1912.] PUBLIC DOCUMENT — No. 31. 39 



On the basis of increase as compared with the no-nitrogen 

 plots the relative standing for the different nitrogen fertilizers 

 for the twenty-two years is as follows : — 



Per Cent. 



Nitrate of soda, 100.00 



Barnyard manure, ......... 78.71 



Dried blood, 73.29 



Sulfate of ammonia, ......... 53.74 



It will be noted that nitrate of soda, as in previous years, 

 shows a much greater average increase than either of the other 

 sources of nitrogen. 



One of the most striking results of the past season was the 

 relatively large yield produced on the no-nitrogen plots. It 

 amounts to about 95 per cent, of the average yield on all the 

 different plots which have received an application of nitrogen 

 annually. This result, it will be readily understood, was no 

 doubt due to the fact that clover for three years had |)receded 

 the corn crop of the past year. The figures em})hasize in a 

 most striking way the extent to wdiich rotations including a 

 legume may be made to take the place of the use of nitrogen 

 fertilizers. 



II. MUKIATE AS COMPARED WITH SuLFATE OF PoTASir. 



These comparisons were begun in 1892. Five pairs of plots 

 are under comparison. From 1892 to 1899 potash salts were 

 used in quantities (varying in different years, but always in 

 equal amounts, on the two members of a pair of plots) ranging 

 from 350 to 400 pounds per acre. Since 1900 the quantity 

 used has been uniform on all plots, and at the rate of 250 

 pounds per acre annually. The only other fertilizer material 

 applied has been fine-ground bone to each plot at the uniform 

 rate of 600 pounds per acre. The past year is the twentieth 

 year of these experiments. The crops during the je&v were 

 alfalfa on one pair of plots, clover on one pair, and asparagus, 

 rhubarb and blackberries, each occupying a part of a pair of 

 ]dots. The rates of yield per acre on the different potash salts 

 are shown in the following table : — 



