236 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1949 
crop or of the crops that can be grown on the soil anyway. Rather 
we must think of the various combinations of crops and practices, 
and their immediate and longtime influence upon the soil and upon 
one another, to the end that a combination will be developed which 
will maximize the ratio of production to labor and materials on a 
permanent basis. 
LITTLE PLACES AND BIG PLACES 
It is obvious that some sort of soil classification is essential, since 
the world has a great many thousands of kinds of landscapes, kinds of 
soil profiles, and kinds of mineral-organic cycles. Of course, one cannot 
deal with all these soils at one time, nor do they present equal con- 
trasts. Actually, there are few sharp lines between soil types; rather the 
soil of the world is a continuum that may be divided into reasonably 
homogeneous units according to the state of our knowledge and the 
demands for accuracy and scientific prediction. The soil is a natural 
product, and no two soil profiles are identical any more than two oak 
trees or two college professors are. Soil types are man-made creations. 
In one soil type are included all the soils that appear to have the same 
kind of profile, even though they are not alike in every single respect. 
This is not the place to go into the age-old problem of classification. 
All the natural sciences have the same problem. A classification is good 
to the extent that it serves the purpose of remembering characteristics, 
seeing relationships, and developing principles. A classification is bad 
to the extent that scientists become slaves to it, and twist their data 
and ideas to fit the classification. It improves as our knowledge 
grows. Some wonder when soil classification will “settle down’— 
when names and definitions will no longer be changed. This will 
happen when soil science has ceased to discover anything new—in 
other words, when it dies. 
Let us now consider the significance of the lower groups, or local soil 
types, in contrast to the great soil groups, or continental soil types. 
The differences that are apparent between our garden and our neigh- 
bor’s, or between one plot of crops or trees and the adjoining one, are 
differences related to the local conditions of rocks, relief, and age. 
The soil of one garden is derived from sandstone and another from 
granite; one garden is hilly and one is flat; one is on an old slope and 
one is on a young stream terrace. Associated with these differences 
are characteristics of great practical and scientific interest. Soils too 
sandy for gardens are often found mixed in an intricate pattern with 
soils that are too heavy in clay; soils too steep for cultivation with 
soils that are flat and wet. If these soils are studied carefully, one 
can determine how they differ from one another and what direct rela- 
tionships exist between the soil characteristics and the factors of the 
environment. Nevertheless, serious errors may be made as to the 
