44 BULLETIN 157, U. S. DEPARTMENT OF AGRICULTURE. 
fallow; seeding, cultivation, and harvesting the crop; frequency of 
cropping; and diversity of crops in rotation. 
The tests dealing with stubble treatment immediately after harvest 
were begun in the fall of 1911. The results so far obtained are not 
conclusive enough to warrant publication. 
The average results for five years, 1909 to 1913, inclusive, show 
that spring plowing was better than fall plowing for moisture con- 
servation, in yield of grain, and in cost of producing the crop. Spring 
plowing gave an average yield of 18.5 bushels per acre, as compared 
with 16.8 bushels for fall plowing. Owing to this difference in yield 
and the lower cost of producing the crop, spring plowing gave a net 
acre profit of $3.03 more than fall plowing. 
The results of five years show that there was no advantage in 
deep plowing or subsoiling over shallow plowing so far as moisture 
conservation is concerned. There was no material difference in the 
yields obtained from plats plowed at different depths, varying from 
5 to 18 inches. The highest average yield was obtained from plats 
plowed 10 inches deep, and the lowest average yield was from the 
plats subsoiled 18 inches deep, while the 5-inch plowing yielded 
higher than the 15-inch subsoiling. 
One year's results from a test of deep fall plowing and shallow 
spring plowing compared with shallow fall plowing and deep spring 
plowing show no difference in soil moisture and but slight difference 
in yield. 
The results of Hve years' experiments on fall-plowed fallow show 
that the moisture of the cultivated plats remained practically the 
same throughout the season, while that of the uncultivated plats 
rapidly declined, until by fall it was reduced to a comparatively 
low point. It is probable that weeds and volunteer grain were 
important factors in this loss of moisture. The average acre yield 
of the cultivated plats was 17 bushels, as compared with 13 bushels 
on the uncultivated plats. 
The results of one season on spring-plowed fallow show no differ- 
ence in the moisture content of the plats cultivated or not cultivated. 
The yields, 11.9 and 9.5 bushels per acre, favor the noncultivated 
plat. 
The results of 10 years show no correlation between the time of 
sowing winter wheat and the yield, but the best yields have usually 
been obtained from plats seeded between September 1 and October 
15. There was no significant difference between the average mois- 
ture content of the plats for any one or for all years. The chief 
problem in the time-of -seeding tests of winter wheat now seems to be 
a mechanical one involving some improvement of the machinery 
used in seeding. It is believed that this will obviate the necessity of 
