Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; 190
Title: The stimulation of plant response on the raw peat soils of the Florida Everglades through the use of copper sulphate and other chemicals
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 Material Information
Title: The stimulation of plant response on the raw peat soils of the Florida Everglades through the use of copper sulphate and other chemicals a preliminary report
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: p. <33>-80 : ill. ; 23 cm.
Language: English
Creator: Allison, R. V ( Robert Verrill ), b. 1896
Bryan, O. C ( Ollie Clifton ), b. 1894
Hunter, J. H ( James Horace ), 1901-
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1927
Subject: Plants, Effect of chemicals on   ( lcsh )
Plant-soil relationships -- Florida -- Everglades   ( lcsh )
Peat soils -- Florida -- Everglades   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: by R.V. Allison, O.C. Bryan, and J.H. Hunter.
General Note: Cover title.
General Note: "Contribution no. 1 from the Everglades Experiment Station"--T.p.
 Record Information
Bibliographic ID: UF00026388
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000923497
oclc - 18172938
notis - AEN4048
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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

September, 1927

Agricultural Experiment Station


(A Preliminary Report)


(Contribution No. 1 from the Everglades Experiment Station)

Fig. 13.-General view of one section of plant response studies at the
Everglades Experiment Station.

Bulletins will be sent free upon application to the
Agricultural Experiment Station

Bulletin 190

P. K. YONGE, Chairman, Pensacola E. L. WARTMANN, Citra
E. W. LANE, Jacksonville J. T. DIAMOND, Secretary, Talla-
A. H. BLANDING, Leesburg hassee.
W. B. DAVIs, Perry J. G. KELLUM, Auditor, Tallahassee

WILMON NEWELL. D. Sc.. Director ERNEST G. MOORE, M. S., Asst. Ed
JOHN M. SCOTT, B. S., Vice-Director IDA KEELING CRESAP, Librarian
S. T. FLEMING, A. B., Asst. to Di- RUBY NEWHALL, Secretary
rector K. H. GRAHAM, Business Manager


W. E. STOKFS, M. S. Agronomist
W. A. ,LETKEL, Ph. D., Assn.
C. R. ENLOW, M. S. A., Asst.
FRED H. HULL, M. S. A., Asst.
JOHN M. SCOTT, B. S., Animal
R. W. RUPRECHT, Ph.D., Chemist
R. M. BARNETTE. Ph. D., Asst.
C. E. BELL, M. S., Asst.
H. L. MARSHALL, M. S., Asst.
J. M. COLEMAN, B. S., Asst.
J. B. HESTER, B. S., Asst.
W. A. CARVER, Ph. D., Asst.
M. N. WALKER, Ph. D., Asst.
E. F. GROSSMAN, M. A., Asst.
RAYMOND CROWN, B.S.A., Field Asst.

L. W. GADDITW, Ph. D., Asst.
C. F. AHMANN, Ph. D., Asst.

J. R. WATSON, A. M., Entomologist
A. N. TISSOT, M. S., Asst.
H. E. BRATLEY, M. S. A., Asst.

A. F. CAMP, Ph. D., Asso. Hort.
M. R. ENSIGN, M. S., Asst.
G. H. BLACKMON, M. S. A., Asst.

O. F. BURGER, D.Sc.. Plant Pathologist
G. F. WEBER, Ph. D., Asso.
K. W. LOUCKS, B. S., Asst.
ERDMAN WEST, B. S., Mycologist

C. V. NOBLE, Ph. D., Ag. Economist A. L. SHEALY, D.V.M., Veterinarian
BRUCE MCKINLEY, A. B., B. S. A,, D. A. SANDERS, D. V. M., Asst.
Asst. E. F. THOMAS, D. V. M., Lab. Asst.
M. A. BROKER, M. S. A., Asst.

W. B. TISDALE, Ph. D., Plant Pathologist, in charge, Tobacco Experiment
Station (Quincy)
Ross F. WADKINS, M. S., Lab. Asst. in Plant Pathology (Quincy)
JESSE REEVES, Foreman, Tobacco Experiment Station (Quincy)
J. H. JEFFERIES, Superintendent, Citrus Experiment Station (Lake Alfred)
W. A. KUNTZ, A. M., Assistant Plant Pathologist (Lake Alfred)
R. L. MILLER, Assistant Entomologist (Lake Alfred)
W. L. THOMPSON, Assistant Entomologist (Lake Alfred)
GEO. E. TEDDER, Foreman, Everglades Experiment Station (Belle Glade)
R. V. ALLISON, Ph. D., Soils Specialist (Belle Glade)
J. H. HUNTER, M. S., Assistant Agronomist (Belle Glade)
J. L. SEAL, M. S., Assistant Plant Pathologist (Belle Glade)
H. E. HAMMAR, M. S., Field Assistant (Belle Glade)
L. O. GRATZ, Ph. D., Assistant Plant Pathologist (Hastings)
A. N. BROOKS, Ph. D., Associate Plant Patholgist (Plant City)
A. S. RHOADS, Ph. D., Assistant Plant Pathologist (Cocoa)
STACY O. HAWKINS, Field Assistant in Plant Pathology (Homestead)
D. G. A. KELBERT, Field Assistant in Plant Pathology (Bradenton)
R. E. NOLEN, M. S. A., Field Assistant in Plant Pathology (Monticello)
FRED W. WALKER, Assistant Entomologist (Monticello)


(A Preliminary Report)


In the year 1850, 20,424,972 acres of swamp and overflow
land were granted to the State of Florida by a Congressional
Act of that year, the primary purpose, as expressed in the Act,
being to aid in the reclamation of such lands by means of dikes
and canals. Included in this aggregate was the vast area of
the Everglades, that broad, level tract of overflow land occupy-
ing the greater portion of the interior of the lower part of the
peninsula and doubtless constituting the largest continuous
area of peat land in the world. This grant was not definitely
established until regular patents were issued by the Federal
Government. The patent finally transferring the Everglades
to the State of Florida was not obtained until April 29, 1903.
Thus, while comprehensive plans for the drainage of certain
portions of this extensive grant were made as early as 1881,
and partially executed in the years immediately following, active
responsibility for the perfection of this project, so far as the
Everglades was concerned, was not definitely placed upon the
State until the actual issuance of the patent by the National
Government. The earlier drainage work referred to came to
a standstill in 1893 and there was little progress in this respect
until, following the transfer of the patent in 1903, it became a
very active issue in the program of Governor Broward in 1904.
It was during this period of definite reorganization with re-
spect to the drainage work that the question of the agricultural
merit of the soils of the proposed area came up rather persist-
ently for discussion. As a result of this, the cooperation of the
United States Department of Agriculture was enlisted in carry-
ing out an agricultural survey of the general area. This extra-
ordinary piece of work was carried out in 1906 and furnished
important information, not only upon the character of the soil

*Professor of Agronomy, College of Agriculture.

Florida Agricultural Experiment Station

and subsoil materials encountered in the course of the first
traverse of this most difficult area, but also, through the com-
plete east-west and other lines of levels established, pointed out
the entire feasibility, from an engineering standpoint, of the
drainage of the general area of the Everglades.


While rapid progress was made in carrying forward the engi-
neering part of the drainage program following this period, no
further attention was given to the organization of a definite
program of agricultural research until 1921, when the Legis-
lature authorized' the establishment of an experiment station
in the Everglades. Following the designation by the Trustees
of the Internal Improvement Fund, on August 24, 1921, of the
tract of state-owned land to be used for the experiment station,
the State Board of Control, under the authority of the Board
of Commissioners of the Everglades Drainage District, the
Trustees of the Internal Improvement Fund, and the State
Board of Education, took over, on September 21, 1923, the re-
sponsibility of its operation as a definite part of the University
of Florida Agricultural Experiment Station.
The Everglades Experiment Station is thus a regular branch
station of the University at Gainesville and is located in Sec-
tion 3, Township 44 S, Range 37 E (Tallahassee Meridian), in
Palm Beach County. In relation to Lake Okeechobee, it is
about three and one-half miles to the east and south of the up-
per locks of the Hillsboro Canal and thus about five miles from
the main body of the lake proper. The section of land indi-
cated, which has been designated in its entirety for the use of
the Experiment Station, is divided into two parts by the Hills-
boro Canal. The portion to the south of the Canal, represent-
ing an area of 160 acres, has been placed under dike and pump
and it is here that the present buildings and field operations
are located. To the time of construction of the first buildings
and when the first land was broken in December, 1923, the en-
tire area was covered, in most seasons, with tall saw-grass, with
the exception of a strip, about 200 feet wide, along and on the
south of the Canal. This strip was occupied by elders. The

1Chapter 8442, Laws of Florida, 1921.

Bulletin 190, Stimulation of Plant Response etc.

disposition of the station area now under development has been
discussed in some detail in the reports of the Director for 1924,
1925, and 1926.


A review of the literature dealing with soil investigations
indicates that highly organic peat soils are not ordinarily very
well adapted to the growth of agricultural plants. This is par-
ticularly true during the earlier periods of their weathering
following drainage. During this period it is commonly found
that the response" of most agricultural plants is extremely poor
and in a number of cases entirely negative. This has been found
to be true with the majority of plants tested on freshly broken
saw-grass peat at the Everglades Experiment Station, when
no chemical treatments were made.
The accumulation of plant residues under conditions of ex-
cessive moisture usually constitutes peat soils. Under such con-
ditions the anaerobicity, or lack of air, largely prevents the de-
composition of the freshly fallen material beyond a certain
stage; hence the accumulation of such organic deposits from
century to century.
It is readily apparent, therefore, that an adequate system of
drainage is the first and most important necessity in the re-
clamation of such areas. Because of the highly organic and
combustible nature of peats when dry, the drainage system
should provide for a proper supply of water under control, as
well as for the removal of excess water.
There are a number of factors that may affect the agricul-
tural value of peat soils. The character of the original plant
growth and the nature of the substratum-whether lime, clay
or sand-as well as the climatic conditions under which the peat
exists, may have a considerable influence on the value of peat
soils. Thus, if the peat is deposited upon sand or heavy clay
out of contact with lime or lime-containing waters, it is almost
certain to be acid in character. Furthermore, it may be exposed
to subterranean waters carrying chemical substances which
may be directly or indirectly deleterious to plant growth.

