

Soil Conservation Service (Ia-154) 



DOWNHILL PLOWING INVITES EROSION 



We have removed the native cover of trees, shrubs, vines and grass. We have pul- 

 verized the soil and exposed it to the elements year after year, as in row-crop or 

 clean-culture farming. With this treatment, the rich soil is v/ashed from the upper 

 portions of slopes, burying the crops at the bottom 



1936), and developed on an enormous scale in Germany. During the 

 First World War the shortage of nitrogen compounds threatened to set 

 a limit to further fighting, especially in the central nations. The nitrogen 

 supply was important for military activities as well as for raising crops 

 and for industry, since all explosives are based on nitrogen compounds. 

 Haber's invention solved the nitrogen problem for the Germans, and en- 

 abled them to hold out for many months longer than would otherwise 

 have been possible, 



Haber died in Switzerland, an exile from his native land. In the 

 meantime, the leading nations of the earth have been using his process, 

 with various improvements, for converting atmospheric nitrogen into 

 ammonia, nitric acid, and other essential compounds. These are widely 

 used in fertilizers, in industry, and in explosives. In this way these na- 



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