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218 NORTHEAST EXPERIMENT FARM. 
ieties, planted on better drained soil, gave this year 209.6 
bushels per acre. In 1901 the potatoes were planted ona 
sandy soil well drained with the exception of two corners, 
which were low. Upon these low spots, aggregating one-fifth 
of the field, the crop was completely ruined by rains, but the 
rest of the field averaged 158 bushels per acre. 
The yield for 1902, when the crop was placed entirely 
upon well drained soil averaged for the fields, 202.9 bushels. 
This figure is as fair as any to represent the average possi- 
bility for potatoes, when mistakes are avoided. Under good 
management it may be higher, as is shown by the average 
yield of the potatoes grown in variety tests for six years. 
These plots naturally received the best location and treat- 
ment. They gave 242.7 bushels for all kinds, good and poor 
during that period. But the average of the fields, omitting 
the year of ’99, was 149.6 per acre, the difference being due 
largely to drowning out. 
The question of variety, with potatoes, is one of great 
importance, as there is a wide difference in yield. The 
difference averaged for 48 varieties, for two years, 214 
bushels per acre, the highest yield being 246.3 bushels 
and the lowest, 132.3 bushels. Earliness, shape, color, 
size, keeping qualities and flavor give a wide range of 
choice, but between two varieties of equal merits in other re- 
spects, the question of yield is all important. It is not easy 
to test a large number of kinds for yield and be sure that the 
results really represent their relative producing power. The 
sensitiveness of potatoes to moisture in the soil causes a 
variation in yield every few feet, due to slight elevation or 
depression of the surface level, or change in the soil texture. 
There are other minor sources of variation not due to the 
potatoes, but the difference produced by moisture is far in 
excess of any other. The varieties to be tested should be 
grown in plots small enough toconfine them all to a piece of 
ground which can be selected of fairly uniform character. If 
an equal number and weight of seed pieces be planted of each 
variety, an average of four or five years vields may be trust- 
ed to fairly indicate the best yielders, were it not for this 
variation due to soil moisture. There is a simple way of 
