“Heating Isn’t Enough: Soil Needs Carbon & Nutrients to Boost CO₂ Emissions”

Recent research shows that warming soil by itself does not cause a rise in carbon dioxide emissions unless microbes are also supplied with accessible carbon and nutrients. Scientists from North Carolina State University explored how increased temperature, combined with added carbon and nutrients like nitrogen and phosphorus, affects soil CO₂ release.
Microbes—such as bacteria, fungi, and others living in the soil—are responsible for much of the CO₂ released. But their activity depends not just on temperature, but on the availability of “food.” If soil lacks easily usable carbon and nutrient sources, boosting temperature alone won’t make microbes more active. As assistant professor Debjani Sihi puts it: “The findings show that if you don’t have the carbon and nutrients in easily available forms that soil microbes need to grow and thrive, then heating alone will not increase the loss of carbon.”
The team used soil from a long-term warming site in subtropical Georgia—soil that was nutrient-poor because it had formerly been used to grow cotton. They heated samples by about 2.5 °C and tested combinations of added nutrients and carbon. They found that warming plus carbon addition (and nutrients) was needed before CO₂ emissions rose significantly.
Interestingly, simply adding nutrients without accessible carbon did not substantially increase CO₂ output. The soil’s previous history—its fertility, content of usable carbon—played a major role in how microbes responded. Sihi likens microbial needs to a balanced diet: “Microbes are breathing and they are getting their energy from carbon. And then they’re also fulfilling their demand for nutrients from the same food that they’re getting.”
This work suggests that models predicting carbon release under climate warming should account for substrate (carbon) availability and nutrient constraints. Without those, predictions may overestimate how much CO₂ warming alone will force out of soils.
Key Phrase: Warming soil microbes nutrients
Meta Title: “New Study Shows Carbon + Nutrient Limits Microbial CO₂ Emissions Under Warming”
Meta Description: “Study reveals that soil warming alone fails to increase CO₂ emissions unless microbes receive accessible carbon and nutrients, challenging climate change models.”