Carbon Sinks
A carbon sink is a natural or man-made reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period.
The main natural sinks are:
- Absorption of carbon dioxide by the oceans
- Photosynthesis by plants and algae
The main manmade sinks are:
- Landfills
- Carbon capture and storage proposals
The process by which carbon sinks remove carbon dioxide from the atmosphere is known as CO2 sequestration or carbon sequestration.
Methods that significantly enhance carbon sequestration in soil include no-till farming, residue mulching, cover cropping and crop rotation — all of which are more widely used in organic farming than in conventional farming. Because only 5% of North American farmland currently uses no-till and residue mulching, there is a large potential for carbon sequestration. Conversion to pastureland, particularly with good management of grazing, can sequester even more carbon in the soil.
Biochar amended soils (aka Terra Preta) are an excellent CO2 sequestration mechanism. The pyrolysis of biomass results in storing up to half of the original carbon in the form of biochar. Biochar can persist in soil for centuries and makes a useful soil amendment, especially in tropical climates.