WHAT IS BECOMING OF OUR SOILS? 213 



" Along the banks of the Ohio River and in very 

 many portions of the South hundreds of fields that were 

 once covered with sturdy forests of oak, maple, walnut, 

 and pine, and which bore under cultivation-, after being 

 cleared of the natural growth, large crops of wheat, 

 maize, tobacco, and cotton, may now be seen furrowed 

 with gullies as with the wrinkles of age, and abandoned 

 to brush and briers. 



" A surface layer of good agricultural soil 6 inches 

 deep resulting from the slow and gradual disintegra- 

 tion and decay of rocks and accumulation of humus 

 may have required hundreds of years for its natural 

 formation, and yet it is liable to be washed away in a 

 single storm. 



" This excessive erosion, or washing, of lands may be 

 prevented, and the already gullied fields may be recov- 

 ered, and steep slopes of loose material may be held and 

 prevented from washing : 



" (1) By chemical means, in the application of 

 manures and fertilizers and in the accumulation of 

 organic matter, which change the texture of the soil 

 and make it more porous and more absorbent of water, 

 so that there is less to run off over the surface. 



" (2) By means of cultivation and underdrainage, 

 which prevent erosion by distributing the surface flow 

 over the ground and increase the amount carried off 

 by underdrainage. 



" (3) By reforestation, or the planting of trees, 

 which act mechanically to prevent washing. 



" (4) By grass and similar vegetation, which bind 

 the soil grains and prevent their washing away. 



" The erosion of a soil is caused by the wearing of 

 the rain and snow waters which can not penetrate into 

 the soil fast enough to be carried away by underdrain- 



