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Group Title: Research report - UF Central Florida Research and Education Center ; SAN-85-14
Title: Carrot fertilization trials at Zellwood, Florida, 1974-75
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Permanent Link: http://ufdc.ufl.edu/UF00075829/00001
 Material Information
Title: Carrot fertilization trials at Zellwood, Florida, 1974-75
Series Title: Research report - UF Central Florida Research and Education Center ; SAN-85-14
Physical Description: Book
Language: English
Creator: Forbes, Richard Brainard
Publisher: Central Florida Research and Education Center, University of Florida
Publication Date: 1985
 Subjects
Spatial Coverage: United States -- Florida -- Zellwood
 Record Information
Bibliographic ID: UF00075829
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 123071491

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






C-F
S- L University of Florida

Central Florida Research and Education Center

Sanford, Florida

Research Report SAN 85-14 June 1985

CARROT FERTILIZATION TRIALS AT ZELLWOOD, FLORIDA: 1974-75

R. B. Forbes


A field experiment to provide information for development of an
improved program for processor carrots was conducted at this center's
Zellwood farm during the 1974-75 winter vegetable season. In addition,
other information was sought on the possible relationship of soil
fertility to root disease problems, and the effects of fertilization and
cropping on residual nutrients in the soil at harvest.

The experimental area had been in use fo: -~ `yieairs', ~Ai' fo
vegetable crops, with a consequent buildup in residual fertility. So 1
was Lauderhill muck, a Lithic Medisaprist, re resen j14.eof3 the
shallower organic soils underlain with lime r ck.

Materials and Metho J.F.A.S.-Univ. o Forida

Processing type carrots (Chantenay 503, Asgrow) were grown on low 4
row beds with a plot -sizeof 6 X 20 feet or 0.0028 acres. Nitrogen was
supplied from ammonium nitrate, phosphorus from superphosphate,
potassium from muriate of potash and magnesium from Emjeo (fertilizer
grade MgS04). Fertilizer treatments for a 2 X 2 X 2 X 2 factorial
design were applied to the plots by band, then incorporated into the
soil as beds were being formed. The treatments (shown in Table 1) were
replicated 6 times in randomized blocks. Carrots were planted December
20, 1974, and harvested May 8, 1975. Soil samples were taken before
planting or fertilization and again at harvest. Soil pH (by glass
electrode in 1:2 soil:water suspension) soluble salts (by conductivity)
and nitrates (by diphenylamine procedure) were done at AREC-Sanford.
After samples were screened and dried, extractable (by ammonium acetate
@ pH 4.5) Ca, Mg, P and K were determined in the IFAS Soil Science
Department Soil Testing and Analytical Services Laboratory at
Gainesville.

Results and Discussion

Yields.- At harvest, the carrots were graded into U. S. Grade A and
total marketable carrots. Results are given in Tables 1 and 2. Yield
trends were similar for both grades of carrots. The total marketable
yields were greater since larger sizes were included. In both grades
there were significant responses to N and K, but not to P nor Mg.
Yields were not decreased by P or Mg; however, none of the interactions
NxP, NxK, NxMg, PxK, PxMg, or KxMg proved significant in either grade of
carrots.








Disease Ratings.- Counts were made during harvest of 20 feet of row per
plot of the number of roots showing symptoms of infection by Pythium sp.
Typically, the carrot root would be "stubbed off" short at the point
where the fungus had more or less girdled the developing tap root of the
young carrot. Data are summarized in Tables 3 and 4. There were
relatively few roots affected by Pythium and no significant effect shown
by the fertilizer treatments in relation to diseased roots.

Soil Data.- A composite soil sample from each replicate was taken prior
to application of fertilizer treatments. These data are shown in Table
5. Analyses were typical of muckland in central Florida under
cultivation for a number of years. Levels of calcium and magnesium were
high, with moderate to high levels of phosphorus and potassium. Nitrate
nitrogen was at medium levels at-the time samples were taken. However,
nitrates may fluctuate greatly during a single season as influenced by
weather conditions, so nitrate analyses at planting do not necessarily
reflect the needs of the crop later in the growing season.

At harvest, samples were taken from each individual plot. Analyses
are given in Table 6. The effect of each nutrient level on extractable
P 2O, K2O and MgO in the soil at harvest is given in Table 7. At
harvest, nitrate levels averaged medium to low for the zero N
treatments, showing a drop from the pre-treatment levels. Where N was
applied, the effect of the treatment could still be noted at harvest in
the medium to high levels remaining in the soil. The N treatments had
little or no effect on P205, K20 or MgO in the soil at harvest.

Phosphorus.- P 0_ levels averaged 56 lb/A before planting and were down
to 38 1b/A at-navest in plots with no P 0 added. Where P 0 was
applied at 100 lb/A, the level at harvest averaged 101 lb/A. This
treatment also showed slightly higher K20 levels than the 0 P 05
treatment: 308 lb/A compared to 282.

Potassium.- K 0 levels averaged 246 lb/A at planting but at harvest were
reduced to 182 in the 0 K 0 treatment. The 120 lb/A K20 treatment gave
an increase in extractable K 0 with the treated plots averaging 362
lb/A, a slight decrease in extractable P 0 and little effect on MgO
levels.

Mannesium.- Although MgO levels were high and remained high throughout,
added MgO (60 lb/A) did give a detectable increase in extractable MgO in
the soil at harvest. The MgO treatment made no difference in
extractable K20 but reduced P205 by 10 lb/A.
2 25 >
Calcium.- CaO levels were very high throughout due to the nature of this
soil with calcareous material present in the profile.





3


Summary and Conclusions

Nitrogen and potassium treatments both gave significant yield
increases whereas there were no significant effects from either P2 0 or
Mg0 additions. Both the latter were present in the soil at high enough
levels to permit normal crop growth without addition of either P20 or
MgO. None of the treatments showed any significant effect on occurrence
of stubbed off roots caused by Pvthium sp. (fungus).

Nutrient levels were relatively high in this soil at the start. At
harvest, the treatments with N, P ,0, K 0 and MgO were reflected in
nutrient levels present in the soil, indicating that the treatments gave
sufficient nutrients for the crop uptake plus moderate residual
build-up.








Table 1. Carrot yields, fertilizer trial, Zellwood, FL, 1974-75.

Yield1
U.S. Total
Fertilizer treatment grade marketable
N P 0 K 0 MgO A carrots

--------------lb/A--------------- ---------T/A--------

0 0 0 0 7.98 11.03
0 0 0 60 7.91 11.18
0 0 120 60 12.34 15.10
0 100 120 60 11.11 13.72
0 100 0 0 8.71 11.54
0 100 120 0 10.74 13.36
0 100 0 60 9.44 11.90
0 0 120 60 10.24 12.92

60 0 0 0 9.51 12.12
60 0 0 60 12.70 15.75
60 0 120 60 .11.83 14.74
60 100 120 60 11.61 14.37
60 100 0 0 9.87 12.49
60 100 120 0 12.56 15.24
60 100 0 60 10.74 13.21
60 0 120 0 12.20 14.81

LSD 0.05 3.38 3.43


ANOV F F F Table
summary value value .05 .01

N levels 6.94* 5.75* 3.96 6.96
P205 levels <1 <1 "
K20 levels 10.62** 9.44** "
Mg0 levels 1.53 1.70 "
Interactions All N.S. All N.S.

1Average of 6 replicates.








Table 2. Carrot fertilizer trial 1974-75: effect

average yield for each nutrient level.


U.S. Grade A

----T/A-----

9.80
11.38

10.58
10.60

9.61
11.57

10.22
10.96


of each element and


Total marketable

------T/A-------

12.59
14.07

13.46
13.21

12.39
14.28

12.94
13.73


Nutrient


lbs/A


N
N

P205
P205

K20
K20

MgO
MgO


0
60

0
100

0
120

0
60


Average yield of all replicates of given nutrient level including all

combinations with other elements.