2The term "response", as used herein, has reference to the reaction of
the plants, namely growth, to their environment and especially with re-
gard to the condition of the soil in which they are grown.

Florida Agricultural Experiment Station

As a rule all peat soils have a low mineral content, and defi-
ciencies of both phosphoric acid and potash are commonly ob-
served to follow the inauguration of regular systems of crop-
Aside from the matter of general plant development, the pres-
ence of adequate supplies of the above-mentioned nutritive ele-
ments is frequently found to go far in developing stability and
shipping quality in both fruit and vegetables. Peat soils are
frequently associated with decidedly inferior marketable crops,
and any improvement that can be effected through the proper
nourishment of the plant is readily seen to be a very important
matter. This paper deals essentially with the possible deficien-
cies of the Everglades peat in still other elements that are less
commonly regarded as necessary for the normal development
of plant growth.


The greater part of the Florida Everglades consists of a vast
plain (about 3,000,000 acres) of raw saw-grass peat, varying
from about three to ten or more feet in depth. While the total
area of the Everglades exceeds 3,000,000 acres, much of that
to the south is exceedingly shallow, the lime rock appearing as
surface outcrops in some places.
Along the southern and eastern shores of Lake Okeechobee
there is a narrow and slightly elevated rim from 1 to 212 miles
wide of a true muck, locally known as "custard apple" land.
On the average this muck contains about 40 to 50 percent of
inorganic matter, or ash, in contrast with 9 to 12 percent in the
case of the raw saw-grass peat of the open Glades. Since this
area of true muck is in the line of natural overflow from the
lake, it appears to have had its mineral content developed large-
ly as outwash of silt and fine sand from the lake. There are
other small areas of true muck on the outer margins of the
saw-grass peat.
Occupying a position intermediate between the "custard
apple" muck and the saw-grass peat is a belt of what is com-
monly referred to as "weed land" or "elder land". This mate-
rial represents a more advanced stage of weathering than the
raw saw-grass peat, due, doubtless, to natural advantages of
drainage and its consequent earlier occupation by weed or elder

Bulletin 190, Stimulation of Plant Response etc.

growth. The ash or mineral content is also somewhat higher
in this material than in the raw saw-grass peat but considerably
lower than in the "custard apple" soil. This soil is thus inter-
mediate in many of its qualities between the two diverse types
on either side of it.
While the peat soils of the Everglades have the characteristics
of peat soils in general, they have certain advantages over
many of those in other parts of the country. Perhaps the most
important of these is a sub-tropical climate. A further advan-
tage in favor of the Everglades peat, when compared with other
peat lands, is its high lime content and on this account it has
a comparatively alkaline rather than acid reaction. Some ex-
ceptions to this are found on the outer margin of the Everglades
where the peat deposit overlies sand rather than lime rock.
Too much importance cannot be placed upon the high lime con-
tent of the Everglades soils, for this is one of their most import-
ant natural features. While the acid peats in other parts of
the State and country have a lime (CaO) content as low as one-
tenth of one percent or less, the Everglades peats have a lime
content of 3.0, 4.0 and even 5.0 percent.



The poor plant response usually associated with raw peat
soils has been the consistent experience with practically all types
of agricultural plants tested on the raw saw-grass soils at the
Everglades Station. Here failure, in most instances, has been
early and complete. A rather outstanding exception, however,
is found in the case of the Irish potato, as good yields of this
crop are commonly obtained on freshly broken saw-grass peat.
In this connection it is interesting to note that a number of
weeds and other non-agricultural plants are found to thrive
luxuriantly in this soil environment after it has been exposed
to the influence of drainage for a time. Among these, elder
(Sambucus intermedia Carr), "careless weed" (Amaranthus
sp.), dog fennel and others seem to follow along after drainage
in a more or less definite succession in the displacement of the
original saw-grass growth which becomes naturally weakened
as the water recedes.

Florida Agricultural Experiment Station


Earlier Observations: During the past two decades copper
sulphate has frequently been observed to stimulate plant growth
under a variety of conditions. The most frequent observation,
however, has been incidental to the use of copper as a fungicide
in Bordeaux mixture. These observations in many cases have
been made quite independently and in widely separated places."
In a number of instances stimulation of plant growth from the
use of Bordeaux spray has been suspected by farmers in the
Everglades territory.
Although the farmers had no definite understanding as to why
certain crops grew better on the raw saw-grass soil when they
followed potatoes, it became a common practice in some locali-
ties to definitely arrange the rotation in relation to this effect.
Since only small amounts of copper were applied in this way,
and this at more or less irregular intervals, nothing more than
casual interest was attached to the significance of such re-
During the earlier periods of investigation at the Everglades
Experiment Station, the extremely poor plant growth on the
raw peat soils was attributed to such causes as (1) a lack of
aerobic soil organisms due to poor drainage, (2) a lack of cer-
tain plant nutrients, as phosphorus and potassium, (3) pres-
ence of certain toxic organic compounds in the soil, (4) unfav-
orable soil reaction, (5) certain soluble salts, and (6) patho-
genic soil organisms. The preliminary investigations seemed to
indicate that this poor plant response, or growth, could not be
positively associated with any of the causes just mentioned.
Observations at the Everglades Experiment Station: During
the summer of 1924, Director Wilmon Newell made a series of
pot experiments, using top soil from the grounds of the Ever-
glades Experiment Station property, in the course of which ap-
plications of manure, garden soil, lime, gypsum, copper sulphate,
superphosphate, potash, and other materials were tested as to
their effects upon the growth of Brabham cowpeas. In these
trials, best growth and vigor of the plants were secured follow-
ing the application of copper sulphate; followed somewhat

3E. L. Felix, of Cornell University, has recently noted beneficial re-
sults from the use of Bordeaux mixture and copper sulphate on certain
peat lands in New York.

Bulletin 190, Stimulation of Plant Response etc.

closely, in the order named, by sulphate of potash, hardwood
ashes, and manure.
During the summer of 1925 a number of soil treatments were
made at the Everglades Station, these including fertilizers, farm
manures, sewage, lime, sulphur and a productive soil. The
treated areas were then planted to corn, cowpeas, sorghum, soy-
beans, beans, and peanuts. In an effort to control certain in-
sects during the summer months, a 50-50 mixture of powdered
Bordeaux-calcium arsenate was dusted on the corn and cow-
peas in some of the plots. After an interval of two weeks it was
observed that where the Bordeaux-arsenate had been applied

Fig. 14.-Response of sorghum plants upon raw sawgrass peat at the
Everglades Experiment Station to treatment with copper (1925).
the plants were growing in good shape, while those on the un-
treated area were dead. From these results it was suspected
that the copper in the Bordeaux was the stimulating agent, and
on this assumption another series of plots was started which
included soil treatments with copper, aluminum, zinc and man-
ganese sulphates, sulphur and boric and sulphuric acids. These
plots were then planted to corn, sorghum and cowpeas, with the
result that the copper-treated plots produced outstanding plant
growth, whereas the plants upon the check, or non-treated,
plots produced very little or no growth. Figures 13 and 14
show the responses of corn and sorghum to the copper treat-
ment. Some responses also were noted to sulphur and zinc,

Florida Agricultural Experiment Station

but they were of minor importance compared with copper.
After noting the rather positive plant responses through the
application of copper sulphate to the raw saw-grass peat at the
Experiment Station a number of farmers in the community ob-
tained similar plant responses with this material. Some of them
recall similar response resulting from the use of Bordeaux mix-
ture in previous years, but these observations had not been fol-
lowed up.


As a result of the unusual plant response following the ap-
plication of small quantities of copper, either as a fungicide or
directly to the soil, an enlarged program of experimental work
along this line was started at the Experiment Station in the
early spring of 1927.
Since copper and a number of other heavy metals are known
to occur normally in most productive soils as well as in the ash
of a majority of green plants, it was thought that the poor
plant response so commonly observed upon the natural peat
might be due to a deficiency of these elements and on this as-
sumption the work herein reported was begun.

The experimental work was conducted on about four acres
of freshly broken saw-grass peat at the Everglades Station.
The area was laid off in two tiers 100 feet wide with a 4-foot
alley between them. Each tier was then subdivided into 38
plots, 20 x 100 feet, making a total of 76 plots.
Tier 1 was planted to garden truck crops for the most part,
while tier 2 was planted largely to field crops. The rows of
the different crops extended the entire length of the tiers, but
across the plots.
The chemical compounds used, together with the rates at
which they were applied, are listed in Table I. The rates per
acre were selected arbitrarily, although preliminary trials

Bulletin 190, Stimulation of Plant Response etc.

showed that 30 to 50 pounds of copper sulphate to the acre gave
as good results as higher applications. These treatments were
duplicated in each tier. Instead of duplicate plots being oppo-
site each other, in the two tiers, they were "staggered". Every
fifth plot in each tier was left untreated as a check. Only single
treatments were made on any plot. The treatments were made
on March 10 and 11, and the plantings March 15, unless other-
wise indicated. The crops planted are listed in Table II.

