The science behind agricultural carbon sequestration offers a snapshot of the constant dialogue between the atmosphere, plants, and soils.
It starts with photosynthesis—and continues in exchanges between plant roots, animals, and microbes living within the soil. Implementing regenerative practices that support soil microbial communities promotes active carbon cycling, thereby accumulating soil organic matter long term, particularly in deeper soil layers. This persistence is what ultimately allows farmers to get paid for the carbon in their soil and supporters to receive high-quality credits through Indigo’s Carbon program.
Persistent forms of carbon can be produced in soils, and this cycling process can be enhanced by:
- Bringing high-quality inputs to the land that support, rather diminish efficient microbial activity
- Reducing disturbances (like tillage, which digs up the topsoil) to preserve the biological, physical, and chemical processes already taking place
Visualize the Process
1. |
The sun provides an endlessly renewable energy source for plants to perform photosynthesis. |
2. |
Plants capture carbon dioxide from the atmosphere, tossing aside the two oxygen molecules and keeping the carbon to build up its leaves, stems, and roots. |
3. |
Plants secrete some of their carbon reserve from their roots in nutritious offerings known as “exudates,” or simple sugars, proteins, amino acids, organic acids and other important regulators for the microbial community living in the soil. |
4. |
Worms ingest a combination of organic materials (plant residue) and inorganic materials (soil), once that material passes through their guts it gets excreted as soil "casts." These soil casts, composed of many small microaggregates, are bound together in a stronger way that helps make robust soil aggregates that physically protect newly added surface plant material from decomposition. |
5. |
Carbon is moved deeper within the layers of soil, and transformed into more stable forms over time, in a continuous cycle of microbial consumption and transformation of plant-derived carbon. Some carbon, usually simple sugars or other small biomolecules, dissolves out of crop residues. If the dissolved carbon comes into contact with bacteria or fungi, the microbes can use that as energy to grow bigger. Because microbes are in such close proximity to the mineral soil, when they die, the carbon that was contained in their bodies joins with these mineral surfaces. Over time, this conversion of dissolved carbon into microbial tissue increases the size of the microbial pool, and when they die, a lot of that microbial carbon cycles through the soil – eventually increasing soil carbon stocks. |