52 FERTILIZERS 



will carry the soluble portion to the deepest roots, 

 wherever, in fact water can go. There, reversion to 

 insolubility may and probably does occur in a few 

 days, but the phosphoric acid is where the roots can 

 act on it directly. (8) (35). 



Nitrate of soda should not be applied in late fall 

 or winter months while growth is dormant, as it 

 would probably be leached away before the tree could 

 take it up. Organic forms should be applied in Janu- 

 ary or February. 



AMOUNT TO APPLY. 



78. The quantity of fertilizer that should be used 

 varies with the conditions. It depends upon : 



1. The percentage richness of the fertilizer. 



2. Record of past experience. 



3. Natural richness of soil. 



4. Age and number of trees per acre. 



5. Kind of tree or crop. 



One popular way of estimating the amount to use 

 is to say one pound of high grade fertilizer to each 

 year of age of the tree. This, while very inaccurate, 

 gives good results, but the practice of citrus culture 

 has demonstrated the wisdom of using considerably 

 more than this amount, probably two pounds for 

 each year of age of citrus trees will be fully war- 

 ranted in most cases. 



This is particularly true of trees over twelve and 

 fifteen years old. If the fertilizer is low grade, the 

 amount used should be increased. 



If trees have been topped for budding or very 

 severely pruned, the amount may be reduced accord - 

 dingly. 



