14 BUU:.ETIN 1306, U. S. DEPARTMENT OF AGRICULTURE 
soiled when plowed to a depth of from 6 to 8 inches below the plowing 
and then is plowed without subsoiling for two years. Aside from the 
subsoiling this plat is treated the same as plat B, the other fall-plowed 
plat in this series. A plat is listed in the fall for each of the small 
grains and worked down level shortly before seeding. For corn the 
listing is done at the time of planting, a lister planter being used. 
For winter wheat, spring wheat, and flax the fall plowing without 
subsoiling showed higher average yields for the 6-year period than 
the subsoiling, although there were instances in some years when the 
subsoiling yielded most. For winter wheat the average yields were 
14.2 and 13.5 bushels per acre, respectively, for the ordinary fall 
plowing and the subsoiling, for spring wheat 13.9 and 13.1 bushels, 
and for flax 5 and 4 bushels. 
With oats the difference in the average yields of the two plats was 
only 0.3 of a bushel. Barley on the subsoiled plat showed a slightly 
increased yield each year that a crop was produced, but it averaged 
only 3.5 bushels more than on the plat not subsoiled, the average 
yields for the six years being 24.6 and 21.1 bushels, respectively. 
This increase is not enough to pay for the extra work of subsoiling. 
Corn averaged 0.4 bushel more of grain and 150 pounds less of stover 
on the subsoiled plat than on the one not subsoiled. 
Every crop except barley yielded less on listmg than on ordinary 
fall plowing. The difference in yield ranged from 0.4 bushel per acre 
with flax to 7.8 bushels of grain and 510 pounds of stover with the 
corn crop. Barley yielded 0.8 bushel more by the listmg. The 
extra work required to put the listing in condition for seeding to small 
grains amounts to fully as much as the saving in the first tillage 
operation, and consequently listing for small grains can not be 
recommended. 
RESULTS WITH SOD CROPS 
Two rotations containing sod crops, one with alfalfa and one with 
brome-grass, are included in the experiments. Both are 6-year 
rotations in which the brome-grass and the alfalfa occupy the lan(? 
for three years, including the year of seeding. The sod is plowed up 
after the crop is taken off in the third year and is followed by oats, 
corn, and wheat in succession. No crop is secured the year of seeding 
the brome-grass or alfalfa. The }delds of brome-grass and alfalfa 
were included in the general report on crop yields summarized earlier. 
Yields of the other crops in these rotations do not vary noticeably 
from those obtained under similar conditions in other rotations. 
EFFECT OF SORGO ON SUCCEEDING GRAIN CROPS 
Sorgo (sweet sorghum) is grown in two rotations in which the 
yields following this crop may be compared with those following corn 
or other crops in other rotations. The average yield of sorgo was 
shown in Table 4, accompanying the discussion of average yields. 
Rotation 48 is sorgo, wheat, and oats, all on spring plowing. The 
average yield of wheat following sorgo for the 6-year period was 13.9 
bushels. This is 3.2 bushels less than the yield following corn and 
1.1 bushels less than that following other small grains in the rota- 
tions. The yield following sorgo was slightly less than that following 
corn each year and was lower than that following other small grains 
in three of the five years in which a crop was produced. The average 
