113 The Agricultural Economy of the American Bottoms 
in a given area, farmers in general show intelligence in the selection of 
crops which are adapted to soil characteristics. 
Climate and weather —Climate exercises a dominant influence on the 
types of crops that persist in a region over a long period of time. Weather 
is highly significant in determining the success or failure of crops in a 
particular season. The farmer's remote interest is in climate; his im- 
mediate interest is in weather. Since weather conditions from year to 
year are characterized by marked variations in the American Bottoms 
and adjoining areas, climatic data may vary materially from comparable 
weather data for a given year (Table 5). The weather conditions that 
prevailed at particular times during past years are not reliable indices 
as to weather conditions that will prevail at corresponding times during 
a current year. While the rule of averages reveals the mode, there is 
considerable variation in the particular time when different farmers 
engage in such activities as planting, cultivating, and harvesting. Such 
differences are due in part to individual interpretations of weather 
phenomena and their effects. Although a farmer may plan his work 
just as carefully one year as another, weather variations, especially as 
to precipitation and temperature, result in appreciably different yields. 
“If we get the right kind of weather, we shall have a good crop” is a 
current expression among farmers. Scarcely a year passes without the 
occurrence of some weather phenomena which the farmers consider 
unusual. Unusual weather phenomena may be considered normal oc- 
currences of the American Bottoms. 
The last killing frost in spring occurred on March 29th! in 1933; 
the first killing frost of autumn occurred on November 8th. The time 
span of 224 days was fifteen days longer than the average length of 
the growing season, which was a favorable span for raising the custom- 
ary crops. The precipitation for March and April was slightly above 
normal; the precipitation for May was almost twice the normal amount 
(Fig. 20). The wet spring delayed planting and resulted in much 
fallow land, especially in poorly-drained sections. The mean tempera- 
tures for March, April, and May, were close to normal (Fig. 21). The 
mild, rainy weather for these months favored wheat, except where €x- 
cess water remained too long on the surface. June, however, was the 
warmest June on record (1837-1933), and the second driest June. Wheat 
1Roscoe . : 
ese: Darema, 1034) 2 ze eleorological Summary for St. Louis, Missouri (St. Louis? 
