FIELD EXPERIMENTS WITH FERTILIZERS. 



145 



Table 74. 

 Average yield per acre in Station soil test during twelve years. 



While some slight differences are shown as to the peculiar 

 needs of crops, the soil as a whole seems to be lacking in all 

 three of the essential fertilizer ingredients. The following con- 

 clusions as to the needs of particular crops seem warranted. 

 Oats have shown marked increase in yield from the use of ni- 

 trogen and phosphoric acid, while corn has seemed to need all 

 the ingredients applied in the fertilizers. Potatoes, on the other 

 hand, have been most benefited by applications of potash. Thus 

 the special needs of different crops are to some extent indicated 

 by these tests. They can only be told with certainty, however, 

 by long experimenting, under similar conditions. 



