Historic note
 Bearing trees
 Nitrogen and Phosphorous
 Potassium, secondary elements,...
 Mixed fertilizer: Amount to use,...

Group Title: Sub-Tropical Experiment Station - mimeographed report ; no. SUB68-1
Title: Fertilizing mango trees in Florida
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00067790/00001
 Material Information
Title: Fertilizing mango trees in Florida
Series Title: Mimeographed report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Young, T. W
Sub-Tropical Experiment Station
Publisher: University of Florida, Sub-Tropical Experiment Station
Place of Publication: Homestead Fla
Publication Date: 1967
Subject: Mango -- Fertilizers -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: T.W. Young
General Note: "Aug 1967."
Funding: Mimeographed report (Sub-Tropical Experiment Station) ;
 Record Information
Bibliographic ID: UF00067790
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71756500

Table of Contents
    Historic note
    Bearing trees
        Page 1
    Nitrogen and Phosphorous
        Page 2
    Potassium, secondary elements, and soil pH control
        Page 3
    Mixed fertilizer: Amount to use, fertilizer application, and young non-bearing trees
        Page 4
Full Text


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

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida

. 4

AUG 1967


University of Florida
Institute of Food and Agricultural Sciences
18905 S. W. 280 Street
Homestead, Florida 33030

T. W. Young

Bearing Trees

Climatic factors have such a strong controlling influence on the flowering and
fruiting behavior of mangos in Florida that it has been difficult to determine
the influence of mineral nutrition on yields. Temperatures below about o00 but
above freezing during the bloom reduce yields on some varieties, Haden, Zill and
Edward for example. Yields also are reduced by crowding and by inadequate dis-
ease control. But there is some fairly reliable information as a guide to fer-
tilizer manipulation for satisfactory results. This is discussed here.

Fruit bud differentiation on commercial varieties of mangos in Florida takes
place generally during fall and early winter on shoot growth that developed
during the summer. Weather sufficiently dry and/or cold to check growth in the
fall after shoots have matured favors flowering. It is possible that in some
years at least, relatively heavy applications of fertilizer, especially of
nitrogen, in late summer or early fall might promote vegetative growth at the
expense of flower bud formation. As a precaution against this, it would be
well to withhold at least nitrogen between late August and November. Other-
wise, time of application of fertilizer probably has little effect on the
amount of fruit produced if the tree receives an adequate supply. There is
some evidence that nitrogen applied to trees on light sandy soils a few weeks
before fruit maturity may increase incidence of "soft-nose" breakdown in the
fruit. On the calcareous rock soil (Rockdale), with nitrogen fertilization no
greater than needed for satisfactory yields, soft-nose is not generally severe
enough to be of economic importance, regardless of time of fertilization.

Good yields are obtained consistently on the deep sands and loams with one fer-
tilizer application a year, usually made in summer immediately after harvest.
Leaching losses probably are not often of great magnitude on well-drained deep
sands, where rooting is deep. Limited harvest data for Kent mangos on well-
drained light sand, however, show some trend toward slightly greater yields
when the same total amount of fertilizer for the year is divided between two
applications. On poorly drained soils and on Rockdale soil, where rooting is
shallow, leaching losses may often be important. On such soils, dividing the
total annual fertilizer between applications in about late July, November and
February would be advisable. On Rockdale soil, where possibility of increas-
ing soft-nose is not an important consideration, it might be well to divide
the fertilizer in approximately equal amounts in July, November, February and
April. If. only a light crop was set, the April application could be omitted.

Reproduced by Dade County Agricultural Agent's Office


The amount and analysis of fertilizer for best results will vary with variety,
previous crop, size of trees, their spacing, soil type, amount and distribution
of rainfall and/or irrigation, and past fertilizer practices. Only general recom-
mendations are given here. These often will need some modification to make them
more suitable for particular conditions. Continuing research will dictate changes,
no doubt.