Table 3. Effect of fertilizer treatment on numbers of diseased roots.

Treatment Diseased roots
N P205 K 0 MgO per 20' of row

-------------------lb/A------------------
-- --- l--b/A--------------


0
100
100
100
100
0


100
100
0


0
0

120
120
0
120
0
120

0
0
120
120
0

120
0
120


1.5
1.0

1.8
1.8
1.7
2.2
1.7
1.8

1.3
1.2
3.0
1.2
1.3

1.8
1.5
2.0

N.S.


LSD 0.05


1Average of 6 replicates.








Table 4. Effects of fertilizer treatment on diseased roots: effect

of each element.

Diseased roots1
Element lb/A per 20' of row

N 0 1.60
N 60 1.66

P205 0 1.70
P205 100 1.65

K20 0 1.40
K20 120 1.95

MgO 0 1.70
MgO 60 1.65


Average of all replicates of given nutrient level including all

combinations with other elements.








Table 5. Carrot fertilizer trials 1974-75: pre-fertilization soil

analyses.


2 Soluble Extractable nutrients1
Composites pH NO- salts CaO MgO P20 K 0

--ppm-- -----------lb/a------------
Repl. A 7.0 Med. 200 16790 2470 68 222
B 6.6 182 15210 2503 58 229
C 6.4 182 15210 2403 48 236
D 6.4 164 15210 2336 50 257
E 6.4 200 15210 2336 52 264
F 6.5 200 15810 2303 60 271

Average 6.6 Med. 188 15573 2392 56 246


Extracted with 1 N ammonium acetate buffered at pH 4.8.
2Nitrates determined by diphenylamine method.
Nitrates determined by diphenylamine method.








Table 6. Carrot fertilizer trials, 1974-75. Soil analyses at harvest.

Sampled May 8, 1975: Soil analyses .

Treatment Soluble Extractable Nutrients2
N P205 K20 MgO pH NO, salts CaO MgO P205 K20

-------lb/A------- --ppm-- ---------lb/A---------

0 0 0 0 6.6 med-low 164 15810 2203 36 188
0 0 0 60 6.6 273 14300 2137 36 167
0 0 120 60 6.5 273 15810 2369 38 410
0 100 120 60 6.6 382 16790 2369 110 361
0 100 0 0 6.5 273 15210 2237 132 174
0 100 120 0 6.6 255 14830 2104 84 340
0 100 0 60 6.5 309 16300 2303 84 132
0 0 120 0 6.6 237 15210 2072 38 368


60 0 0 0 6.5 med-high 291 15810 2203 40 188
60 0 0 60 6.4 med 291 14830 2303 36 208
60 0 120 60 6.5 237 15210 2237 36 389
60 100 120 60 6.4 328 15210 2303 80 320
60 100 0 0 6.4 273 15810 2203 120 208
60 100 120 0 6.5 med-high 291 16300 2336 100 368
60 100 0 60 6.4 med 291 15210 2270 96 195

60 0 120 0 6.4 high 309 14830 2170 40 340


Average of 6 replicates.

2Extracted with 1 N ammonium acetate buffered at pH 4.8.








Table 7. Effect of individual nutrient treatments on levels of

extractable P205, K20, and MgO in the soil at harvest.


Treatment
Nutrient


N
N

P205
P205

K20
K20

MgO
MgO


Rate

Ib/A

0
60

0
100

0
120

0
60


Extractable Nutrients2
P Og2 0 K2O MgO

--------------lb/A---------------

70 268 2224
68 277 2253

38 282 2212
101 308 2266

72 182 2232
66 362 2245

74 272 2191
64 273 2274


1Extracted with 1 N ammonium acetate buffered at pH 4.8.

2Average of all replicates of given nutrient level including

combinations with other elements.




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