CROP ROTATION IS RELATION TO SOIL PRODUCTIVITY 
21 
FOUR-YEAR ROTATION AND CONTINUOUS CULTURE 
Table 12. — Comparable yields of corn in the 4-year rotation and in continuous 
culture, Missouri 
[Yields in bushels per acre] 
4-year rotation (corn, oats, wheat, clover) 
Continuous culture 
Year 
Farm manure 
Xo fer- 
tilizer, 
plot 39 
Plot 34 
Plot 35 Plot 3T 
Plot 38 
No fer- 
tilizer, 
Average plot 17 
or sum- 
mar y 
Farm 
manure, 
plot 18 
1898. 
1902. 
1906. 
1911. 
1915. 
35.3 
34.3 
28.2 
54.0 
50.9 
34.0 
31.7 
78.5 
50.9 
34.0 
31.7 
79.6 
41.1 
17.1 
23.9 
38.0 
60.7 
30.3 
2! 
79.4 
29.9 
37.3 
31.8 
33.8 
6-year average. 
55.6 
34.3 
55.6 
13.2 
38.0 
28. 
25.1 
4. r .7 
44.5 
Table 13. — Comparable yields of oats in the 4-year rotation and in continuous 
culture, Missouri 
[Yields in bushels per acre] 
Year 
4-year rotation (corn, oats, wheat 
clover; 
Continuous culture 
No fer- 
tilizer, 
plot 39 
Farm manure 
Xo fer- 
tilizer, 
plot 16 
Farm 
manure, 
plot 15 
Plot 34 
Plot 35 Plot 37 ; Plot 38 
Average 
or sum- 
mary 
1891 
21.6 
31.6 
26.3 
29.7 
40.6 
32.2 
29.7 
40.6 
32.2 
18.4 
28.1 
13.4 

25.9 
1895 
422 
1899 
27 .3 
1903. 

1907 
6-year average.. 
26.8 
30.3 
30.6 
37.8 
14.4 
37.8 
40.2 
42.9 
21.9 
29.3 
29.0 
37.4 
1912. 
1916. 

40.8 
42.9 
51.6 ; 53.8 
32.4 
30.2 
27.9 
37.2 
23.4 
32.6 
"""! 
Table 14. — Comparable yields of wheat in the 4-year rotation and in continuous 
culture, Missouri 
[Yields in bushels per acre] 
4-year rotation (corn, oats, wheat, 
Continuous culture 
clover) 
§ 
Farm manure 
C5 
O 
Farm manure 
Year 
P, 
• 
Z 
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z 
Ch 
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PL, 
2- 
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1889. 
25.8 
14.0 
28.7 
26.9 
15.2 
37.3 
26.9 
15.2 
37.3 
8.2 

1.7 
8.1 
15.0 
11.8 
17.0 
20.9 
23.0 
4.0 
14.7 
16.0 
1893 

4.0 
1897. 
13.8 
6.1 
8.4 
S. 2 
14. S 
11.0 
1901. 
34.0 
37.2 
37.2 
15.6 
23.3 
25.2 
24.1 
23.6 
28.5 
27. 2 
25. 3 
1905. 
20.8 
31.8 
31.8 
12.4 
15.4 
15.6 
15.6 
20.7 
17.7 
1909 
21.7 
13.8 
15.7 
27.8 
15.7 
26.5 

8.8 
~L5.~9~ 
15.2 
16.9 
11.7 
17.4 
13.8 
17.3 
10.4 
22, 5 
21.9 
20.9 
14. 6 
1913. 
28.3 
25.1 
24.9 
i 
1917 
30.0 
39.4 
39.4 
0.2 
10.9 
10.9 
8 - y e a r 
average 
23.6 
28.8 
4.9 
14. S 
1 
