CARBONATE OF LIME. 147 



where fertility is steadily manufactured. There 

 will be air in such a soil and bacteria in enormous 

 abundance, among them the useful bacteria that live 

 upon any sort of decaying humus in the soil and 

 gather nitrogen from the air, the new-found azobac- 

 ter. Thus there is a perpetual fertility-gathering 

 plant established right in the soil. 



It all depends, after all, on the possession by the 

 soil of a large amount of carbonate of lime. If that 

 is absent the fertility put there in excess of the 

 needs of the plants soon leaches away and is gone. 

 The writer has traveled in lands very deficient in 

 lime, so deficient that the well water was almost as 

 pure as distilled water, and there has noted that not 

 only were the fields incredibly poor, but even such 

 places as barn lots had in them very little richness 

 indeed, though manure had been wasted therein for 

 a century or more. 



Think how old the world is ! And since the rocks 

 cooled and vegetation started to cover the earth 

 roots have been decaying in the soil and leaves fall- 

 ing thereon with stems and branches and all man- 

 ner of debris. Enough vegetable matter, enough 

 humus-forming material, has fallen to the earth and 

 become buried in the earth nearly everywhere, to 

 make the soil incredibly rich. Instead we commonly 

 find even wild soils rather poor. Why? Because of 

 the lack of carbonate of lime. That is the one thing 

 that can fix fertility and hold it for use in future 

 years. 



On the old farm at Arlington, near Washington, it 