[Rate of Applica-
Element Compound or Material Applied tion (Lbs. per

Antimony ............... Antimony trichloride ........ .. 22.8
Barium -...-..- ...-..-- Barium hydroxide ................ .... 27.5
Boron ................ Boric Acid .................................. 68.1
Copper .................. Copper sulfate (bluestone) ......... 30.0
Calcium ............... Calcium oxide (CaO) .. ............... 250.0
Calcium .............. Calcium hydroxide (Ca(OH) ) .... j 330.0
Mercury ................. Mercuric chloride ....... ................ 16.2
Nickel ................ Nickelous sulfate ........ ...-... 57.4
Manganese ............ Manganous sulfate .................... 40.9
Arsenic .................... Sodium arsenate .-....................I 17.0
Tin ....-........- ............. Stannic chloride ........... ........ .. ..26.3
Sulfur .................. Flowers of sulfur ....---. ..---. .......... 300.0
Chromium ............ Chromium sulfate ........- ....-....... 45.3
Lead ..... ...... Lead acetate ................. ... 21.9
Zinc .. ................. Zinc sulfate .... ................. ..... 49.5
Compost ................. .................... 2000.0

Following the preparation of the soil, shallow planting fur-
rows were opened. The chemicals, in a finely divided condition
or in solution, were applied, either alone or mixed with a small
amount of dry peat. All materials were applied in furrows to
prevent, as far as possible, subsequent drifting of chemicals
from plot to plot by wind. After being mixed in the furrow
with a small plow and covered lightly, the materials were al-
lowed to stand for three or four days. The furrows were then
reopened and the plantings made. In work of this nature, great
care should be used in preserving the isolation of the different
chemicals or preventing their contamination from plot to plot
at the time of application and subsequent cultivation.

Florida Agricultural Experiment Station

These crops were planted lengthwise of the tiers and crosswise of the in-
dividual plots.

Chinese cabbage
Brussels sprouts
Sweet potatoes
Rutabaga turnip
Kohl rabi
Swiss chard
English pea
Hubam clover
Sweet clover
Sugar cane (Crystalina)
Sugar cane (U. S. 663)
Corn (Cuban Flint)

Sorghum (Sugar Drip)
Sorghum (Early Amber)
Sorghum (Shallu or Chicken
Velvet bean (Arlington)
Velvet bean (Tracy)
Soybean (O-too-tan)
Soybean (Goshem Prolific)
Soybean (Laredo)
Soybean (Virginia)
Soybean (Biloxi)
Cowpea (Groit)
Cowpea (Iron)
Cowpea (Brabham)
Cowpea (Columbia)
Cowpea (Victor)
Jack bean
Mung bean
Peanut (Improved Valencia)
Crotalaria juncea
Crotalaria retusa
Tangier pea
Japan clover


Due to the fact that satisfactory quantitative plant response
could not be obtained from experiments of this nature to indi-
cate the extent and character of the plant growth under treat-
ment, resort has been made to the use of photographs as a basis
for discussion. The photographs represent the average size
plants for the individual treatment.
Since at present it is desirable to place the greater emphasis
on the positive responses, those of negative or slightly positive
nature will not be given much discussion, though many of them
are interesting. Barium and lead have given indications of
slight, but never pronounced, response with a number of plants.
The absence of response to calcium hydroxide with practically
all plants is of particular interest in comparison with the de-

Bulletin 190, Stimulation of Plant Response etc.

cided response from caustic or unslaked lime. Arsenic and bo-
ron, especially, produced rather definite toxic effects in most
cases. However, there were some instances in which no re-
sponse was noted.
It is not necessarily meant that these minor responses are of
no importance, for even in the case of those showing consistent-
ly negative or toxic effects it is possible that smaller applica-
tions might give different results.
The different plants studied will be grouped in a more or
less arbitrary manner for convenience in discussing the results.
The arrangement of this grouping is as follows:
Group I. Lettuce, chard, etc.,-Chinese cabbage, lettuce, en-
dive, spinach, swiss chard, and parsley.
Group II. Cruciferous plants,-radish, turnips, rutabaga,
rutabaga turnip, kohl-rabi, cabbage, brussels sprouts, and rape.
Group III. Root types,-beets, carrots, sweet potatoes, arti-
choke, and Irish potatoes.
Group IV. Miscellaneous garden plants,-eggplant, tomato,
asparagus, beans, garden peas, sunflower, and chufas.
Group V. Sugar cane, corn, etc.,-corn, sugar cane, sor-
ghums, and grasses.
Group VI. Soybeans and cowpeas,-soybeans (5 varieties)
and cowpeas (5 varieties).
Group VII. Miscellaneous legumes,-peanut, Hubam clover,
Melilotus indica, jack-bean, velvet bean, horse bean, mung bean,
Crotalarias, Clitoria, guar, Tangier pea, Sesbania, beggarweed,
and Japanese clover (Kobe lespedeza).


In contrast with the field crops which were planted at about
the same time, the truck crops were naturally the first to de-
velop sufficiently to indicate the presence or absence of positive
response to the treatments.

The response of the members of this group has been some-
what difficult to interpret, due to the rather poor stand as well
as to the delicate nature of the plants, especially under the
March sun in such a peat environment. Nevertheless, striking

Florida Agricultural Experiment Station

results were obtained with the lettuce and endive on the copper-
treated plots as is indicated in Fig. 15.
Chinese cabbage (Pe-Tsai). Chinese cabbage made a consid-
erable growth on practically all plots, including the checks,
though boron and arsenic proved definitely injurious; caustic
and hydrated lime were also injurious but to a lesser extent.
Copper treatment gave an outstanding response and produced

2 3

Fig. 15.-Response of lettuce to treatments with copper sulphate and
manure on the raw saw-grass soil of the Everglades. 2. Copper sul-
phate. 3. Manure. 4. Check (no plants remaining). Seeded March
15, 1927. Photographed April 21, 1927.

plants that were much superior in size. Manganese and manure
also showed considerable advantage over the untreated plots.
In most cases, however, the growth was rather loose and open
for this plant except upon the copper-treated plots, where it
was firmer.
Lettuce (Big Boston). Lettuce showed earliest response to
copper, nickel, and manganese treatments. This effect appeared
three weeks after planting. Response to manure was apparent
the fourth week after planting. Fig. 15 shows the comparative
development of lettuce following the application of copper and
manure. At the time this photograph was taken the plants on
the check plots had entirely disappeared. Boron and arsenic
injury appeared early and caused premature death of all plants,
both endive and lettuce.
Endive (Green Curled). The response on the copper-treated
plots was outstanding. Although the stand was irregular, the
growth within the mass was so dense that it became self-
blanched, even under the exposure to the June sun. Good re-
sponse also was obtained with manganese and manure treat-
ment. A minor response was obtained with nickel. Plants on

Bulletin 190, Stimulation of Plant Response etc.

the check plots lived somewhat longer than did the lettuce, but
they ultimately disappeared, as did those on the other treated
areas that did not show a permanent response.
Spinach (Bloomdale). Spinach proved the most transient of
all the plants and, aside from a definite response to copper, no
response was noted. Thus on May 3, when the two copper-
treated plots were still showing a light stand of plants 5 to 10
inches tall and of good color, those on practically all the other
plots had already perished. Boron and arsenic showed toxic
effects very early.

2 f 3 Y 4

Fig. 16.-Response of radish to treatment with copper, manganese, and
manure on raw saw-grass soil of the Everglades. 1. Copper. 2. Man-
ganese. 3. Manure. 4. Check. Seeded March 15, 1927. Photographed
April 21, 1927.

Swiss Chard. Swiss chard also seemed to lack hardiness to
endure the conditions of the experiment. Response to copper
treatment was apparent as early as April 6, as well as lesser re-
sponses to antimony and caustic lime. Later, nickel, manganese,
and manure showed favorable effects, but by early May, all
plants except those on the copper, manganese, and manure
treated plots were dead. Toxicity from boron and arsenic ap-
peared very early; and later, to a lesser extent, from zinc.
Parsley (Extra Double Moss Curled). Parsley was unusu-
ally slow in responding. For a considerable time the plants
were too small to detect any tendencies toward response or minor
injury, though definite retardation in growth and positive in-
jury appeared rather early in the case of treatments with bo-
ron and arsenic. By early May, however, response was decidedly

Florida Agricultural Experiment Station

apparent to copper, tin, and manure and, to a lesser degree, to
manganese and antimony. The plant responses were frequently
found to be' rather contradictory upon different plots receiving
the same treatment.


In the case of practically all the cruciferous plants tested, the
response to a number of treatments was marked. While the
most outstanding and consistent responses were found to cop-
per, there were a number of others which were pronounced in
character. It is thought that many of the less marked re-

Fig. 17.-Response of turnips to treatment with copper sulphate on the
raw saw-grass soil of the Everglades. 1. Copper sulphate. 2. Check.
Seeded March 15, 1927. Photographed April 21. 1927.

sponses are significant, however, and worthy of further care-
ful investigation.
Radish (Long White Icicle). The general character of re-
sponse of the radish plantings to certain of these treatments
is well indicated in Fig. 16. The response to copper, manganese,
and manure was pronounced by March 30, while by April 6, nickel
and caustic lime were showing favorable effects. By April 14,
mercury also was showing a favorable influence. By this lat-


Bulletin 190, Stimulation of Plant Response etc.

ter date the slight growth of plants had nearly all disappeared
from most of the checks and plots where the treatments were
toxic or did not induce a positive plant response. The radishes
on the more favorable treatments grew to a distorted old age
and produced large, pithy roots, two or three inches in diameter
and seven to ten inches long. Boron and arsenic toxicity ap-
peared very early and practically destroyed the plants while still
very young.

