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Mimeo Report CFES 67-4

June 28, 1967

NUTRITIONAL STUDIES ON CALADIUMS

R. B. Forbes, and P. J. Westgate

In 1965 and 1966 fertilizer and minor element experiments were carried out
on newly cleared Istokpoga peat on the farm of L. L. Holmes, Lake Placid.

Four different experiments were conducted in 1965:
Experiment I, NPK Fertilizer trial (3 rates of each element in all
possible combinations, making 27 treatments).

Experiment II, Soil Amendments, Liming Materials.

Experiment III, Minor Elements.

Experiment IV, Experimental Controlled Release Fertilizer Materials
(slowly available nitrogen and potash carriers from Sun Oil Co.).

Caladium tubers of the variety Candidum were used in all of the experiments.
All treatments were replicated 5 times except in Experiment IV, where 3 replicates
were used. A minor element mixture was applied uniformly to all plots except in
the minor element experiment at the rate of 40 pounds per acre. Soil samples were
analyzed from all experiments.

Data from each experiment were statistically analyzed and results may be
summarized as follows:

Experiment I NPK Factorial Fertilizer Trial, 1965

No.

1
2
3
4
5
6
7
8
9

100
100
100
100
100
100
100
100
100

Treatments and Tuber Yields
lbs/A

Po

0 o

1AUG1b6 1967
100
100
I.F.AS. U- o C F l" ridn
--.-...--......... o-..--- --
200
100
200
0
100
200
0
100
200
0

K20

0
200
400
0
200
40o
0
200
400
4oo
0
0
0
200
200
200
400
400
400

Average
yield
lbs/plot

1.50
2.18
1.94
2.28
2.34
2.04
1.74
1.66
1.82
1.72
1.54
1.90
1.60
2.08
1.60
1.94
1.66
1.46

150 copies

CENTRAL FLORIDA EXPERIMENT STATION
Sanford, Florida

-2-

200
200
200
200
200
200
200
200
200

Treatments and Tuber Yields
lbs/A
P205

200
0
100
200
0
100
200
0
100

0
0
0
200
200
200
400
400
400

Average
yield
Ibs/plot

1.80
1.88
1.62
1.34
1.94
1.84
1.88
2.22
1.70

1Average of 5 replicates, to convert to lbs/A multiply Ibs/plot X 2608.
Harvested area 16.7 sq. feet from center row of each plot.

Analysis of the yield data showed no significant differences from any of the
treatment factors. However certain trends were evident after studying the separate
effects of each element: (a) There was little or no response to nitrogen; (b) there
appeared to be a slight yield gain from the first 100 pound increment of phosphorus
and the first 100 pound increment of potassium.

As a matter of interest the 5 best-yielding treatments are shown:

0
0
200
0
100

Treatment:
lbs/A
P20 5

100
100
0
0
200

Av. yield
lbs/plot

K20
O
200
0
400
200
200

2.34
2.28
2.22
2.18
2.08
1.50

Unfertilized:

Soil analyses showed fairly high levels of P2 0and K20 at
definite build-up by harvest from the fertilizer applications.

Analyses of Samples taken before planting:

Sample Description

Soluble
pH salts

the start and a

Available Nutrients Ibs/A
Nitrates P205 K20 CaO MgO

1. North half composite
2. South half

4.4 55 High
4.3 50 High

73 192 7554 1212
53 131 5456 901

_ __ __ _____ _____

-3-

Samples taken at harvest:

Treatment, lbs/A
N P,0O

Soluble
salts

KPO
20

Available Nutrients1

Nitrates P20 K20

CaO

lbs/A
MgO

U- -L
1. 0 0 0 4.6 26 VL 48 118 4449 663
2. 100 100 200 4.5 22 54 181 4393 705
3. 200 200 400 4.5 22 68 243 4329 635
4. 0 100 200 4.6 20 64 250 4393 663
5. 0 200 400 4.6 26 82 299 5064 705
6. 0 0 400 4.5 30 48 361 4393 608

