VIII 



Domesticated Earthworms 



IN THE unhurried processes of nature it may require from forty 

 to fifty years for native earthworms to spread slowly from a 

 single breeding colony and fully impregnate an acre of ground. 

 In England, where the earthworms had been working in a fairly 

 favorable environment through geological ages, Darwin found 

 native earthworms in numbers ranging from 25,000 to 50,000 

 or more per acre in some soils, which means less than one worm 

 per cubic foot of surface soil. Even in these small numbers, as 

 has been pointed out, Darwin estimated that from ten to eighteen 

 tons of dry material per acre passed through the bodies of 

 earthworms in England each year to be deposited in and on 

 the surface as castings. 



We have previously mentioned the earthworms in the State 

 of Ohio, where they have been found in bluegrass land in num- 

 bers upwards of a million per acre. If we figure an average 

 working depth of thirty inches, one million worms per acre 

 would mean, in round numbers, about ten worms per cubic foot. 

 A population of two to four native earthworms per cubic foot 

 in farm soil or other soil is considered a quite numerous earth- 

 worm population. In previous pages we have shown the almost 

 incredible amount of cultivation and translocation of soil which 

 earthworms perform under favorable conditions. In intensive 

 propagation and use, we control the environment and create 

 nutritional conditions which are most favorable to proliferation 



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