60 BULLETIN 1377, U. S. DEPARTMENT OF AGRICULTURE 
EFFECT OF SOIL REACTION ON ROTATION AND USE OF FERTILIZERS 
It may be of interest to summarize the effects of soil reaction on 
the conjoint action of rotation and the use of fertilizer in increasing 
fertility. In such a study only the results obtained on wheat, corn, 
and oats at Wooster are available. This summary is given in Table 
54. 
Table 54. — Effect of soil reaction on the conjoint effect of rotation and of the use of 
fertilizers in increasing soil productivity, Wooster, Ohio 
LIMED SOIL 
Kind of fertilizer used 
Period of 
experi- 
ment 
covered by 
study 
Maintenance yield 
Additive effects of 
rotation and use 
of fertilizers 
Crop 
Years 
selected 
for 
5-year 
average ' 
5-year 
average 
Average Sumofin- 
yield, creases in 
rotation | produc- 
conjoined tivity ef- 
with use fected by 
of ferti- \ rotation 
lizer and use of 
fertilizer 
when 
practiced 
separately 
<r+/) 
Actual in- 
crease in 
produc- 
tivity ef- 
fected by 
conjoint 
action of 
rotation 
and use 
of 
fertilizer 
1906-1918 
1901-1905 
Bushels Bushels Bushels 
8. 5 32. 2 19. 5 
9. 1 i 26. 8 16. 7 
Bushels 
23.7 
Wheat 
(Manure 
1906-1918 1901-1905 
16.7 
Corn 
Oats. . 
/Chemical fertilizer 
(Manure 
1900-1918 ; 1895-1899 
1900-1918 1895-1899 
lirJr^mo ll90O-1904 
29.6 
27.2 
19.5 
21.6 
54. 5 6. 
48.9 4.8 
53. 2 34. 
24.6 
21.7 
33.7 
Manure 
\ 1905-1918 
/ 1901 
U905-1918 
}l900-1904 
44.0 
20.8 
22.4 
UNLIMED SOIL 
Wheat.... 
Corn 
[ Chemical fertilizer 
\Manure 
f Chemical fertilizer 
\Manure 
1906-1918 
1906-1918 
1900-1918 
1900-1918 
1901-1905 
1901-1905 
1895-1899 
1895-1899 
8.5 
9.1 
29.6 
27.2 
31.7 
25.1 
48.9 
44.2 
17.6 
14.9 
1.4 
0.6 
23.2 
16.0 
19.3 
17.0 
Oats 
C hemical f er tili zer 
/ 1901 
U905-1918 
J1900-1904 
19.5 
52.8 
31.2 
33.3 
Manure 
/ 1901 
\1905-1918 
}l900-1904 
21.6 
41.9 
18.1 
20.3 
1 5-year average based on yields given in Tables 30 and 32. 
Here it is to be observed that only in the case of corn does lime 
effect an increase exceeding 3 bushels per acre from the conjoint 
action of rotation and the use of fertilizer. However, it may be 
concluded that changing or altering the soil reaction by liming 
tends to increase the conjoint effectiveness of rotation and fertilizers. 
GENERAL DISCUSSION 
Two methods have been employed in evaluating the effectiveness 
of rotation in crop production, and in determining the additive 
effects of rotation and the use of fertilizers when these two farm 
practices are conjoined. Although in one method the evaluations 
are based on the increases over the yields obtained on check plots 
in continuous culture and in rotation, and in the second method, 
