248 REPORT OF THE CROP PRODUCTION. 
The necessary proportion of potash—Observations which the 
writer has made in watching the growth of plants in pot culture | 
with known supplies of plant food has led him to inquire whether 
the practice of computing the needs of a crop on the basis of 
what it contains of potash and certain other ingredients is 
rational. Does the plant need all the potash it takes up? If 
not how much does it need? In the experiments of 1898-1899 
the peas grew as rapidly and matured as fully with .146 grams 
of potash per pot as with 1.462 grams. Many facts have come 
to light which go to prove that the proportion of mineral com- 
pounds taken up by plants is much modified by the soil supply 
of these compounds. This being the case, what is the minimum 
proportion necessary for the fullest development of the plant? 
This is an important question. A crop of potatoes may with- 
draw 100 lbs. of potash from an acre of fertile soil, but if 50 lbs. 
would have been sufficient it is greatly desirable that the farmer 
should understand the fact. 
This problem is just now the subject of investigation at this 
Station and it is hoped that by giving it extended study reliable 
conclusions may be reached. | 