2 3 4

Fig. 18.-Response of kohl-rabi to treatment with copper sulfate, manga-
nese, and manure on the raw saw-grass soil of the Everglades. 1. Cop-
per sulfate. 2. Manure. 3. Manganese sulfate. 4. Check. Seeded
March 15, 1927. Photographed May 5, 1927.
Turnip (Purple Top Globe), Rutabaga turnip (Improved
American), Rutabaga, and Kohl-rabi. In general, this group of
crucifers showed the same progressive response. The response
to copper appeared in the case of the turnip, rutabaga turnip,
rutabaga, and kohl-rabi as early as March 28, and by March 30
the effects of the nickel, manganese, manure, and caustic lime
treatments as well, were all apparent. Fig. 17 indicates the
effect of copper sulphate alone on the development of turnips,
and Fig. 18 that for a series of treatments on rutabaga. In
this group, boron and arsenic proved very toxic as usual, the
effect appearing as early as March 28 in all cases. The radishes
showed a positive response to mercury by March 14. On this
date tin and zinc were showing detrimental effects.
Cabbage (Charleston Wakefield). The cabbage response to
the various treatments was more or less similar to that of the

Florida Agricultural Experiment Station

group above, though somewhat delayed in a few cases. Thus,
while its response to copper and manganese was apparent as
early as March 30, the response to nickel and manure did not
appear until April 14, and that to mercury and caustic lime was
not so marked until May 3. While caustic lime appeared injuri-
ous to this plant earlier, later it appeared to stimulate growth.
There was some head formation upon the plots receiving the
copper treatments and rather marked stimulation in this direc-
tion in the case of some of the others. The stand and condi-
tion of the plants on the treatments not showing response and
on the check plots were very poor indeed.

a'I fi 41

Fig. 19.-Response of rape to a series of treatments on raw saw-grass
soil of the Everglades. 1. Copper sulfate. 2. Manure. 3. Manganese
sulfate. 4. Check. Seeded March 15, 1927. Photographed April 21,

Brussels sprouts (Improved Long Island). These plants were
not set until March 25 and they showed the poorest response of
any of the Cruciferous plants tested. The response to copper,
manganese, and nickel had appeared by April 14, and that to
manure by May 5. Caustic lime seemed rather injurious dur-
ing the earlier and later periods of growth. By May 5, the plants
on the copper-treated plots had an average height of 12 inches
and a leaf spread of 6 inches, as against plants on the check
plots with a height of 6 inches and a breadth of 3 inches. The

Bulletin 190, Stimulation of Plant Response etc.

responses to manganese, manure, and nickel were even less pro-
nounced. Mercury produced no response at any time.
Rape (Dwarf Essex). Rape, on the other hand, gave one of
the most striking responses observed in the group. Figure 19
shows the development of this plant upon a series of treatments.
Sixty days after seeding, this plant was showing a most extra-
ordinary response to copper, manganese, and manure in par-
ticular, minor response to caustic lime, and still less response
to calcium hydroxide, mercury, and nickel. Barium and tin
also gave the appearance of slight response at one time. Dur-
ing the later period of development on the copper-treated plots,
the tops reached a height of nearly 30 inches and a breadth of

Fig. 20.-Development of rape roots in raw saw-grass soil under treat-
ment with copper sulfate. Seeds planted March 15, 1927. Photo-
graph taken June 4, 1927.

nearly 3 feet. Its development was somewhat less marked on
the plots receiving manganese and manure. During the middle
of the day when transpiration was greatest, the plants on the
copper-treated plots, though largest, seemed to preserve a near-
ly normal turgor, while plants of less size on the other plots
frequently were drooped or partially wilted.
An examination of the development of the root systems of
the plants under different treatments was made to see if this
might explain the difference in behavior of the leaves. A
transverse block of the soil was cut from the copper-treated
row to a depth of 14 inches. This block, 12 x 18 inches, extend-
ed from the line of the planting to the middle of the rows. At

Florida Agricultural Experiment Station

this time many of the stems were three-fourths to one inch in
diameter and very woody, while the plants on the check plots
had disappeared entirely. Attempts were made to wash the
soil from the network of roots, but this was found impossible.
After washing the surface for a time and removing most of the
loose material as well as a considerable number of the finer
roots, the photograph shown as Fig. 20 was taken. It is seen
that the strong, heavy laterals extend out the full 18 inches
of the block and were found to have a diameter of about 1/20
inch. Others were traced outward as far as three feet, where
they tended to grow downward.
Following the removal of the block of soil from its position,
an examination of the hole showed that the clean, white roots,
most of them very fine, had penetrated to a depth of 25 inches
or more into areas where the peat was brown and fibrous. Ap-
parently the greater portion of the root system of these plants
was projected far beyond the zone of direct contact with the soil
receiving the copper application. This would seem to afford
evidence in support of the assumption that copper is directly
necessary in the plant metabolism.
Examination of the plants upon the manure-treated plot
showed that the root development was not nearly so great in
either direction, nor did the roots have as good color.


Carrots (Improved Long Orange). While the toxic effect of
boron and arsenic on carrots appeared early, the beneficial influ-
ence of copper, and to a lesser degree manganese and manure,
did not appear until about April 15. Caustic lime and antimony
also appeared to be more or less toxic. Nickel showed a slightly
favorable influence. Plants on the copper-treated plots were six
to eight inches long. Those from the other favorable treat-
ments were somewhat smaller. By the middle of May, or
shortly after, the plants on the untreated plots, which had never
attained a height of more than 21/ inches, had entirely disap-
Beets (Kilgore's Extra Early). Beets responded compara-
tively early to copper, nickel, and manganese, and a little later
to manure. By May 5, however, living plants were to be found
only on the areas previously treated with copper, manganese,

Bulletin 190, Stimulation of Plant Response etc.

and manure. Representative plants from these areas are shown
in Fig. 21. With the exception of the copper-treated plots, the
plants were present as a rather poor stand. Toxicity due to
boron and arsenic appeared early and, later, to a lesser degree,
to antimony and zinc.
Sweet Potato. The sweet potato plants were fairly well de-
veloped when set on April 4, and no particular response to any
of the treatments was apparent up to May 4, all plants being
in bad shape, yellow, and without much vigor. By July 22, a
tremendous response in vine development had appeared on the


21 3

Fig. 21.-Response of beets to treatment with copper, manganese, and
manure on the raw saw-grass soil of the Everglades. 1. Copper sul-
fate. 2. Manganese sulfate. 3. Manure. 4. Check (plants died ear-
lier). Seeded March 15, 1927. Photographed May 5, 1927.

copper-treated plots. The vines had grown to a length of 8
feet. Despite the heavy vine development, however, little prom-
ise was to be found in the development of potatoes. Minor re-
sponses of this same type were apparent to treatments with
caustic lime, manganese, and manure and, to a lesser extent,
to zinc and antimony. Boron and arsenic were rather toxic
from the beginning.
Artichoke (Green Globe). In general, little response from
any of the treatments was observed in the case of the artichoke.
Boron and arsenic proved somewhat toxic. Copper and man-
ure were the only treatments that showed a stimulation. The

Florida Agricultural Experiment Station

plants with these treatments were slightly larger and the leaves
had a better color, but the margin seemed to be slightly burned
in some instances, similar to the leaves on plants growing on
the check and other treated plots.
Potatoes (Spaulding Rose). Little difference was observed
through the greater part of the growth period of these plants
with any treatment. Boron and arsenic did appear somewhat
injurious. As the vines began to ripen, however, the plants on
the cbpper-treated plots continued normally green for a consid-
erably longer time than did the other treatments. The copper-
treated rows also produced a few more potatoes than did those
of any of the other treatments. Sulfur, chromium, caustic lime,
and manure seemed to show some advantage from the stand-
point of tuber development, while antimony, barium, and zinc
appeared somewhat injurious, though to a lesser degree than
either boron or arsenic.


Eggplant (Kilgore's Bright Red Manatee Special). Due to
the poor condition of the plants when taken from the seedbed,
too much weight cannot be attached to the responses observed
under different treatments. By May 5, definite positive re-
sponse was noted on the copper-treated area. At this time the
height of the plants varied from four to nine inches, whereas
those on the check plots were but two and one-half to four and
one-half inches high. Cut-worms did considerable damage to
the stand except in the case of the copper-treated plots. The
plants on these were rather large for the worms to cut. At
the same time they were observed to attack the foliage to a con-
siderable extent. Though no fruit was produced on the plants
of any of these treatments, other plants from the same seed-
bed, set in a garden area adjacent, produced an abundance of
well formed fruit of good color and quality, following an appli-
cation of copper sulfate.
Tomatoes (Marglobe). The tomato has given an outstanding
response to copper sulfate. Positive response to copper and
manure appeared as early as March 30, as did also negative re-
sponse to boron and caustic lime. Indications of injury also
were apparent under treatments with arsenic, zinc, and sulfur
as early as April 6, when mercury, nickel and manganese were

Bulletin 190, Stimulation of Plant Response etc.

beginning to show signs of favorable effects. Fig. 22 shows the
development of the plants on an untreated area in comparison
with those on a plot treated with bluestone. A close inspection
of the illustration will show the heavy development of fruit on

Fig. 22.-Response of tomatoes to treatment with copper sulfate on the
raw saw-grass soil of the Everglades. 1. Copper sulfate. 2. Check
(no treatment). Plants set March 15, 1927. Photographed May 5,

the larger plant. At the time the photograph was taken rec-
ords of the fruit on the plots giving favorable responses also
were taken and the results are indicated below.

