NATURE OF SOIL 



29 



Phosphoric acid is P2O5. Common table salt is NaCl (sodium 

 and chlorin). 

 Following are the formulas for various common substances : — 



Acetic acid C2H4O2 



Ammonia NH3 



Aniline NH^CCeHs) 



Arsenious oxid .... AsjOa 



Carbon dioxid .... CO2 



Carbonic oxid .... CO 



Chloroform CHCI3 



Ferric oxid (iron rust) . . FejOa 



Ferrous oxid FeO 



Hydrochloric acid . . . HCl 



Mercuric oxid .... HgO 



Nitrate of soda .... NaNOg 



Nitric acid HNO, 



Nitric oxid NO 



Nitric peroxid .... NO2 



Nitrous oxid N2O 



Saltpetre KNO3 



Starch CgHioOs 



Strychnine C21H22N2OJ 



Sugar, cane CijHjjOn 



Sugar, grape or glucose . CeHijOe 



Sulfate of potash . . . K2SO4 



Sulfuretted hydrogen . . HjS 



Sulfuric acid ..... H2SO4 



Sulfuric oxid SO3 



Sulfurous oxid' .... SO2 



The Soil 



The soil, as the farmer understands it, is the soft tillable covering or 

 epidermis of the earth. It is derived primarily from disintegrated rock, 

 but all productive soils contain organic remains, or materials derived 

 directly from these remains. Some soils, as those in swamps, are very 

 largely organic. 



Classification of soils in respect to origin (Merrill) 



Sedentary 



IB 



^ 



J [Transported 



I Residual deposits 

 Cumulose deposits 

 CoUuvial deposits 



Alluvial deposits, 

 including the 



aqueo-glacial . 



^olian deposits . 



Glacial deposits . 



I Residuary gravels, sands, clays, wacke, 



I laterite, terra rossa, etc. 



j Feat, muck and swamp or palludal 



I soils, in part. 



j Talus and cliff debris, material of 



I avalanches. 



r Modern alluvium, marsh and swamp 



J deposits, estuarian clays. Loess and 



[ adobe in part. 



I Wind-blown material, sand-dunes. 



I Adobe and loess in part. 



(Morainal material, either lateral, ter- 

 minal, or ground moraines, drum- 

 lins, etc. 



Classification of soil constituents 



Name 



1. Gravel 



2. Coarse sand 



3. Medium sand 



4. Fine sand 



5. Very fine sand 



6. Silt 



7. Clay^ 



(U. S. Dept. Agric.) 



Size of Particles 

 (diameters in millimeters) 

 2.0 to 1.0 

 1.0 to 0.5 

 0.5 to 0.25 

 0.25 to 0.1 

 0.1 to 0.05 

 0.05 to 0.005 

 0.005 to 0.0000 



