Soil, the very basis of our civilization, is in danger.  That thin layer of topsoil, only three feet deep, that has nourished all life on this planet for hundreds of thousands of years, is eroding away.  It is also losing its richness, that wealth of nutrients that get absorbed into our plants and eaten by us and the other animals on this precious earth.   The Financial Times has an informative article called "Soil under strain: A thinning layer of life evokes concern".

“The world’s cropland is losing topsoil through erosion faster than new soil is forming, thereby reducing the land’s inherent productivity,” warns Lester Brown, founder of the Earth Policy Institute, in his book Plan B. “Where losses are heavy, productive land turns into wasteland.”

Farmland across the world has been affected.  Soil degradation has been impacted by increased population pressure everywhere, but the impact has been particularly heavy in Africa, where immediate needs often overrun good agricultural practices and "result in a vicious cycle of declining yields, deepening poverty and a loss of the soil base".  According to the International Centre for Soil Fertility and Agricultural Development, "Africa loses about 8m tonnes of soil nutrients a year, while more than 95m hectares of land have been degraded to the point where productivity is greatly reduced."

The planet has seen these problems before.  Some archaeologists believe that the collapse of past civilizations such as the Mayans, the Easter Islanders and Norse settlers in Greenland were caused by severe climate change and the overuse and subsequent depletion of their soil. 

Enough Soil for 12 Years?

"Scientists estimate that there is enough suitable uncultivated land to meet increased demand until at least 2020," providing that existing fields remain productive.  Twelve years from now, according to the Financial Times article?  Yikes!  Here are more details:

There is increased salinity in the underground aquifers in Australia, and erosion by water and wind in Spain and Italy.  In places where soil has fallen out of use, the bare land is vulnerable until wild plants take hold. In Eastern Europe about a third of the soils are deeply degraded from pollution.  It's even worse in China, where rivers run black with industrial effluent.  The increased demand for water has meant that marginal farm lands have been swallowed up by desert. 

Since the terrible dust bowl conditions in the U.S. in the 1930's, the US has had programs in place to protect soils.  Nevertheless, we've lost topsoil at 1 percent per year.   Here in Washington State, in the dry wheatlands of counties like Lincoln, Grant and Douglas, in Central and Eastern Washington, roughly 50-75% of the original organic matter, the material that makes soils fertile, has been used or has washed away. 

Africa at Risk

The problem is most acute in Africa, "where farmers tilling some of the world’s oldest soils are among the least able to take action to protect their most important resource".

"Africa’s soils suffer from several disadvantages. First, the continent is geologically old and has been home to people for a long time. Ancient soils are thin and often lack the structure necessary to hold water and nutrients. The deep red colour characteristic of the continent’s soils betrays another difficulty: such earth is heavily laden with iron, which “binds” phosphorus, rendering it unavailable to plants. African soil also often lacks the key nutrients of nitrogen and potassium, as well as less important substances such as zinc, says Otto Spaargaren, head of the World Data Centre for Soils at the International Soil Reference and Information Centre."

"Traditional farming practices that might have preserved the soils have fallen away under the pressure of feeding so many more mouths."  Farmers are no longer able to leave ground fallow because the plots are increasingly smaller. 

What Has Changed

What has changed is population pressure: "There are now more than 6.5bn people on the planet, a figure that is forecast to rise to 9bn by mid-century. Though scientists estimate that there is enough suitable uncultivated land to meet increased demand until at least 2020, feeding the world demands that existing fields remain productive."

Here's the article.