LESSONS FOE AMEEICAN POTATO GROWERS. 5 
as to other reasons. We have, in fact, better soils than Europe in 
almost unlimited area, including types especially adapted for pota- 
toes, and we actually produce, in a few sections where potato growing 
is made a specialty, as large crops as the Germans. 
CLIMATE. 
It must be recognized that northern Europe, with its cool and 
equable summer, has a climate better adapted to the potato than any 
except possibly the most northern part of the United States. The 
average mean temperature for Jury in Posen, in north Germany, is 
64° F. Practically all of our potato districts, with the exception of 
Aroostook County, Me., lie south of the isotherm of 65° F., and the 
average summer heat in most of our potato States is not far from 10° 
higher than in Germany. Most of our varieties of potatoes are unable 
to withstand high temperatures and in the southern two-thirds of our 
country are subject to tip-burn, sun scald, and other troubles, which 
result in abnormal maturity. Farther south, as is well known, only 
early spring or fall crops can be grown. Much of the area of the 
United States is not in the potato belt. 
On the other hand, the rainfall of Germany is often less than is 
needed for maximum production, and if we had a heat-resistant potato 
our more liberal precipitation would give us a decided advantage. 
The average annual rainfall in Posen is less than 19 inches, of which 
nearly 13 inches fall in the growing season, from April to October, 
inclusive. Northern Maine has, however, 20 inches during the same 
summer period, western New York about 24 inches, and Michigan 
20 inches. In the irrigated districts of the Western States the pota- 
toes receive perhaps even more water than they require. The cool 
nights of these regions and their midday heat subject the potatoes 
to temperature changes greater than are found in Germany. 
COMPETITION WITH MAIZE AND PETROLEUM. 
There is a fundamental economic condition in the United States 
that will always influence the extension of potato culture. The hot 
summers which are so injurious to the potato plant are ideal for the 
development of Indian corn, so that in the corn belt there can be no 
profit in growing potatoes in excess of those needed locally for table 
use. Corn can be produced more economically, is better for stock 
feeding, and is a cheaper source of starch, glucose, and alcohol. The 
scarcity and high cost of farm labor in the United States are other 
economic factors that influence the result. Farther north, however, 
and in the elevated districts of the West where corn can not so well be 
grown, the potato has a larger place. 
