COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
STATE OF FLORIDA
COLLEGE OF AGRICULTURE, AGRICULTURAL EXTENSION SERVICE
UNIVERSITY OF FLORIDA. AND V e Cab p COUNTY AGENT AND
UNITED STATES DEPARTMENT Vegetable Co Spelt HOME DEMONSTRATION WORK
OF AGRICULTURE, COOPERATING V E G E T AJR IA N GAINESVILLEI FLORIDA
No. 21 July 10, 1953
MR. COUNTY AGENT:
Forwarded you several research reports dealing with AgBt control in our last
newsletter. If you missed checking them, believe it will be to your advantage to
look back before plans for fall planting snow you under.
To sort of round out the picture, here's another newsletter you can use...
this time considering certain key topics from the soils and horticultural angles.
Dr. W. T. Forsee, Jr., Chemist in Charge
Everglades Experiment Station, Belle Glade
PEAT SOILS--change in P and K needs.
Peat soils undergo considerable change as they become more thoroughly broken
down by oxidation, Not only do they change in physical structure but they under-
go certain chemical changes which alter the fertilizer needs of plants growing on
A very strong tendency for increased nhoRnhate requirements of vegetable
crops has been observed. The virgin Everglades peat soils require little or no
phosphate for maximum production. Six to 8 percent P205 in the mixed fertilizer
is all that is normally recommended. As these soils age, the phosphate requirement
goes 2u to such an extent that 12 to 16 percent P205 is frequently recommended.
The soils assume certain properties which causes them to fix phosphates. This
characteristic makes it advisable to use band applications of this element on many
crops. There are soils at the Everglades Station that have been in almost contin-
uous production of row crops for approximately 25 years that show a lower water
soluble phosphate level than the virgin soils which have never received phosphate
applications. This condition exists in spite of the fact that the older cultivated
soils have received varying amounts of superphosphate annually during the entire
At the same time that phosphate requirements increase there seems to be a
slight decrease in potash requirements. For example, on virgin soils a 24 percent
K20 fertilizer is usually recommended whereas on the older soils the recommenda-
tion is usually from 10 to 16 percent K20 in the mixed fertilizer.
MINOR ELEMENTS--insurance or immediate needs?
Considerable minor elements including copper, manganese, zinc and boron are
included in the annual application of fertilizers to vegetable crops. Much of
this is insurance against the appearance of such deficiencies and it is usually
However, on crops that are sprayed at regular intervals for the control of
diseases and insects the immediate needs for manganese and zinc, and perhaps boron,
can be more efficiently supplied by applying these as nutritional strays. This,
of course, refers to old cultivated areas in which residual levels of these minor
elements have been built up by frequent applications of fertilizers containing
the minor elements.
Mananese may be u;ed at 2-4 pounds of the sulfate in 100 gallons water, sin
at 1-2 pounds of sulfate in 100 gallons, and boron at the rate of 1/2 pound borax
in 100 gallons. The latter should be dissolved separately and poured into the
spray tank with the agitator running after the other ingredients have been dissolved.
Manganese and zinc may be applied to beans in the sulfur dust. Such dusts
usually contain 10 percent manganese sulfate and 3-5 percent zinc sulfate and are
applied at the rate of 30 pounds of dust per acre.
Sweet corn particularly is susceptible to burning by the soluble forms of
manganese and zinc. This is due to the fact that excess quantities of the sprays
collect in the whorl and are concentrated by evaporation. The less soluble forms
of manganese and zinc, such as the oxysulfates, are effective on corn and other
Dr. G. M. Volk, Soils Chemist
Main Station, Gainesville
CHELRINE--reduce amounts in potato fertilizers.
Fertilizer added in the drill at time of planting has gone up to about 2500
pounds of 7-8-8 or 7-9-8 in many instances for Irish potatoes. It is noted that
much of this fertilizer carries up to 6 and 8 percent of chlorine. It should be
held to less than 3 percent if possible. The cost of making up the material with-
out using chlorides would be about $2 more per ton than where high chlorine is
-S DETERMINATIONS--can be improved.
It is recommended that all organizations using glass electrode pH meters have
a "stand soil" or two for checking in addition to the regular buffer solutions.
Many soils are less highly buffered than the solutions, therefore the use of a very
sandy soil of known pH will be a good check to see that the machine is sensitive
to a weakly buffered soil as well as to the strong buffers with which it is set.
pH determination after liming is very unreliable if done within one year, es-
pecially if the soil is not continuously stirred by tillage to allow for complete
reaction of the lime. pH is especially inadequate as a measure of soil condition
if the lime has been applied to the surface or has been only noorly incorporated.
LEAF ROLL--watch other crops.
Solonaceous crops should be closely watched for signs of nutritional leaf roll
on all new lands, and increased nitrates used to help correct the trouble. There
is little need for concern on old land of pH 5.5 or above, because nitrification
should be good in such soils.
Dr. Philip J. Westgate, Horticulturist
Central Florida Experiment Station, Sanford
CHOELTES & RITS--easy, boys.
