280 TWENTY-FIFTH ANNIVERSARY REPORT. 
some in treatment of onion diseases, which are discussed elsewhere 
(p. 140); and one series*’ extending over one season on one farm 
and four seasons on another, in which various quantities of ferti- 
lizer were compared. 
It is the practice of onion growers in this section to supply their 
crops with large amounts of plant-food, in some cases as much as 
a ton or more of high-grade complete fertilizer annually. Consider- 
ing any possible demand of the onion crop on the soil, these large 
amounts appeared wasteful; and the tests proved this to be the 
case. 
On each farm and in each year duplicate tenth-acre plats were 
left without commercial fertilizer or received, in amounts increasing 
by 500 pounds, as much as a ton to the acre. The seasons varied 
from poor to good, so far as onion production was concerned, and 
accidental interferences, like floods, and insect and fungus pests, 
affected the different plats to a similar extent so that the tests gave 
dependable indications of the effect of the different quantities of 
fertilizer. In each year of the four-year series there was a satis- 
factory increase and good profit from the use of 500 pounds to 
the acre, and a slight increase and small profit from the 1,000 
pounds and 1,500 pounds applications, but a financial loss from 
the use of the additional 500 pounds which raised the application 
to a ton to the acre. 
On the other field, in which the test was made for only one year, 
the ground had grown onions and been well manured for several 
years. The crops gave only a slight profit from the use of the 
smallest amount of fertilizer, 500 pounds, and a loss from the use 
of amounts greater than this. 
“The results of these experiments show clearly that the crops 
were limited more by other conditions than by the extent of the 
plant food supply. With the best conditions of season and water 
supply, the smallest amount of fertilizer supported the maximum 
crop.” 
POTATOES. 
In few, if any, other Stations has as much attention been given 
to the potato, and along certain lines of investigation the work of 
the Station is classic. In early years the study of the seed received 
almost uninterrupted attention for eight or ten seasons, and it 
would seem that no possible factor was overlooked that might in- 
“Bul. 206; same, Rpt. 20:236-244 (1901). 