SAverage Height of Plants Number of Fruits
Soil Treatment (inches) Set (Average
per plot)
Copper ............................. 22 to 30 (Av. 2 plots) 65
Manure ......................... 17 to 30 (Av. 2 plots) 17
Manganese ................. ........ 15 to 26 (Av. 2 plots) 4
Nickel .................................... 15 to 21 (Av. 2 plots) 3
Check ....................................... 9 to 16 (Av. 8 plots) 0.75

Florida Agricultural Experiment Station

The plants continued to develop and the fruits became so
heavy on the copper treatments that the plants were pulled to
the ground. The fruits in the case of this treatment were of
good average size, exceptionally smooth, and of good quality.
With further maturity they colored perfectly. The manurial
treatment gave results almost equal to the copper but the qual-
ity of the fruit was not nearly so good.
Asparagus and Chufas. The asparagus (Washington) seed
germinated rather slowly, although well, and the seedlings grew
off slowly. As late as early May the plants were still very small,
with no response apparent except in the case of copper and this
was very slight. The plants on all the plots finally died after
making only small growth. The chufa seed germinated well but
growth practically ceased after a short while and no consistent
differences have been noted between the treatments.
Bean (Refugee). The development of this single bean varie-
ty has been of particular interest from the standpoint of the
delayed nature of its response to copper as well as to the other
treatments to which this plant has reacted in one way or
another. Thus, while response to antimony, sulfur, and zinc
was apparent as early as April 6, that to copper, manure, tin,
nickel, and manganese was not noticeable until April 15, and
even then, that to copper was comparatively slight. By early
May the copper response was more pronounced and the early
advantages shown by the nickel, tin, and zinc treatments were
fading rapidly. Effects from manure, manganese, and sulfur
held on considerably longer and the plants reached the blossom-
ing stage in every instance. Following this period, however,
the antimony, manganese, and sulfur responses broke down
rather completely and few, if any, of the plants produced pods.
The plants on the copper- and manure-treated plots, however,
remained in good shape with good color of foliage and good de-
velopment of bush. Marketable beans were produced under both
of these treatments. However, the beans on the copper-treated
plots were better than those on the manure plots. The possible
importance of these diverse responses will be referred to again
under the discussion of miscellaneous legumes. Of all the treat-
ments, boron and arsenic alone appeared to be distinctly toxic.
Garden Peas (Little Marvel). The response of garden peas
to the treatments was generally similar to that of the beans,
just discussed. Responses to antimony and sulfur were appar-

Florida Agricultural Experiment Station

The contrast in development between treated and untreated
areas is well shown in Figs. 23 and 24. The corn and sorghum
shown in Fig. 23 represent the development as it appeared on
July 9. In Fig. 24 the response of the same plants is shown
to treatments with caustic lime. In contrast with the growth
upon treated plots, whether with copper sulfate or caustic lime,
the check plot upon this date was entirely barren of any corn
plants. In Fig. 24 the order of the plants is reversed in compari-

Fig. 23.-Response of sugar cane, corn, and sorghum (3 varieties) to cop-
per sulfate on the raw saw-grass soil of the Everglades. At the time
of this photograph, all plants on the adjacent check plot, upon which
the camera was standing, were dead. Left to right, sugar cane (U. S.
663), corn (Cuban Flint), sorghum (Sugar Drip, Early Amber, Shal-
lu or chicken corn), and velvet beans. Seeded sorghum March 25,
others March 15, 1927. Photographed July 9, 1927.

son with that in Fig. 23. While the development of the plants
shown upon the plot treated with caustic lime does not equal
that on the copper-treated plot, it is a decided contrast in com-
parison with the barrenness of the check area or any of the
other treatments immediately beyond.
In Fig. 24 the lines drawn in the soil in the foreground indi-
cate the position of the alleyway between the check plot and the
one receiving treatment with caustic lime.
Sorghum (Sugar Drip, Early Amber, and Shallu). Sorghum
has been recognized for some time as being decidedly sensitive

Bulletin 190, Stimulation of Plant Response etc.

ent by April 6, as in the case of the bean, but the effect of the
zinc did not appear until later when responses to manure as well
as tin, and to a slighter degree, mercury, were apparent. No
response to nickel was observed, as in the case of beans. Most
of these responses appeared as variations in the character and
vigor of the foliage, except for copper, where there was a dis-
tinct effect noted in the filling of the pods. No great variations
were observed in the development of the vines. The response
of outstanding interest in this planting was found in the copper
treatment, where the tendency toward superior filling of the
pods was so striking. Blossoms and pods were produced on all
plots, including the checks, but the pods remained entirely flat
except in the case of the copper treatment. Boron toxicity ap-
peared very early and persisted, while the arsenic injury ap-
peared to be more or less temporary.
Sunflower. The sunflower seed germinated, but, outside of
the copper-treated plots no treatment appeared able to carry
the plants through to maturity. Fig. 32 shows the response to

Corn (Cuban Flint). The response of corn to the series of
treatments has been of great interest. Boron and arsenic both
produced injury rather early. By April 15, zinc, manure, and
manganese, as well as tin and antimony, appeared to be giving
beneficial results. At this time the copper still showed no par-
ticular effect. By May 11, however, copper was showing a de-
cided response, though it still stood about third in the group,
being preceded by manure and manganese, and followed by
caustic lime, chromium, and zinc. At the time of maturity
(July 18, 1927), development on the copper plot was found to
be far in advance of any other treatment and was followed by
manure, caustic lime, chromium, and manganese. Plants on the
copper plots produced good sized stalks and well filled ears of
normal size. The manurial treatment also produced good sized
stalks with both large and small ears. The plants on both the
chromium and caustic lime plots produced a few small ears,
while upon those treated with manganese no grain at all was
produced, though some of the plants reached the tasseling stage.
All plants disappeared from the check plots as well as from most
of the other plots where no positive response had been shown.

Bulletin 190, Stimulation of Plant Response etc.

to saw-grass peat and consequently its response through such
a series of treatments is of particular interest. In the first
seeding the stand was very poor, but it was reseeded on March
25. Boron and arsenic injury appeared very early. Slight re-
sponse to copper, manganese, manure, zinc, and antimony was
apparent as early as April 15. By May 15, caustic lime was
showing decided benefit, as was also nickel, though to a much
lesser extent. By the middle of July, however, the only re-


Fig. 24.-Response of sugar cane (planted March 15, 1927) and 3 varieties
of sorghum (planted March 25, 1927) to application of lime on the
raw saw-grass soil of the Everglades. At the time of this photograph,
all plants upon the adjacent check plot upon which the camera was
standing were dead. Same crops as in Fig. 23. Photographed July
26, 1927.

sponses that continued outstanding were those to copper, caus-
tic lime, and manure. The former, as indicated in Figs. 23, 24,
and 25 was much superior at this date while the latter two were
fairly comparable in their development. Seed development on
the plants in these plots appeared to be perfectly normal in every
respect. Fig. 24 shows the development of sorghum on the du-
plicate copper treatment. The growth of velvet beans and soy-

Florida Agricultural Experiment Station

beans on copper treatments is also shown in this photo. It is
to be noted that the velvet beans have taken over a good por-
tion of the first row of sorghum, having climbed entirely to the
top of these tall plants.
Sugar Cane (U. S. 663 and Crystalina). Two varieties of
sugar cane were used in these tests. U. S. 663 was provided
through the courtesy of the Federal Experiment Station for
Cane Breeding at Canal Point, and the Crystalina provided by

Fig. 25.-Response of sorghum, velvet beans, and soybeans to applica-
tions of copper sulfate on the raw saw-grass soils of the Everglades.
Left to right, soybeans (O-too-tan), velvet beans, and sorghum. Soy-
beans and velvet beans planted March 15, sorghum March 25, 1927.
Photographed July 26, 1927.

Mr. F. L. Williamson from Clewiston. Sufficient material of the
former variety was available to plant across but one set of the
treatments. This was planted March 15. The Crystalina was
obtained and planted April 12, and was used in completing the
row occupied in part by U. S. 663 as well as a full additional
row, thus giving results upon this variety across a triplicate
set of the various treatments.
While boron proved injurious to both varieties, little or no
injury was observed in the case of any of the other treatments.

Florida Agricultural Experiment Station

During the previous year, however, very outstanding re-
sponse was secured in the case of both Italian rye and red top,
on areas treated with copper sulfate.

Soybeans (O-too-tan, Laredo, Goshem Prolific, Virginia, and
Biloxi). None of the treatments gave as striking results with
soybeans as with the majority of the other plants. This is due
to the fact that the development of soybeans upon the untreated
areas does not appear to have been as seriously depressed as
in the case of a number of other plants.
Boron and arsenic injury appeared very early and continued
serious throughout the period of growth with all varieties.
Positive response to antimony and sulfur appeared as early
as April 17, while that to zinc, tin, chromium, manganese, and
nickel was apparent by April 15. Copper, manure or caustic
lime did not show definite response until later. By May 25, the
average positive response for all varieties was in the following
order: copper, manure, caustic lime, and manganese. Some of
the earlier responses had begun to fade by this time, particularly
in the case of certain varieties. By the latter date blooming was
well under way in the Biloxi variety and many pods had already
appeared on the Virginia variety. The pods on this variety were
much more complete under the copper treatment than under
any other treatment.
By the latter part of July the copper-treated plots had pro-
duced a large amount of vegetative growth which remained vig-
orous in all cases except Virginia and Laredo varieties. The
Virginia was harvested early, while the Laredo had its foliage
more seriously attacked by insects than the other varieties.
Fig. 27 shows the comparative development of Biloxi upon the
untreated and copper-treated plots. This variety did not do
as well upon the untreated soil as did some of the others, par-
ticularly O-too-tan and Goshem Prolific. Even among these,
however, there was considerable variation on the various check
plots. While the Goshem Prolific variety was generally com-
parable to O-too-tan in size, its foliage was rather inferior in
color. The development of the O-too-tan variety continued
strongly vegetative and by July 25, the growth on the copper
plot was about three feet tall and had spread to the middle of
the three-foot rows. The character of the growth of this var-

Bulletin 190, Stimulation of Plant Response etc.

