264 



Bulletin 261. 



TABLE IV 



Table Showing the Apparent Increases in Yield Due to the Different 



Fertilizing Elements 



No. 



of 



Plats 



I 

 I 

 1 

 I 

 I 

 I 



4 

 2 



Fertilizing Elements 



Average 

 of 3 

 years 



Nitrogen 



Phosphorus 



Potassium 



Nitrogen and phosphorus 



Nitrogen and potassium 



Phosphorus and potassium 



Nitrogen, phosphorus and potassium 

 Farm manure, 10 and 20 tons 



lbs. 



1,211 

 682 

 988 



1,614 

 2 ,082 

 1,079 

 3.230 

 4,075 



It will be noticed that when the fertilizers were applied singly, nitrogen 

 stood first in increasing the yield, potassium second and phosphorus 

 third. When they were applied in combinations of two, nitrogen and 

 potassium stood first, nitrogen and phosphorus second, and phosphorus 

 and potassium third, while the most marked increase was obtained 

 when a fertilizer containing all three of the elements was add^d. How- 

 ever, the figures in Table V referring to the complete fertilizers are at 

 first a little misleading from the fact that some of the plats thus treated 

 received larger amounts of the single elements than when only one or 

 two elements were applied ; thus, when the quantities of the elements on 

 the several plats remained the same, the average increase during the past 

 three years for the complete fertilizer is 2082 pounds per acre. The 

 plats that received mineral fertilizers only, and more especially the one 

 that received the single application of potassium, produced a rank growth 

 of alsike clover, and it is without question that this is partly the cause 

 of the increase in yield on these plats. When nitrogen was added the 

 growth of clover was not noticeable. 



RELATION OF NITROGEN TO PHOSPHORUS 



It has been pointed out in a previous report on this experiment that 

 in the production of timothy hay on Dunkirk clay loam the relation of 

 nitrogen to phosphorus is a matter of considerable importance. If we 

 examine Table V closely it will be evident that the effect of adding 

 relatively large quantities of phosphorus, as compared with the amount 

 of nitrogen added, has been to decrease very decidedly the yield of hay. 



