242 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1949 
Returning to the relationship between man and the soil, or land- 
scape, where he finds himself: the optimum or ideal adjustment can 
be approached by changing the environment, changing the soil, or 
by man adapting himself to the environment. Actually, of course, 
man does some of both, and science helps both processes. From our 
understanding of the soil and the environment we learn how to change 
it, and how to adapt ourselves to it. 
The soil is not easily changed, however, for in spite of all we learn 
to do through husbandry there still remains a closer relationship 
between the quality of foods and the natural soil type than there is 
between their quality and modern agricultural practices. Of course, 
irrigation of the desert or drainage of swamp land by means of large- 
scale engineering devices brings an immediate change. But most 
changes come slowly and often indirectly. A little change in the 
soil can set into motion a whole series of fundamental changes. 
For example, most of the soils developed in humid forested land- 
scapes are acid. Although they are productive for a time, these soils 
produce only a few of the plants man needs. By adding some lime, 
often some phosphate, and sometimes some other materials in rela- 
tively small amounts, the farmer can widen his choice of crops. He 
can grow the deep-rooted legumes where he could not before. These 
crops, in turn, have a pronounced influence on the soil and upon the 
crops that follow them. Similarly, the farmer in the humid region 
can develop a soil approaching the notoriously productive Chernozem 
of the subhumid grasslands by making up through fertilization for 
the extra leaching in the humid climate. Although fertilizer has not 
been found to have a dependable influence on the quality of food 
crops, through fertilization the farmer can so expand his range of 
crops that he can select those most nutritious for animal feed and 
human food. 
Every natural soil has certain limits to its potentialities. Through 
modern science these limits may be expanded in terms of kinds of 
crops and yields. No very close relationship exists between the natural 
fertility of soils and their actual productivity in society. The important 
factor is their response to management. Some of the most productive 
soils in the United States are in the southeastern region, soils that are 
notoriously infertile when first cultivated as compared to the black 
soils of the Middle West. 
NEED FOR SYMMETRY 
Man’s adjustment to the natural soil is not merely a matter of doing 
afew things. Itis the process of substituting a new environment, with 
all its varied effects on living matter and the dynamic processes within 
the soil, for the old one. With the smooth-lying soils of the Iowa 
prairies the farmer gets nearly maximum yields from his first cultiva- 