The most marked response in the case of either variety was to
copper sulfate. U. S. 663 has shown some response to chromium
and manure and, to a lesser degree, to zinc, caustic lime, and
barium. These latter, however, were decidedly weak in com-
parison with the copper.
Crystalina also has responded well to copper but, up to the
present time, to no other treatment. Fig. 26 shows this re-
sponse. These stools were growing upon Plots 5 and 6 of Tier
1, No. 5 being the copper-
treated plot and No. 6 the
adjacent check plot. The
tops of the plants on the
check plots were more or
less tangled. This seems
to be particularly character-
istic of this variety under
these adverse conditions,

Fig. 26.-Response of sugar cane (var. Crystalina) to treatment with
copper sulfate on the raw saw-grass soil of the Everglades. Left,
copper sulfate. Right, check (untreated). Planted April 12, 1927.
Photographed July 26, 1927.

and is characterized by failure of the forming leaf whorl to un-
roll in a normal way. In the case of the Crystalina variety, the
growth on the check plots has been somewhat better than that
of U. S. 663. This is doubtless due, in part, to the larger size
of the seed-canes used in planting.
Grasses (Timothy and Red Top). Of the grasses, timothy
and red top alone were seeded in this series. While there was
some germination, the plantings disappeared very early and al-
most simultaneously on all treatments. Failure was doubtless
due, in large part, to the dryness of the seedbed combined with
the hot sunshine.

Bulletin 190, Stimulation of Plant Response etc.

iety is indicated in the left of Fig. 25. While there had been
a rather continuous set of blossoms in this variety the set of
pods has been almost entirely lacking on the copper-treated plot,
as well as on the manure and caustic lime plots, the response of
which was less than that of copper. The development of O-too-
tan on the man-
ganese treated
plot at this date
was only slight-
ly superior to
that on the clos-
est check plot.
The Laredo
variety developed
pods under all
treatments, i n-
cluding the
checks, though
the pods remain-
ed flat for the
most part, even
on t h e copper-
treated plots
which were the
best. The order
of response to
the various
treatments was
copper followed
by manure and
caustic lime.
T h e Virginia
variety matured
early and was
harvested on
June 15. The
set of pods on
this variety was Fig. 27.-Response of Biloxi soybean to treatment
of row saw-grass soils of the Everglades with
best of all. The copper sulfate. Vines on left nearly four feet
copper showed a tall. Left, copper sulfate. Right, check (un-
treated). Planted March 15, 1927. Photo-
distinct response graphed July 27, 1927.

Florida Agricultural Experiment Station

in the development of mature seeds. The order of response to
tops was identical with that of the other varieties, though the
extent of the development was less, due to its earlier maturity.
The general development of the Biloxi variety resembled that
of the O-too-tan and the Goshem Prolific, as it produced vegeta-
tive growth with limited blossoms and fruit. The plants of this
variety grew to a height of nearly four feet and the stems be-
came very heavy and woody on the copper-treated plot. How-
ever, growth on the untreated areas was less than that of 0-too-
tan and the Goshem Prolific varieties.
Cowpeas (Groit, Iron, Brabham, Columbia, and Victor). Con-
trasted with soybeans, cowpeas were particularly sensitive to the
deleterious soil conditions of the raw saw-grass peat. Conse-
quently the pronounced benefits derived from certain of these
treatments have been more striking.

Fig. 28.-Response of a series of cowpea varieties to treatments with cop-
per sulfate on the raw saw-grass soil of the Everglades. Left to right,
Victor, Columbia, Brabham, Iron, Groit, and, extreme right, Biloxi

By April 17, antimony, manganese, sulfur, and chromium
were showing pronounced benefit to all varieties. To this list
zinc, tin, nickel, and caustic lime were added by the middle of
the month. As in case of soybeans, no response to copper was
noted up to this time. However, by May 25, the response to
copper was considerably ahead of any of the other treatments,
and as a rule manure was second, caustic lime third, and manga-
nese fourth. Fig. 28 shows the development of the cowpeas
under copper treatment. There were some temporary responses
to tin and barium. Some of the treatments had a distinct stimu-
lating effect in early growth but were unable to carry the plants

Bulletin 190, Stimulation of Plant Response etc.

through to maturity. In the absence of soil treatment of any kind
the best development was made by the Groit, followed by the
Iron variety. The Victor made consistently poor growth in the
check plots and the Brabham and Columbia did little better.
There were considerable variations in all varieties on the un-
treated plots.
By July 25 the order of the outstanding positive responses
was copper, manure, caustic lime, and manganese. The differ-
ence in these responses was one of extent of growth rather than
of character. Thus, by this date the growth on the copper plots
was so dense that the individual rows were scarcely definable.
The growth of the plants under the other treatments differed
only in being less extensive. While all the varieties produced
vine growth on the copper, manure, caustic lime, and manganese
treatments, none of them produced normal pods except the Col-
umbia. As in the case of the soybeans, the promising early re-
sponses from zinc, tin, antimony, and sulfur failed to carry the
plants through and, in some cases, the response broke down so
completely that the plants were in as bad condition as those
on the untreated plots.

With the exception of peanuts, the miscellaneous leguminous
seeds were furnished by the Office of Forage Crops, Bureau of
Plant Industry, Washington, D. C. In order to compare the
outstanding responses with those of other legumes already dis-
cussed, the character of the individual response to soil treat-
ments will be briefly reviewed.
Peanut (Valencia). While the peanut plant is usually asso-
ciated with a sandy soil environment, its possible adaptability to
peat soil has become a matter of considerable interest. The
response of this plant in contrast with the other legumes is
therefore of interest.
Boron and arsenic toxicity appeared early. Sulfur toxicity
appeared to a lesser extent through a temporary period. Bene-
fits from manganese appeared as early as April 7, while definite
response to zinc, antimony, nickel, and to a lesser extent, cop-
per and sulfur, had appeared by the middle of April. At this
time the effect of copper was but slight while that of the zinc
was rather pronounced, producing a slender, upright growth
rather than a typical, bushy growth. By May 15 benefits from

Florida Agricultural Experiment Station

manure and caustic lime were apparent and the response to cop-
per sulfate was decidedly more marked than on April 7. At
this time, however, the earlier responses from antimony, nickel,
and zinc had receded and these plots were showing no particular
advantage over the check plots. In the zinc-treated plots the
plants were considerably taller and of a decidedly different form
from those in the check plots. They also showed distinct in-
jury in the form of increased yellowing of the leaves, burning
of the margins and dying back of the growing points. Later
they showed a worse condition than those on the check plots.

-1 2

Fig. 29.-Response of peanuts to application of copper sulfate on raw
saw-grass soil of the Everglades. Left, treated, right, check. Plant-
ed March 15, 1927. Photographed July 27, 1927.

Fig. 29 shows the development of the plants grown on the
check plot compared with those grown on the copper sulfate
plots. The total dry weight of the two plants from the check
plot was 9 grams and that from the copper treatment, 185
grams, the latter including 38 grams of nuts.

Bulletin 190, Stimulation of Plant Response etc.

Number 1 in Fig. 29 is quite typical. The plants in the
check plots usually develop first into a low, flat rosette form of
the leaves which soon become chlorotic and blotched brown to
brownish yellow. Later this is succeeded by a few rather
spindling shoots from the growing center of the rosette, which
gradually develop into some such form as that shown in the pic-
ture. Nuts have never been observed to set upon plants of this
The earlier growth of the plants on the copper-treated plots
was quite the same as those on the check plots. The well de-
veloped plants shown in Fig. 29 grew from stunted plants sim-
ilar to those on the check plots, after they had remained in the
stunted condition almost a month before responding to the cop-
per stimulus.
While the plants receiving copper were considerably superior
to those receiving any of the other treatments, those receiving
manure, lime, and manganese gave responses that placed them
more or less in the same category. The development of the
plants upon the manure and caustic lime plots was very similar,
both in the character of the vegetative growth and the set of
nuts. However, the plants on the manganese sulfate plots were
decidedly inferior to those on the manure and lime plots, as no
fruit was produced.
Melilotus (M. indica and Hubam clover). The growth of
Hubam was much more satisfactory than that of the Melilotus
indica. The stand of the latter was not good and practically all
of the plants disappeared rather early except those on the plots
receiving copper and manure.
The best response of Hubam was on the copper-treated plots,
followed by that on the plots which received, respectively, caustic
lime, manure, and manganese. The plants on the copper plot pro-
duced good growth of tops and well-matured seed, normal in
all respects. The plants on the lime- and manure-treated plots
were decidedly inferior to those on the copper treatments. The
response to the manganese treatment was inferior to that on
the caustic lime or manure treatments, though a stand was
maintained for a considerable time and a few seeds were pro-
Jack Bean and Velvet Bean. The germination of both the
jack bean and the velvet bean seeds was very poor, though a

Florida Agricultural Experiment Station

sufficient stand of plants was obtained to gain a fair indication
of their response.
Boron and arsenic injury to the jack bean was early apparent.
The sulfur apparently produced some temporary injury. By the
middle of April, zinc, tin, sulfur, and antimony were showing
positive responses, though the color of the plants on the zinc
plots was rather poor. A little later, responses to copper, manure,
manganese, and caustic lime appeared but by this time the
positive responses from the other chemicals had, for the most


*^ ^-^y i:

Fig. 30.-Response of velvet beans (var. Tracy) to application of copper
sulfate on the raw saw-grass soil of the Everglades. Left, treated,
right, check. Planted March 15, 1927. Photographed July 27, 1927.

part, receded. Final observations showed that the plants on
the copper-treated plots were larger and greener and decidedly
superior to those of any of the other treatments, with numer-
ous blossoms and a few large pods. The plants on the caustic
lime and manure plots were inferior to those on the copper:treat-

Bulletin 190, Stimulation of Plant Response etc.

