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
Fertilization Guide for Vegetables
Grown in Full-bed Mulch Culture
Kenneth D. Shuler and George J. Hochmuth*
Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida, Gainesville / John T. Woeste, Dean
Introduction (Note: Operations "C" through "I" must be done in
-- .... rjipJd cquei Ie to Li, iid loss of fumigant; not more than a 5
This report presents fertilization guidelines for a full- to 8 n.pqte delay is rec-mmended. A 20-minute delay
bed, mulch-culture system for vegetables. Information on W 4A r lI 18fG tions can result in a 40% loss of fumigant.)
the sequence of operations in the mulch system, on fertilizer Library
management, and on soluble salt damage control is included.
This information has been developed from results ofresearch Step III
in Florida, and, iffollowed, should provide adequate nutrition J UL g. 1l tenance f adequate soil moisture.
for optimum yields. B. Seeding or transplanting.
Sequence of operations University Cf Fi j addition via frequent overhead irrigation
in hb, dry weather to reduce soluble salt injury,
The following list details a sequence of opera ions ""- "'e-tt"itheplants, and prevent wilting.
which should serve as a guide for full-bed plastic mulch
culture. Operations are grouped so that growers can combine Crop nutrient requirements
two or Iore tasks to increase efficiency.
A. Land preparation to include disking and leveling.
B. Soil sampling.
C. Drainage and irrigation system development.
D. Lime addition (if needed).
E. Soil moisture maintenance.
A. Application of soil-incorporated fertilizer
materials (if used).
B. Application of soil-incorporated insecticide (if
D. Shaping and pressing of beds.
E. Application of herbicide, fungicide, and mole
cricket bait on bed surface (if they are to be
F. Application of remainder of fertilizer in one or
more bands on bed surface.
G. Initial cross ditching.
H. Installation of drip tubing on bed (if a drip
irrigation system is used).
J. Complete cross ditching.
Extension Agent Vegetables, Cooperative Extension
Service, Palm Beach County, Delray Beach, FL, andAssociate
Professor, Extension Vegetable Specialist, University of
Florida IFAS, Gainesville, FL
Plants require 16 elements for normal growth and
reproduction: carbon (C), hydrogen (H), oxygen (0),
phosphorus (P), potassium (K), nitrogen (N), sulfur (S),
calcium (Ca), magnesium (Mg), iron (Fe), boron (B),
manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo),
and chlorine (Cl). The crop nutrient requirement (CNR) for
a particular element is defined as the total amount in
pounds per acre (Ib/A) of that element needed by the crop to
produce optimum yield. This nutrient requirement can be
satisfied from many sources including soil, water, air,
organic matter, or fertilizer. For example, the CNR of
potassium can be supplied from K-containing minerals in
the soil, from K retained by soil organic matter, or from K
The CNR for a crop is determined from field
experiments that test the yield response to levels of added
fertilizer. For example, a watermelon study using different
fertilizer rates of K,0 might be conducted on a soil which
tests very low in extractable K. In this situation, the soil is
expected to contribute low or reduced amounts of K to
watermelon growth and yield. The researcher then plots
the relationship of crop yield to K-fertilizer rate. The CNR
is equivalent to the fertilizer rate above which no significant
increases in yield are observed. If data are available from
several experiments, then reliable estimates of CNR values
can be made.
CNR values vary according to soil type and vegetable
crop. CNR values have been determined for many vegetable
crops on several soils in Florida. For other situations, CNR
values have been estimated because no research data are
available. Table 1 presents CNR values as we currently
understand them for vegetable crops in Florida. Using the
CNR concept when developing a fertilizer program will
ensure optimum yields while minimizing both pollution
from overfertilization and loss of yield due to
The CNR values listed in Table 1 are those amounts
shown by research to be needed to produce optimum yields
from a fertilization standpoint. It is important to remember
that these amounts of nutrients are supplied to the crop
from both the soil and the fertilizer. The amounts listed
in the table should be applied as fertilizers only when a
properly calibrated soil test indicates very low extractable
amounts of these nutrients to be present in the soil.
Therefore, soil testing must be conducted to determine the
exact contribution from the soil to the overall CNR. Based
on such tests, the amount of fertilizer that is needed to
supplement the native-soil-nutrition component can be
It is important that soil samples represent the field or
management unit to be fertilized. A competent soil testing
laboratory which uses calibrated methodologies should
analyze the samples. Not all laboratories can provide
accurate fertilizer recommendations for Florida soils. Details
on soil testing and how to make it work effectively can be
found in Extension Circular 596, Procedures Used by the
IFAS Extension Soil TestingLaboratory, andInterpretations
Liming and pH
The target pH for most vegetables in Florida is 6.5.
