UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 5 



Contribution from the Bureau of Soils 

 MILTON WHITNEY, Chief 



Washington, D. C. 



June 26, 1917 



VARIATION IN THE CHEMICAL COMPOSITION OF 



SOILS. 



By W. 0. Robinson, L. A. Steinkoenig, and William H. Fry, Scientists in Chem- 

 ical Investigations. 



CONTENTS. 



Introduction 1 



Description of soils analyzed 1 



Preparation of samples and methods of analy- 

 sis 4 



Results of analyses 5 



Petrographie examination 8 



Discussion of data 9 



Relation of soil to subsoil 10 



Extreme variation 10 



Variation in the same province 12 



Variation in soils of the same type 13 



Limit of error in analytical work 14 



Summary 16 



INTRODUCTION. 



In a previous paper 1 complete analyses of a number of important 

 American soils were presented and discussed chiefly from the point 

 of view of the occurrence of rare elements seldom sought in soils. 

 In that paper, although the analyses were presented under soil- type 

 names and classified by soil provinces, the data were not considered 

 sufficient to warrant any discussion of the chemical variation of soil 

 types or of soil provinces. 



Since then, analyses of additional samples, for major constituents 

 only, have been made, and it has seemed that these, together with 

 those already published, might furnish a basis for some general dis- 

 cussion of the variation in chemical composition of American soils. 



The additional data, given for the first time in the present paper, 

 include the results of the analysis of 45 samples, representing 18 

 distinct soil types, distributed in 4 soil provinces. The samples come 

 from 22 different localities in 8 States, and were taken with extreme 

 care by men familiar with the various soils under field conditions. 



DESCRIPTION OF SOILS ANALYZED. 



The soil-type names, location, character of samples, and short de- 

 scription of the soils follow : 



1. Colorado sand. T. 5 N., R. 65 W. Near Greeley, Col. Soil, depth to 14 

 inches. This type consists of old stream-borne material derived from the harder 



87828°— Bull. 551—17 



i U. S. Dept. Agr. Bui. No. 122 (1914). 



