BULLETIN OF THE 



iMmmoFAiiaini 



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. O. 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 



No'ffi- — 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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