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 
