In Northern Missouri, we have lost half our topsoil after 150 years of farming. We are on a collision course with ruining our land and our agriculture. Read David Montgomery's book, Dirt: The Erosion of Civilizations. Preserving the topsoil we have right now is the biggest key to soil quality for centuries to come.
Soil erosion has led to the collapse of dozens of early historic and prehistoric civilizations, agriculture in the U.S. Piedmont and continues to have an impact on corn and soybean yields in central Missouri. The value of topsoil is important for all civilizations.
See the full presentation on Erosion and the value of topsoil: the long view (PDF).