Routine applications of lime materials without regard to
soil testing can result in excessively high soil pH which
greatly reduces fertilizer efficiency.
Table 1. Crop nutrient requirements of nitrogen,
phosphorus, and potassium for selected crops on
N-P,O,-K20 Number of
Crop lb/A' Supplemental
Broccoli 110-150-150 0-3
Cabbage 120-160-160 0-3
Cauliflower 110-150-150 0-3
Chinese cabbage 110-150-150 0-3
Cucumber 90-120-120 0-3
Eggplant 120-160-160 0-3
Muskmelon 120-160-160 0-3
Pepper 160-160-160 0-5
Squash 90-120-120 0-3
Strawberry 120-160-160 0-4
Tomato 160-160-160 0-4
Watermelon 120-160-120 0-3
'These amounts should be applied as fertilizer only to soils
testing "very low" in P and K. Use a soil test to determine
precisely how much fertilizer is needed.
2These CNR's are sufficient to produce optimum yields
under most circumstances. Supplemental fertilizer may be
needed after leaching rainfall, or when more than three
harvests are anticipated for pepper, eggplant, or
tomato. In these cases, the fertilizer should be applied
through the mulch into the side of the bed with a liquid
fertilizer injection wheel. Supplemental applications
should be made in amounts of approximately 30 lb N and
20 lb KO0 per acre. For long-term crops (August to April
cropping), supplemental N and KO2 can be added after a
particular harvest in anticipation of the next harvest.
There is no practical method of lowering pH of
limestone soils. In those soils, benefit might be achieved
from band application of micronutrients to reduce soil
fixation. On old vegetable land where micronutrients have
built up from routine fertilizer and pesticide applications,
the soil pH should not be allowed to drop below 6.0 because
increased availability of the micronutrients to the plants
could cause toxicities.
Some micronutrients (Cu, Mn, and Zn) have built up
in soils in Florida to levels which may become toxic to
plants. Build-up has resulted from insurance applications
of complete micronutrient fertilizer packages and from
micronutrients contained in several commonly used
fungicides and bactericides.
Until recently, very little Mehlich-I soil-test calibration
data existed for vegetables. Therefore, growers tended to
rely on insurance applications of micronutrients to guard
against deficiencies. Recent research has provided data to
make it possible to better predict situations where responses
to added micronutrients will result.
The IFAS Extension Soil Testing Laboratory tests
soils for Cu, Mn, and Zn content. Interpretation of results
depends on the soil pH. As the soil pH increases, so does the
probability of response to added micronutrients. Under
high pH, these micronutrients can be fixed in unavailable
forms. Therefore a micronutrient index could be interpreted
as "adequate" under one pH situation, but "low" under a
higher pH regime.
Currently, about 5 lb per acre Mn, 5 lb per acre Zn, and
3 lb per acre Cu are recommended for situations where a
Mehlich-I soil test indicates a probability of response to
micronutrients. Growers should add only the deficient
micronutrient(s). Present soil testing calibration does not
permit determinations of exact amounts of micronutrients
to be added between zero and the maximum amounts above.
However, soil testing has progressed far enough to be able
to predict those situations where response or lack of response
Micronutrients are most efficiently applied when the
amount of soil they are mixed with is minimized. Therefore,
micronutrients should be placed in the bed area by
incorporation or banding. On very alkaline soils, such as
the rockland of Dade County, micronutrients should be
banded. If deficiencies on these soils persist, foliar
application of certain micronutrients might be needed.
Micronutrients can be supplied from several sources
including sulfates, nitrates, and chelates. Finely ground
oxides also are effective sources of micronutrients.
Calcium, magnesium, and sulfur
In general, Ca, Mg, and S problems have not been
widespread in Florida. Calcium usually occurs in adequate
supply for most vegetables when soil pH is maintained at
5.5 or above. Soils on the lower east coast with pH values
above 6.5 are unlikely to be more productive with additional
calcium from lime materials or gypsum. A Mehlich-I Ca
index of 250 to 300 ppm or above would be indicative of
adequate Ca for most vegetables.
Maintaining correct soil moisture plays an important
role in Ca nutrition by providing Ca to the roots and
ensuring that Ca is moved in the plant water stream to
leaves and fruits. Foliar sprays of Ca are not likely to
correct serious deficiencies brought on by improper irrigation
management. Calcium is not mobilized from the older
leaves to deficient leaves.
Magnesium fertilizer might be needed if the Mehlich-
I soil-test index is below 15 ppm. In this case, about 30 lb
Mg/A should be adequate as fertilizer.
