1903.] 



PUBLIC DOCUMENT — No. 33. 



Ill 



of the clover sod, as shown hy the fact that the potato crop 

 of 1900 grown upon the clover sod was almost as good 

 where no nitrogen fertilizers have been used for eleven 

 years as it was where such fertilizer has been annually used 

 in fairly liberal amounts. The cro}) in 1901 was soy beans. 

 For the present season it was potatoes. The average jdelds 

 for this year as well as for the previous years during which 

 the experiment has continued are shown by the table : — 



Effect of Ler/inninous Crops upon the FoUoiving Crop (Pounds). 



Effect of Leguminous Crops upon the Following Crop (Pounds) 



— Concluded. 



1 Dry beans and straw. 



There are three plots in the field which have received 

 neither manure nor fertilizer supplying nitrogen since 1884, 

 and the figures showing yields are the averages for these 

 plots. The figures for the nitrogen plots show the average 

 products of the eight plots in the field which have yearly 

 received an application of materials furnishing nitrogen in 

 fairly liberal amounts. These materials are as follows : 

 barnyard manure, one plot ; nitrate of soda, two plots ; 

 sulfate of ammonia, three plots ; and dried blood, two plots. 

 At the rates at which they are used, these materials furnish 

 45 pounds of nitrogen per acre, and they are so used that 



