1118 
Journal of Agricultural Research 
Vol. XXX, No. 12 
The stand of corn has been excellent 
on both fields. On Field III the imma¬ 
ture ears of corn were badly damaged 
by birds in 1915 and the yields of 
grain were computed on the data from 
uninjured plants constituting 50 to 60 
per cent of the total. Stands of small 
grains have been uniformly good. 
The arrangement of cropping con¬ 
trol plots is the same as for Field I. 
Those of Field II received the complete 
fertilizer at the normal rate in 1916 
and 1918, and those of Field III were 
similarly treated in 1915 and 1917. 
In other years no fertilizers have been 
applied to these plots. The control 
plots throughout the two fields have 
been cropped in tobacco and wheat 
in regular rotation. The average yields 
are summarized in Tables VI and VII. 
Because of serious injury from joint 
worm the yields of wheat on Field 
III in 1918 are not included in the 
averages. 
One of the facts brought out in 
Tables VI and VII which should be 
mentioned is that tobacco and wheat as 
indicators of relative productivity of 
different soil areas do not always give 
similar results. Thus, the yields of 
wheat on Field II indicate a greater 
superiority in productiveness of Di¬ 
vision 1, as represented by Plot 3, over 
Divisions 2 and 3, represented by 
Plots 8 and 13, than is indicated by the 
yields of tobacco on the same plots. 
Again, on Field III the yields of to¬ 
bacco would indicate that Section A as 
a whole is considerably more produc¬ 
tive than Section C. This is contrary 
to the results with wheat, and the gen¬ 
eral lay of the land and the character 
of the soil indicate that for most staple 
crops Section C is at least equal, if not 
superior to Section A in productivity. 
Under the circumstances it seems logi¬ 
cal to depend primarily on results with 
wheat in dealing with small grains, but 
to rely more on results with tobacco in 
considering the hoed crops. 
The average results obtained on 
Fields II and III with the small grains 
after each of the three hoed crops are 
summarized in Table VIII. In this 
table it is a simple matter to compare 
the effects of the different hoed crops 
on each of the small-grain crops and 
also compare these crop effects with the 
effects of the different fertilizer treat¬ 
ments. 
Taking first the wheat crop, the 
average yields of wheat on the control 
plots for the wheat division (Plot 3) 
of Sections A, B, and C of the two 
fields are 11.4, 11.8, and 11.3 bushels, 
respectively, indicating substantial uni¬ 
formity in productivity of the cropping 
units involved. It appears, therefore, 
that corn has had a decidedly depressing 
action on yield of both grain and straw 
of wheat, while there is only a slight 
difference in the effects of tobacco and 
potatoes. These relations hold true 
under all the fertilizer treatments 
used. The fertilizer treatments also 
clearly affect the yields of wheat, 
omission of phosphorus having a 
markedly depressing action. It is 
interesting to note that although the 
fertilizer treatments influence the wheat 
yields in any particular case, they 
show no well-defined tendency to over¬ 
come the differences in effects of the 
preceding crops of tobacco, potatoes, 
and corn. 
Turning to the oats crop, the average 
yields of wheat on the control plots for 
the oats division (Plot 8) of the sections 
of the two fields occupied respectively 
by tobacco, potatoes, and corn are 9.6, 
9.5, and 9.2 bushels. These yields 
stand at a somewhat lower level than 
those for the wheat division of the fields, 
already discussed, but these yields agree 
satisfactorily among themselves, indi¬ 
cating approximate uniformity in pro¬ 
ductivity of the cropping units occupied 
by oats. Here, again, the depressing 
effect of corn on the yields of oats is 
noticeable, and there is also an appre¬ 
ciable gain in yield after potatoes as 
compared with the yield after tobacco. 
The fertilizer treatments have affected 
the yields, but these effects are not 
sharply defined in all cases. In this 
instance omission of nitrogen from the 
fertilizer rather than phosphorus has 
had the greatest depressing effect, al¬ 
though after corn omission of phos¬ 
phorus seems to be of significance. As 
in the case of wheat, the fertilizer treat¬ 
ments do not accomplish much in over¬ 
coming the differences in effects of the 
three preceding hoed crops. 
Considering finally the rye crop, the 
average yield of wheat on the control 
plots of the rye division (Plot 13) of the 
two fields is 8.5 bushels alike for the 
tobacco, potatoes, and corn sections. 
Potatoes as a preceding crop seem to 
favor the growth of rye, the yields 
of both grain and straw being markedly 
increased as compared with results 
after tobacco and corn. The yields 
after tobacco are only slightly better 
than those after corn, but the differ¬ 
ences seem to be appreciably influenced 
by the fertilizer treatment. When 
potassium or phosphorus are omitted 
from the fertilizer, the differences in 
yield after tobacco and after corn are 
increased. With tobacco as the pre¬ 
ceding crop, nitrogen seems to be the 
chief plant nutrient limiting yields, 
