Group Title: Research report - Ft. Pierce Agricultural Research and Education Center ; 93-2
Title: Controlled-release, fertigation, and traditional fertilization of young 'Midsweet'Carrizo trees
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Permanent Link: http://ufdc.ufl.edu/UF00055963/00001
 Material Information
Title: Controlled-release, fertigation, and traditional fertilization of young 'Midsweet'Carrizo trees
Series Title: Ft. Pierce AREC
Physical Description: 6 leaves : ill. ; 28 cm.
Language: English
Creator: Boman, Brian J
Agricultural Research and Education Center (Fort Pierce, Fla.)
Publisher: University of Florida, Insititute of Food and Agricultural Sciences, Agricultural Research and Education Center
Place of Publication: Fort Pierce Fla
Publication Date: 1993]
 Subjects
Subject: Citrus -- Fertilizers -- Florida   ( lcsh )
Citrus -- Field experiments -- Florida   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Brian J. Boman.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00055963
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 66905818

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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




/oo)


s L

C Controlled-Release, Fertigaton, and Traditional
Fertilization of Young 'Midsweet'/Carrizo Trees

BRIAN J. BOWMAN
Bni vrsity of F
PROCEDURE
A field study was designed to determine the growth response of young trees
with controlled-release and fertigation applications as compared to traditional
fertilization of young citrus trees. Bareroot 'Midsweet' orange on Carrizo
citrange rootstock trees were planted in double-row beds at the University of
Florida's Ft. Pierce AREC on May 5, 1991. Trees were planted at a 10 foot
within-row by 23 feet across-row on 50-foot wide beds, resulting in a tree
density of 174 trees per acre.
Four fertilizer materials were compared, each applied at three rates, plus
additional sets of trees which received no fertilization (Table 1). The
fertilizer materials included two slow release products, fertigation, and
traditional broadcasting of soluble granular fertilizer. The 13 treatments were
each replicated 4 times in a randomized complete block experimental design. Each
plot consisted of four trees on which measurements were taken. Buffer trees
separated fertigated trees from those receiving dry applications. Except for
fertilization, all cultural practices were identical for all of the trees.
The slow release materials included Osmocote 17-6-9 (N-P-K), designated SR-
1, and Meister 17-6-12, designated SR-2. The slow release materials were applied
in one application per year (7 June 1991 and 3 March 1992). The fertilizer was
incorporated into the soil by making a shallow trench about 10 inches from the
tree trunk with a hoe, spreading the material in the trench, and then raking the
soil back over to cover the trench.
The fertigated trees (FERT) had 17 applications of liquid fertilizer in
* 1991 and 30 in 1992. Fertigations were generally on a 7-10 day interval. The
fertilizer was injected into the irrigation line with an electric metering pump
followed by a brief flushing period. Total fertigation and flush cycle times
were typically about 30 minutes. The liquid fertilizer was an 8-2-8 analysis
made from NH4NO, H3PO4, and KC1.
The fert a izations made using the traditional broadcast applications of
soluble granular materials (TRAD) were made at 6 week intervals in 1991 (June 7,
July 19, Aug. 30, Oct. 11, and Nov. 22) and 8 week intervals in 1992 (Feb. 18,
April 14, June 25, Aug. 12, and Oct. 23). The 8-4-8 analysis material was made
from NH NO3, H3PO4, and KC1. For each application, the fertilizer was broadcast
in a 3-foot diameter area around the tree by hand.
A microsprinkler irrigation system was used to irrigate the trees.
Microsprinkler assemblies consisted of "green" base spray emitters on stakes
connected to the PE lateral tubing with 2-foot lengths of spaghetti tubing.
Stake assemblies were positioned about 2 feet from the tree trunk. Young-tree
deflectors on the emitters confined the discharge to about a 5 foot diameter
circle. Separate lateral lines were installed for each of the fertigated
treatments so that fertigations could be run independently form irrigations.
The tree canopies had been pruned at the nursery prior to transplanting,
so tree height and canopy width were very uniform. On 6 June 1991, initial tree
physical measurements were taken. Trunk diameter was measured 4 inches above the
bud union with a caliper. Trunk diameter, tree height, and canopy widths were
again measured on each tree on 21 February and 10 December 1992. Canopy volume
was calculated as: Vol = (Ht X W2)/4; where Vol = canopy volume, Ht = height, and
W = canopy width. Spring flush leaves were sampled from each plot for analysis
on 4 September 1992. All parameters were analyzed using standard analysis of
variance procedures.
RESULTS
The 1991 mid-June through October period received above normal rainfall
* (Table 2). No irrigations were required in July, August, September, or November.
Fertigation applications were difficult to schedule to the excess rainfall during

