we try to do — to include Indigenous and local knowledge that’s often generated by generations of knowledge of the local land.”

Jeffery said such precise forecasts are likely a few years in the future.

But he also predicted further streamlining that could allow a farmer to simply use a smartphone instead of the technology kit they’ve developed so far.

“Phones themselves have MEMS sensors in them, so it could well be that we can use mobile phones to take these seismic signals, which then opens up a world of possibilities,” Jeffery said. “Phones are everywhere.”

Mosongo said the value of the Earth Rover program will come from giving farmers the information to “make [the] right decisions at the right time.”

“It’s an affordable technology, which means that even the poorest of the farmers are able to implement this,” he said. “If they implement this, then I see increased farm productivity, not only in Kenya or sub-Saharan Africa, but across the world.”

But critical to making the technology work for farmers is making sure it stays affordable. That’s why the team has resisted a path toward commercialization, Jeffery said.

Mosongo pointed out that the cost of the program’s technology has already come down by a factor of 100 to around 100 British pounds ($135), and the goal is to drive it even lower.

“Our ultimate goal is to make this as freely available for everybody as possible,” Jeffery said. “We really are in it for the for the greater good.”

Banner image: Farmers on a 1.6-hectare (4-acre) plot of oranges, avocado, maize and vegetables in Kenya. Image by McKay Savage from London, UK via Wikimedia Commons (CC BY 2.0).

John Cannon is a staff features writer with Mongabay. Find him on Bluesky and LinkedIn.

Correction: A previous version of this article misspelled the name of Simon Jeffery. We regret the error.

Citations:

Pimentel, D. (2006). Soil erosion: A food and environmental threat. Environment, Development and Sustainability, 8(1), 119-137. doi:10.1007/s10668-005-1262-8

Yigini, Y., & Panagos, P. (2016). Assessment of soil organic carbon stocks under future climate and land cover changes in Europe. Sci Total Environ, 557-558, 838-850. doi:10.1016/j.scitotenv.2016.03.085

Reinsch, S., Lebron, I., de Jonge, L. W., Weber, P. L., Norgaard, T., Arthur, E., . . . Robinson, D. A. (2025). The fraction of carbon in soil organic matter as a national-scale soil process indicator. Globe Change Biology, 31(11), e70572. doi:10.1111/gcb.70572

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