64 The Inexhaustible Resource of Technology 



be revised as such additional knowledge becomes available, and im- 

 proved classification schemes better founded on soil morphology 

 might make possible a more rational separation of soils adapted for 

 different use. Under such an improved classification scheme some 

 soils might best be used for agriculture, some for forestry, but others 

 as areas of ground-water recharge or for other water management 

 purposes. 



Although the effectiveness of erosion control programs has in- 

 creased, this improvement has come principally, in my opinion, from 

 empirical trials rather than a greatly increased depth in knowledge of 

 the erosion process. Basic understanding of principles appears to me 

 to offer the main source of further improvement in erosion manage- 

 ment techniques. 



We cannot of course prevent erosion in the broad sense, any more 

 than we can prevent in the broad sense aging or growth in plants or 

 animals; we can in a small, but to a constantly increasing, degree 

 modify such phenomena and take advantage of our knowledge of the 

 controlUng principles in order to achieve effects more nearly in accord 

 with our desires. Soil conservation practices, based on such knowl- 

 edge, give great promise not only in the maintenance of present soil 

 resources, but also in reducing the sediment load carried by the 

 streams, and deposited in reservoirs. A preliminary report on Brandy- 

 wine Creek, Delaware, shows evidence of the effectiveness of land 

 management programs for control of sediment; -^ it indicates a reduc- 

 tion of 38 per cent in the sediment load from this small eastern drain- 

 age basin- within an eight-year period as the result of adoption of a 

 watershed treatment program with practically no dams or other struc- 

 tures. 



In general, we can say that watershed treatment programs will be 

 especially effective in control of sediment movement; their effect on 

 the disposition of water probably needs more study before we can 

 arrive at a definite conclusion, 



I am also intrigued at the long-range possibilities of research on the 

 nutritional requirement of specific crops, including laboratory studies 



-^ H. P. Guy, "The Trend of Suspended-sediment Discharge of the Brandy- 

 wine Creek at Wilmington, Delaware, 1947-1955," U.S. Geological Survey 

 Open File Report, 1957, 55 pp. 



