36 
BULLETIN 1377, U. S. DEPAKTMENT OF AGRICULTURE 
Table 34. — Effects of crop rotation and of the use of fertilizers on the yields of 
wheat, corn, and oats. Wooster, 25-year results 
(Rotation and fertilization practiced separately) 
Plot 
Crop 
Cultural conditions 
Average 
yield 
per acre 
Increase 
over 
check 
plot 
in con- 
tinuous 
culture 
Relative 
value of 
crop ro- 
tation, as 
compared 
with fer- 
tilizers, 
in 
effecting 
larger 
yields 
11 
2 
[wheat 
>Corn 
[Crop rotation without the use of chemical fertilizer (r) 
I Use of chemical fertilizer without crop rotation (/)... 
(Crop rotation without the use of manure (r) 
Bushels 
11.54 
19.74 
11.28 
16.56 
27.24 
35.88 
27.62 
30.53 
31. 92 
39.17 
31.78 
29.85 
Bushels 
3.77 
11.97 
3.10 
8.38 
10.36 
19.00 
14.29 
17.20 
11.06 
18.31 
10.06 
8.13 
Per cent 
31. & 
20 
37.0 
J 5, 6 
lUse of manure without crop rotation (/). 
11 
J 2, 3 
[Crop rotation without, the use of chemical fertilizer(r). 
lUse of chemical fertilizer without rotation (./) 
[Crop rotation without the use of manure (r) 
54.5 
20 
83.1 
15,6 
[oats 
[Use of manure without rotation (/)... 
11 
12.3 
[Crop rotation without the use of chemical fertilizer (r) . 
1 Use of chemical fertilizer without rotation (/) 
[Crop rotation without the use of manure (r)_.. 
60.4 
20 
123.7 
5 
(Use of manure without rotation (.0 
1 Average. 
The comparative separate effects of crop rotation and the use of 
fertilizers in effecting larger yields of wheat, corn, and oats, under 
the conditions of the Wooster experiments, are reflected in the relative 
values of rotation. Here it is snown that, in each case, the rotation 
effects in the manure series are relatively higher than in the chemical- 
fertilizer series, the average relative values for rotation being 81.3 
per cent and 48.8 per cent, respectively, for the tw T o series. 
RESULTS WHEN CROP ROTATION AND THE USE OF FERTILIZERS ARE CONJOINED 
In Table 35 are summarized the results of the Wooster experiments 
when rotation of crops and the use of fertilizers are combined, show- 
ing the relative values for rotation (R) and the additive effects of 
conjoining rotation and the use of fertilizers. 
Table 35. — Relative values of rotation (/?) and additive effects of conjoining rotation 
and the use of fertilizers, Wooster, Ohio 
Cultural conditions 
Average 
yield per 
acre 
Values for 
iJand F 
Relative 
value of 
R 
Additive effects of ro- 
tation and use of 
fertilizers 
Crop 
R 
F 
Sum of 
increases 
effected by 
rotation 
and use of 
fertilizer 
when 
practiced 
separately 
(r+f) 
Actual 
increase 
effected by 
conjoining 
rotation 
and use of 
fertilizers 
Wheat 
Rotation and use of chemical 
fertilizer 
Bushels 
28.12 
19.69 
46.60 
42.81 
51.24 
39.52 
Bushels 
8.38 
3.13 
10.72 
12.28 
12.07 
9.67 
Bushels 
16.58 
8.41 
19.36 
15.19 
19.32 
7.74 
Per cent 
50.5 
37.2 
55.4 
80.8 
62.5 
124.9 
Bushels 
15.74 
11.48 
29.36 
31.49 
29.37 
18.19 
Bushels 
20 35 
Corn 
Rotation and use of manure.. 
Rotation and use of chemical 
fertilizer 
11.51 
29.72 
Oats 
Rotation and use of manure. . 
Rotation and use of chemical 
fertilizer 
29.48 
30 38 
Rotation and use of manure l 
17.80 
1 Residual effects, manure is applied to corn and wheat in the rotation. (See Table 28.) 