Of the elements supplied by fertilizer, nitrogen (expressed on fertilizer tag as N)
has the greatest influence on tree growth and yield. It is utilized by the tree in
relatively large amounts. It is also the most readily lost from the soil by leach-
ing, and must be supplied in relatively large amounts in the fertilizer. The best
basis for determining the amount of N and other fertilizer elements to apply on
bearing mango trees is a consideration of tree size combined with a qualified
estimate of the current potential bearing capacity of the tree. Trees just coming
into bearing should receive much more fertilizer, proportionately per bushel of
fruit, than mature trees to provide for tree growth. A young tree with a potential
of one bushel might well receive a total of 1 pound of N for the year. As the tree
increases in size, amounts applied should be reduced gradually until on a mature
tree program. Between 0.2 and 0.3 pound of N per year per potential bushel of fruit
has given consistently good results on mature trees. The lower figure is suggested
for mature trees, such as Haden, which produce large numbers of seedless fruits that
soon shed, regardless of fertilizer levels. The greater amount of N can be used to
an advantage on varieties, such as Kent, which shed large numbers of seeded fruits,
apparently because of crop strain. Yields have been increased substantially on
mature Kent trees on deep sands by increasing N fertilization from about 1 pound
per tree per year to around 3 pounds.

All the commonly used chemical sources of N give satisfactory results with mangos.
Among these are ammonium nitrate, nitrate of soda, nitrate of potash, calcium
nitrate, sulphate of ammonia, urea and ammoniated superphosphate. On acid soils,
physiologically acid sources, such as sulphate of ammonia, should not be used excess-
ively unless a stringent program of liming for pH control is used. Calcium nitrate
supplies calcium and may help alleviate soft-nose on acid soils. The more expensive
natural organic sources of N, such as guano and sludge, are not justified on deep
soils, but on Rockdale soil perhaps 20% of the N in the fertilizer should be from
natural organic sources to decrease leaching losses.


On organic soils (muck and peat), N probably can be omitted from the fertilizer.
Other elements should be supplied at approximately the same rates as suggested for
mineral soils.

Phosphorus (expressed as phosphorus pentoxide, P205) is used in relatively small
amounts, as compared with N and K. It is not readily leached from the soil. In
old groves, or in previously farmed areas, where P has been used in large amounts
for a number of years, it can be omitted from the fertilizer, at least for several
years, without deleterious effects on tree growth or yield. Even in newly planted
groves on virgin soil, P205 in the fertilizer at about one-quarter the N content
once or twice a year should be sufficient. The superphosphates (single and double
or triple) are the more common and satisfactory sources of P in mixed fertilizers.



Next to N, potassium (expressed as potash, K20) is the fertilizer element most often
controlling growth and yield. Common and satisfactory sources are muriate of potash,
sulphate of potash, nitrate of potash and sulphate of potash magnesia. There is con-
siderable loss of K by leaching. It should be supplied on acid soils in quantities
about equal to that for N. At this level yields tend to increase and soft-nose
decrease. On calcareous soils, it probably is advantageous to use about 25% more
K20 than N. Extremely heavy applications of K, as have been used on some groves on
Rockdale soil, should be avoided. Such treatments tend to lower the uptake of cal-
cium and magnesium, and may result in salt damage to the trees.

Secondary Elements

While magnesium (expressed as magnesium oxide, MgO) is classed with the secondary
fertilizer elements, it is required in somewhat larger amounts than P. In mixed
fertilizers, Mg is usually and satisfactorily derived from magnesium sulphate or
sulphate of potash magnesia. It should be included in the fertilizer at about
one-half the K20 content. On acid soils, where dolomite is used for pH control,
lesser amounts will be sufficient.

