BULLETIN OF THE 
C 
No. 122 
Contribution from the Bureau of Soils, Milton Whitney, Chief. 
August 24, 1914.. 
(PROFESSIONAL PAPER.) 
THE INORGANIC COMPOSITION OF SOME IMPORTANT 
AMERICAN SOILS. 
By W. 0. Robinson, Scientist in Soil Laboratory Investigations. 
INTRODUCTION. 
There is now recorded an enormous number of analyses of extracts 
of soils. These extracts have been prepared by treating the soil with 
aqueous solutions of acids, salts, various organic substances, and mix- 
tures. There are, however, very few analyses available of the soil 
itself — that is, showing the total constituents, or the total amount of 
any particular constituent — and more especially are wanting such 
analyses made by quantitative methods of approved validity. 
The advancement of soil and biological chemistry requires a knowl- 
edge of the actual chemical composition of the soil, including not 
only the common but the rarer elements. Such data are necessary 
for the comparison of soils and subsoils, for tracing the genetic rela- 
tions of soils and rock materials, processes of soil formation, and for 
studying certain relations of soils and plants. The absorption of min- 
eral nutrients, whether necessary to the plant or merely incidental or 
accidental, the possible functions of so-called catalytic fertilizers, 
and many other problems of the soil and plant require a definite 
knowledge of the mineral composition of the soil. The work presented 
in the following pages is a systematic investigation of those types of 
American soils which, for agricultural reasons, are of relatively greater 
importance. So far as reliable methods have been available, quan- 
titative results are given. 
SELECTION OF SOIL TYPES. 
The classification of soils which has proved the most practical for 
field investigations and which is employed in the Bureau of Soils is 
Note.— This bulletin gives the results of chemical and mineralogical investigations of certain important 
soils. The inorganic part alone is considered, and special attention is given to the so-called rarer elements. 
It is technical and intended for the use of research workers in agricultural chemistry and teachers in the 
same field. It will also be found of secondary interest to practical agriculturists. 
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