UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 551 
Contribution from the Bureau of Soils 
MILTON WHITNEY, Chief 
J^^ft. 
Washington, D. C. 
June 26, 1917 
VARIATION IN THE CHEMICAL COMPOSITION OF 
SOILS. 
By W. O. 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 
Petrographic examination 8 
Page. 
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 '. IS 
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—1; 
•U. S. Dept. Agr. Bui. No. 122 (1914). 
