52 Home Vegetable Gardening 



almost entirely upon their use, that probably it will 

 be best to explain the subject as thoroughly as I can 

 do it in very limited space. I shall try to ^ive the 

 theory of scientific chemical manuring in one 

 paragraph. 



We have already seen that the soil contains within 

 itself some available plant food. We can determine 

 by chemical analysis the exact amounts of the va- 

 rious plant foods — nitrogen, phosphoric acid, potash, 

 etc. — which a crop of any vegetable will remove 

 from the soil. The idea in scientific chemical ma- 

 nuring is to add to the available plant foods already 

 in the soil just enough more to make the resulting 

 amounts equal to the quantities of the various ele- 

 ments used by the crop grown. In other words : 



Available plant food elements in 



the soil, plus 

 Available chemical food elements 

 supplied in fertilizers 



That was the theory — a very pretty and profound 

 one! The discoverers of it imagined that all agri- 

 culture would be revolutionized; all farm and 

 garden practice reduced to an exact science ; all older 

 theories of husbandry and tillage thrown by the 

 heels together upon the scrap heap of outworn 

 things. Science was to solve at one fell swoop all 

 the age-old problems of agriculture. And the whole 

 thing was all right in every way but one — it didn't 



Amounts of food ele- 

 — ments in matured 

 crop 



