1122 
Journal of Agricultural Research 
Vol. XXX, No. 12 
The yields of potatoes are small and 
it is doubtful if the apparent crop 
effects are significant. Phosphorus 
and nitrogen are the most significant 
fertilizing elements. The yields of 
corn on Field II have rapidly declined 
in later years after oats and especially 
after rye, but this result is probably 
due in part to original differences in 
productiveness of the soil. On Field 
III no differences have developed thus 
far in the effects of wheat, oats, and 
rye on the yields of corn. Nitrogen is 
the important fertilizing element in 
the corn yields. 
ments being applied. The two fields 
used are IV and V. The location and 
the general characteristics of the soil 
of the two fields are shown on the soil 
map and accompanying report. The 
plan of Field IV, together with the de¬ 
tailed system of cropping, are shown 
in Figure 11. The plan of Field V is 
the same in all respects, except that 
lack of a sufficiently large area of suit¬ 
able soil made it necessary to locate 
the rye division apart from the re¬ 
mainder of the field and immediately 
adjacent to Field IV, as shown on the 
soil map. 
TOBACCO, POTATOES, AND CORN IN 
ROTATION WITH SMALL GRAINS 
AND LEGUMES 
Addition of legumes to the cropping 
systems last discussed constitutes the 
final step in testing the value of the 
type of rotation under study and 
should throw more light on the relative 
merits of the several possible combina¬ 
tions of hoed crops and small grains 
included in the tests. These tests are 
essentially repetitions of the previ¬ 
ously described tests with hoed crops 
in rotation with small grains, with the 
important difference that grass and 
various legumes are grown as soiling 
crops on the plots of each cropping 
unit instead of different fertilizer treat- 
As in the preceding tests, tobacco, 
potatoes, and corn are grown in 
parallel strips, followed by wheat, oats, 
and rye seeded crosswise these strips. 
Each of the nine cropping units thus 
formed is subdivided into seven plots, 
of which one is used as a cropping 
control. Of the remaining plots, one 
receives no additional crop, while the 
others are seeded to hairy vetch, 
crimson clover, cowpeas, soy beans, and 
a grass mixture, respectively. In this 
way the effects of two summer legumes 
and two winter legumes as annual 
soiling crops are compared with a non- 
leguminous soiling crop and with 
fallowing. The summer legumes are 
planted shortly after harvesting the 
small grains and the other soiling crops 
