5io 
Journal of Agricultural Research 
VoL XIV, No. It 
ferences in the depth of plowing. Where wheat follows wheat the three 
combinations, (i) deep-tilled each year, (2) the first crop after deep 
tillage, and (3) the second crop after deep tillage on plots alternately 
deep- and shallow-tilled, exhibit no difference. The plot that received 
no deep tillage shows an apparent increase over any of these combinations, 
but a careful analysis of the results of the four plots from year to year 
points very strongly to the belief that this apparent increase may be 
within the limits of the experimental error. 
Table XVI.— Yields at Akron (Colo.) Field Station of wheat and corn in deep- 
tillage experiment for the years 1911 to 1916 , inclusive 
Crop and treatment. 
Pre¬ 
vious 
crop. 
Plot.® 
' Yield (bushels per acre).* 
iyxx 
1912 
1913 
1914 
1915 
19x6 
Grain. 
Avei 
Fod¬ 
der. 
■ages. 
Similar 
treatment 
after both 
wheat and 
com. c 
Grain. 
Fod¬ 
der. 
WHEAT. 
Deep tillage each 
Wheat. 
E 
22. 5 
0.3 
17-1 
25*5 
3*5 
13*8 
16.2 
year. 
First crop after deep 
...do.,.. 
J-M 
22.9 
•3 
16.4 
24-5 
3*2 
i 3*5 
18.0 
Second crop after 
...do.... 
M-J 
29.2 
, 2 
14-8 
22.7 
13*8 
18.7 
deep tillage. 
Ordinary plowing... 
.. .do.... 
K 
32.8 
•3 
17-7 
22.4 
2. 7 
15*2 
21.0 
Deep tillage each 
Com.. 
D-N 
33 -o 
3, 5 
18.7 
29.6 
8.1 
18.6 
year. 
First crop after deep 
.. .do.... 
B-O 
40.0 
9.6 
2X. 9 
33-3 
7*7 
tillage. 
Second crop after 
...do.... 
C-P 
45-9 
5-3 
28. I 
30.9 
7.6 
23.6 
deep tillage. 
Ordinary plowing... 
...do.... 
A-Q 
54-7 
IO. 5 
31-9 
30.0 
6.4 
26.7 
CORN. 6 
Deep tillage each 
Corn... 
F 
1,000 
45-3 
2,320 
20. X 
35-6 
1,360 
33*6 
1*560 
29*3 
1,606 
year. 
First crop after deep 
...do.... 
H-E 
864 
40.7 
2,320 
16.9 
27.0 
1,600 
28.2 
i >595 
26. 5 
2,080 
tillage. 
Second crop after 
.. .do.... 
E-H 
432 
41.7 
1,960 
17.7 
36.3 
1,160 
3 i *9 
1,184 
26. 9 
1*511 
deep tillage. 
Ordinary plowing... 
.. .do.... 
G 
720 
43.1 
2, X20 
x 6 - 6 
40.0 
1,400 
33. 5 
1,413 
1,652 
28.9 
1,666 
Deep tillage each 
Wheat. 
N-D 
32.3 
9.8 
32.8 
year. 
First crop after deep 
.. .do.... 
P-C 
3>456 
37 -i 
2,760 
10.9 
26.3 
1,480 
24.8 
2,56s 
tillage. 
Second crop after 
.. .do_ 
O-B 
1,904 
21. 7 
2,090 
11.2 
32.7 
2X. 9 
1,838 
deep tillage. 
Ordinary plowing... 
.. .do.... 
Q-A 
1,904 
29.8 
2,8lO 
8.7 
34*2 
1,040 
24. 2 
1,918 
a Where two plots appear under the same heading, the crop is on the first one in the odd years and on 
the second in the even years. 
* For three years, 1911, 1913, and 1916, when little or no grain was produced the yield of com is in total 
pounds per acre. 
c Example: Average yield of wheat for deep tillage after both wheat and com is 13.8+18.6-5-2=16.2. 
In the four plots where wheat follows com there is a more pronounced 
evidence of a positive result. The heaviest yield has been on the ordi¬ 
nary-plowed plot, the next heaviest from the second year after deep 
tillage, the third heaviest from the first year after deep tillage, and the 
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