Ft. Pierce AREC 93-2










Table 1. Fertilizer rates and materials applied by treatment during 1991 and 1992.
19911 19922
Material Total N Material Total N
Treatment Analysis App. per appl. per year App. per appl. per year
(No.) (ID) (N-P-K) (No.) (g) (Ib/oz) (g) (Ib) (No.) (g) (lb) (g) (lb)

1 SR-1 17-6-9 1 176 6 oz 30 0.07 1 352 0.78 60 0.13
5 SR-1 17-6-9 1 352 12 oz 60 0.13 1 704 1.55 120 0.26
9 SR-1 17-6-9 1 529 18 oz 90 0.20 1 1058 2.33 180 0.40
2 SR-2 17-6-12 1 176 6 oz 30 0.07 1 352 0.78 60 0.13
6 SR-2 17-6-12 1 352 12 oz 60 0.13 1 704 1.55 120 0.26
10 SR-2 17-6-12 1 529 18 oz 90 0.20 1 1058 2.33 180 0.40
3 FERT 8-2-8 17 45 0.10 90 0.20 30 90 0.20 180 0.40
7 FERT 8-2-8 17 68 0.15 135 0.30 30 136 0.30 270 0.60
11 FERT 8-2-8 17 90 0.20 180 0.40 30 180 0.40 360 0.80
4 TRAD 8-4-8 5 225 0.50 90 0.20 5 450 1.00 180 0.40
8 TRAD 8-4-8 5 338 0.75 135 0.30 5 676 1.50 270 0.60
12 TRAD 8-4-8 5 450 1.00 180 0.40 5 900 2.00 360 0.80


ITreatment SR applications made
Aug. 30, Oct. 11, and Nov. 22,
Treatment SR applications made
June 25, Aug. 12, and Oct. 23,


on June 7, TRAD applications made on June
FERT applications made June-Dec.
on March 3, TRAD applications made on Feb
FERT applications made Feb.-Dec.


7, July 19,

18, April 14,








these months, therefore fertigation applications extended into December to get
the target amount of nutrients applied. Rainfall in 1992 was adequate for much
of the year. During the last 10 days of June, rainfall occurred every day, with
more than an inch on 5 of the days. There were dry periods from mid-April
through mid-June, much of July, early October, and again in December. Again,
fertigation applications extended into December due to heavy rainfall preventing
scheduled fertigations earlier in the season.
In the February 1992 tree growth measurements, there was no response to
fertilization rate for the TRAD or FERT plots for height, canopy volume, or
cross-sectional area (Table 3). The two slow-release materials exhibited a fairly
linear response to increasing rates of N applied (Fig. 1) for trunk cross-
sectional area. The SR-2 also had linear response for the height and canopy
volume response to increased rates of fertilization. The SR-1 trees had more
inconsistently. The middle application rate of the SR-1 treatment had equivalent
or greater response than the high rate for the parameters of canopy volume and
trunk cross-sectional area.
The December 1992 measurements showed trends similar to the February 1992
measurements (Fig. 1). The FERT and TRAD plots continued to show no response to
increased N applications, while the slow-
release materials had greater growth with Table 2. 1991 and 1992 rain,
the medium and high rates as compared to the irrigation, and fertigations.
low rate. For some reason, several trees in and fert
the middle rate TRAD plots showed little Month Rain Irrig. fertig.
growth, thus the treatment means are less (in.) (No.) (No.)
than the lower rate of application and only
equal to that of the non-fertilized trees. 1991
The highest leaf N levels were found June 5.4 7 0
in the middle and high rates of the TRAD July 13.9 0 2
trees, both of which were above 3% (Table 3, Aug. 8.1 0 4
Fig. 2). The lowest leaf N levels were in Sep. 6.9 0 3
the SR-1 low and SR-2 medium trees. However, Oct. 4.5 1 3
leaf N levels could not be correlated with Nov. 0.9 5 2
growth. In fact, growth of the TRAD trees Total 41.0 21 17
with the elevated leaf N was less than that
of other treatments with low leaf N. 1992
Measurements taken on the trees Jan. 0.7 2 0
shortly after planting showed no statistical Feb. 2.7 3 0
differences in trunk cross-sectional area March 2.0 6 2
when they were planted. In the December April 2.6 6 4
1992, the high rates of the slow-release May 1.0 10 3
materials tended to have the largest trunk June 15.5 1 3
areas, while the low rates of these July 3.5 2 6
materials had trunk areas similar to the Sep. 5.5 0 2
non-fertilized trees (Fig. 3). An important Oct. 3.7 0 3
consideration, which is difficult to Nov. 8.2 0 1
quantify, is the canopy fullness. During Dec. 2.8 3 3
the summer flushes, the fertigated trees and Total 54.7 34 30
the high rate of TRAD tended to have
asymmetrical growth. Oftentimes there would
be shoot growths of 15-20 inches, leaving a
sparse canopy. Those trees fertilized with the other treatments tended to have
fuller canopies and fewer long shoots extending beyond the bulk of the canopy.
If these growth differences are significant, they will be reflected in the yield
in the coming year or two.

