forest openings, the vegetative cover is destroyed to the very 

 roots, run-off is accelerated, and erosion begins its destructive 

 work. 



When the settler cuts his woodland and grubs out the 

 stumps and roots, or when he turns under the natural sod 

 cover; when in addition he cultivates the soil to a powdery 

 state easily carried by even thin sheets of running water; 

 and when he finally arranges drainage so that precipitation 

 is rushed to ditches and the streams; he increases the relative 

 proportion of run-off. This run-off if he is not a careful 

 farmer in this respect, as most have not been proceeds not 

 gradually but at an accelerating rate, and carries with it out 

 of the reach and usefulness the fertile top layer of soil which 

 is the farmer's greatest asset. Sheet erosion is the least 

 spectacular but for that reason the most dangerous form of 

 erosion. Gradually the per acre productivity of the farmer's 

 land declines as the elements for plant life are leached out 

 or are carried away bodily with the entire mass of the soil 

 itself; gullies form and eventually the farm is ruined; and 

 progressively the farmer sinks to the level of striving to eke 

 out a meager existence by seeking bread in gravel and stone. 



Studies of soil losses from various causes have been made 

 at agricultural experiment stations, and in the following table 

 are reproduced data from the erosion experiment station of 

 the Soil Conservation Service at Bethany, Mo. Inspection 

 of it discloses that the greatest average annual soil and water 

 losses are from fallow (spaded) soils, and the next greatest 

 from continuous single cultivated-crop soils (in this instance 

 corn) ; while the losses are much less from soils where there is 

 rotation of grass and cultivated crops, and are almost negli- 

 gible from soils covered continuously with grass or alfalfa. 

 Such exact data give indications of the nature of the agricul- 

 tural technique, to be considered later, which should be 

 observed by all farmers; one that will result in a rational bal- 

 ance of current income with conservation of soil assets. 



No nation, however vigorous it may otherwise appear to 

 be, can survive a progressively declining agriculture. The 

 sustenance it draws from the soil determines its powers of 



34 



