CROP ROTATION IN RELATION TO SOIL PRODUCTIVITY 
45 
some of the crops in the rotation, 
show but little or no response to a 
In this study of the comparative 
effects of rotation and the use of 
fertilizers, all of the long-time lim- 
ing tests can not be considered, but 
only "those that meet with the con- 
ditions which make possible the 
evaluations of the effects of crop 
rotation and the use of fertilizers 
on crop yields. The liming tests 
that are thus in harmony with 
these conditions are those on wheat, 
corn, and oats at Wooster, Ohio, 
and those of a shorter duration on 
cotton at Florence, S. C. 
The published results of the 
Wooster experiments are for the 
rotation plots only, including a 13- 
year test on wheat (1906-1918), a 
19-year test on corn (1900-1918), 
and a 15-year test on oats (1901 
and 1905-1918) (12, pp. 598-601). 
The 6-year results (1914-1919) re- 
ported on cotton by the South 
Carolina Experiment Station are 
for both the rotation and continu- 
ous-culture plots (1). 
Since lime is applied to the west 
ends of the Wooster rotation plots, 
the plots selected for comparable 
yields in these liming tests are the 
same as those heretofore chosen 
(see Table 29), the average yields 
for each crop being determined for 
its liming period, on both the limed 
and unlimed plots. In case of the 
South Carolina cotton experiments, 
those plots were selected which re- 
ceive the same fertilizer treatments 
under both limed and unlimed 
conditions, as shown in Table 46. 
other than clover or alfalfa, may 
direct application of lime. 
6>4///Qe£/?/r£l?TO 
TO /=EGr/L/*jEGS 
Fig. 6. — A graphic summary of the comparable 
yields of cotton obtained at Florence, S. C., 
showing the average yield obtained from cul- 
tivation alone, the gain resulting when to cul- 
tivation is added crop rotation or the use of 
chemical fertilizer, and the total increase ef- 
fected when to cultivation are added both 
rotation and the use of fertilizer. The num- 
bers at the bottom of the bars are the plot 
numbers 
Table 46. — Limed and fertilized plots at Florence, S. C. 1 
Lime treatment (per acre) 
Plot 
Fertilizer treatment 
No lime. 
{ 
2 11,21,31 
24 
17 
18 
22 
23 
No fertilizer. 
1,000 pounds burnt lime. . . 
250 pounds dried blood, 500 pounds acid 
phosphate, 83.3 pounds muriate of potash. 
>No fertilizer. Results averaged. 
\ Same fertilizer treatment as on plot 24. Re- 
/ suits averaged. 
2,000 pounds ground limestone 
1,000 pounds burnt lime 
2,000 pounds ground limestone 
Plots are numbered the same in the continuous-culture series for cotton as in the rotation series. 
Average. 
