Soil erosion: devastating threat: "The United States is losing soil 10 times faster -- and China and India are losing soil 30 to 40 times faster -- than the natural replenishment rate.

As a result of erosion over the past 40 years, 30 percent of the world's arable land has become unproductive."

Soil erosion: devastating threat: "The United States is losing soil 10 times faster -- and China and India are losing soil 30 to 40 times faster -- than the natural replenishment rate.

As a result of erosion over the past 40 years, 30 percent of the world's arable land has become unproductive."