86 



PRINCIPLES OF AGRICULTURAL CHEMISTRY 



average 31 per cent, coarse sand particles, the sands 37 per cent, 

 of fine sand particles, the fine sands 57 per cent, fine sand 

 particles. The clays contain 42 per cent, clay particles. 



AVERAGE COMPOSITION OF SOIL TYPES AS ANALYZED IN CONNECTION 

 WITH THE SOIL SURVEYS. 



The classification of soils with regard to physical composition, 

 as used by the Bureau of Soils, 1 is shown in the following table. 

 The classification is controlled by field observations. 



CLASSIFICATION OF SOIL MATERIALS. 

 Soils containing 20 silt and clay : 



Coarse sand . f 2 5-f fine gravel and coarse sand, 



\ and less than 50 any other grade. 



c an( j I 2 5+ fine gravel, coarse and medium 



\ sand, and less than 50 fine sand. 



!5o-f fine sand, or 25 fine gravel, 

 coarse and medium sand, 50+ 

 very fine sand. 



Very fine sand 50+ very fine sand. 



Soils containing 20-50 silt and clay : 



Sandy loam . / 25+ fine gravel, coarse and medium 



( sand. 



Fine sandy loam | 50+ fine sand, or -25 fine gravel, 



(. coarse and medium sand. 



Sandy clay 20 silt. 



Soils containing 50+ silt and clay : 



Loam 20 clay, 50 silt. 



Silt loam 20 clay, 50+ silt. 



Clay loam 20-30 clay, 50 silt. 



Silty clay loam 20-30 clay, 50+ silt. 



Clay 30-1- clay. 



1 Bulletin No. 78. 



