230 REPORT ON Crop PRODUCTION. 
to be continuously used. The outcome of extensive experiments 
for four years on four farms presents good reasons for question- 
ing the wisdom, under the conditions involved, of applying more 
potash on potatoes than any other ingredient. It is now a trite 
statement, but a true one, that each farmer must discover for 
himself the fertilizer needs of his farm. Such experiments as 
these are suggestive, but the results are put to their best use 
when they serve as the basis for similar observations by indi- 
vidual farmers. 
One fact, no less important than any other mentioned, to which 
these experiments point, is that the proportion of available plant 
foed in the soil is only one factor in crop production. It is not 
enough that a plant have within reach all the raw materials 
from the mineral world that it needs for luxuriant growth. Its 
environment must be congenial both in the soil and out of ik 
if the raw materials are to be appropriated to the maximum 
extent. This means that soi] texture and warmth, conditions 
which are largely dependent upon culture and the supply of 
humus, must be given careful attention. The result of neglect- 
ing these conditions can never be fully overcome by the liberal 
purchase of fertilizers. yey 