ment but decidedly superior to those on the manganese treat-
ments. Blosoms were produced but no pods were set. The
plants on the check plots were decidedly scrubby and were in-
ferior, even, to those on the manganese plots. The Arlington
velvet bean was decidedly better than the Tracy, particularly
from the standpoint of vine growth, although both varieties pro-
duced pods satisfactorily under certain treatments. The boron
and arsenic treatments were the only ones that actually pre-
vented the development of the plants. On the check plots the
plants were small and more or less bunchy, with little vining,
but were of good color. Fig. 30 shows the Tracy variety on
the copper-treated and untreated plots.
Besides response to copper, both varieties produced an approxi-
mately equal vine growth on the manure- and caustic-lime-
treated plots but the pods were decidedly inferior to those on
the copper treatments. The response to manganese was less
than that to caustic lime or manure.
While zinc, tin, sulfur, and antimony seemed to give early re-
sponses as was the case with most legumes, the benefit seemed
to disappear later. No injury from any of these treatments
was noted.
Horse Bean (Vicia faba). The horse bean showed decided in-
jury from boron and arsenic treatments very early, the plants
being inferior to those of the check plots. Positive response
was obtained, however, to both copper and manurial treatments
and the plants on these areas appeared quite healthy for a time.
Those on the copper-treated plots grew to a height of more than
12 inches and at one time appeared quite normal, while those
on the check plots were withered and practically dead after
having grown to a height of four or five inches. Before blos-
soming, however, the leaves of those plants in the copper-treated
plots showed blackened margins. Following the appearance of
this injury they continued to wither and finally all of them died,
but after those in the manure-treated plots had died.
Mung Bean. Besides boron and arsenic, sulfur and caustic
lime gave the appearance of temporary injury during the early
period of growth. By the middle of April, sulfur as well as tin,
antimony and zinc were showing slight response, but by May
20 tin only, of this group, showed any response. Copper and
manure appeared decidedly favorable at this time. July 25, liv-
ing plants were to be found only in the plots treated with copper

Florida Agricultural Experiment Station

and manure. Those on the copper-treated area were strong
and well branched and much better than those on the manure
treatment. However, the color of the foliage was rather light.
An abundance of blossoms was produced but only a few pods
were set. There was a general tendency toward vegetative
growth, particularly at the beginning of the rainy season. This
was true also with cowpeas, soybeans and a number of the other
Aside from the poorer stand and more limited setting of pods,
the response to the manure treatment was not much inferior
to that of the copper treatment.
Crotalarias (juncea and retusa). The response of the two
Crotalarias tested, juncea and retusa, was most diverse. In-
jury from boron and arsenic appeared early and proved to be
permanent while that from sulfur was more or less temporary.
The development of the retusa variety on the copper-treated
plot was low, bushy and somewhat abnormal but with foliage
of good color. A considerable number of blossoms was produced
at different times and these were frequently followed by devel-
opment of mature seed. The general type of plant response to
manure was similar to that of copper, but to a less degree.
Blossoming was followed by a less number of pods and fewer
seeds. Caustic lime was third in response, the plants blossoming
less freely than those on the plots treated with copper or man-
ure. The plants on all other plots died by the latter part of
Juncea responded temporarily to both zinc and sulfur, and,
slightly, to antimony. The responses to copper, manure, caustic
lime, and manganese were somewhat delayed but they were per-
By the latter part of July, a tremendous growth had devel-
oped upon the copper-treated plots, where the plants were 6
to 8 feet tall. The plants blossomed early and at various times
but failed to set pods. Manure and caustic lime produced about
equal plant responses, but they were decidedly poor compared
to copper. The plants blossomed early but set no pods. The
plants on the manganese-treated plots were inferior to those on
the manure and caustic lime plots but better than those on the
check plots, which were practically all dead.
Clitoria (ternata). Clitoria, like most of the other legumes,
showed very early injury to both boron and arsenic treatments.

Bulletin 190, Stimulation of Plant Response etc.

Favorable' stimulation from sulfur, antimony, and caustic lime
appeared by April 15, but had almost disappeared by May 15.
Copper, caustic lime, and manganese showed more favorable
response by May 15, at which time the plants were blooming.
By July 25 the plants on the copper treatments were decided-
ly superior to those on any other treatment. They had a dense

Fig. 31.-Response of guar to treatments with copper sulfate and caustic
lime on raw saw-grass soil of the Everglades. Left to right, copper
sulfate, caustic lime, check.

Florida Agricultural Experiment Station

mass of fine vine, 24 to 30 inches long, with numerous blossoms
and good seed pods which developed to maturity. The charac-
ter and quality of the plants upon the manure and caustic lime
plots, were more or less similar to those on the copper-treated
plots but the pods did not fill. The manganese treatment pro-
duced a rather light positive response over the check plot. This
plant showed a rather striking tendency to develop under all
treatments. While the plants were small and, in many treat-
ments, dwarfed, the roots and tops were usually in good condi-
tion even five months after planting.
Guar. Guar showed injury from boron and arsenic treat-
ments as early as March 28, and slight injury from sulfur by
March 30. By April 15 there was an apparent response to zinc
and to a lesser extent to sulfur and antimony. By May 15
these responses had disappeared, but copper, caustic lime, man-
ganese and manure had produced rather positive response, be-
ing the only materials that produced responses as late as July,
when few plants remained in the check plots. Fig. 31 shows
the comparative development of Guar following applications of
copper sulfate and caustic lime. The check plants were small
and scrubby but the roots were firm and sound, as were those
of Clitoria.
The growth on the copper-treated plots was from 30 to 36
inches tall, blossomed abundantly and set pods freely, the lat-
ter appearing to fill well. Caustic lime treatment produced
plants up to 30 inches in height, but the foliage was more or
less mottled and no blossoms appeared. The manganese and
manure plots developed plants to a height of 10 to 12 inches
but produced no blossoms.
Tangier Pea. Early and permanent injury to the pea was
shown by both boron and arsenic. By May 15, positive responses
were apparent from zinc, sulfur, antimony, manganese and, to
a lesser degree, copper, mercury, nickel, and chromium. Later
development favored copper to a considerable extent as well as
manure and caustic lime, but further records are not available
for this plant.
Sesbania (macrocarpa) also showed early injury from boron
and arsenic. By April 15 it was responding to zinc, tin, sulfur,
antimony, caustic lime, manganese and, to a lesser degree,
nickel, chromium, and mercury. By May 20, the effects of cop-
per and manure also were apparent, while only caustic lime,

Bulletin 190, Stimulation of Plant Response etc.

manganese, mercury, and sulfur of the former group continued
effective to this date. By July 25 copper, manure, caustic lime,
and manganese alone were showing a pronounced degree of
stimulation. The plants on the check plots varied considerably
in size. Numerous blossoms were formed and normal pods were
On the copper-treated plots the plants had reached compara-
tively large proportions by the latter part of July, but were ap-
parently normal in every respect. The tops were very bushy,
with stiff limbs and a light development of foliage. The stalks
had reached a height of 9 to 10 feet. This development is in-
dicated by Fig. 32, which is from a photo made at an earlier
date. The development on the manure plots was slightly infe-
rior to that on copper plots. Blossoming and seed production
were continuous for some time. The growth on the caustic
lime plots was very similar to that on the manure plots.
Beggarweed. Beggarweed was another plant that showed an
ability to produce more or less normal growth in the presence of
the majority of chemicals used. However, in the boron and
arsenic plots injury appeared early and proved to be more or
less permanent, that due to boron being much more serious. As
with a number of legumes, sulfur showed definite indications of
injury March 30 but later showed a temporary positive response.
By April 15, benefits from zinc, sulfur, antimony, caustic lime,
and, to a lesser extent, from tin, manganese, and mercury, were
apparent. By May 25, responses to copper and manure had ap-
peared. Benefits from manganese, caustic lime, sulfur, and, to
a slight extent, barium, were noticeable.
By late July the treatments showing beneficial effects had
narrowed to copper, manure, caustic lime, manganese, barium,
and sulfur, the extent of the response being in the order named.
The plants on the zinc treatments were showing decided indica-
tions of injury.
The plants on the copper treatment had grown to an aver-
age height of about seven feet and were still laden with blos-
soms and seeds in various stages of maturity. The plants on
the manure and caustic lime plots, were almost identical in de-
velopment, averaging 5 to 6 feet tall. The character of this
growth is well indicated in Fig. 32. Manganese, as the fourth
of the major responses, produced a heavy vegetative growth,
the plants reaching a height of 3 to 5 feet.

Florida Agricultural Experiment Station

While there was a fair development of plants on a number
of the check plots, no blossoms were observed in any case. By
July 25 plants on both the barium and nickel plots had produced
flowers and seed in small numbers. Barium gave indications of
slight positive response from the standpoint of general develop-
ment. Plants on the nickel plots showed no other indication of
Almost invariably the roots of beggarweed plants have been
found apparently healthy and sound under all conditions of the
experiments but no nodules were found.

Fig. 32.-General view of plant responses to copper treatment. Left to
right, sunflower, lespedeza (low plant), beggarweed, Sesbania (tall
plant by 6 foot stake), and Sesbania on the check plot. Planted March
15, 1927. Photographed June 3, 1927.

Japanese Clover (Lespedeza). Boron produced characteristic
injury to Japanese clover at an early date. Zinc, tin, sulfur,
antimony, and, to a lesser extent, manganese, produced some
positive response by April 15. By May 25, these responses,
with the exception of manganese and possibly tin, had largely
disappeared. But copper, caustic lime, and manure were show-
ing a decided response, and by the latter part of July the stimu-
lation was even more outstanding. The response to caustic lime
was superior to that to manganese, and that to tin had disap-
peared at this date. The plants were a complete failure on the
check plots as well as on all other treatments not here men-
tioned. Fig. 32 shows the character of the development of
this plant, about 10 inches high, on the copper-treated plot.
The best treatments, in order of response produced were cop-
per, manure, caustic lime and manganese.

Bulletin 190, Stimulation of Plant Response etc.