Sulfur deficiencies have not been documented for
Florida vegetables. Deficiencies of sulfur are very unlikely
where a sulfate fertilizer material is used to supply K or Mg,
or where the groundwater used for irrigation contains S.
Sources of N, P, and K
Nitrogen: About 25 to 50% of the nitrogen should be
supplied in the nitrate form on soils treated with a
multipurpose fumigant, or for winter crops where soils are
likely to be cool. Otherwise, N can be supplied from various
mixtures of nitrate and ammoniacal sources of N. For long-
season crops such as pepper, tomato, eggplant, or
strawberries, benefit might be obtained by applying 25 to
30% of the N from a slow-release material such as sulfur-
coated urea or isobutylidene-diurea (IBDU).
Phosphorus: Superphosphates (normal and triple)
and diammonium phosphate (DAP) can be used to supply
the fertilizer-phosphorus needs of vegetables. Early work
on virgin soils low in P and micronutrients reported yield
reductions in watermelon where DAP was used as the P
source and was banded with the micronutrients. One
theory for the response was that large amounts of DAP
banded with micronutrients reduced micronutrient
availability to the plant. Recent work showed that potential
problems could be alleviated by following soil-test predicted
P fertilization and by incorporating DAP in the bed.
Potassium: Several sources can be used to supply
potassium. These sources include potassium chloride,
potassium sulfate, potassium nitrate, and potassium-
magnesium sulfate. If soil-test predicted amounts of K
fertilizer are adhered to, there should be little concern
about the K source or its relative salt index.
Fertilizer timing and placement
1. Apply all P, micronutrients, and 10 to 20% of the
N and K fertilizer either broadcast in the bed,
onto a rough false bed, or banded in the bed. The
amounts are determined by soil testing. For
example: if the soil test showed the need for 160
lb N, 50 lb P20 and 160 lb K,0/A, then a
fertilizer such as a 15-25-15 might be used at
200 lb/A to supply the in-bed starter. This
material should contain any needed micro-
2. After the bed is shaped and pressed, apply the
remaining N and K in bands in grooves made in
the surface of the bed. For the example, this
would be 500 lb/A of 26-0-26.
Fertilizer should be applied in two bands for 1-row
crops such as tomato, and multiple bands (1, 2, or 3) for
twin-row crops such as pepper. Where multiple bands are
used, the bed should be wide enough so that the fertilizer
bands are at least 8 inches from the plants.
Where irrigation is supplied solely from overhead
sprinklers, all fertilizer can be incorporated in the bed. An
alternative for strawberries is to incorporate 25% of the
fertilizer in the bed and band the rest 2 to 3 inches deep in
the center of the bed.
All P, micronutrients, and 20 to 40% of the N and K
should be incorporated in the bed. Where sub-surface
irrigation is to be used to keep beds moist in the plant
establishment phase, no more than 20% of the N and K
should be incorporated. The remaining CNR N and K
should be applied through the drip tubes in increments
daily or weekly as the crop develops. Growers should start
with small amounts (0.5 to 0.75 lb N per acre per day) and
increase the rate as the crop develops. Maximum N injection
rate would be about 2.0 lb N per acre per day.
Foliar application of fertilizer
Plant leaves are not well adapted to absorb large
amounts of nutrients. This is particularly true of N, P, and
K. Research in Florida clearly shows that foliar application
of N, P, or K does not result in consistent yield increases.
Recent work has documented severe yield reductions with
foliar nutrient sprays. Foliar application ofmicronutrients
can be beneficial to correct deficiencies that periodically
appear in certain situations. These situations include the
high-pH soils of southern Florida where the high pH fixes
some micronutrients in unavailable forms.
It is important to remember that overapplication of
micronutrients can be toxic to plants. Research in Florida
documents yield decreases with shot-gun foliar
micronutrient applications. Large amounts of certain
micronutrients are applied to crops as pesticides and
micronutrients can accumulate in the soil and can become
toxic to plants. For more information on this subject,
consult Vegetable Crops Extension Report VEC 87-07,
Foliar nutrition of vegetables.
Soluble salt management
Soluble salt problems are common in the production
of vegetables in Florida. These problems can arise where:
a. excessive fertilizer was applied
b. fertilizer was placed too close to the plants
c. too much fertilizer was broadcast in the beds of
d. irrigation water with high soluble salt content
The following is a discussion of some factors
contributing to salt problems and suggestions on techniques
to reduce chances of salt injury. More information is
available from Vegetable Crops Extension Report VEC 87-
8, Diagnosing nutritional disorders and salt damage.
The primary principle involved is that dissolved salts
from fertilizer and irrigation sources move with soil water.
