THE SOIL PARTICLE 



S3 



size of particle predominating, the name of that particular 

 separate is prefixed, giving still more data regarding the soil 

 in question. Thus, a loam in which clay is dominant will be 

 classified as a clay loam. In the same way, we may have a 

 sandy loam, silt loan^ and so on. It is to be noted that the 

 loams make up half of the class names. In fact, the greater 

 proportion of the soils so far classified in the United States 

 are loams, which is fortunate as the loams in general are more 

 favorable for crop production than any of the other class 

 groups. 



The mechanical analyses of some of the more common 

 classes^ are listed in Table XVI : 



Table XVI 



Coarse Sands . . . . 



Sands 



Fine Sands 



Sandy Loams. . . . 

 Pine Sandy Loams 



Loams 



Silt Loams 



Sandy Clays 



Clay Loams 



Silty Clay Loams 

 Clays 



Fine 

 Gravel 



12 

 2 



4 

 1 



2 

 1 



1 

 

 1 



Coarse 

 Sa]sd 



15 



3 



5 



8 



Medium 

 Sand 



19 



10 



4 

 5 

 1 

 8 

 4 

 1 

 2 



Fine 

 Sand 



20 

 37 



57 



At) 



15 



5 



30 



8 



Very 

 Fine 

 Sand 



6 



11 

 17 

 13 



17 



Xo 



8 



Silt 



7 

 7 



40 

 65 

 13 

 38 

 61 

 36 



Clay 



5 

 5 



4 

 12 

 12 



15 



27 

 26 

 25 

 42 



It is evident that a mechanical analysis of a soil is nothing 

 more or less than an expression of class, and the inferences 

 that may be derived from either are in general the same. This 

 leads to a consideration of class determination. 



45. Determination of soil classes. — The common method 

 of class determination is that employed in the field. It con- 



^ Whitney, M., The Use of Soils East of the Great Plains Be^ion; 

 U. S. Dept. Agr., Bur. Soils, BuL 78, p. 12, 1911. 