The residual effects of the treatments which showed positive
responses may prove to be of importance. Sufficient time has
not yet elapsed to permit of securing much experimental evi-
dence on this point.
However, following the removal of most of the garden crops
from Tier 1, this area was reseeded to a number of crops with-

Fig. 33.-Response of corn and sorghum on the raw saw-grass peat of
the Everglades to copper residual from earlier treatments with copper
sulfate. Left: Early Amber sorghum; 2, copper sulfate residual. 1.
check. Right: Cuban Flint corn; 2. copper sulfate residual, 1, check.
Planted June 10, 1927. Photographed July 27, 1927.

out making further treatments. The residual effect of some of
these treatments has apparently enabled the plants to grow in
good shape. This has been true particularly in the case of the
copper-treatment (see Fig. 33). This photograph was made a
little over six weeks after planting. The response of these
plants, following the second seeding, was apparently more

Florida Agricultural Experiment Station

prompt than that directly following the original treatment. The
plants on the check plots were total failures, as will be seen by
referring to Fig. 33.
The residual effect of copper sulfate on raw peat has been ob-
served elsewhere to carry over for more than a single cropping
season. During the earlier work at the Experiment Station
(1925) the residual effects of copper on red top grass were pro-
nounced the following year. A number of farmers in the
Glades also have reported residual effects from the use of cop-
per the past year.


The response of most agricultural plants to soils consisting
largely of raw, fibrous peat almost invariably has been observed
to be notably poor, particularly during the earlier periods of
weathering following drainage. The fact that the raw saw-
grass soil of the Everglades is no exception to this general ten-
dency is now a matter of common knowledge.
An extensive series of plots was laid out upon the raw saw-
grass peat at the Everglades Experiment Station and treated
with a number of special chemicals. The response to these ap-
plications of about 60 different agricultural plants has been
tested and the results are discussed in the present paper.
The unusually favorable responses of the great majority of
the plants tested to a number of these treatments have proven
most encouraging and it is thought that these results, consid-
ered in detail, tend decidedly to support the view that the nor-
mal physiological processes of these plants are closely depend-
ent upon the presence of certain of these rarer elements. These
responses have been most outstanding with treatments of cop-
per, caustic lime, manure, and manganese.
In the case of benefits derived from application of manure, it
is possible that they were due to small amounts of these special
elements contained in the manure in available form. The bene-
fits derived from caustic lime may be due to the rigorous reac-
tion involved in its slaking in place, thereby releasing some of
these elements already present in the soil in unavailable form.
In this connection, it is possible that the normal growth of
a number of plants such as the pigweed ("careless weed"), fen-
nel, etc., and even potatoes, in the comparatively raw peat might

Bulletin 190, Stimulation of Plant Response etc.

find partial explanation in their having (1) a greater "feeding
power" for such of these rarer elements as are present in the
native material or, (2) a definitely lower requirement of such
plants for these special elements.
Plant responses to a considerable number of other elements,
notably zinc, antimony, nickel, tin, sulfur, and barium, appeared
at some time during growth but these responses appeared less
significant than those obtained with copper, caustic lime, and
manure. They were commonly more transient in their occur-
rence and did not enable the plant to make a normal growth
through any definite period. When these responses began to fail
the plants had the appearance of positive injury. Chromium
and mercury also gave positive responses of this nature with
some plants. Practically all plants gave a decidedly negative re-
sponse to both the boron and arsenic treatments in the quan-
tities applied.
In regard to the order of plant response to the different ma-
terials, the response of most garden plants to copper sulfate ap-
peared very early and the plants seemed to derive continuous
benefit from the beginning of their development. In the case
of most leguminous plants, however, response to this material,
as well as to others that showed sustained stimulation, was com-
monly found to be delayed for several weeks. During this time
the plants frequently appeared almost identical in development
with those on the untreated plots.
On the other hand, the responses of these leguminous plants
to zinc, nickel, etc., commonly appeared much earlier than to
copper but, as previously noted, they were not able to carry the
plants through to maturity. The successive nature of these
suggests the possibility of obtaining still further increments of
benefit to plant growth through the application of combinations
of such special elements. If the stimulation in one case occurs
early, though it may not be able to carry the plant through,
while another, seemingly of quite a different type, appears late
and is able to carry the plant on in good shape, the combination
of the two might logically be expected to give a more continu-
ous response. Studies in this connection are already in progress
and have given results which appear to indicate the correctness
of this presumption. However, further work will need to be
done along these lines before definite statements can be made.

Florida Agricultural Experiment Station

The present studies have been preceded by numerous investi-
gations and observations upon plant responses of similar nature
in other environments and under other conditions. From the
comparatively small quantity of the special chemicals found
sufficient to produce stimulation it is believed that many of the
notable results observed to follow the use of copper as a fungi-
cide, whether upon foliage or seed, may be attributable in good
part to the utilization of this element directly by the plant,
rather than indirectly.
These results are in keeping with the earlier assumption that
plant response to materials of this nature are indicative of
definite deficiencies of these elements in an available form in
this soil. Thus it would appear that, as the result of further
study, we may come to regard the need for the application of
certain of these special elements to the soil under certain con-
ditions in quite the same light as that of those materials (nitro-
gen, phosphoric acid, and potash) which we now recognize as
of the common fertilizer type.
While it has been found that many plants respond remark-
ably well, on the raw peat soils of the Everglades, after treat-
ment with certain' chemicals, it must be emphasized that, re-
gardless of the striking nature of these results which have
been brought about, this discussion, and the data here present-
ed, does not imply their specific recommendation. However,
it seems not unreasonable to believe that normal crops may, in
many instances, be produced on raw peat soils in the Everglades
with an application of 30 to 50 pounds of copper sulfate per
acre. As a result of the work at the Experiment Station, grow-
ers, in a number of separated parts of the Everglades, are
already securing similar and highly satisfactory crop responses
following the application of copper sulfate.
It should be emphasized again that these results represent
only a short period of investigation and the Experiment Station
is unable to say, at the present time, just what effect a continu-
ous application of copper would have on the yield and quality
of the crops. These results do furnish a tremendously import-
ant basis for the organization of further investigation and it is
readily apparent that it is largely in recognition of the use that
is being made of them in this way that they have been pre-
sented and briefly discussed in this general preliminary report.

Bulletin 190, Stimulation of Plant Response etc.

In considering this response of a considerable number of agri-
cultural plants to applications of copper sulfate (bluestone) and
certain other materials to raw saw-grass peat from the stand-
point of their immediate usefulness, a point that should be
emphasized in particular at the present time is that of balanced
agriculture. In other words, there is a serious need for caution
in the use of material of this type for, unless supported by
a definite knowledge of the availability in the soil of the other
more common elements necessary for plant growth, continuous
use of such materials in this way may lead to definite exhaus-
tion of one or more of those other ingredients through the heavy
cropping that follows. There may thus develop failure in crop
response quite as serious as the original condition encountered,
which the application of these special materials was adopted to
remedy. Furthermore, in the face of a breaking down of the
response to such materials as bluestone when used in this way,
the natural tendency might be to increase the application. Such
a resort not only could not give results under the circumstances
but might also prove undesirable from the standpoint of the
composition of the soil with regard to this element if such appli-
cations were excessive. The real need, therefore, is for a thor-
ough study of such responses under controlled conditions, where-
in the possible appearance of such other deficiencies will be well
guarded against and thus proper evaluation be made of the use-
fulness of these special chemicals in this way through a period
of time.
The preliminary nature of this report has made it appear un-
necessary to include a review of certain phases of the literature
that will be found to have a direct bearing on the general prob-
lem. It is hoped, however, that this may be possible in a fu-
ture paper.


Aside from the natural "rawness" of newly broken peat soils,
there is a further very important difficulty that interferes with
their ready usefulness in an agricultural way. That is, they
are commonly known to be "cold". This is true, no matter
where they are found, when comparison is made with areas of
mineral soils immediately adjacent. Thus in the North, even
in the case of comparatively restricted areas of soils of this na-

Florida Agricultural Experiment Station

ture, peat soils are recognized as decidedly more susceptible to
frosts than the mineral soils bordering them. This unusual
frost risk, characteristic of soils of this type, is thought to be due
in considerable part to the slowness of heat transfer through it
and therefore the slowness of radiation from it of the reserve
heat accumulated during the course of the day.
Even in the Everglades region there is frost risk at certain
times, and this seems to increase considerably as one recedes
from the lake toward the interior parts of the Glades. This fact
is now a matter of common knowledge and experience and
should be met by the adoption of proven crop types and rota-
tions which will reduce to a minimum the possible damage from
frost during the winter months.
One of the most important problems from the agricultural
standpoint of peat soil in general is that of shrinkage and ex-
cessive drying as a result of drainage. If the Everglades is to
develop into a durable agricultural project more importance
should be placed upon this than any other single consideration.
In order adequately to protect peat soils against fire and con-
ditions of excessive drought, absolute water control will be
necessary and this should be the aim in starting an agricultural
development of this nature. In the case of excessive drought,
even in the absence of fire, such conditions tend to accelerate
natural oxidation processes and result in a further net loss of
the material.
From this standpoint in particular the whole project is not
a problem for the engineer alone. It is rather one in which agri-
cultural research must play an important part in developing
systems of cropping and rotation that will coordinate with the
condition and movement of the water table in such a way as to
afford maximum protection against this loss. To those who
have a broad, sincere interest in the development of this area
as a state resource, the matter of subsidence and water control
con not be over-emphasized. Indeed, we have need but to refer
to the experience of the English upon the fenland of that coun-
try where, with time, strata of peat several feet thick have al-
most disappeared and drainage lines and cultivation are now
largely in the clays with which the peat was formerly underlaid.
Since the peat soils in the Everglades area are underlaid with
limestone rock or by sand over lime rock, the need for caution
in its unnecessary exposure is readily seen.

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