326 A NATIONAL PLAN FOR AMERICAN FORESTRY 



be no question that a much larger part of the rainfall now finds its way imme- 

 diately into this stream and is carried off in floods, leaving a much smaller part 

 to soak into the ground to supply the wells, springs, and streams during periods 

 of dry weather. 



Near Kennett, Calif., all vegetation has been destroyed on an area 

 upward of 67,000 acres and partial destruction has occurred on 86,000 

 acres additional. Without the protecting vegetative cover, the surface 

 soil of the denuded portions was soon washed off, exposing an inert 

 subsoil which continues to wash and gully at a rapid rate. Munns M 

 estimated a total of more than 35 million cubic yards had been 

 removed from the Kennett area in 10 to 15 years. Conditions are 

 very similar in other smelter areas. 



CLEARING FOR AGRICULTURE 



Hundreds of millions of acres once in forest have been cleared for 

 crop production. This was a natural process in the settlement of the 

 United States. At the time many were cleared little was known of 

 the productive capacity or the erosiveness of the soils, and it is natural 

 that many areas have later proven to be unsuited for permanent 

 agricultural use. In the section of this report entitled " Agricultural 

 Land Available for Forestry", the Bureau of Agricultural Economics 

 estimated that today there are over 50 million acres of cleared land, 

 which, abandoned or idle, are available for reforestation. Of these 

 probably 11 million will require artificial reforestation. Present 

 trends indicate an additional abandonment of some 25 or 30 million 

 acres of potential forest land in the next 20 years. 



These areas, abandoned or in process of abandonment, have largely 

 passed such usefulness as they had for crop production. Many owe 

 their abandonment to loss of productivity through erosion of the 

 fertile topsoils and in some instances of large amounts of the subsoil. 

 They are found most often in hilly and mountain regions, in regions of 

 more level topography but having soils which erode with extreme 

 ease, and in regions where the soils dp not erode readily, but where 

 the topsoil is so shallow and the subsoil so unproductive that the loss 

 of a few inches of soil by erosion renders them practically worthless. 

 These lands are widely distributed east of the Great Plains, but are 

 found in parts of the West as well. 



Through the adoption of contour plowing, terracing, crop rotation, 

 and other suitable methods of cultivation doubtless much of the 

 slightly eroding agricultural land can remain in crop production or in 

 pastures. Such land is beyond the scope of this report. On most of 

 the 50 million acres of abandoned lands, however, the loss of soil pro- 

 ductivity has reached such proportions that cropping methods can- 

 not be expected to overcome the active erosion and hazards of agri- 

 cultural production. As Bennett 30 has stated: 



When the mellow topsoil is gone, with its valuable humus and nitrogen, less 

 productive, less permeable, less absorptive, and more intractable material is 

 exposed in its place. As a rule this exposed material is the "raw" subsoil, which 

 must be loosened, aerated, and supplied with the needed humus to put it into the 

 condition best suited to plant growth. This rebuilding of the surface soil requires 

 time, work, and money. In most places this exposed material is heavier than 



29 Munns, E. N. Erosion and Flood Problems in California. Calif. State Bd. Forestry Rpt. to the 

 Legislature 1921 on Sen. Con. Res. 27. 1923. 



30 Bennett, H. H. "Parti. Some Aspects of the Wastage Caused by Soil Erosion." Pp. 1-3. Dept. 

 Agr. Circ. 33, "Soil Erosion a National Menace." (H. H. Bennett and W. R. Chapline) 1928. 



