69 



RESULTS OF THE ADDITION OF PHOSPHORIC ACID TO 



Nothing, 



Large, bushels per acre,- 17.89 — 1.44 

 Small, " " —2. 



Value of net average increment, $1.41. 



Financial result, 3.39 loss. 



RESULTS OF THE ADDITION OF POTASH TO 



Nothing. 



Large, bushels per acre, 84.17 

 Small, " " —9.00 



Value of net average increment, $42.03. 



Financial result, 38.83 gain. 



RESULTS OF THE ADDITION TO NOTHING OF 



The teaching of the results of these comparisons is perhaps some- 

 what less obvious than it would have been, had plot 10 been planted 

 at the same time as plots 1 to 9. There appears no other sufficient 

 reason why 10 should have given a poorer crop than 9, since nitrate 

 of soda which was added to the fertilizer used on 9, in other cases 

 proved quite beneficial. Still the teaching of the results of the 

 experiment, as a whole, is clear. This soil stands in greater need of 

 potash for potatoes than of either of the other ingredients of the 

 fertilizers used. It is significant that the requirements of corn on 

 similar soil, as shown liy the experiments of 1889 and 1890 were the 

 same. In view of the confirmatory results of the experiments of 

 three successive years upon it, a very marked deficiency of potash in 

 this soil cannot reasonably be doubted. 



Neither lime nor plaster benefited the crop of potatoes of this 

 year ; and the same was true of the influence of these substances 

 upon the corn crops of the two preceding years. 



For this soil, a jpotato fertilizer should have about the same compo- 

 sition as recommended for Marblehead {p. 56. ) 



