For centuries, biology textbooks have told a simple story: plants inhale carbon dioxide through their leaves, use sunlight to create energy, and release oxygen back into the air. Their roots, we were taught, only draw in water and minerals. But a groundbreaking new study has upended that long-held view showing that plant roots can also “breathe,” absorbing carbon dioxide directly from the soil. The discovery, led by Dr. Amiran Khabidovich Zanilov and his team at Kabardino-Balkarian State University in Nalchik, Russia, could reshape how scientists understand the global carbon cycle and how plants help regulate Earth’s climate.

The Underground Carbon Exchange

Dr. Zanilov’s research used an innovative experimental system two airtight chambers isolating the leaves and roots of maize plants, each equipped with precise carbon dioxide sensors. Over forty days, the researchers varied light, fertilizer, and atmospheric conditions to track how carbon moved through the plant. The results were striking. When sunlight disappeared and photosynthesis halted, roots began absorbing carbon dioxide from the soil air, even as the leaves released it. This underground respiration effectively balanced the plant’s overall carbon flow, revealing a dynamic exchange that continues even after sunset.

“Root-based CO₂ absorption isn’t just an anomaly, it’s an alternative pathway for carbon nutrition,” said Dr. Zanilov. “When light is abundant, roots may act as a stabilizer, ensuring that plants maintain a steady carbon intake despite environmental fluctuations.”

READ MORE: Cascadia’s Hidden Risk: How One Earthquake Could Sink the U.S. Pacific Coastline Beneath Six Feet of Water

Light, Darkness, and Root Coordination

The study found that roots become most active when air carbon levels fall between 367 and 417 parts per million (ppm) roughly equivalent to today’s atmospheric concentrations. This suggests that root absorption happens naturally in fields and forests, not just in controlled laboratory environments. The connection between leaf and root behavior proved remarkably synchronized. When the leaves stopped taking in carbon, the roots immediately began. Researchers calculated a correlation coefficient of -0.859, showing a near-perfect inverse relationship, a physiological handoff between above- and below-ground systems. Interestingly, plants exposed to brighter light delayed this switch. Their leaves continued holding carbon for about 80 minutes after sunset, thanks to stored energy reserves from extended daylight. The finding hints at an internal timing mechanism balancing photosynthesis and underground respiration.

Fertilizer’s Hidden Side Effect

The experiment also revealed how nitrogen fertilizers can disrupt this delicate rhythm. When the researchers added ammonium nitrate, the plants’ leaves released more carbon dioxide while absorbing less during the day. Daily uptake dropped from 92.3 ppm to 70.4 ppm, indicating that the extra nitrogen temporarily hampered photosynthesis.

“The nitrogen boost comes at a cost,” explained Dr. Zanilov. “It increases metabolic activity but weakens carbon fixation efficiency. Farmers may need to rethink how and when they apply fertilizers to avoid interrupting carbon uptake.”

Roots also responded to the fertilizer shock: they first released carbon, then resumed absorption days later, suggesting a reset period before normal function returned. The team noted that nitrogen-based fertilizers accelerate soil microbial activity, depleting organic carbon faster. To maintain balance, the researchers recommend adding straw or compost to replenish lost carbon stocks.

Rising CO₂ Could Mute the Root Effect

The study also tested how rising global carbon dioxide levels might influence this process. When air CO₂ concentrations were increased from 500 to 1,500 ppm, root absorption stopped entirely and the direction of gas flow reversed. That reversal, the team says, is a warning sign. In a high-carbon world, the hidden breathing mechanism beneath the soil could weaken, reducing plants’ ability to buffer atmospheric carbon.

“If soil CO₂ becomes oversaturated, roots can’t absorb it,” said Dr. Zanilov. “That makes the underground carbon exchange vulnerable in a warming climate.”

Rethinking the Carbon Cycle

For decades, scientists assumed that plant roots only released carbon dioxide through respiration. This study challenges that paradigm, showing that under normal conditions, roots can act as both emitters and absorbers. The discovery implies that current carbon balance models which treat plants’ below-ground respiration as a one-way emission may underestimate how much carbon ecosystems actually capture. The findings could reshape agricultural practices as well. By managing light exposure, fertilizer timing, and soil health, farmers could potentially enhance root-based carbon absorption, improving yields while helping soils act as stronger carbon sinks.

“We’ve focused on leaves for centuries,” Dr. Zanilov said. “But the soil holds half the story and half the solution.”

Explore OneStop ESG Marketplace: Environmental Engineering

A Quiet Breakthrough from Nalchik

The study emerged not from a major research hub, but from the Center for Decarbonization of the Agro-Industrial Complex at Kabardino-Balkarian State University, a modest lab in southern Russia. Yet the team’s meticulous experiment may force a global scientific rethink.

“This work shows that breakthroughs don’t always come from the biggest institutions,” said Dr. Zanilov. “Sometimes, they grow quietly in a sealed chamber, inside the roots of a maize plant, waiting to be discovered.”

By revealing that roots breathe as much as they drink, the study opens a new chapter in plant science, one where the hidden half of nature’s lungs could help humanity better understand, and perhaps rebalance, the planet’s carbon future.

Explore ESG Solutions on our marketplace - OneStop ESG Marketplace.

Keep abreast of the top ESG Events on OneStop ESG Events.

OneStop ESG Educate: Your go-to source for top ESG courses and training programs tailored to your needs.

Stay informed with the latest insights on OneStop ESG News.

Discover meaningful career opportunities on OneStop ESG Jobs.