32 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 46 



Fig. 32. — Feeding guns or lances can be devised by an ingenious indi- 

 vidual who wishes to apply liquid plant food to his trees. Several types of 

 these devices are manufactured and can be purchased. 



A tree food consisting principally of highly soluble forms 

 of nitrogen, phosphorus, and potassium should be used in liquid 

 feeding. The food, in dry form, is added to water in the spray 

 tank. Then each tree is fed the necessary number of gallons of 

 solution to supply the required amount of food. The manufac- 

 turer's dosage recommendations should be followed. Safe dosages 

 of most tree foods used in liquid feeding appear to be 1 to 3 

 pounds of the material per 5 inches of trunk diameter at breast 

 height. The amounts of the less highly soluble materials, such 

 as 10-8-6 and 10-6-4, needed for liquid feeding are the same as 

 for dry feeding. 



Feeding Rates for Deciduous Trees. — A deciduous tree hav- 

 ing a trunk of less than 6 inches in diameter at breast height 

 should receive one-fourth pound of available nitrogen per inch 

 of trunk dbh. Larger trees should receive one-half pound of avail- 

 able nitrogen per inch of trunk dbh. Formulas of several tree 

 foods, for dry or liquid feeding, are given on page 29. A tree 

 with a trunk of 4 inches dbh requires one-fourth pound per inch, 

 or 1 pound, of available nitrogen. A tree with a trunk of 12 

 inches dbh requires one-half pound per inch, or 6 pounds, of 

 available nitrogen. The method of calculating the amount of 

 tree food needed is described on page 29. The amount of 10-8-6 

 tree food required to supply 1 pound of available nitrogen is 

 10 pounds (1 -^ 0.10). The amount of 12-6-4 tree food required 

 to give 6 pounds of available nitrogen is 50 pounds (6 -^ 0.12). 



