The Interaction Between Soil & Plant Carbon Is Subtle But Could Reduce Global Warming. Plants Extract Carbon Dioxide From The Atmosphere & Sequester Carbon In the Soil.
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The ability of plants to use carbon dioxide as they photosynthesis has been known for a long time. What hasn’t been appreciated, until recently, is that plants are able to sequester some of the carbon within the soil. Carbon sequestration is important as we try to reduce atmospheric carbon (CO2) in a bid to reduce global warming.
Soil is one of the largest and best carbon banks available within the natural world. But sadly, over the years, soil carbon has been lost to the atmosphere, making the situation worse rather than better. the loss had been largely due to soil cultivation. As we cultivate the soil carbon is lost to the air. The more we cultivate the greater the lose. And the deeper we cultivate the greater the lose.
However, when soil cultivation is reduced, as in regenerative agriculture, or No Dig gardening, the soil carbon levels increase and can remain in the soil for millennia, PROVIDED the soils are not cultivated again.
We often read that planting a tree is a useful way to offset carbon, and indeed trees can retain useful quantities of carbon provided the wood is not burnt or allowed to decay. But the real carbon retention associated with trees is the fact that the trees mean soil is undisturbed for long periods and build soil carbon.
How Soils Retain Carbon
When plants remove carbon, as carbon dioxide, from the air they use it via photosynthesis to produce organic materials. These organic material include leaves, fruit, branches, stems, roots etc.
Soil carbon fixation cycle through the microbial loop
The plant organic matter is then consumed, used as animal bedding, etc and turned into farm yard manures. Or it is eaten by humans, again, resulting in organic matter production.
When added to soils the organic matter produces soil organic matter (SOM) which locks the carbon into the soil.
Plants also produce plant root exudates within the rhizosphere, to encourage soil fungi and bacteria.
The addition of organic matter and plant root exudates not only fixes carbon within the soil, it also improves soil structure. And improved soil structure leads to better moisture retention, improved drainage, less flooding, more plant nutrients and improved yields of tasty and nutritious crops.
