214 DRY-FARMING 
fertility the spring is not so desirable as the fall for 
germination. More important, grain sown in the, 
fall under favorable conditions will establish a good 
root system which is ready for use and in action in 
the early spring as soon as the temperature is right 
and long before the farmer can go out on the ground 
with his implements. As a result, the crop has the 
use of the early spring moisture, which under the 
conditions of spring sowing is evaporated into the air. 
Where the natural precipitation is light and the 
amount of water stored in the soil is not large, the 
gain resulting from the use of the early spring mois- 
ture often decides the question in favor of fall 
sowing. 
The disadvantages of fall sowing are also many. 
The uncertainty of the fall rains must first be con- 
sidered. In ordinary practice, seed sown in the fall 
does. not germinate until a rain comes, unless indeed 
sowing is done immediately after a rain. The fall 
rains are uncertain as to quantity. In many cases 
they are so light that they suffice only to start ger- 
mination and not to complete it and give the plants 
the proper start. Such incomplete germination fre- 
quently causes the total loss of the crop. Even if the 
stand of the fall crop is satisfactory, there is always 
the danger of winter-killing to be reckoned with. 
The real cause of winter-killing is not yet clearly 
understood, though it seems that repeated thawing 
and freezing, drying winter winds, accompanied by 
