CROP ROTATION IN RELATION TO SOIL PRODUCTIVITY 
Table 25. — Average effects of the conjoint action of crop rotation and the use of 
manure on the yields of oats 
Plot No. 
Cultural conditions, rotation and check plot in continuous 
culture 
Average 
yield per 
acre 
Average 
increase 
over check 
plot in 
continuous 
culture due 
to rotation 
and use of 
manure 
• 
11,12,14,19,20 
16 
6-year rotation: 
Bushels 
34.6 
19.5 
Bushels 
15. 1 
34, 35, 37, 38 
16 
4-year rotation: 
37.2 
23.4 
13.8 
Average yield and increase effected by rotation and use 
of manure. 
35. 9 14. 5 
Table 26.- 
■Average effects of the conjoint action of crop rotation and the use of 
manure on the yield of timothy 
Plot No. 
Cultural conditions, rotation and check plot in continuous 
culture 
Average 
yield per 
acre 
Average 
increase 
over check 
plot in 
continuous 
culture due 
to rotation 
and use of 
manure 
11, 12, 19, 20 
6-year rotation: 
Pounds 
5,379 
2,894 
Pounds 
2,485 
23 
The average yields and increases given in Tables 21, 23, 24 and 25 
are summarized in Table 27, in which are given the relative values 
of rotation {R) in effecting increases when conjoined with the use 
of fertilizers, and the additive effects of the conjoint action of rota- 
tion and the use of fertilizers on the yields of wheat, corn, and oats. 
Table 27. — Relative values of rotation (R) and additive effects on the yields of 
wheat, corn, and oats when rotation of crops and use of fertilizers are conjoined 
Values of 
.Rand F 
Additive effects of rota* 
tion and 
lizer 
use of ferti- 
! 
Sum of 
Average 
Relative 
increases 
Actual 
Crop 
Cultural conditions 
yield 
value of 
effected by 
per acre 
.Ri 
rotation 
effected by 
R 
F 
fertilizer 
when 
practiced 
separately 
(r+/) 
conjoining 
rotation 
and use of 
fertilizer 
Bushels 
Bushels 
Bushels 
Per cent 
Bushels 
Bushels 
Wheat 
Rotation and use of manure. 
28.2 
9.1 
9.1 
100.0 
20.0 
19.1 
Rotation and use of chemical 
30.0 
3.6 
9.9 
36.4 
21.5 
17.5 
fertilizer. 
Corn. 
Rotation and use of manure . 
47.7 
10.6 
10.2 
103.9 
29.8 
25.3 
Oats 
Rotation and use of manure. 
35.9 
2.8 
8.3 
33.7 
17.9 
14.5 
1 Relative value of R is obtained by dividing the increase effected when rotation is added to cultivation 
and the use of fertilizer by the increase effected when the use of fertilizer is added to cultivation and 
rotation. 