Chelated Iron (Fe ED&A) has given favorable response when applied as a side-
dressing to iron chlorotic vegetables on acid sandy soils in the Sanford area.
Between 20 and 40 pounds per acre of the Fe EDTA (12% Fe) have given satisfactory
results without injury to established plants in the field. Chelated iron may be
injurious to germinating seeds, and to foliage when applied as a spray.
Fritted Trace Elements have failed to green iron chlorotic vegetables on acid
sandy soils in the Sanford area.
Dr. R. A. Dennison, Horticulturist
Vain Station, Gainesville
Investigations are being carried on at Gainesville in an effort to obtain
information as to the factor or factors causing "gray-wall" to develop in tomato
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fruit. This is being investigated as a nutrition problem and both sand culture and
water culture methods are being used. It is felt there may be an antagonism or
interference between certain ions with the plant failing to obtain or translocate
all of the essential elements the fruit and the growing points need, resulting in
breakdown of the vascular tissue of the fruit.
Gray-wall is a fruit disorder which is a serious problem only periodically.
It is usually found in fruit from plants which have made good growth. The fruit
with gray-wall are most commonly found under the foliage where they are well
shaded. A number of fruit with gray-wall are often found following a heavy rain.
QuILITY--nutrition and fertilizer practice.
A. Influence of source of potash. The use of sulfate of potash in the fer-
tilizer applied for tomato crops produced fruit which ripened firmer than when
muriate of potash was used. In the case of cabbage the heads were firmer with the
use of muriate of potash.
B. Influence of nitrogen side-dressing on firmness of tomatoes. Some com-
mercial buyers contend they will not take tomatoes which have been side-dressed
with nitrogen because the fruit ripen aoft. Experimental studies which have been
made have not shown this to be true. However, time of application with respect
to stage of development of the plants and levels of nitrogen applied have not been
investigated sufficiently to reach any definite conclusions. Treatments with 3
levels of nitrogen side-dressing and 3 times of application with regard to stage
of development are currently being studied. Research has improved techniques to
evaluate the quality of the fruit.
SHADED VS. EXPOSED FRUIT--"white" tomatoes.
Many tomato buyers are placing a premium on light colored fruit as compared
with dark green fruit. If the fruit are light colored it indicates they have been
protected by the foliage of the plant against direct exposure to the sunlight
whereas the dark green fruit have been exposed to the light.
Studies indicate the shaded fruit are firmer and develop a better color.
However, the differences depend to a large degree on the temperatures for a period
of several days prior to harvesting the fruit. If the temperature is low there
is very little difference in the fruit, but if the temperatures are high the dif-
ferences between the two lots of fruits increase.
The production of shaded and exposed fruit is closely related to cultural
practices of which the fertilization program is a very important consideration.
If the fruit are going to be protected from the light the plants must make a vigor-
ous growth so they will have sufficient foliage.
SPECIAL FERTILIZER MIXES--superior quality?
A number of tomato growers have fertilizer made up special and will nearly
always claim their special mix produces far superior tomatoes to anything their
neighbors have. Because of the insistence of a number of growers on these s-ecial
fertilizer mixes it increases the grades of fertilizers which the industry must
produce. Probably most of these growers would produce tomatoes with just as good
quality by using some of the standard grades of fertilizer.
Dr. John L. Malcolm, Soils Chemist
Sub-Tropical Experiment Station, Homestead
TOMTO FERTILIZERS--variety differences?
Each new tomato variety may have distinctly different fertilizer requirements
from those varieties which are now being grown. For example, the Homestead variety
appears to have a much lower phosphate requirement than the older varieties such
as the Grothen and the Rutgers. In addition to this, its more vigorous growth
habit makes it better able to utilize nitrogen and potassium from the fertilizer.
Under the conditions of experiments at the Sub-Tropical Station, there was
no apparent difference in the manganese and magnesium required by these varieties.
It must be remembered, however, that the Station farm is well supplied with both
of these elements. The Homestead tomato seems able to extract fertilizer elements
retained by the soils and to make very good use of the easily leached elements
added in the fertilizer.
POTATO FERTILIZERS--differences in marl soils.
Experience with potatoes this year points out the difference in soils rather
than in varieties. On the East Glade Farm a commercially mixed 5-10-10 at the
rate of 500 pounds per acre was compared with 1500 pounds of 2-8-6. Both mixtures
contained magnesium and manganese. Although the yields were general poor and
the stand inconsistent, the potatoes receiving the 500 pounds of 5-10-10 out-vielded
those receiving the 2-8-6.
In one cooperative experiment 1000 pounds of 5-10-10 was compared with 2000
pounds of 2-8-6. In this case the yields on both plots were the SuSa as nearly
as could be determined. In a second cooperative experiment, 1000 pounds of the
5-10-10 was compared with 2000 pounds of 4-8-6. In this case the yield from the
plot fertilized with 5-10-10 was inferior by more than 15 percent. Since the
field averaged about 450 bushels per acre, this was a loss of some 70 bushels of
This experience suggests that although careful experiments can establish the
fertilizer requirements of a crop in a particular field, care must be used in
applying these results over a wide area.
Forrest E. iye)s