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Group Title: Central Florida Research and Education Center research report - Central Florida Research & Education Center ; SAN-86-13
Title: Lettuce fertilization trials at Zellwood
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 Material Information
Title: Lettuce fertilization trials at Zellwood
Series Title: Central Florida Research and Education Center research report - Central Florida Research & Education Center ; SAN-86-13
Physical Description: Book
Language: English
Creator: Forbes, Richard Brainard
White, J. M.
Publisher: Central Florida Research and Education Center, IFAS, University of Florida
Publication Date: 1986
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Bibliographic ID: UF00075859
Volume ID: VID00001
Source Institution: University of Florida
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Resource Identifier: oclc - 122270477

Table of Contents
    Main
        Main 1
    Materials and methods
        Page 1
    Results and discussion
        Page 2
    Summary and conclusions
        Page 3
    List of Tables
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
Full Text





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




I 00
R o r Central Scier
c Library

I3 University of Florida IFAS OCT 23 1
Central Florida Research and Education ter
Sanford, Florida Univers.ty of F

Research Report SAN 86-13 June 1986

LET UCE FEIRILIZATION TRIALS AT ZELLWOCD

R. B. Forbes and J. M. White


Experiments to provide more information on fertilization
requirements of Romaine lettuce on muck land were conducted at this
Center's Zellwood Farm during the winter/spring vegetable seasons of
1976-77, 1977-78, and 1978-79.

The experimental areas had been in use for about 20 years with
consequent buildup of plant nutrients. The soil was Lauderhill muck, a
Lithic Medisaprist a shallow organic soil underlain with lime rock and
marl. Each year a different site was used, but all were on this
Center's farm at Zellwood.

Materials and Methods

Romaine lettuce (cv. Valmaine) was grown on beds approximately 3 ft
wide with a plot length of 20 ft giving a plot area of 0.0014 acres (A)
) during the first 2 years; in 1978-79, a double width plot (2 beds or
0.0028 A) was used. Phosphorus was supplied by superphosphate,
potassium from muriate of potash, and magnesium from Emjeo (fertilizer
grade of MgSO ). Fertilizer treatments are shown in Table 1 and
included 4 rates of phosphorus, 3 rates of potassium, and 2 rates of
magnesium in all possible combinations in a 4 x 3 x 2 factorial. In
1976-77, all plots received Mn (20 lb/A) from MnSO. In both the next 2
years, a micronutrient mixture (Frit 175 G @ 30 lb/A) was applied
uniformly. The fertilizer treatments were mixed and applied by hand,
then incorporated into the soil by a rotary tiller as the beds were
being formed. -In 1976-77, all plots received N (60 lb/A) from NH4 NO3
at planting. Nitrate levels in the soil were checked periodically
during the 1977-78 and 1978-79 trials, but remained high enough so that
no supplemental N was needed. Treatments were replicated 5 times in
randomized complete blocks.

The lettuce was direct-seeded, then thinned to a stand of one plant
per ft. Untreated guard rows were used on both sides of the
experimental area. Planting and harvest dates were as follows:

Season Planting Date Harvest Date Field Location

1976-77 15 Dec. 1976* 5 May 1977 B:12-13.5
1977-78 15 Nov. 1977- 22 Mar. 1978 A:29-30.5
1978-79 16 Nov. 1978 21 Mar. 1979 A:34.5-38.5
*Replanted 8 Feb. 1977. December planting destroyed by January freeze.









Soil samples were taken before fertilization and again at harvest.
In 1976-77 and 1977-78, the pre-tertilization samples were composites
for each block. In 1978-79, each individual plot was sampled before
treatment and again at harvest. Soil pH (by glass electrode in 1:2
soil:water suspension) soluble salts (SS) (by conductivity), and
nitrates (by diphenylamine) were done at Sanford as were sample
screening and drying. A portion of each sample was submitted to
IFAS-Soil Science Department Soil Testing Laboratory at Gainesville for
determination of Ca, Mg, P, and K on double acid (0.05 M BC1 in 0.025 M
HC1) extracts. A 10-ft segment of row was harvested for yield
determination.

