ECONOMIC ASPECTS OF CITRUS-FRUIT GROWING IN FLORIDA 25 
The average quantity of fertilizer used per tree per year on bear- 
ing groves was influenced very little by the age of the tree or the 
variety of fruit. In Tables 19, 20, and 21, summaries of fertilizer 
applications per tree are given for the different ages of fruit by va- 
rieties. Grapefruit averaged a pound more fertilizer per tree than 
oranges, and tangerines averaged 6 pounds more per tree than oranges. 
There is little evidence that there was any strict practice among the 
growers as to the quantity of fertilizer best suited to the needs of 
trees at various ages. With respect to the use of fertilizer and yields, 
the evidence shows that higher-than-average yields are associated 
with a higher-than-average application of fertilizer per tree. It was 
not uncommon for growers to adjust somewhat the rates of-applica- 
tion in the February and June fertilizings to the prospects of the 
crop in their groves. 
The individual trees, in a grove with trees of the same age and of 
the same variety of fruit, vary considerably in physical condition 
and fruit-carrying ability and the intelligent grower adjusts the quan- 
tity of fertilizer for each tree according to the needs of the individual 
tree. 
TABLE 19.—Distribution of bearing orange groves by age groups with quantity of 
fertilizer used per tree annually, and yield per tree; average 1917-1922, Polk 
County, Fla. 
| | | ai | 
Aver- | Ferti- | ~: | Age groups classified Ferti- | <-: 
2 Yield | : . Yield 
age | lizer | | by pounds of ferti- lizer 
Age classes age of Trees Groves per | ee | lizer per tree per | Groves per pe 
trees tree | | annum tree 
; | | 
Years Number Number Pounds Bozes 
| 
| Number Pounds\ Bores 
| Lessthan20pounds--| 4, 14} 287 
| 21 to 30 pounds___-____ 11 | 26 1. 88 
All classes _______ 15 | 57, 592 92 42 |} 2.27 |431 to 40 pounds__-_-____ 29 | 36 2. 00 
41 to 50 pounds_-_-_-____ 30 45 Ve 2558 
Over 50 pounds______- 18 | 59 3.57 
Less than 20 pounds__| 1 18| 1.05 
_ |}21 to 30 pounds------- 1 | 23! 3.81 
26 yearsand over_| 28] 2,040 6 44 | 2.89 431 to 40 pounds_______ 1 40 3.31 
||41 to 50 pounds_______ 1| 45| 239 
Over 50 pounds- -__--- | 2 | 68 3. 56 
Less than 20 pounds-__|________ ee eS 
||21 to 30 pounds________ 3 | 25 1.83 
21 to 25 years____| 23 | 10,605 15 Ae 220625316040 = ee a 3 | 37 3. 01 
'141 to 50 pounds__-_____ 7 46 2. 66 
Over 50 pounds_--_-____ 2 68 4.60 
‘Bess:than-20 pounds —|2=:-.=__[. 2 = eee 
21 to 30 pounds-__--_-_-_-- 3 26 . 84 
16 to 20 years___- 18 | 7, 755 15 48 | 2.68 |431 to 40 pounds__-____- 2 37 3. 88 
41 to 50 pounds__--_-_-__} 6 7 2. 68 
Over 50 pounds- --__--- 4 7 3. 44 
Less than 20 pounds- -| 3 13 2.31 
21to30pounds__...| 2 a7} 1.64 
11 to 15 years____ 13 | 28, 200 30 40 | 2.17 |431 to 40 pounds__-____- 12 36 2. 03 
41 to 50 pounds_-_-_-___- 6 45 2. 59 
Over 50 pounds_____-- 7 58 3. 49 
Less than 20 pounds -|_ =. 23. -}_- 2 eee 
21 to 30 pounds_______- 2 27 1. 53 
6 to 10 years_____ 8 | 8,996 26 40 | 1.69 /431 to 40 pounds-_-_-----) 11 35 1.08 
41 to 50 pounds_--___-- 10 = 2. 22 
Over 50 pounds_-_-_-_-_- 3 53 1. 67 
| 
