Carbon Isn’t Just A Climate Challenge  

Carbon isn’t just a climate challenge, it’s a molecule that moves through air, plants, soil, oceans, and living organisms as part of a much larger global cycle. It’s constantly on the move, shifting between different parts of the Earth system. What has changed in recent history is not the carbon cycle itself, but the pace and volume of carbon entering the atmosphere. 

In this blog, we explore how carbon travels from atmosphere to acre — how it moves, how plants capture it, and why healthy soils are one of the most practical places to store it. Think of it as a closer look at how carbon “gets dirty”: how it moves underground where it can do the most good. 

How Carbon Enters The Atmosphere  

For most of human history, natural carbon inputs and outputs were roughly in balance. But human activities have shifted that equilibrium through a number of ways such as: 

• Burning fossil fuels releasing carbon that was stored underground for millions of years. 
• Land conversion exposing carbon-rich soils to oxygen, causing rapid CO₂ release. 
• Intensive tillage accelerating microbial respiration and carbon loss. 
• Soil degradation reducing the land’s ability to reabsorb and store carbon. 

Carbon is always in flux. CO₂ is released through a number of processes in nature such as respiration (animals, plants, microbes etc. “breath out”) and decomposition (organic matter breaks down). At the same time, plants are pulling CO₂ out of the atmosphere via photosynthesis. 

Photosynthesis: Nature’s Carbon Capture Technology 

Plants take in CO₂ through tiny pores on their leaves called stomata. Once inside the leaf, that CO₂ is converted into sugars using sunlight. These sugars become the building blocks for everything the plant grows — leaves, stems, grain, roots — and the fuel the plant uses to live. 

But plants are not just capturing carbon; they are also releasing it. Plants respire, and microbes (and soil organisms) break down organic matter as they use energy. So at any moment, carbon is moving both into and out of the living soil system.  

Whether an ecosystem acts as a carbon sink or a carbon source depends on which process is winning:  

• If photosynthesis brings in more CO₂ than plants and microbes respire, the system is a sink (net carbon gain).  
• If respiration exceeds photosynthesis, it becomes a source (net carbon loss). 

This balance is called net ecosystem exchange (NEE) and it’s defined from the atmosphere’s point of view. A negative NEE means that more carbon is being stored in biomass and soil than in the atmosphere. That is what we aim for in regenerative systems: more carbon building the plant and soil than being respired back into the air.  

When conditions are right — healthy plants, sunlight, moisture, thriving microbes — more carbon moves into biomass than out. This sets up the entire pathway for carbon to enter the soil. The total carbon captured through photosynthesis is called gross primary productivity (GPP); after plants use some for respiration, the carbon left for biomass growth and soil inputs is net primary productivity (NPP). When NPP is high, more carbon is available to enter the soil through roots, residues, and microbial transformation—laying the foundation for long-term soil carbon storage. One of the main pathways for that carbon to reach the soil is through root exudates. 

Root Exudates: The Underground Carbon Highway 

Once plants create sugars, they don’t keep all of them. A surprising amount — sometimes up to 40%— is pushed out through the roots into the soil as root exudates. These are liquid carbon compounds that act like food for soil microbes. 

As microbes consume these compounds, they “breathe” too, releasing CO₂ through microbial respiration. The more active the microbial community, the more respiration you see — but this isn’t a bad thing. It means the system is alive, cycling nutrients, and building soil structure. The key is timing: as long as the plant is capturing more carbon than the microbes release, the ecosystem remains a net sink. 

Root exudates do more than feed microbes. They help: 

• Form soil aggregates
• Improve soil porosity and bulk density
• Strengthen nutrient cycling
• Increase water retention
• Create microhabitats where carbon can be protected from rapid breakdown 

This constant exchange — photosynthesis bringing carbon in, root exudates transferring carbon below ground, and microbes transforming it — is how carbon begins its journey into Soil Organic Carbon (SOC).   

Soil Organic Carbon: Where Carbon Actually Gets Stored 

By the time carbon reaches the soil, it has already moved through several steps — captured by plants, cycled through roots, and transformed by microbes. What stays behind becomes Soil Organic Carbon (SOC). 

 We go deeper into SOC and bulk density in our last blog, but here’s the simple version: healthy, well-structured soils create the spaces where carbon can settle in and remain. When soils have strong aggregates and good bulk density, they hold water better, support thriving microbial communities, and physically protect carbon from breaking down too quickly. 

This is why soil health matters so much. The better the soil structure, the easier it is for carbon to enter, stay longer, and eventually become part of the stable carbon pool. Regenerative practices and microbial inputs help build these conditions, allowing more carbon to move from the atmosphere into the soil where it can do the most good. 

A Living System In Balance 

Carbon never stops moving. It cycles between atmosphere, plant, and soil in a constant exchange, one that is microbially mediated and deeply dependent on soil health. When soils are degraded, the cycle breaks down because stressed plants capture and absorb less CO₂ through photosynthesis, while microbes may continue releasing it through respiration. But when soils are thriving, the system becomes balanced again: plants capture more carbon, soil stores more carbon, and ecosystems become more resilient.