26 BULLETIN 157, U. S. DEPARTMENT OF AGRICULTURE. 
not later than October 1. When seeding is delayed until very late 
in the fall there is great danger of injury to the young plants if 
germination occurs, from what may be termed "fall killing." They 
are in a very critical condition when freezing weather arrives. An 
open winter following this injury results in almost total failure of 
the crop, regardless of the tillage methods used in preparing the 
land and of the amount of moisture stored in it. 
As practical examples of the points brought out in the preceding 
discussion, the past four seasons, 1909-10 to 1912-13, are worthy 
of consideration. The seedings on August 15 and September 1, 
1909, were made when, owing to recent rains, there was plenty of 
moisture in the first foot to cause good growth. The yields of these 
plats in 1910 were high in comparison with those of the plats sown 
later, when the weather was dry and cold. The seedings on Sep- 
tember 15, 1910, were made under conditions similar to those in 
August, 1909. The yields on these plats were higher than those 
seeded "in the dust" in August and those sown late in October. 
In the fall of 1911 and again in 1912 the weather was dry until 
early October, after which time there was plenty of moisture, but 
the weather was cold. As a result of these conditions the yields 
of both early-sown and late-sown crops were low. Figure 15 shows 
the relation of precipitation to yield in this instance. The black- 
ened portions of the figure illustrate the daily precipitation from 
August 1 to November 30, inclusive, and the curves represent the 
yields in bushels per acre of the two varieties of wheat seeded on 
different dates during these months. 
It will be seen that early seeding if done in wet weather gave 
high yields, while it gave low yields, and sometimes almost failures, 
when done in dry weather. It is also shown that late seeding, even 
when there was plenty of moisture, often resulted in serious loss 
because of injury to the tender plants by freezing. There seems 
to have been some difference in the effect of these climatic condi- 
tions on the two varieties. This may have been due to a difference 
in the time of germination between the hard (Turkey) variety and 
the soft (Koffoid) variety. The writer is of the opinion that this 
difference in germination is largely responsible for the differences in 
yield. The soft wheat seems to germinate more rapidly than the 
hard wheat, and for this reason it is more advanced on a given date 
than the latter variety. This may not always be advantageous to 
it, as it may be in a tender stage of growth when drought or cold 
weather strikes it, and thus it may be injured more than the un- 
germinated seed of the hard variety. On the other hand, the soft 
wheat may be sufficiently far advanced to protect it from injury, 
while the slower germinating Turkey wheat may be still in a tender 
stage of growth. 
