SELF-MAINTAINING FERTILITY 225 



(including their valuable constituents, and an aver- 

 age application for small areas) : 



SOME VERY CHEAP FERTILIZERS 



Lime is valuable for lightening heavy soils and 

 sweetening sour ones. That is, it makes conditions 

 more favorable for the bacteria cooks. If you have 

 any old plaster lying around use that; it is slower 

 to act but useful just the same. 



Salt is a good weed killer, and yet an excellent 

 fertilizer for asparagus. 



Wood ashes are excellent providers of potash, 



