330 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1957 



abandoned or passed on to another who continued the skimming 

 process. The greater part of the habitable land was occupied within 

 a century. Then followed a period of soil-exhausting agriculture 

 when the unimproved soils were bled not only to keep their owners 

 alive, but also to feed the teeming urban populations of Europe and 

 thereby to provide some capital for founding American industry. The 

 land got back little for what it gave, but in the mushrooming cities 

 seeds were being sown which would bring forth a rich harvest of 

 soil fertility. 



The disastrous effects on unfertilized American soil of huge exports 

 of food, mainly to Europe, are very evident at the present time in the 

 widespread occurrence of soil erosion, a disease from which many 

 other parts of the world are also suffering. Food exports, of course, 

 were only one of many causes of the rapid exhaustion of American 

 soils that in its turn was the immediate cause of soil erosion by the 

 physical breakdown of soil structure. That all this erosion should 

 have happened is usually regarded as unfortunate, sometimes as 

 tragic, and occasionally as sinful. Taking a global view of agricul- 

 ture, soil erosion is certainly a phenomenon of tremendous signifi- 

 cance today. It has been described as a symptom of maladjustment 

 between society and the soil, but I regard it, rather, as a symptom of 

 a normal stage of the evolution of soil under Man's control. Human 

 society destroys soil fertility before it begins to create it, and there is 

 nothing society can do about it until it has created a great surplus of 

 wealth, over and above what the land can produce, with which to 

 fertilize the soil. 



Unlike Europe, North America has not evolved a cast-iron social 

 system to check the outflow of fertility from the soil. Events have 

 moved too quickly. But in the 1930's the soil-conservation-district 

 movement was started in the United States, by which the farmers of 

 a district voluntarily organized themselves, with Federal and State 

 backing, to farm according to established soil-conservation practices. 

 The movement spread with astonishing rapidity, and today most of 

 the farmland is included in soil-conservation districts. In many dis- 

 tricts good intentions are more evident than soil conservation, but 

 that the movement should have swept the whole country in less than 

 20 years is most significant. The much greater effect on soil fertility 

 of a phenomenal increase in industrial production has to some extent 

 masked the direct effects of soil-conservation measures. 



Although the event is still too recent for us to be certain about its 

 significance, the economic depression of the 1930's may have been 

 the turning point in the evolution of American agriculture from soil 

 exhausting to soil conserving. During the depression millions of 

 acres of overworked land got a rest, and the virtues of grass as a 

 protector of the soil from erosion and as renovator of soil fertility 