Results and Discussion

Treatments and yields for all 3 years are shown in Table 1 with the
effects of each element of the factorial partitioned out in Tables 2 and
3. In 1976-77, none of the elements gave a significant effect on yield.
In the next 2 seasons, however, the lettuce responded with small, but
significant yield increases from the first increment of P. There was a
slight yield decrease from the highest K rate in 1977-78 and a slight
yield increase from added Mg. The K x Mg interaction proved
significant. Added Mg tended to lessen the decrease in yield with the
higher K rates. No visible growth differences among the treatments
could be seen.

In 1977-78, a fungus disease known by the growers as "lettuce drop"
caused by Sclerotinia sclerotiorum was prevalent enough that counts were
made of the number of diseased plants in each plot. Analysis of the
data failed to show any significant effects on disease from any of the
fertilizer elements applied, nor were any of the interactions
significant. Apparently, nutrition had no effect on Sclerotinia
incidence under the conditions of this experiment.

Soil analyses from samples taken before treatment and again at
harvest are given in Tables 4 through 10. The 1976-77 crop started out
with relatively high levels of extractable nutrients (as seen in Table
4) which helps explain the lack of response to added nutrients. The
effect of the treatments in the soil at harvest time is shown in Tables
4 and 5. The treatments with P, K, and Mg resulted in higher levels of
these elements than where none of a given element was applied. In this
latter case, a reduction occurred by harvest time. For instance, where
no K was applied, the K levels found at harvest had dropped from an
average of 410 ppm in December to 112 ppm at harvest. P, Ca, and Mg all
remained at high levels.

In the 1977-78 fertilizer trials, unfortunately, the pre-treatment
samples were apparently lost or discarded by mistake before extractable
nutrients could be determined, so it was not possible to compare
nutrient levels in the soil before and after treatment. Effects of
fertilization on the soil are shown in Tables 6 and 7. P was raised by
the treatments in a step-wise manner by each increment added. The same
effect was also evident for K, with 3 district soil levels reached by
the 3 treatments. Ca levels were high all the way through the data and
apparently not influenced much by the treatments applied. Mg levels
were also high, but did show a definite increase in extractable Mg from
the Mg applied.









In 1978-79, a complete set of pre-fertilization samples was taken
with data shown in Table 8. As in the experimental sites of the
previous trials, Ca and Mg were very high again as a result of the marl
and lime rock in the soil profile. P and K were also quite high at the
start. This, no doubt, is the main reason why there was so little yield
response from fertilization with these elements. Analyses of samples
taken at harvest are shown in Tables 9 and 10. The effects of P and K
additions are again shown in the step-like increases in extractable P
and K (see Table 10). The MgO addition, even though only 60 lb/A,
produced a measurable increase in extractable Mg in the soil.

In each season, P additions tended to lower the soil pH slightly;
the other elements had no effect on pH.

Summary and Conclusions

In general, during all 3 years of these trials on 3 different field
sites on the experiment station farm at Zellwood, residual fertility
levels were high so that there was only minimal response to
fertilization. Also, none of the treatments had any effect on incidence
of Sclerotinia. No visible differences in growth were seen.

The treatments for all 3 elements gave measurable, step-like
increases in levels of extractable nutrients in the soil during all 3
years of the trials.









Table 1. Lettuce yields from fertilizer plots, Zellwood, Florida,


1977-78-79.


