24 BULLETIN 1173, U. S. DEPARTMENT OF AGRICULTURE. : 
Table 11 shows that the highest average yield of winter wheat was 
obtained from plowing for summer fallow on April 1 and thesecond — 
highest average yield from plowing early in the fall with the mold- 
board plow. The lowest average yields were obtained from the late | 
fall and early summer plowing. 
In the years 1914 to 1919, inclusive, when two types of: plows were 
used for the fall-plowing experiments, the average yields obtained — 
were as follows: 
Disk plow, ‘carly (dry).-27 sacs. ee eee 24.8 bushels per acre. 
Disk plow, late (wet):..22.-. 07. i= eee 23.7 bushels per acre. 
Moldboard plow, early (dry)..................-- 27.2 bushels per acre. 
Moldboard plow, late ret. BaP ee Se ek Fa Me 24.3 bushels per acre. 
These results indicate that for early fall plowing the moldboard 
plow was the better type. However, in considering the yields of 
the check plats it appears that the ground on which was located the 
series of plats plowed early in the fall with the moldboard plow was 
considerably better than that on which was located the series plowed 
late in the fall. The average yield obtained from the early fall 
plowing, therefore, undoubtedly is higher than it should be when 
compared with those for the other dates of plowing. 
The physical texture of the soil at Moro is such that when plowed 
dry in the fall with a moldboard plow it turns up in large lumps, so 
that the ground is left very rough during the winter. ‘This is not 
true of the late fall plowing, which is done after the autumn rains 
have penetrated the soil sufficiently to make the ground plow easily 
and well. The disk plow, even when the ground is plowed dry, has 
a tendency to leave the surface finer and more even after plowing. 
The draft, of course, is much greater when the ground is plowed dry 
than when plowed wet. 
The average yields obtained from the April plowing were signifi- 
cantly higher than those obtained from either the May or the June 
plowing. The check-plat yields indicate that the productivity of the 
sou of the June-plowed series was not quite so great as that of the 
April-plowed and May-plowed series, but, notwithstanding this, the 
yields obtained from the April-plowed series were significantly higher, 
especially when the fact is considered that they represent the average 
yields of 8 tenth-acre plats each year. ( 
The average acre yield of the April-plowed series in the 9-year 
period was 6.3 bushels per acre more than the average yield of the 
June-plowed series and 2.3 bushels more than the average yields of 
the May-plowed series. The 9-year average yield of the plats of the 
May-plowed series was 4 bushels more than that of the June-plowed 
series. 
In the nine years for which results are available the yield from the 
June-plowed series slightly exceeded the average yield of the April- 
plowed series in two years, 1917 and 1918. In fact, during these 
two years the average yields of the series of plats plowed in all three 
months varied but little. For the years 1913 and 1919, on the other 
hand, the average yield of the April-plowed series was nearly twice 
that of the June-plowed series. 
The yields obtained from the plats plowed in the fall for summer 
fallow were consistently lower than the yields obtained from the plats © 
plowed early in the spring, except in the case of the early fall plowing 
