New YorK AGRICULTURAL EXPERIMENT STATION. 229) 
In 1898, the first year, when the yield of potatoes was fairly 
large, the entire absence of potash from the fertilizer was with- 
out influence on any one of the four farms. Forty pounds of 
nitrogen and eighty pounds of phosphoric acid per acre without 
potash caused as large an increase of tubers aS when accompanied, 
by one hundred pounds of potash. In the two succeeding years, 
while the crops were small on all plats, potash either in small or 
large proportions had little effect. It must be conceded that up 
to the point to which these experiments have been carried, nitro- 
gen and phosphoric acid, one or both, were the ingredients upon 
which dependence could be placed as a source of profit. 
Experimental results no more extensive than those herewith 
reported should not be taken as justifying the exclusion of potash 
from commercial fertilizers. This is in any case a local question. 
There are good reasons for inquiring, however, whether, consider- 
ing the capacity of our soils and in view of considerable experi- 
mental data, the importance of potash salts has not been some- 
what overestimated by Long Island potato growers. 
PRACTICAL LESSONS TAUGHT BY THESE 
EXPERIMENTS. 
It seems to the writer that practical lessons of great value may 
be drawn from the results of these experiments. In the first 
place, it is clearly shown that the use of very large quantities of 
commercial plant food is attended with great financial risk unless 
all conditions of soil and season are favorable. But even when 
the best conditions prevail, the largest crop which may be secured 
by a very liberal application of fertilizers is not necessarily the 
most profitable. The money balance from a medium crop may 
often be larger than from a maximum yield for the reason that 
the fertilizer cost per unit of production increases very rapidly 
after the production passes a certain point. It is only with very 
high priced crops that excessive feeding is justifiable from the 
standpoint of good business management. 
Again, it is well worth much time and careful observation to 
discover the needs of a soil upon which commercial fertilizers are 
