Global Warming and Soil Carbon Sequestration
The dark material at the surface of the soil is partially decomposed organic debris resulting from the natural composting of leaf litter, old plant roots, and animal residues. Being organic in natures, the material is high in carbon. In fact, compared with the 39,000 billion tons of carbon stored in the oceans and the 4,000 billion ton stored in fossil fuels, soil organic matter is the third largest pool of carbon known on Earth, weighing roughly 1,500 billion tons. Carbon sequestration in the soil exceeds the sum of the carbon stored in the atmosphere (~ 750 billion tons) and all living plants (~610 billion tons).
Not only does soil provide a major storage of carbon, it is also a significant contributor to the carbon dioxide load in the atmosphere thought to be causing global warming. Whereas fossil fuel combustion accounts for an annual 5.5 billion ton contribution of carbon dioxide, the natural microbial process of organic matter decay contributes 60 billion tons. Conservation practices that increase the storage of carbon and decrease the decomposition of organic matter may very well have a positive impact on stabilizing or even reducing global temperatures.