A few random quotes from J. Russell Smith, writing in 1929, to get us started:
"Forest - field - plow - desert - that is the cycle of the hills under most plow agricultures... Indeed we Americans, though new upon our land, are destroying soil by field wash (erosion) faster than any people that ever lived - ancient or moder, savage, civilized, or barbarian. We have the machines to help us destroy as well as create. The merciless and unthinking way in which we tear up the earth suggests that our chief objective may be to make an end of it."
"We in America have another factor of destruction that is almost new to the white race - the thunderstorm. South Europe has a rainless summer. North Europe has a light rainfall that comes in gentle showers. The United States has the rippling torrent that follows the downpour of the thunderstorm. When the American heavens open and pour two inches of rain in an hour into a hilly cornfield, there may result many times as much erosion as results from two hundred inches of gentle British or German rain falling on the wheat and grass."
"In this way we have already destroyed the homelands fit for the sustenance of millions. We need an enlarged definition of treason. Some people should not be allowed to sing 'My Country.' They are destroying it too rapidly."
"Can anything be done about it? Yes, something can be done. Therefore, this book is written to persons of imagination who love trees and love their country, and to those who are interested in the problem of saving natural resources - an absolute necessity if we are to continue as a great power."
The answer? Tree Crops. Permanent Agriculture.