How does CO2 contribute to a healthy ecosystem and how to store it back into the soil?
Extract of the talk given during The Soft Protest, re-chewing & Digest's dinner
in October 2019 at Corridor project space in Amsterdam.
“Habitats that are important for nature, such as forests, meadows, coastal wetlands, peatland and grasslands store and sequester carbon into the soil. When degraded or destroyed, through industrial agriculture or deforestation, these ecosystems start to emit the carbon they have stored for centuries into the atmosphere and oceans and become source of greenhouse gases. Protecting and restoring the health of these areas could, therefore, have a huge effect and help to keep global warming below 1.5°C.
But first, how do we get CO2 into the soil? To answer this question, it is first relevant to understand what CO2 is and does. Carbondixide, also called atmospheric carbon or C02, is the primary source of life on earth, it is a gas that plants utilize to make photosynthesis for growth. Today the quantity of C02 in the atmosphere due to anthropogenic emissions has surpassed the boundaries of the planet. This has created an invisible shield around the earth which traps heat… also called the greenhouse effect.
Plants take in carbon dioxide from the air and combine it with water to form simple sugars. Many of these sugars are used for the growth of the plant, however a significant amount of liquid carbon are leaked into the soil as, so-called, “root exudates”. Why would a plant leak important sugars? The answer is to feet microbes! Because it is their life source. In return the microbes supply the plant nutrients and minerals which they are able to access in the soil. Microbes supported by root exudates are essential to the production of humus, a highly stable and long living form of organic carbon with high water holding capacity, and other essential qualities. And in order to keep land from depletion, hydrology is everything!
So we need carbon in the soil where it feeds bacteria which feeds plants and creates humus, a highly fertile soil, which stores water and carbon where it is needed. To get more CO2 away from the atmosphere and into the soil, we need to stimulate grass growth. This is where the cow comes in. Cows are very efficient grazers, which means they are like living grass mowers, they eat the grass at the perfect length for regrowth, if they have enough grass so to mention. This creates a ‘healthy stress’ in the grass, and when plants are slightly stressed they expand their root net, which makes them more resilient. And to build root net, they need… CO2 from the atmosphere!
And the cow not only takes from the grass, it also brings back nutrients and organic matter back to it in the form of cow dungs, which also stimulates growth and the wellbeing of plant and soil life. But is there limits to grass growth? - Well there is uncertainty about it, some scientists say the carbon storage has a limit of approximately 30 years, some say that carbon sequestration is nearly endless - it might be highly dependent on the specific context of the soil.”