Some things have not changed much since da Vinci’s time, 500 years ago. For many, soil is a mix of dirt and dust. But in reality soils are one of Earth’s most amazing living ecosystems. Millions of plants, bacteria, fungi, insects and other living organisms – most of them invisible to the naked human eye – are in a constantly evolving process of creating, composing and decomposing organic living matter. They are also the unavoidable starting point for anyone who wants to grow food.
Soils also contain enormous amounts of carbon, mostly in the form of organic matter. On a global scale soils hold more than twice as much carbon as is contained in terrestrial vegetation. The rise of industrial agriculture in the past century, however, has provoked, through its reliance on chemical fertilisers, a general disrespect for soil fertility and a massive loss of organic matter from the soil. Much of this lost organic matter has ended up in the atmosphere in the form of carbon dioxide (CO2) – the most important greenhouse gas.
The way that industrial agriculture has treated soils has been a key factor in provoking the current climate crisis. But soils can also be a part of the solution, to a much greater extent than is commonly acknowledged. According to our calculations, if we could manage to put back into the world’s agricultural soils the organic matter that we have been losing because of industrial agriculture, we would capture at least one third of the current excessive CO2 in the atmosphere. If, once we had done that, we were to continue rebuilding the soils, we would, after about 50 years, have captured about two thirds of the excess CO2 in the atmosphere. In the process, we would be constructing healthier and more productive soils and we would be able to do away with the use of chemical fertilisers, which are another potent producer of climate change gases.
Via Campesina has argued that agriculture based on small-scale farming, using agro-ecological production methods and oriented towards local markets, can cool the planet and feed the population (see Box 1). They are right, and the reasons lie largely in the soil.