Microbial carbon mineralisation
Microbial carbon mineralisation (MCM) is a geochemical carbon removal method that involves adding microorganisms to agricultural fields to accelerate the sequestration of atmospheric CO₂. These microbes grow alongside plant roots, safely and durably storing carbon in the form of carbonate minerals.
Introduction
Microbial carbon mineralisation is a novel carbon removal method that works alongside plants to take up carbon and store it securely in mineral form. By harnessing a natural process, these microorganisms accelerate the capture and storage of carbon, making this an efficient and durable method.
The microbes also improve plant and soil health, reducing the need for GHG emitting fertilisers and makes agricultural practices more efficient and secure.
The Steps
Microbe Cultivation
Microorganisms are grown and added to agricultural soils, where they live in the root zones of crops. As healthy plants grow, they take in carbon via photosynthesis and transport it down into the roots, releasing it into the surrounding soil.
Mineralisation
Microbes grow alongside crops and accelerate the transformation of carbon produced by the crops into a stable, mineral form of carbon in the soil.
Carbon Storage
The stable carbon stored in minerals is transported deeper into the soil where it will remain unless major disturbances occur. It can be transported through groundwater reservoirs to eventually reach ocean sediments, over long periods of time by natural processes.
How it works
Microbes
The process begins with the cultivation of microbes which are spread over agricultural fields when seeds are planted. These microbes then grow in the root zone of crops where they use nutrients released by the plant roots to survive.
Soil Carbon
Healthy plants produce very carbon rich soil by capturing CO₂ through the atmosphere via photosynthesis. They release this carbon into soil through their roots.
The microbes can then convert that organic carbon into inorganic minerals, such as bicarbonate. This process occurs naturally, but the microbes added to the soil accelerate it, promoting efficient carbon sequestration.
Silicate Breakdown
The microbes also accelerate the breakdown of silicate minerals found in the soil. Silicates are minerals that contain silicon and oxygen, as well other nutrients like calcium and sodium that are essential to plant growth. When silicates break down, these micro- and macro-nutrients are released into the soil, making it more fertile.
Carbon Storage
The nutrients released by silicates combine with bicarbonates to form stable carbonate minerals. These minerals then rapidly percolate deep into the soil. Over long periods of time, they are transported through soil and groundwater, and eventually make their way to the ocean and marine sediments. These minerals can persist for thousands of years in the absence of disturbances.
Scalable, efficient, durable
This is an easily adoptable technology that works alongside existing farm operations, creating huge potential for carbon removal across agricultural lands. As global populations rise, there is a growing demand for agricultural land, which also presents an opportunity to support the green transition. Carbon removal through MCM can support farmers’ livelihoods while creating climate impact.
By harnessing and accelerating the natural abilities of microorganisms, this process efficiently converts atmospheric CO2 into stable carbon-based minerals.
As well as carbonates offering highly permanent storage, the use of microbes requires low energy input, and therefore, can be implemented in a widespread manner. This novel solution has wide potential scope to spread quickly and accessibly, making it a strong carbon removal pathway to develop into the future.
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Carbon mineralisation offers highly permanent and stable carbon storage for up to 10,000 years. While upper layers of soil are susceptible to disturbances, the minerals used here migrate downwards in the soil, reducing the chance of carbon being re-released.
The ease with which microbes can be added to soil means this is a highly scalable solution that requires little energy input or infrastructure. But, as this is a novel technology, it has not been studied at length and certain elements remain unproven so far.
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This method provides environmental co-benefits for the soils and agricultural products that it is added to. Adding microorganisms to the root area of crops has the potential to increase plant growth, water retention, and overall soil health. Furthermore, this can financially benefit farmers who participate in the projects, as higher crop yields can offer them additional income.
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