THE EFFECTIVE USE OF LAND AS SHOWN BY YIELD 3 
portions of the United States decline while those in the much longer 
occupied lands of Europe increase? The soils of northwestern 
Europe are producing high yields, whereas less than 200 years ago 
the yields on these same soils were actually as low as those realized 
on some of our poorest soils (73, p. 93). 
There are individuals who persist in making such comparisons 
and insist that our agriculture is deteriorating. We are told of 
yields in former days considerably above those ‘of to-day. These 
rumors, however, can not be substantiated in the light of available 
facts. The statistics of the yield per acre of our principal crops 
(with the exception of cotton) show an upward trend in acre-yields 
during the last half century. This has occurred in spite of the 
fact that a not inconsiderable portion of our agriculture is still on 
an extensive basis, the soils of which are subject to pioneer methods 
of exploitation. 
Long before soil fertility assumed the scope of a national question 
individual localities encountered the problems that are associated 
. with the transition from a predatory type of agriculture to a perma- 
nent-use type. In many sections of the humid eastern portion of 
the United States pioneer methods of agricultural exploitation have 
completely disappeared, and, as economic conditions permitted it, 
scientific methods of production have replaced the cruder methods 
of former days. Entering on a period of permanent use the produc- 
tive capacity of the soils of the East has been greatly increased and 
is now producing yields considerably above those of the early period 
of the agricultural history of these sections. 
PURPOSE AND SCOPE OF STUDY 
In view of the fact that our agricultural frontier can no longer 
be pushed farther to the west, although much land still remains to be 
turned by the plow, the productive capacity of our soils is more than 
ever (as has been pointed out above) becoming a subject of study 
and concern. To correct the notion that our soils are steadily being 
exhausted, that our agriculture is deteriorating, it is desirable to 
examine the facts and determine both the present situation and the 
past trend in productivity, as far as it can be shown by the acre-yields 
of some of our principal crops. 
The purpose of this study is primarily to show the past trend in 
the yield per acre of certain of our food and feed crops, and to com- 
pare the general level of yields at present with those at different 
times in the period covered by the data, in order that we may see 
a little more clearly how much of the increased supply of certain 
foods and feeds has come from increasing yields of these crops and 
how much from increasing acreage.” It is dangerous to hazard any 
prophecies as to the future, nevertheless an examination of the trend 
in yields in the past may give some idea of what we may expect; 
and even a general! idea of what may be expected with reference to 
crop yields will be helpful in estimating the need for more crop land 
in the future. ; 
2The yield data for corn, wheat, oats, and potatoes are presented in this bulletin. 
These crops, excluding hay, comprise the most important of our food and feed crops. 
