1911.] PUBLIC DOCUMENT — No. 31. 35 



The different materials furnishing either nitrogen or potash 

 are used on the several plots in such amounts as to furnish, re- 

 spectively, equal quantities per plot of nitrogen and of potash; 

 two of the three no-nitrogen plots which serve as checks receive 

 potash in the form of muriate, the other in the form of sulfate, 

 and all the plots in the field receive an equal liberal application 

 of dissolved bone black as a source of phosphoric acid. 



The crops grown in the order of their succession have been: 

 oats, rye, soy beans, oats, soy beans, oats, oats, clover, potatoes, 

 soy beans, potatoes, soy beans, potatoes, oats and peas, corn and 

 clover for the last three years. The clover crop of the past 

 year, as was true of the two preceding years, was considerably 

 mixed with grass. The seed was sown early in August, 1909, 

 and just previous to the sowing of the seed one-half of each of 

 the plots in the field received a dressing of lime, at the rate of 

 a ton and one-half to the acre. It was thought that such an 

 aj)plication of lime would increase the efficiency of the sulfate 

 of ammonia as a source of nitrogen, and to some extent this ex- 

 pectation appears to have been realized. The differences, how- 

 e\'cr, between the limed and unlimed halves of the plots were 

 relatively small, and the yields on the two halves were not sep- 

 arately determined. 



The best crop of the past year was produced where nitrate 

 of soda was nsed as a source of nitrogen ; but the yields on 

 dried blood and on sulfate of ammonia used in connection 

 with sulfate of potash were not much inferior. On the basis of 

 100 for nitrate of soda, the relative standing of the different 

 nitrogen fertilizers and the no-nitrogen plots as measured by 

 total yield during the jiast season was as follows : — 



Per Cent. 



Nitrate of soda, 100.00 



Dried blood, 93.73 



Sulfate of ammonia, 95.53 



Barnyard manure. . . . . . . . . ,94.75 



No nitrogen, 91.79 



The relative standing of the different materials as indicated 

 by total yield for the twenty-one years during which the experi- 

 ment has continued is as follows : — 