ACKNOWLEDGEMENTS
Trade names are used in this publication to provide specific information
and their mention does not constitute an endorsement by the University of
Florida. Funding, services, and equipment for this project was provided by
Becker Groves, Diamond R Fertilizer Company, Helena Chemical Company, Grace-
Sierra Company, Pioneer Labs, the St. Lucie County (Florida) Soil and Water
S Conservation District, Maxijet, Inc., and Rain Bird Sales, Inc..


Ft. Pierce AREC 93-2








Table 3. Mean tree measurements for February 21, 1992 and December 10, 1992 by
fertilization treatment (n=16).

Total N February 1992 December 1992 Sept.
applied Tree Trunk X/C Canopy Tree Trunk X/C Canopy 1992
Trt. 1991 1992 height area volume height area volume leaf N
(g) (g) (cm) (cm2) (m3) (cm) (cm2) (m3) (%)

NF 0 0 108 b 4.0 de 0.08 c 156 bdc 9.4 d 0.65 cde 1.8 bc

SR-1 30 60 109 ab 3.6 e 0.10 bc 152 dc 9.8 cd 0.61 de 1.7 bc
SR-2 30 60 109 b 4.2 bcde 0.13 ab 156 bdc 10.7 bcd 0.68 cde 1.3 c

SR-1 60 120 118 ab 5.1 ab 0.17 a 167 abc 13.5 a 1.07 a 1.2 c
SR-2 60 120 114 ab 4.9 abcd 0.14 ab 166 abcd 11.9 abc 0.79 bcd 1.7 bc

SR-1 90 180 118 ab 5.4 a 0.15 a 164 abcd 13.4 a 0.98 ab 1.7 bc
SR-2 90 180 118 ab 5.0 abc 0.14 ab 172 ab 13.4 a 0.85 bc 2.3 abc
FERT 90 180 120 a 4.8 abcd 0.14 ab 177 a 12.4 ab 0.79 bcd 1.6 bc
TRAD 90 180 116 ab 4.2 bcde 0.15 a 153 dc 11.5 abcd 0.68 cde 2.8 ab

FERT 135 270 115 ab 4.8 abcd 0.12 abc 158 bdc 11.7 abcd 0.72 cde 2.4 abc
TRAD 135 270 117 ab 4.1 cde 0.13 ab 148 d 9.3 d 0.56 e 3.1 a
FERT 180 360 118 ab 4.5 abcd 0.14 ab 168 abc 12.2 ab 0.76 cde 1.8 bc
TRAD 180 360 120 a 4.7 abcd 0.15 a 160 abcd 11.2 abcd 0.66 cde 3.5 a


Means within columns followed by the
according to Duncan's Multiple Range


same letter are not
Test.


significantly different


(p=0.05)






Feb. 1992


E 0.17

-0.14


o
t-
> 0.1 1
C-

S0.08
o0


6-
E
5-
c..5


x
>3


50 100 150
50 100 150


F


1.1


0.9

n "7


Q.
S05
0


120


-115 l


-1 10.0
0

105


0eeee SR-1
**** SR-2
DcEBB FERT
Uens TRAD
g,0 NF


E 13-
(.


X


200


applied in 1991 (g)


11


9
0 200
1991+1992


175,
o
1 65 --

155.2

-145










400 600
N applied (g)


Fig. 1. Mean tree growth measurements 2/92 and 12/92 (n=4).


, , ,


Measured


Measured


Dec. 1992


~B~o


13


4 -t


















2 .5 -- ............. ... ....................................
Z
2 .0 ...............................

1.5-
High
Medium
1.0 Low
SR-1 SR-2 FERT TRAD NF

Fig. 2. Mean leaf N for leaves sampled 9/4/92 (n=4).








14-
13. .. .






11
S10-
High
10- Medium

SR-1 SR-2 FERT TRAD NF

Fig. 3. Mean trunk cross-sectional area in December
1992. (n=4).




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