1Available nutrients through the cooperation of Dr. J. NeSmith, Soil Testing
Laboratory, Florida Agricultural Extension Service, Gainesville.
Experiment II Soil Amendments for Caladiums
Lake Placid, 1965-66

This experiment was adjacent to the fertilizer trial, in the same field, with
the same type of plots and treatments replicated 5 times. Treatments were as
follows:
Avg. yield, Ibs/plot
1. Dolomitic limestone, 1 ton per acre 1.20
2. 2 tons 1.48
3. Hydrated lime, 1 ton 1.22
4. Gypsum, 1 1.50
5. Basic slag 1 1.70
6. Magnesium sulfate (Emjeo), 100 Ibs MgO per acre 2.06
7. Check, untreated 1.74

All plots received 500 pounds of 10-10-10 plus 40 pounds of a minor element
mixture per acre when the initial treatments were applied on May 19-20, 1965.
An additional 500 pounds of 10-10-10 was applied on July 8, 1965.

The only treatment better than the untreated checks was the magnesium sulfate.
The increase proved statistically significant. The whole field had received a
pre-planting application of 2.5 tons of dolomite per acre, so these treatments
were in addition to that.
Soil analyses (9-2-65 Samples):

Treatment

rate/A
1 T dolomite
2 T dolomite
1 T hydrated lime
1 T gypsum
1 T basic slag
100 lbs MgO
Check

Soluble Nitrate
pH salts Nitrogen

4.7
4.8
4.7
4.3
4.6
4.4
4.4

Med
M-L
M
M
ML
M
M

Available Nutrients
P20 K20 CaO

174
181
195
167
181
188
188

5386
5596
5596
4589
4855
4393
4589

Pre-treatment (5-20-65) 4.3

lbs/A
MgO

1103
1268
663
469
763
663
564

_ _______ I~

-- -- --

- ----------~---~-----

- 4-

Summary

Highest yields in this trial were from the magnesium sulfate applications.

Soil analyses from time to time over the season showed very low pH's at the
start, a slight rise by July and the maximum rise in the September and October
samples. The highest pH found was 5.0 from the 2 ton rate of dolomite in the
October samples. Dolomite was very effective in bringing up the calcium and
magnesium content of the soil, more so than the basic slag.

Experiment III Minor Element Trial, Caladium:
Lake Placid, 1965-66

This experiment was adjacent to the other trials, in the same field, with
the same size plots and carried out at the same time. Treatments were replicated
5 times and were as follows:
Avg. yields lbs/plot
1. Untreated check 1.18
2. Minor Element Mixture 40 lbs/A 1.04
3. 80 1.66
4. Zinc Sulfate 20 lbs/A 1.06
5. Manganese Sulfate 20 lbs/A 1.18
6. Iron Sulfate 1.20
7. Copper Sulfate 2.34
8. Borax 10 lbs/A 1.38

All plots received an initial application of 500 pounds of 10-10-10 per acre.
The minor element treatment was mixed with the 10-10-10, using the fertilizer as
a diluent or carrier. The fertilizer containing the treatments was then broadcast
between the rows and cultivated in. The treatments were applied May 20, 1965 and
an additional 500 pounds of 10-10-10 was given on July 8, 1965.

Yield differences proved very highly significant. The main response noted
was from the copper treatment. The mean yield for this treatment was about twice
that of the check plots. Also, the 80 pound rate of the minor element mix (con-
taining copper) was the next highest yielding.

This response to copper was the most striking yield increase found in this
whole series of caladium experiments. When observations and pictures were made
on October 5, 1965 with the plants at maximum foliage, this treatment (copper)
was noted then as one having the best growth.

At planting time a composite sample showed the following:
Solubridge Nitrate
pH Reading Nitrogen
4.3 50 H

1The minor element mixture was a commercial minor element supplement (Chase & Co.,
Sanford) containing manganese, copper, zinc, iron, boron and molybdenum.

