TIME OF PLOWING SMALL-GRAIN STUBBLE. 11 
f • 
from fall plowing, when wheat and corn gave higher yields from spring 
plowing, was 1912. This was a year when the yields of oats were near 
the maximum in that locality for the variety used — Kherson. In 
only one year "(1911) out of the six did fall plowing give the best 
results with all three crops. This also was the year in which early 
fall plowing gave a marked increase over late plowing with winter 
wheat. 
The yields of winter wheat on plats A and B, presented in Table V, 
are of interest. Three years out of the six one plat was plowed earlier 
than the other. The condition of the surface of the plats during the 
winter was the same, both being devoid of stubble and equally level. 
The only important difference in treatment was the time of plowing. 
In all three instances the higher yields have been on the earlier plow- 
ing. The only marked difference, however, was in 1911, when the 
earlier plowing had been done immediately after heavy rains and a 
large growth of weeds occurred on the later plowed plat before it was 
plowed. In the three years when there was no difference in time of 
plowing there was no difference greater than 1.3 bushels in yields. - 
While, this was a difference of more than 60 per cent, it will be noted 
that both plats were practically failures in that year (1913). In the 
six years the only marked difference in yields was in 1911, when the 
plowing was done 22 days earlier on plat B than on plat A and plat 
B yielded 5.1 bushels more than plat A. Except when early plow- 
ing had stored moisture by stopping weed growth, there was no 
marked difference in yields. The late fall plowing usually lost 
available moisture hj weed growth, which was not offset by a greater 
winter accumulation, as in spring plowing. 
In studying each year separately it is necessary to consider the 
precipitation. Data on the moisture content of the soil in the fall 
and spring and at harvest time will aid in giving an idea of the relative 
importance of fall and winter precipitation and the amount used by 
the crop. 
Figure 1 shows that in the fall of 1908, up to which time the plats 
had had uniform treatment, there was no moisture in the soil available 
to plants. August and September were very dry and plowing was 
not done until the weeds had been killed by frost. While there was 
heavy precipitation in November, 1908, and in March, 1909, the 
increase in moisture content was practically the same, the third foot 
of both plats being partially filled. Plat A gave a yield of 14.3 
bushels, and there was still some moisture available at the time of 
harvest. The greater number of weeds growing with the wheat in 
plat B probably accounts for the greater loss of moisture and the 
smaller yield. This statement is borne out by the yields of corn, 
which were practically the same from both the spring and the fall 
