Tens of billions of tonnes of carbon formerly trapped in soil have been lost to the atmosphere in the form of carbon dioxide since the mechanisation of agriculture began a few hundred years ago. Restoring this lost carbon could help limit climate change and improve food security.
A lack of carbon makes crop production inefficient, says Rattan Lal, director of the Carbon Management and Sequestration Centre at Ohio State University. And depletion of soil carbon is particularly problematic in sub-Saharan Africa, south and central Asia and Caribbean and Andean regions. He suggests management practices — such as use of compost and manure to fertilise crops — would increase soil carbon, allowing improved water and nutrient retention, and better yields.
At the same time, storing carbon in soil can offset fossil fuel emissions by five to 15 per cent each year. The amount of carbon potentially stored in soils is one billion tonnes — in climate change mitigation terms, the equivalent of global renewable energy production in 2001.
Reference Science 304, 1623 (2004)