-5-

At harvest, a composite sample of the plot area was taken. The analysis
shows the overall fertility status of the soil at this time:

Solubridge
Reading

4.5

Nitrate
Nitrogen

VL

Experiment IV Experimental Controlled I
1965-66.
Treatments and Yiel

Treatment

Available nutrients, lbs/A
P20 KO2 CaO MgO

48 125 4924 635

Release Fertilizer Materials,

Lds:
Treatment
mean
lbs/clot

1. 100 lbs N
100% Urea + K from KC1

2. 100 lbs N
100% CRNF 67*

4. 50-50
(urea-CRNF) +

5. 50-50
(urea-CRNF) +

+ K from KC1

+ 100% of K from K-19*

K from KC1

1.27

1.47

1.77

1.30

1.37

1.33

1.13

K from K-19*

6. 100% urea + K from K-19*

7. Check no fertilizer

There was considerable variation in yield from plot to plot within a given
treatment and yield differences did not prove significant. However, the highest
yield were in treatment 3, in which both the nitrogen and potassium were derived
from the new, slow release materials, resistant to leaching.

*X419-67 and X519-19 respectively, experimental fertilizer compounds from Sun
Oil Company. The assistance of Sun Oil Company in providing a grant-in-a-id
in support of these experiments is gratefully acknowledged.

s _

t ?

-6-

1966 Caladium Experiments

Again four different trials were carried out on the Holmes farm near Lake
Placid, but in another new field, a peat soil similar to that used in 1965.
These are as follows:
Experiment I NPK Mg Factorial Fertilizer Trial (2 rates of N, P, Mg
with 3 rates K)
Experiment II Lime vs. no Lime
Experiment III Minor Elements
Experiment IV Controlled Release Fertilizer Materials.

Again Candidum tubers were used in all trials. The minor element mixture
was added to all treatments except those used in the minor element experiment, and
5 replications were used throughout. A more even stand was present than in 1965,
and in general, growth was better. This was reflected in higher yields, generally
than for 1965. This area also received a pre-planting application of 2.5 tons of
dolomite per acre.

Experiment I

Rates of nitrogen were 0 and 100 pounds per acre, P20 0 and 100 pounds per
acre, KO2 0 200 and 400 pounds per acre and MgO 0 and 1l0 pounds per acre
making a total of 24 treatments.
Fertilizer treatments and yields are as follows:

Treatments:

P205
0
0
0
0
0
0
100
100
100
100
100
100

100
100
100
100
100
100
100
100
100
100
100
100

lbs/acre

0
0
0
0
0
0
100
100
100
100
100
100

KO
20
0
0
200
400
200
400
0
200
400
0
200
400
0
0
200
200
400
400
0
200
400
200
400
0

Avg
Yield
MgO lbs/plot

0 3.1
100 3.3
100 2.7
100 2.8
0 2.7
0 2.8
0 2.6
0 3.6
0 2.6
100 2.2
100 3.1
100 2.2
0 2.7
100 3.0
0 3.2
100 2.8
0 3.4
100 2.2
0 2.2
0 2.7
0 3.0
100 2.6
100 2.7
100 2.6

--

---~--

-7-

There was little response to added nitrogen, phosphorus, potassium, or
magnesium fertilizers, with only 4 treatments yielding higher than the unfertilized
check plots. These were as follows:

Treatment, Ibs/A
N P205

0 100
100 0
0 0
100 0
Unfertilized checks

K20

200
400
0
200

MgO

0
0
100
0

Avg
Yield lbs/plot

3.6
3.4
3.3
3.2
3.1

Available plant nutrients were present at fairly high levels in the soil
before fertilization, as shown by analyses below of pre-fertilization samples:
Soluble Available Nutrients, lbs/A
Sample description pH Salts Nitrates P205 K20 CaO MgO
25 2,,,

I, west half
I, east half
II, Composite
III, "
IV, i"

4.7
4.7
4.9
4.9
4.6

4.76 19 Med-low

Experiment II Lime Plots

This experiment included only two treatments this year. In addition to the
treatments, all plots received 10-10-10 fertilizer at the rate of 500 pounds per
acre plus the minor element mixture at 40 pounds per acre.

