6 BULLETIN OF THE 



Origin of clays. Varieties. Kaolin. Pipe-Clay. "Soap- 

 stone. " Brick Loam. 



Tints imparted to clays by Iron changes by oxidation 

 and reduction. 



By Manganese by Carbon how recognized. 



Recapitulation of the properties of clay as a soil ingredient. 

 Iron. Widely diffused, omnipresent, Nutritive as well as me- 

 chanically important. Tonic. 



Hygroscopic efficacy of ferric oxide; chemical inertness. 



Proto salts poisonous. Reduction of ferric oxide by veg- 

 etable matters. Yellow mud and blue mud. 



Bottom lands blue subsoils "rusting" soils. 



Iron in surface soils and subsoils. 



"White or "Crawfishy" soils Black pebble or bog ore sub- 

 soils. Deterioration of soil thereby: causes. 



Chalybeate Springs. Formation of Ferruginous sand- 

 stone. 



Manganese. Vicarious of Iron. Less important. 

 Copper. In very minute quantities, in wheat, potashes, etc. 



Non-metallios. 



Silicon. Silica predominant ingredient of soils. 

 Sand and silicates. 



Apparently unessential to plants but very largely ab- 

 sorbed by grasses, pines, etc. "Lodging" of grain. 

 Silica in drain waters Acid soils Action of lime. 

 Sulphur. Sulphates omnipresent. Small percentage in soils. 

 Often deficient. 



Cheaply supplied by gypsum. Sulphates in drain water. 

 Effects of fermentation on sulphates. Iron pyrites, etc. 



Remedies. 

 Phosphorus. Phosphates of highest importance to nutrition of 



plants and animals. 



Derivation of soil phosphates. Small percentage re- 

 lation to Potash. 

 Accumulation in seeds. Small-seeded plants on soils 



poor in phosphates. 



Their deficiency a common cause of sterility. 

 Must be currently restored to cultivated soils. 

 Effect of bone-dust on old pastures. 

 Chlorine. Present in all soils and plant ashes. 



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