Under full-bed mulch culture and with seepage irrigation,
the soil water moves upward by capillary action to the
exposed soil surface around seedlings, where it evaporates,
leaving the salts at or near the surface. Reciprocally, salts
move downward when soil water moves in that direction
under the force of gravity such as during flooding rains or
overhead irrigation. Since salt tends to move up to the
highest point in a plant bed with seepage irrigation, it is
suggested that single row crops be planted on almost flat-
top beds. Two-row crops such as pepper, or strawberries,
should be planted on a moderate center-crown bed.
^r -T- T UNIVERSITY OF FLORIDA
3 1262 04969 1982
Amount of fertilizer
Soluble fertilizers contribute to the total salt complex
of the soil. Use of more fertilizer than necessary to satisfy
the CNR is wasteful of materials, energy, and money, and
increases the hazards of soluble salt injury to the crop.
Weather and environmental conditions favoring rapid
evaporation also favor accumulation of soluble salts at the
soil surface. These conditions are high temperature, intense
sunshine, high winds, and low humidity. To lessen the
effects of these conditions, growers can:
a. use white or aluminum-colored plastic to reflect
some of the sun's radiant energy (Fall and late
b. irrigate to maintain optimum soil moisture in
plant bed (over-saturation of the soil will tend
to dissolve too much of applied fertilizer into soil
water at one time)
c. top-water or use overhead sprinklers (as needed
every two or three days, except after one-quarter
or more inches of rain), to dilute and disperse
soluble salts from the seedling site
d. use slow-release fertilizer materials, which resist
leaching and have a low salt index, as a portion
of the fertilizer to reduce both lack of nutrients
during wet weather and excess salt during dry
Quality of irrigation water
Soluble salts found in some irrigation water can
contribute significantly to the total salt concentration in the
soil. When it evaporates, irrigation water leaves its dissolved
salts in the soil.
Irrigation water should be as low as possible in
soluble salts. Lab tests are available through the University
of Florida, IFAS, Ext. Soil Testing Lab for determination of
water quality. Soluble salts in water are estimated by
measuring the electrical conductivity (EC) of the sample
and are reported in millimhos (mmhos/cm). Water with an
EC of less than 0.5 mmhos/cm can be considered acceptable
for irrigation. The higher the level of salts in water, the less
desirable it is for irrigation. Water with an EC of greater
than 1.5 mmhos/cm can be used only with difficulty.
Double-cropping will increase the benefits to be
obtained from the polyethylene mulch, fertilizer, and soil-
applied chemicals. Fertilizer for the second crop can be
applied by either the drip irrigation system or with a liquid
fertilizer injection wheel. Electrical conductivity
measurements of soil at optimum soil moisture content
should be made to help guide the placement of seeds or
plants in the bed for the second crop. Levels of EC above 4.0
mmhos/cm would indicate potential problems from soluble
salt damage for most vegetables. Details on double-cropping
vegetables are available from a separate publication VEC-
87-11, Double-cropping vegetables on polyethylene-mulched
Hochmuth, G. J. 1988. Commercial vegetable fertilization guide. Univ. Fla. Coop. Ext. Circ. 225-C.
Kovach, S. P. 1984. Injection of fertilizers into drip irrigation systems for vegetables. Univ. Fla. Coop. Ext. Circ. 606.
Stanley, C. D. 1985. Water management with drip irrigation systems. 1985 Florida Tomato proc. VEC 85-2.
Everett, P. H., and R. Subramanya. 1983. Pepper production as influenced by plant spacing and nitrogen-potassium rates.
Proc. Fla. State Hort. Soc. 96:79-82.
Hochmuth, G. J., and R. L. Mitchell. 1987. Double-cropping vegetables on polyethylene-mulched beds. Veg. Crops. Dept.
Ext. Rept. VEC 87-11.
Hochmuth, G. J. 1987. Diagnosing nutritional disorders and salt damage. Veg. Crops Dept. Ext. Rept.VEC 87-06.
Hochmuth, G. J., and E. A. Hanlon. 1989. Commercial vegetable crop nutrient requirements. Univ. Fla. Coop. Ext.
Hochmuth, G. J. 1987. Foliar nutrition of vegetables. Veg. Crops Dept. Ext. Rept. VEC 87-07.
This publication produced at a cost of $366.50, or 15.0 cents each, to provide information on fertilizer management
for commercial vegetables. 5- 2.5M 90.
COOPERATIVE EXTENSION SERVICE, UNIVERSITYOF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T.Woeste,
Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June
30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions
that function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding 4-H and youth
publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers
is available from C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida 32611. Before
publicizing this publication, editors should contact this address to determine availability.
.L ... ."' -" II