Total marketable1
P205 K20 MgO 1976-77 1977-78 1978-79


-lb/A


0
200
400
0
200
400

0
200
400
0
200
400

0
200
400
0
200
400

0
200
400
0
200
400


120
120
120
120
120
120

240
240
240
240
240
240

480
480
480
480
480
480


tons/A


9.1
11.5
12.2
11.5
10.1
13.5

12.6
11.0
12.6
12.6
11.4
11.4

11.3
12.2
12.5
11.5
10.1
13.1

9.0
11.7
13.4
11.7
10.5
12.1


LSD 0.05


11.2
11.5
9.4
11.1
11.2
11.2

12.9
10.1
10.0
14.0
14.4
11.5

12.4
12.3
10.6
11.0
13.1
9.9

11.9
8.5
9.1
10.1
11.5
11.3

2.5


13.9
14.4
13.6
13.6
14.6
14.5

16.9
16.2
16.6
13.4
19.2
15.0

17.9
16.1
15.6
14.2
17.6
16.6

15.0
14.3
13.4
15.8
13.4
11.5

3.8


1Average of 5 replicates.










Table 2.


Effect of each element; average lettuce yield for each
nutrient level
nutrient level


Nutrient Rate 1976-77 1977-78 1978-79
lb/A tons/A--

P205 0 11.3 11.0 14.1
120 11.9 12.1 16.2
240 11.8 11.5 16.3
480 11.4 10.5 14.7

K20 0 11.2 11.8 15.1
2 200 11.0 11.6 15.8
400 12.6 10.4 15.2

MgO 0 11.6 10.8 15.3
60 11.6 11.7 15.4


'Average marketable yield of all replicates of a given nutrient
level, including all combinations with other elements.









Table 3. Summary of analysis of variance ot lettuce yields from

fertilizer plots.


1976-77
-F


P205 levels

K20 levels

Mg0 levels


Interactions

P205 x K20

K20 x Mg0

P205 x Mg0


<1 (NS)

1.65 (NS)

<1


1977-78 1978-79
values found--

4.17**1 4.05**

6.04** <1

5.53* <1


1.36 (NS)

51.48**

2.58 (NS)


<1

2.44 (NS)

<1


1Asterisks denote significance at 0.05 (*) and 0.01 (**) levels,
respectively.










Table 4. Soil analyses from lettuce fertilizer trial, Zellwood, FL,

sampled at harvest 5 May 1977.


Treatment Available nutrients1
P205 K20 Mg0 pH SS Ca Mg P K
---lb/A---- -ppm---

0 0 0 6.0 246 8000+ 2384 209 80
0 200 0 6.1 255 8000+ 2320 214 326
0 400 0 6.0 400 8000+ 2352 222 846
0 0 60 5.8 400 8000+ 2512 216 125
0 200 60 5.9 346 8000+ 2512 215 411
0 400 60 5.9 400 8000+ 2448 213 829

120 0 0 5.9 291 8000+ 2448 320+ 93
120 200 0 5.8 318 8000+ 2480 320+ 338
120 400 0 5.8 410 8000+ 2416 320+ 995
120 0 60 5.9 318 8000+ 2544 320+ 125
120 200 60 5.9 382 8000+ 2576 320+ 357
120 400 60 5.8 473 8000+ 2608 320+ 928

240 0 0 5.8 419 8000+ 2448 320+ 123
240 200 0 5.7 491 8000+ 2480 320+ 525
240 400 0 5.8 455 8000+ 2384 320+ 904
240 0 60 5.7 500 8000+ 2736 320+ 114
240 200 60 5.8 419 8000+ 2480 320+ 448
240 400 60 5.7 500 8000+ 2608 320+ 918

480 0 0 5.6 419 8000+ 2288 320+ 112
480 200 0 5.7 455 8000+ 2320 320+ 232
480 400 0 5.6 682 8000+ 2416 320+ 814
480 0 60 5.7 546 8000+ 2640 320+ 120
480 200 60 5.7 637 8000+ 2672 320+ 997
480 400 60 5.7 774 8000+ 2576 320+ 402


Prefertilization composite samples2


6.3


226


8000+ 3200+


224+ 410


1Double acid extracting solution: 0.0125 M H2SO4 in 0.05 M BC1.

2Average of 5 replicates, one composite sample for each replicate.










Table 5. Ettect ot each element on soil test values at harvest,

1976-77 lettuce fertilizer trial.


2
Extractable nutrients
Treatment Rate pH SS P K Ca Mg
lb/A ----------pp

P205 0 6.0 341 215 436 8000+3 2421
120 5.8 365 320+ 473 8000+ 2512
240 5.8 464 320+ 505 8000+ 2523
480 5.7 586 320+ 446 8000+ 2485

K20 0 5.8 392 320+ 112 8000+ 2500
200 5.8 413 320+ 454 8000+ 2480
400 5.8 512 320+ 830 8000+ 2476

gO0 0 5.8 403 320+ 215 8000+ 2395
60 5.8 475 320+ 215 8000+ 2576


Average value from all replicates
combinations with other elements,

2Double acid extracting solution:


of a given nutrient level
sampled 4 May 1977.


0.0125 M H2S04 in 0.05 M BC1.


3Values with + suffix represent concentration beyond upper limit in
general use by the Soil Testing Laboratory at time of this experiment.


including









Table 6. Soil analyses lettuce fertilizer trial, Zellwood,

Florida, sampled at harvest 22 March 1978.


Treatment Available nutrients1
P205 K20 Mg0 pH SS Ca M P K
----lb/A---- ---- --

0 0 0 6.3 291 20960 1392 187 176
0 200 0 6.3 259 20107 1488 182 469
0 400 0 6.4 284 19147 1488 183 853
0 0 60 6.2 262 19413 1733 184 197
0 200 60 6.4 284 19360 1701 184 416
0 400 60 6.2 302 19093 1563 181 597

120 0 0 6.3 331 19520 1584 208 363
120 200 0 6.2 240 19520 1275 228 496
120 400 0 6.2 244 19467 1424 209 587
120 0 60 6.1 266 19573 1573 227 171
120 200 60 6.4 315 19627 1573 216 491
120 400 60 6.3 335 19573 1509 243 683

240 0 0 6.2 253 19680 1424 254 160
240 200 0 6.2 320 19787 1381 254 427
240 400 0 6.2 291 19733 1477 235 667
240 0 60 6.1 317 19680 1445 237 155
240 200 60 6.1 245 19307 1520 233 320
240 400 60 6.2 253 19627 1371 256 704

480 0 0 6.0 295 20000 1221 262 208
480 200 0 6.2 362 19893 1349 267+ 443
480 400 0 6.1 387 20053 1456 267+ 608
480 0 60 6.0 291 19787 1509 267+ 160
480 200 60 6.2 335 19573 1403 267+ 379
480 400 60 6.1 488 20000 1669 267+ 597


Prefertilization composite samples 15 November 19772


6.0


879


1Double acid extracting solution.

2Average of 5 replicates, one composite sample


for each replicate.












Table 7. Effect of each element on soil test values at harvest,


1977-78 lettuce fertilizer trial.


Extractable nutrients2
Treatment Rate pH SS P K Ca Mg
lb/A pmL-

P205 0 6.3 280 184 451 19680 1561
120 6.2 288 222 465 19547 1490
240 6.2 280 245 406 19636 1436
480 6.1 360 267+3 399 19884 1434

K20 0 6.2 288 228 199 19827 1485
200 6.2 295 229 430 19647 1461
400 6.2 289 230 662 19587 1495

MgO 0 6.2 296 228 455 19822 1413
60 6.2 308 230 406 19551 1547


1Average value from all replicates
combinations with other elements.


of a given nutrient level including


2Double acid extracting solution: 0.0125 M H2SO4 in 0.05 M BC1.

3267+ represents P concentration beyond the upper limit normally in use
by the Soil Testing Laboratory at time of this experiment.










Table 8. Soil Analyses lettuce fertilizer trial, Zellwood, FL,


pre-fertilization samples 16 November 1978.


Treatment Available nutrients
P205 K20 Mg0 pH SS Ca Mg P K
----lb/A- --ppm---


0
0
0
0
0
0

120
120
120
120
120
120

240
240
240
240
240
240

480
480
480
480
480
480


0
200
400
0
200
400

0
200
400
0
200
400

0
200
400
0
200
400

0
200
400
0
200
400


7.2
7.2
7.3
7.3
7.3
7.3

7.3
7.2
7.1
7.1
7.2
7.2

7.1
7.1
7.2
7.3
7.5
7.3

7.2
7.2
7.2
7.1
7.2
7.2


1319
1247
1174
1292
1174
1238

1229
1238
1265
1237
1301
1329

1365
1329
1401
1247
1401
1219

1356
1238
1210
.1238
1201
1274


10240
10320
10080
10000
10000
9840

9920
10240
10000
10000
10080
10000

9920
10000
10080
10080
9920
10000

10000
10320
10080
10080
10080
10080


1488
1504
1464
1536
1472
1552

1544
1472
1488
1448
1496
1544

1568
1536
1536
1528
1640
1504

1608
1432
1464
1432
1416
1504


137
142
125
123
138
124

140
155
157
168
142
141

144
162
149
145
126
146

166
133
138
144
142
136


379
403
365
357
365
384

395
422
422
435
410
403

400
450
390
394
387
408

446
398
387
371
414
408


Avg. 7.2


1272 10057 1507


142 400


1Each value is a mean of 5 replicates.

2Double acid extracting solutions: 0.0125 M H2SO4 in 0.05 M BC1.











Table 9. Soil analyses lettuce fertilizer trial, Zellwood, FL,

sampled at harvest 21 March 1979.


Treatment Available nutrients
P205 K20 Mg0 pH SS Ca Mg P K
--lb/A----ppm

0 0 0 7.4 482 18240 1930 148 125
0 200 0 7.6 462 17600 1891 139 416
0 400 0 7.5 571 17600 1904 130 650
0 0 60 7.6 424 17440 2064 128 141
0 200 60 7.5 546 17600 1920 139 429
0 400 60 7.5 562 17600 1984 125 662

120 0 0 7.4 590 17760 2032 227 109
120 200 0 7.2 600 18240 1776 236 365
120 400 0 7.3 595 17600 1869 233 752
120 0 60 7.2 482 17600 1888 236 144
120 200 60 7.2 602 17760 1984 259 371
120 400 60 7.3 643 17600 2032 221 602

240 0 0 7.2 564 17600 1946 307 122
240 200 0 7.1 655 17600 1968 310 371
240 400 0 7.3 630 17600 1984 272 557
240 0 60 7.3 642 18400 1984 286 131
240 200 60 7.4 721 17600 2112 450 474
240 400 60 7.3 675 17600 1958 359 726

480 0 0 7.1 745 18400 2080 567 138
480 200 0 7.1 620 18400 1738 665 429
480 400 0 7.1 675 17600 1811 536 685
480 0 60 7.0 679 18400 1888 739 112
480 200 60 7.2 575 18400 1888 505 374
480 400 60 7.2 708 18400 1962 522 570


LEach value is mean


of 5 replicates.


2Double acid extracting solution: 0.0125 M H2SO4 in 0.05 M HC1.










Table 10.


Effect of each element on soil test values at harvest,


1978-79 lettuce fertilizer trial.


Extractable nutrients2
Treatment Rate pH SS P K Ca Mg
lb/A ppm-------

P205 0 7.5 508 135 404 17680 1949
120 7.3 585 235 390 17760 1930
240 7.3 648 331 397 17733 1992
480 7.1 667 589 385 18267 1894

K20 0 7.3 576 330 128 17980 1976
200 7.3 598 338 404 17900 1910
400 7.3 632 300 650 17700 1938

Mg0 0 7.3 597 314 393 17853 1911
60 7.3 605 331 395 17867 1972


1Average value from all replicates
combinations with other elements.


of a given nutrient level including


double acid extracting solution: 0.0125 M H2SO4 in 0.05 M HC1.




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