210 THE FARMER OF TO-MORROW 



important matter of making plant food avail- 

 able; and attention is also called to the fact 

 that the decomposition of the organic matter 

 of the soil including both fresh materials 

 and old humus is hastened by tillage and by 

 underdrainage, which permit the oxygen of 

 the air to enter the soil more freely, oxygen 

 being a most active agent in nitrification and 

 other decomposition processes of organic mat- 

 ter, as well as in the more common combustion 

 of wood, coal, and so forth." 



Do soils wear out? 



The hypothesis of Liebig and those who 

 have followed in his path and accepted his 

 theories with the utmost literalness say un- 

 equivocally that they do. Neither is it a re- 

 mote contingency in their eyes ; it is immediate. 

 They take the onus for the lack of bounty in 

 the soil from the shoulders of man and shift 

 it to Providence. Providence has been par- 

 simonious with the elements of the bread 

 and meat we would eat. Nature has pro- 

 vided two storehouses from which we may 

 extract food. One is the soil itself. The 

 other is the mines of plant food minerals which 

 we may scatter in the soil, when the land shows 

 signs of exhaustion. They have computed, as 

 we have seen, how long the soil will continue 



