Ch. 22] THE SOIL-EROSION PROBLEM 389 



land area of the country, has been essentially ruined for further culti- 

 vation. 



About 775 million additional acres, or nearly 41 percent of the total 

 area of the country, has been moderately eroded; 25 to 75 percent of 

 the original surface soil has been lost ; occasional to frequent gullies are 

 present; and in places moderate wind erosion is evident. 



The remaining 700 million acres, or a little less than 37 percent of the 

 total, has suffered either no erosion or only slight erosion, with re- 

 moval of less than 25 percent of the original topsoil. In this class is 

 most of the flood-plain and delta lands, swamps, and the nearly flat 

 plains and prairies. 



The U. S. Soil Conservation Service estimates that the productive 

 capacity of about 110 million acres will be permanently damaged, 

 and about 500,000 acres annually will be essentially ruined for fur- 

 ther cultivation unless this land is placed under a sound conservation 

 farming system within the next 10 to 15 years. On another 110 to 

 120 million acres, soil erosion is proceeding at a less rapid but still seri- 

 ous rate. To prevent serious or irreparable damage to these lands, they 

 should be safeguarded by conservation treatment within the next 15 

 to 30 years. 



Most agricultural specialists agree that, with present farming prac- 

 tices, seed varieties, and available fertilizer, about 2% acres of crop 

 land per person is needed to provide a United States "normal" stand- 

 ard-of-living diet (based on an average family income of $2,000). An 

 additional one-half acre is needed to provide other essentials such as 

 clothing and shelter. At 3 acres per person, the estimated 1949 popu- 

 lation of 150 million would thus require 450 million acres of crop 

 land. The Soil Conservation Service estimates the maximum potential 

 crop land in the United States that can be developed and permanently 

 maintained under existing economic conditions at 466 million acres 

 (that is, land that can be safely used indefinitely under rotation sys- 

 tems of farming and with adequate conservation practices, irrigation, 

 drainage, flood protection, etc.). 



The United States population for 1975 has been variously forecast at 

 162 to 185 million persons (U. S. Congress, 1948). Assuming a median 

 value of 174 million, an increase of 24 million, an additional 72 million 

 acres should be available by that date to maintain without further 

 soil deterioration the present normal standard of living at existing 

 rates of crop production per acre. There is a difference of only 22 

 million acres, however, between the 444 million now needed and the 

 estimated 466 million acres of potential crop land. Thus, even with 

 due allowance for probable increased yields per acre resulting from 



