June is, 1925 Effect of Crops onYields of Succeeding Crops in Rotation 1121 
what more productive than those 
occupied by oats and rye. These latter 
differences are due to apparent soil 
variation in Field II, there being no 
substantial differences in yields of the 
three control plots in any of the sections 
of Field III. As a whole, the differ¬ 
ences in effects of the three small grain 
crops on the hoed crops are compara¬ 
tively small, possibly because there is 
a rather long interval between the time 
of harvest of the former and planting of 
the latter, coupled with the fact that 
the small grains are shallow-rooted 
crops. As to tobacco, there seems to 
be no difference in the effects of wheat 
and oats as preceding crops. Taking 
the average of all fertilizer treatments 
as shown in Figure 10, the tobacco 
yields after the two crops have agreed 
closely each year on the two fields. 
Rye, as compared with wheat and otas, 
appears to have a depressing effect 
which is not overcome or greatly 
modified by any of the fertilizer treat¬ 
ments, except that on Field III the 
complete fertilizer does overcome this 
effect. There is some indication in 
Figure 10 that this effect is progressive. 
Of the three fertilizing elements, 
nitrogen seemed to have the greatest 
effect on the yield of tobacco, while po¬ 
tassium has seemed to have had little 
effect. 
Fig. 10.—Comparative effects of wheat, oats, and rye as preceding crops on the yield of 
tobacco. In general the differences in effects of the small grains on the hoed crops 
are not great. The yields of tobacco after wheat and after oats closely agree each year. 
Eye, in comparison, shows a slight depressing effect. The yields are expressed as the 
combined weights of leaf and stalk 
Table IX.— Summary of results with hoed crops on Fields II and III for the years 
1916 to 1922, inclusive , showing the comparative effects of wheat , oats f and rye as 
preceding crops on the yields of tobacco y potatoes , and corn , under different fer¬ 
tilizer treatments; also, the effects of the fertilizer treatments on the yields of 
tobacco, potatoes , and corn. 
Fertilizer treat¬ 
ment 
Yield of tobacco leaf 
Yield of potatoes 
Yield of corn 
After 
wheat 
After 
oats 
After 
rye 
Aver¬ 
age 
After 
wheat 
After 
oats 
After 
rye 
Aver¬ 
age 
After 
wheat 
After 
oats 
After 
rye 
Av¬ 
erage 
N+P.. 
N+K_ 
P+K.. 
N+P+K_ 
Average... 
Lbs. 
1,122 
1,042 
861 
1,091 
Lbs. 
1,053 
959 
914 
1,087 
Lbs. 
912 
939 
750 
959 
Lbs. 
1,029 
980 
842 
1,046 
Bush. 
64.1 
48 
53.1 
72 
Bush. 
54.1 
42.5 
48.3 
69.4 
Bush. 
50.8 
39.1 
39.6 
57.8 
Bush. 
56.3 
43.2 
47 
66.4 
Bush. 
43.9 
42.1 
35.9 
38.4 
Bush. 
38.9 
35.8 
31.4 
35.7 
Bush. 
33.4 
35.7 
26.6 
34.7 
Bush: 
38.7 
37.9 
31.3 
36.3 
1,-029 
1,003 
891 
974 
59.3 
53.6 
46.8 
53.2 
40.1 
35.5 
32.6 
36.1 
Fertilizer treatment 
Yield of tobacco stalks 
Yield of corn stover 
After 
wheat 
After 
oats 
After 
rye 
Average 
After 
wheat 
After 
oats 
After 
rye 
Average 
N+P_ 
N+K_ 
P+K_ 
N+P+K_ 
Average.- 
Lbs. 
645 
544 
457 
648 
Lbs. 
629 
551 
498 
686 
Lbs. 
516 
521 
357 
562 
Lbs. 
597 
539 
437 
632 
Lbs. 
3,172 
2,903 
2,515 
2,975 
Lbs. 
2,783 
2,404 
2,298 
2,755 
Lbs. 
2,533 
2,429 
2,250 
2,769 
Lbs. 
2,829 
2,579 
2,354 
2,833 
573 
591 
488 
551 
2,891 
2, 560 
2,496 
2,649 
