SOIL EROSION IN THE SOUTH. 23 



In navigable streams the deposition of this sediment in the stream 

 bed causes a fiUing or shifting of the channel and the formation of 

 bars. The Koanoke River is reported to carry 3,000,000 tons annu- 

 ally, the Alabama 3,039,900 tons, the Savannah 1,000,000 tons, and 

 the Tennessee 11,000,000 tons, while other rivers carry hke amounts.^ 

 This indicates the extent of the loss of soil material, together with 

 the additional losses just described. 



The economic aspect of soil erosion has been discussed by a number 

 of authorities,^ who agree that the United States is losing millions of 

 dollars each year from this cause.' The report of the National Con- 

 servation Congress, 1909,^ states that in the United States there are 

 6,076 square miles of farm land, or 3,888,640 acres, devastated by 

 soil erosion an area which is equal to 100,000 farms of nearly 40 



acres. 



SUMMARY. 



Soil erosion is a natural process, tending to level the land. Gen- 

 erally under natural conditions it is slower than the formation of 

 soil material from the parent rocks. 



Destruction of the natural growth and clean cultivation on hilly 

 land, without protection against erosion, results in the removal of 

 the soil material by water more rapidly than it is formed and in a 

 very irregular manner. 



Owing to the climatic and soil conditions the South is especially 

 susceptible to excessive erosion. The economic conditions and type 

 of asrriculture of this section also contribute to the excessive erosion. 



Methods of prevention should be practiced wherever hilly land is 

 used for crops. Terracing is the best and most efficacious method, 

 but should be supplemented by deep plowing and the incorporation of 

 organic matter when permissible. 



The agricultural problem involves the adoption of proper crop 

 rotation in connection with preventative methods best suited to soil 

 conditions and crop production. 



The reclamation of eroded land is possible, but requires careful 

 attention and patience. The use of such land for forestry is com- 

 monly advisable. Nature effects reclamation, but the process is 

 slow and tedious. 



The losses annually to agriculture and in expenses incurred at 

 power sites and in maintaining navigable channels arc enormous, 

 and constitute one of our greatest national wastes. 



» Amer. Rev of Rev., 89, 439 (1909). 



» See: N. S. Shaler, p:conomic Aspect of Soil Emsion, Nat. Oeog. Mag., 7, .328-38 (1896); T. C. Chamber- 

 lain, Soii Wastage, I'roc. of Conf. of Governors on (Jon.servation , IIoiiso Doc. 128, pp. 7.'>-8.'J (1908); Top. 

 8ci. Mo., 73, .5-72 (W)H); W. W. Ashe, Waste from Soil Krosion in liio Soiitii, Amor. Uov. of Kov., !»), 439- 

 4.3 nw/J). 



' Report Nat. Con. Cong., H. J>fx;., No. <>7n, Wth Cong., 2d sess. (1909). 



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