1124 
Journal of Agricultural Research 
Vol. XXX, No. 12 
Summaries of the results with to¬ 
bacco, potatoes, and corn on Fields IV 
and V are given in Table XII. Two 
features are of interest, namely: (1) 
The comparative effects of preceding 
crops of wheat, oats, and rye as modi¬ 
fied by the intervening soiling crops; 
and (2) the comparative, direct effects 
of the soiling crops on tobacco, pota¬ 
toes, and corn. As to the first-named 
feature, the results with tobacco are 
quite similar to those obtained in the 
preceding tests where no soiling crops 
were used. Although the differences 
in effects of wheat, oats, and rye are 
not large, these differences seem to be 
significant, particularly as to the de¬ 
pressing effect of rye on the yields of 
tobacco. Thus, in 1917, the first year 
of the test, the average yield of tobacco 
on the rye division of Field V was 1,340 
pounds per acre and on the wheat 
division the yield was 1,320 pounds. 
In 1921 the corresponding yields were 
1,008 pounds and 1,245 pounds per 
acre. The general effect of the inter¬ 
vening legumes has been to intensify 
the relatively unfavorable effect of rye 
on the growth of tobacco. Grass as a 
soiling crop, on the other hand, seems 
to act in the reverse manner, giving 
somewhat better results after rye than 
after wheat. These effects of the 
legumes are associated with a tendency 
toward increased yields of tobacco, 
while the effects of grass are associated 
with decreased yields. 
The direct effects of the soiling 
crops on tobacco are interesting in 
several particulars. For the com¬ 
paratively short period of the tests, 
vetch, crimson clover, and cowpeas 
as soiling crops have given rather 
large increases of tobacco where wheat 
was the preceding crop, just as was the 
case in the early years of the special 
cropping tests with tobacco which 
have already been discussed. With 
rye as the preceding crop, and to a 
lesser extent with oats, these legumes 
have been much less effective in in¬ 
creasing the yield of tobacco. Of the 
four legumes, soy beans are unique in 
that they are wholly ineffective in all 
cases in promoting the growth of 
tobacco and in some instances have 
actually decreased the tobacco yield. 
Grass as a soiling crop has had a 
remarkable depressing action on 
the growth of tobacco, the yields of 
which are reduced to nearly half those 
of the fallow plots. These relation¬ 
ships are brought out in more detail 
in Figure 12. 
Table XII.— Summary of results with hoed crops on Fields IV and V for the years 
1918-1922, inclusive, showing the comparative effects of wheat, oats, and rye as 
preceding crops on the yields of tobacco, potatoes, and corn, when soiling crops 
intervene in the rotation; also the comparative effects of the soiling crops on the 
yields of tobacco, potatoes, and corn 
Soiling crop 
grown 
Yield of tobacco leaf 
Yield of potatoes 
Yield of com 
After 
wheat 
After 
oats 
After 
rye 
Aver¬ 
age 
After 
wheat 
After 
oats 
After 
rye 
Aver¬ 
age 
After 
wheat 
After 
oats 
After 
rye 
Aver¬ 
age 
Vpfph 
Lbs. 
1,352 
1,410 
920 
1,321 
938. 
489 
Lbs. 
1,041 
1,181 
999 
1,299 
822 
Lbs. 
858 
969 
799 
1,156 
846 
563 
Lbs. 
1,084 
1,187 
906 
1,259 
869 
573 
Bush. 
74.8 
77.8 
59.8 
71.1 
54.1 
38.7 
Bush. 
56.1 
52.5 
51.6 
60 ; 
45.8 
31.2 
Bush. 
53.1 
51.5 
46.4 
65.9 
52.1 
39.5 
Bush. 
61.3 
60.6 
52.6 
66.7 
50.7 
36.5 
Bush. 
59.1 
59.9 
41.4 
58.0 
54.5 
37.8 
Bush. 
59.9 
54 9 
42.9 
53.5 
49.5 
35.1 
Bush. 
53.4 
49.5 
42.0 
55.8 
544 
42.5 
Bush. 
57.5 
54.8 
42.1 
55.8 
52.8 
38.5 
Crimson clover.. 
Fallow. 
Cowpeas- 
Soy beans. 
Grass. 
Average— 
1,071 
1,002 
865 
979 
62.7 
49.5 
51.4 
54.6 
51.8 
49.3 
49.6 
50.2 
Soiling crop grown 
Yield of tobacco stalks 
Yield of corn stover 
After 
wheat 
After 
oats 
After 
rye 
Average 
After 
After 
After 
rye 
Average 
Vetch. 
Crimson clover_ 
Fallow.. 
Cowpeas_ 
Soy beans. 
Grass. 
Lbs. 
784 
776 
514 
729 
468 
219 
Lbs. 
499 
595 
517 
657 
392 
304 
Lbs. 
404 
493 
369 
624 
403 
249 
467 
670 
421 
257 
Lbs. 
4,290 
4,287 
3,230- 
3,930 
3,643 
2,605 
Lbs. 
4,120 
3,899 
3,207 
3,744 
3,349 
2,597 
Lbs. 
3,635 
3,470 
2,962 
3,914 
3,685 
. 3,001 
Lbs. 
4,015 
3,885 
3,133 
3,863 
3,559 
2,734 
Average. 
582 
494 
424 | 500 j 3,664 
3,486 
3,443 
3,531 
