In epizode 74 of the Freakonomics podcast the Soil scientist Asmeret Asefaw Berhe could soon hold one of the most important jobs in science. She explains why the ground beneath our feet is one of our greatest resources — and, possibly, one of our deadliest threats.
The largest impact human communities have had on soil starts at the time when we started settled agricultural practices. Because what happens then is we start tilling the land and extracting resources from the land. And especially in intensive agricultural cultivation systems, the physical stability of the land is destroyed when we over-till it and physically mix it to make it easier for crops to grow.

And that then makes soil vulnerable for loss of nutrients. So, it becomes less fertile. It loses carbon and organic matter that are also critical for plant growth and supporting life and soil in general, but that physical disturbance also renders soil vulnerable to erosion. And in fact, because of agriculture, the rate of soil erosion in particular by wind and water has increased by up to two to three orders of magnitude in different parts of the world. So, we’re talking about significant increase in the rate at which soil is being lost from land — in particular agricultural lands — because of the way we manage it and how vulnerable that management makes soil for erosional loss. The rate at which these change and the rate at which the degradation has been happening has been particularly fast in the last 200 years since the Industrial Revolution.