Treatments and yields were as follows:

Treatment
Dolomite 4 tons/A
Untreated check

Avg yield
lbs/plot
1.4
1.4

Soil analyses from samples taken in October were as follows:

Soluble
pH Salts

Available nutrients,
Nitrates P20 K20 CaO

Dolomite 4 tons/A
Untreated check

5.1
4.4

Med.
Med.

155 5526 2487
155 4729 1741

Expt.
Expt.
Expt.
Expt.
Expt.

Mean:

Med-low

it II
"! "

58
58
56
62
56
58
(high)

4204
4141
4464
4464
3952
4245
(high)

181
167
174
195
167
177
(Med
to
high)

1824
1741
1990
2073
1658
1857
(high)

Treatment

lbs/A
MgO

-8-

Experiment III Minor Elements for Caladiums.

Treatments in this experiment showed far the greatest differences in the
whole series of experiments.

All plots received 10-10-10 fertilizer at the rate of 500 pounds per acre.
The chemicals supplying the minor element treatments were mixed with this ferti-
lizer as a carrier.

Vegetative growth was markedly improved on plots receiving copper, or the
minor element mixture, which contained some copper.

Treatments and yield are shown below:

Minor Element Treatments and Yields of Caladium Tubers, 1966.

__Treatment
1. Minor Element Mixture @ 40 lbs/A
2. @ 80 "
3 @ 120 "
4. Copper Sulfate @ 10 lbs CuO/A
5. 20 "
6. 40 "
7. Manganese Sulfate @ 20 lbs MnO/A
8. Zinc Sulfate @ 20 lbs ZnO/A
9. Iron Chelate @ 20 lbs/A (Hampene 5%)
10. Borax @ 10 Ibs/A
11. Untreated check (10-10-10 only)

Avg Yield
lbs/plot
1.6
1.5
2.1
1.8
2.6
3.7
1.4
0.9
0.8
0.8
1.1

Experiment IV Controlled Release Nitrogen and Potassium
Fertilizer Materials.

All treatments except the check received nitrogen @ 100 pounds per acre.
P 0 @ 100 pounds per acre from superphosphate and K20 at 200 lbs per acre.
audition all plots received the minor element mixture @ 40 pounds per acre.

Treatments and average yields were as follows:

Avg Yield
Ibs/plot

Treatment

1000 of N from Urea, all potassium from muriate of potash
100% of N from X419-67*, all potassium from muriate
100% of N from X419-67*, all potassium from X519-19*
50% of N from Urea, 50% from X419-67*, all potassium from
" all potassium from
100% of N from Urea, all potassium from X519-19*
Check, no fertilizer except minor element mix.

2.5
2.1
2.3
muriate 2.8
X519-19* 2.2
2.0
2.3

*Sun Oil Company Experimental Compounds.

Yields did not vary from treatment to treatment and the small differences
present did not prove significant.

lbsnlo

- c`-~------cl-I~

------

-9-

SUMMARY

Nutritional experiments were conducted with Candidum caladiums on newly
cleared peat at Lake Placid in 1965 and 1966.

This area had received only an application of dolomite (2.5 tons/acre
before planting, yet high levels of the major nutrients were present in this
soil.

The biggest response found in both years to any added nutrient was with
copper. In addition, magnesium gave some yield increase in the 1965 trials but
not in 1966. There was a small response to added phosphorus and potash in 1965
but not in 1966, however in both years the best yields were found in the plots
receiving 100 pounds of P205 and 200 pounds of K20 per acre.

Even though little response was received from applications of major nutrient
elements, it is felt that at least a maintenance application of phosphorus, potash,
and possibly magnesium is needed. Analyses of soil samples from unfertilized plots
through the season showed a definite drop in available nutrients because of plant
uptake and leaching. Available nitrogen levels tended to fluctuate. Although
muck and peat soils are well supplied with total nitrogen, the available nitrogen
at any given time is influenced by temperature and amount of rainfall. There was
no response to nitrogen fertilizer either year of these trials, but there may be
times when added ni-trogen could be of benefit.