26 BULLETIN 1435, U. S. DEPARTMENT OF AGRICULTURE 
TaBLE 20.—Distribution of bearing grapefruit groves by age groups with quantity 
of fertilizer used per tree annually and yield per tree; average 1917-1922, Polk 
County, Fla. 
Aver- Herts Yield Age eroups. classified outs Yield 
age izer y pounds of ferti- izer 
Age classes age of Trees | Groves per per lizer per tree per Groves per per 
trees tree annum tree Hey 
Years| Number| Number| Pounds) Bozes Number|Pounds| Bozes 
Less than 20 pounds_- 4 14 4. 03 
21 to 30 pounds---__-__- 9 26 2. 76 
All classes .-_--- 15 | 44, 745 95 43 | 3.06 |431 to 40 pounds__-_-___- 29 36 2. 40 
41 to 50 pounds___-__- = 33 45 3. 16 
Over 50 pounds______- 20 63 3. 79 
| Less than 20 pounds_ -_ 1 18 252 
21 to 30 pounds---_-_--- 2 25 4, 32 
21 and over-_----- 24 | 2,970 18 44 | 3.07 |;31 to 40 pounds- --_-___-_ 4 38 2.16 
41 to 50 pounds__-_-_-_-_-- Uf 46 3. 06 
Over 50 pounds-_-__-___- 4 62 3. 72 
Less than 20 pounds--_|--______|__._-_._]-_____- 
21 to 30 pounds- __-_---_ 2 26 2. 26 
16 to 20 years---- 18 | 5,355 15 50} 3.44 |431 to 40 pounds__-_-_-__- 2 37 4. 65 
41 to 50 pounds--_-__-__- 6 46 3. 80 
Over 50 pounds-__-___-- 15) 70 3.10 
Less than 20 pounds_-_ 2 10 3. 97 
21 to 30 pounds_______- 2 27 3. 38 
11 to 15 years___-| 13 | 22,876 38 42 | 3.18 |431 to 40 pounds_______- 15 36 2. 48 
41 to 50 pounds________ 12 46 3. 14 
Over 50 pounds-_-__-_-_-_- 7 64 4, 27 
Less than 20 pounds_-_ 1 18 4. 45 
21 to 30 pounds_ -_-_-___- 3 27 2. 03 
‘7 to 10 years-___-_ 9 | 12,600 24 39 | 2.69 |431 to 40 pounds_______- 8 34 1. 74 
41 to 50 pounds_-_-_-__-- 8 44 2. 93 
Over 50 pounds--_-___-- 4 54 3. 44 
TaBLE 21.—Distribution of bearing tangerine groves by age groups with quantity 
of fertilizer used per tree annually and yield per tree; average 1917-1922, Polk 
County, Fla. : 
Aver- ver Yield ae groups dlasiied pene Yield 
age izer y pounds of ferti- izer 
Age classes age of Trees | Groves per per lizer per tree per Groves per pet 
trees tree annum tree Ae 
Years| Number| Number| Pounds| Boxes Number| Pounds| Boxes 
Less than 30 pounds-_- i 19 0. 98 
31 to 40 pounds__-____- 6 37 1. 95 
All classes._.---- 16 | 5,960 40 48 | 2.53 |,41 to 50 pounds_______- 15 46 2. 85 
51 to 60 pounds___-___-- 7 54 3. 25 
Over 60 pounds- ___--- 7 Ui 2. 88 
Less than 30 pounds-_-_ 2 22 . 64 
31'to!40 poundss Sea 2 See ee ay ee 
21 yearsandover_| 25] 2,968 14 51} 2.99 |441 to 50 pounds-_-_-_-_-_-_- 5 47 3. 11 
51 te 60 pounds___-_-_-- 3 52 3. 44 
Over 60 pounds-_-____- 4 68 | ~2.93 
Tess)than, 30;pounds 22/22. sete sae aes | Poon 
31 to 40 pounds-_-_--___- 1 33 1.80 
16 to 20 years-_--- 18 364 4 57 1 2.46 |441 to 50 pounds______-_ 2 44 3. 08 
D1 tO: 60 poUndS2 eis | 29.8 Skee | Pees ee eae 
Over 60 pounds--___-_- 1 107 1. 68 
Less than 30 pounds_-_ 1 3 1.79 
31 to 40 pounds________ 3 38 1.99 
11 to 15 years_-__- 13 | 2,008 8 43 | 2.07 |+41 to 50 pounds- _-_-__-_- 1- 48 1. 60 
51 to 60 pounds-___-___- 2, 58 2000 
Over 60 pounds--___-___ 1 64 3.77 
Less than 30 pounds_-_ 2 23 1. 36 
31 to 40 pounds---_-__-- 2 37 . 88 
10 ‘years and 8 602 14 46 | 1.84 |441 to 50 pounds-_=+-____- 7 45 1. 93 
under. 51 to 60 pounds_______- 2 55 2. 03 
Over 60 pounds--_-_--_-_- 1 96 2. 65 
The analyses of the fertilizer used in 76 groves in 1922 was obtained. 
A majority of the 76 groves were fertilized three times each year, 
but of this number eight growers made no spring application, four 
no summer application, and seven no fall application. 
There was considerable difference of opinion among growers as to 
the grade of fertilizer to use for the best results. The soil and con- 
dition of the trees had much to do with the choice, but a large part 