Manganese, copper and zinc (expressed as oxides MnO, CuO and ZnO, respectively)
are needed in trace amounts. They can be supplied advantageously through foliage
sprays, especially on calcareous soil. Alternating maneb with zineb sprays during
the bloom, and neutral copper after fruit has set, for anthracnose control, gener-
ally will meet requirements for these elements. If greater amounts are required,
they can be supplied to trees on acid soils as the sulphates or as neutral materials
in fertilizer or foliage sprays. On calcareous soils, only foliage sprays of manga-
nese and zinc are effective.

If iron deficiency occurs, it can be controlled best by soil applications of
chelated iron. Use the FeEDTA compound on acid soils and the FeEDDHA compound on
calcareous soils as recommended by the manufacturer. Symptoms of other deficien-
cies, such as boron and molybdenum, which occasionally occur on citrus, have not
been recognized on mango. As a precaution against possible boron deficiency,
include borax in the fertilizer once a year at the rate of 0.1% or 0.2% B203.
At present, no recommendation is made for use of molybdenum on mangos.

Soil pH Control

On acid mineral soils, it is advisable to maintain the pH between 6 and 7 by annual
applications of dolomite or high calcium limestone. Depending upon the character
of the soil and past fertilizer practices, this probably will require 1000 to 2000
pounds of liming material a year. If liming has been neglected, and the soil is
quite acid, it may take several years at the suggested rates to reach the desired
.level. The efficiency of most fertilizer elements is increased by proper pH con-
trol. Furthermore, on acid soils the incidence of soft-nose is reduced by main-
taining a high calcium level in the tree. Control of pH on the calcareous rock
and organic soils is not feasible. The rock soils have a high pH and excess
calcium. Although often quite acid, the organic soils in south Florida generally
contain ample calcium for nutritional purposes. In the rare case on organic soils
where additional calcium is required as a nutrient, it can be supplied by liming
as on acid mineral soils. There will be no measurable change in pH at these rates
on organic soils.

. I I .

Mixed Fertilizer -- Amount to Use

Based on the amounts of individual fertilizer elements recommended here, 10 or 12
pounds per year of an 8-0-8-3 (N-P205-K20-MgO), 8-2-10-4 or similar mixture would
be sufficient for a young tree with a potential yield of one bushel. As trees
increase in size and bearing potential, the total amount of fertilizer applied a
year is gradually increased, but the amount per potential bushel of yield decreases.
For mature trees, 30 to 40 pounds of such mixtures a year should be sufficient for
trees with a potential current yield of 10 or 12 bushels. With a planting of 50
trees per acre, 40 pounds per tree of this fertilizer would supply 160 pounds of N
and this amount or more K20 per acre per year. For closer spacing with trees of the
same potential yield, slightly larger amounts might be justified. But 175 pounds of
N per acre per year is probably about the maximum amount that can be utilized with
measurable benefit by mango trees. For trees with less potential yield, including
smaller trees, the amount of fertilizer should be adjusted downward proportionately.

Fertilizer Application

On young bearing trees, fertilizer should be spread uniformly from near the trunk
to a few feet beyond the leaf drip. As the trees increase in size, and the amount
of fertilizer per tree is increased, the area fertilized is increased until the
spread is from trunk to trunk.

Young Non-Bearing Trees

On young trees for the first year in the field, use one-quarter to one-half pound,
the amount depending upon tree size, of an 8-2-8-2 or similar mixture every six or
eight weeks. Beginning the second year, gradually increase the amount of fertili-
zer at each application and the time between applications until on the young bearing
tree program in four or five years. By then, a tree should be receiving 10 or 12
pounds of the mixture a year in three applications. If trace elements cannot effec-
tively be included in the fertilizer, apply them in foliage sprays once or twice a
year. Spread the fertilizer from within a few inches of the trunk to a foot or so
beyond the leaf drip. If iron deficiency occurs, apply chelated iron to the soil at
recommended rates. Omit fertilizer from mid-October through mid-February as pre-
caution against over stimulation of growth during cold weather. Lime the soil as
for bearing trees.

- I 0

University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs