Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Soil studies
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Permanent Link: http://ufdc.ufl.edu/UF00026434/00001
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Title: Soil studies
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: p. 15-46 : ill. ; 23 cm.
Language: English
Creator: Blair, A. W ( Augustine Wilberforce ), b. 1866
Publisher: Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1906
Copyright Date: 1906
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Subject: Soils -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
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Bibliography: Includes bibliographical references.
Statement of Responsibility: by A.W. Blair.
General Note: Cover title.
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Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: ltuf - AEN2258
oclc - 18159528
alephbibnum - 000921790

Full Text





HISTORIC NOTE



The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida









BULLETIN NO. 87 DECEMBER, 1906

Florida

Agricultural Experiment Station



SOIL STUDIES I.
(Preliminary Report)




















Photo. by H. H.Hume. Beggarweed.

BY A. W. BLAIR

The bulletins of this Station will be sent free to any address in Florida
upon application to the Director of the Experiment Station, Gainesville,
Florida.
E. 0. PAINTER PRINTING CO.. DELAND, FLA.



















BOARD OF CONTROL.

N. P. BRYAN, Chairman .......... .. Jacksonville, Fla.
P. K. YONGE........................... Pensacola, Fla.
A. L. BROWN............... .............. Eustis, Fla.
T. B. KING .............................Arcadia, Fla.
J. C. BAISDEN..............................Live Oak, Fla.



STATION STAFF.

P. H. ROLFS, M.S....... . ................ Director.
"*C. M. CONNER, B.S........ Vice-Director and Agriculturist.
E. H. SELLARDS, M.A., Ph.D............... .. Geologist.
A. W. BLAIR, A.M.........................Chemist.
H. S. FAWCETT, B.S.......... Assistant Plant Pathologist.
E. W. BERGER, Ph.D............ Assistant Entomologist.
R. Y. WINTERS, B.S............. .. Assistant in Botany.
W. P. JERNIGAN. ............... Auditor and Bookkeeper.
M CREWS ............................Farm Foreman.
F. M STEARNS ............................. Gardener.
FRANK WELLER, B.S ........................ Librarian.

Resigned.













CONTENTS.


Page
Introduction ......... ......... ............. .......... 19
Chemical Analysis Alone not a Sure Guide ............. .... t
The Farmer Can Learn Much by Observation .............20
The Geology of Florida Soils ................................. 21
Previous Work on Florida Soils .............................. 2I
A Deficiency of Plant Food Indicated ......................... 22
Lessons from the Pineapple Fertilizer Experiment ............... 24
An U balanced Account ................................... 24
Where the Balance Goes .............. ........ ....... 25
Loss of Phosphoric Acid and Potash ....................... ..
The Absorptive Power of Soils ............ ............... 30
Chem ical A bsorption ...................................... 30
Physical Absorption ........................................ 31
Rapidity of Absorption and Solution ..................... 31
Importance of the Absorptive Power of the Soil ................32
Pineapple Soils Lacking in Absorptive Power .................. 33
Value of Slowly Available Materials for Such Soils ............. .34
Plant Food and Capillary Action ........... ............ .. .34
Some Remedies Suggested ................................... 35
With Especial Reference to Pineapple Soils .................35
Soils Producing General Farm Crops ..........................38
M ore H um us N eeded ....................... .............. 38
A D oubtful P practice ...................................... 4
The Abandonment of Soils .................................... 40
Florida Soils differ from the General Type ................... 41
The Balance Must he Kept Up ................ ............ 41
The Composition of Some Different Types of Soils .............. 42
Table I, Chemical Composition ..............................43
Table II, Physical Composition ......................... .... 44
Sum m ary ................................................. 45
A cknow ledgm ent .......................................... .46


ILLUSTRATIONS.


Beggarweed .......................................... Frontispiece
Nitrogen-Gathering Nodules on Beggarweed Roots ......Plate I















SOIL STUDIES I.a
(A Preliminary Report.)
BY A. W. BLAIR.


INTRODUCTION.

Within comparatively recent years a vast amount of work
has been done along the line of studying the chemical and
physical properties of the soils of the United States, and class-
ifying and mapping them according to certain physical proper-
ties and productive capacities. While much of this has been
of an experimental nature, and may not always have produced
visible results, still we have been accumulating during this
time, a wealth of knowledge in regard to the soil that is of
inestimable value. We have learned that within it dwell
myriads of organisms, which are constantly producing won-
derful chemical changes, and that the success of the crop
may depend upon the presence of these organisms. We have
learned much in regard to the importance of thorough and
frequent cultivation, and the bearing this has upon the mois-
ture content of the soil. We have learned that certain types
are adapted to particular crops and that an effort to grow
some other crop on this type means failure; that certain con-
ditions of texture, moisture content and fertilizer application
will produce a maximum crop, while the failure to maintain
these conditions may mean partial or total loss of crop.
CHEMICAL ANALYSIS ALONE NOT A SURE GUIDE.

It is generally admitted that the productiveness of a soil
cannot be determined by a mere chemical analysis alone.
True, the analysis will show what elements are present and in
what quantities, but it does not show what is absolutely avail-

aA part of the material in this bulletin was presented in a paper
read before the annual meeting of the State Horticultural Society
held in Jacksonville, May, 1906.










20 Bulletin No. 87.

able for the immediate use of the plant. Of two soils showing
great similarity in chemical composition, the one may be
highly productive and the other very unproductive. The
reasons for this may possibly be found in different moisture
conditions, or a difference in physical texture, or in the dif-
ference in the amount of available plant food, or in a com-
bination of all these differences. The chemical analysis may,
however, be of value in showing what the possibilities of the
soil are 'under the proper treatment.
This subject has been studied by the agricultural chemist,
the soil physicist, and the practical farmer, and all have con-
tributed to the fund of knowledge.

THE FARMER CAN LEARN MUCH BY OBSERVATION.

The practical farmer, however, if he be thoughtful and
inquisitive of nature, possesses certain advantages over the
others, in that he is brought constantly in direct contact with
the problems that he is trying to solve. He learns to judge
from the texture and general appearance of the soil, what crop
it is best fitted to produce. He can tell you perhaps, that this
soil is adapted to orange growing and that to vegetables,
though he may not be able to explain to you how he makes
this distinction. He can tell you something about the treat-
ment that should be pursued in the production of the desired
crop, but here it is that all of his wisdom and knowledge
gained through years of close observation are called into play,
for conditions are constantly changing, and the treatment
which gave good results at one time may at another time
produce failure. On this account he should be constantly on
his guard, watching, as a physician watches his patient, for
indications good or otherwise, of the methods he has employed
and the treatment he has applied.
The experienced florist can tell from the development and
appearance of the plant whether it has received the proper
treatment: so with the farmer and fruit grower; each must
watch the appearance and development of the plant or tree,
note its vitality, the diseases or insect ravages to which it is
subject, and the texture and quality of the fruit, for all of










Soil Studies I. 21

these may have a bearing on the condition of the soil or the
treatment it has received, and it is from these symptoms that
we must judge of the cause of the trouble.

THE GEOLOGY OF FLORIDA SOILS.
A recent publication of the Bureau of Soilsa of the U. S.
Department of Agriculture makes the following brief refer-
ence to the Geology of Florida:
"The land surface of the peninsula of Florida, as it stands
today, owes its position to successive upheavals and depres-
sions and to the accumulations of beds. of limestone, sand,
and clay during the period of submergence below the sea.
The primary uplift was in Eocene times, and the deposits
that make up the backbone of the central part of the State
are of Vicksburg age. These are limestones, containing the
disklike fossil remains of the Orbitoides Mantelli, which may
be found a short distance below the surface in any part of the
area. Later formations were deposited over this Vicksburg
limestone, and during the last submergence to which the
region was subjected a heavy stratum of sand was laid down
over the entire peninsula. The breaking up of the land surface
into its present condition has been brought about by the removal
of this mantle of sand by stream action and by the dissolution
of the limestone bed by the chemical and mechanical action
of subterranean waters. These agencies have resulted in an
eroded region, ranging in height from 50 to 200 feet above
sea level, in which are sharply cut valleys and a few areas of
plateau-like appearance, where the original sand cap has not
undergone much change. In the eroded areas the soils vary
as the limestone is approached, and in some places in pro-
portion as the limestone itself has weathered."

PREVIOUS WORK ON FLORIDA SOILS.

In 1897 the Florida Experiment Station issued a bulletin
giving the results of an extensive chemical study of the soils
a Advance Sheets.-Field Operations of the Bureau of Soils, 1904.
bA chemical study of Some Typical Florida Soils by A. A.
Persons. Bulletin No. 43.










22 Bulletin No. 87.

of the State, including analyses of nearly all the different
types found in the State.
In 1898 the U. S. Department of Agriculture issued a pre-
liminary report on The Soils of Floridaa. This report
describes several different types of soils, and the vegetation
characteristic of each, and compares them as to texture, chemi-
cal composition, soluble salt and moisture content.
In bulletin No. 68 of this Station will be found an exhaus-
tive study of the pineapple soils of the State.
More recently the Bureau of Soils of the United States
Department of Agriculture has made surveys of three small
areas known respectively as the Soil Survey of Gadsen
County,b Soil Survey of the Gainesville Areab and the Soil
Survey of Leon Countyb. The results of these surveys are
published in map form showing the relative amounts of the
different types of soils found in each area, together with a
brief history of settlement and agricultural development, brief
remarks on climate, physiography and geology, descriptions
of the types of soils and agricultural methods and conditions.

A DEFICIENCY OF PLANT FOOD INDICATED.

This work, and especially the chemical side of it, together
with much practical experience, has demonstrated the fact
that most of the Florida soils are very deficient in plant food,
when compared with the average type of arable soils.
Assuming that the sandy soils of Florida will weigh
4,000,000 pounds per acre to a depth of one foot, Whitneyc
has shown that there would be about 6,000 pounds of potash,
phosphoric acid and lime per acre, while the amount of these
plant foods present, on the average, in the soils of the humid
regions of the United States is 26,000 pounds per acre. He
has further shown that in no case does the amount of soluble
salts present in the soil moisture reach Ioo pounds per acre

aA Preliminary Report on the Soils of Florida by Milton Whit-
ney. Bulletin No. 13, Division of Soils.
b Field Operations of the Bureau of Soils, 1903, 1904 and 1905
respectively.
c Bulletin No. 13, Division of Soils, pp. 21 and 22.










Soil Studies I. 23

to a depth of one foot; the heavy hammock soils at Ft. Meade
containing as low as 46 pounds per acre to a depth of one
foot, of all kinds of salts dissolved in the soil moisture; and
yet this soil produces naturally a heavy growth of hardwood
trees and is considered fine soil for oranges and vegetables.
Determinations made.by the same methods indicated that
the average soils of the Northern States contain upwards of
one thousand pounds per acre to a depth of one foot of min-
eral salts dissolved in the soil moisture. Thus it is apparent,
that in the main, the soils of Florida constitute a distinct class,
unlike the average soils of the humid regions of the United
States, and as such, they must be studied.
It has, on the other hand, been very clearly demonstrated
that many of these soils will, when rightly fertilized, produce
abundant crops of certain kinds, and whether we accept the
views held by Prof. Whitney and his associates, and set forth
in recent publications from the U. S. Department of Agri-
culture, viz., that the composition and concentration of the
moisture in all soils-good, bad and indifferent-is practi-
cally the same, and that fertilizers and manures are simply
correctives for the poisonous substances which accumulate
about the roots of the growing plant or tree-the effluvia of
the plant-or whether we accept the older views held by
chemists and agriculturists generally, that fertilizers and
manures are real plant food and act upon the plant rather
than on the soil, one thing seems to be pretty firmly estab-
lished, and that is that without the use of fertilizers or
manures of some kind the greater portion of the soils of
Florida will not produce exhaustive crops on a paying basis.
Having thus established this fact, it yet remains for us to
so familiarize ourselves with the characteristics of the soil and
the requirements of the different crops, that we may apply
these fertilizers and manures in the most economical way, as
regards kind, quantity and frequency of application.










24 Bulletin No. 87.

LESSONS FROM THE PINEAPPLE FERTILIZER
EXPERIMENT.a
A very interesting point which has been brought out by
the pineapple fertilizer experiment, is the great discrepancy
between the amount of plant food applied to an acre of
pineapples, and the amount that is actually removed by the
crop that is taken from an acre including fruit slips and
suckers.
AN UNBALANCED ACCOUNT.
To illustrate, we may first take one of the plots from the
experiment, which has received annually 3750 pounds per
acre, of a fertilizer that would analyze 4 per cent available
phosphoric acid, 5 per cent nitrogen and o1 per cent potash.
This plot receives in one year one pound of actual phos-
phosphoric acid, one and one-fourth pounds of nitrogen, and
two and one-half pounds of actual potash. Multiplying these
figures by 150 (the plots being 1-150 of an acre in size)
gives to one acre, 150 pounds of actual phosphoric acid, 187Y2
pounds of nitrogen and 375 pounds of actual potash, or 712Y2
pounds of actual plant food in one year. Now if we allow
that this acre produces 500 crates of pineapples, each weighing
70 pounds net, the amount of plant food removed by the
35,000 pounds of fruit, would be, as calculated from the
average of a number of analyses, 15 pounds of actual phos-
phoric acid, 25 pounds of nitrogen and 79 pounds of actual
potash, or a total of 119 pounds of actual plant food.
This does not take into account that which is removed
with slips or suckersb, which unfortunately has not yet been
determined, but allowing that these would remove as much
as the fruit, which is, I believe, an exceedingly liberal allow-
ance, there would be removed from the acre a total of 238
pounds of plant food, against 712Y applied, a loss some-
where, amounting to 474%2 pounds-66.6 per cent.
To take a more familiar example, the grower who puts
on 3000 pounds per acre, of a fertilizer that would analyze

a Pineapple Culture III. Fertilizer Experiments by H. K. Miller
and A. W. Blair. Bulletin No. 83, Florida Agricultural Experiment
Station.
b Some growers do not remove the suckers to any great extent.










Soil Studies I. 25

4 per cent available phosphoric acid, 5 per cent ammonia and
7Y2 per cent potash, applies 120 pounds of actual plhsphoric
acid, 123 pounds of nitrogen and 225 pounds actual potash
or a total of 468 pounds of actual plant food, and if he
gathers 350 crates of pineapples to the acre, which would be
a good average yield, he removes from his soil 10.36 pounds
actual phosphoric acid, 17.32 pounds nitrogen and 55.26
pounds actual potash or a total of about 83 pounds of plant
food from the acre. If here, as before, we allow that the
slips and suckers taken off, remove an amount of plant
food equal to that removed by the fruit, the total amount in
this case would be 166 pounds against 486 applied, a loss
somewhere of 302 pounds-64.5 per cent. But this prob-
ably does not represent the entire loss, for in many instances
there is added, over and above what has been counted, some
phosphoric acid which is not reckoned as available, but which,
nevertheless, does become slowly available and no doubt some
of this, too, would be lost.
"WHERE THE BALANCE GOES.
Now what becomes of this lost plant food? If it remains
near the surface of the ground, the soil should increase in
fertility more rapidly than it does. Indications point to its
being carried down by the rains, and finally lost in the water
table below. Perhaps a small amount of the nitrogen escapes
into the air.
In an effort to explain this unprecedented loss, for certain-
ly in no other field crop is the percentage of loss so great,
I made some tests to show the rate at which water percolates
through different types of soils, and the consequent loss of
plant food; and while it is true that the conditions in the
laboratory were not the conditions that exist in the field, still
the results are relative and serve in a way, to illustrate what
takes place in the soil.
Four glass tubes of equal size were taken and one end
closed with a perforated disc and filter paper, thus retaining
the soil but allowing a solution to pass through. Into each
was placed air dried soil as follows:
No. i, 15o grams (between 5 and 6 ounces) of South











26 Bulletin No. 87.

Carolina clay soil; No. 2, 150 grams Columbia County virgin
soil; No. 3, 150 grams of typical pineapple soil, and No. 4,
150 grams of muck soil. Into each was poured ioo cubic
centimeters of water (a little less than a gill) containing in
solution one gram of sulphate of ammonia, and the following
observations made:
(i.) Time required for the solution to begin dropping
through.
(2.) Time of completion.
(3.) Per cent of the water retained by the soil.
(4.) Per cent of sulphate of ammonia retained by the soil.
(5.) Per cent of sulphate of ammonia retained after
pouring through an additional Ioo cubic centimeters of dis-
tilled water.
The results were as follows:






Type of Soil.

0. V


o7 in. 3o in.
East Coast Typical Pineapple Soil. in. 6 in. 3 34.5 5.77 a


No -part of the first cubic














Muck Soil ........................ centimeters of the solution 9o.9
passed through this soil.
South Carolina Clay Soil.......... hus 4 hours 55 759 7.8


Columbia County Virgin Soil...... 8 min. 23 min. 52 58.25 6.6


East Coast Typical Pineapple Soil. s^ min. 6F min. 30 34.5 5.77

No part of the first loo cubic
Muck Soil................. .... centimeters of the solution 90.9
passed through this soil.










Soil Studies I. 27

Here it will be observed that it required two hours and
seventeen minutes for the solution to begin dropping through
the clay soil, as against one and one-half minutes in the pine-
apple soil; also that the time of completion with the clay soil
was four and one-half hours as aganist six and one-half min-
utes for the pineapple soil.
Surely there could be no plainer demonstration of the
open character of the pineapple soil as compared with the
ordinary type of clay soil.
The superior power of the clay soil to hold water and plant
food, is also shown by its retaining 55 per cent of the water
and 75.9 per cent of the sulphate of ammonia, as against 30
per cent of the water and 34.5 per cent of the sulphate of
ammonia for the pineapple soil.
While the Columbia county soil is not so open as the
pineapple soil, still as compared with the clay soil it is very
open as will be seen by the fact that the water passed through
this in about 1-12 the time required for it to pass through
the clay soil.
The wonderful power of physical absorption possessed by
the muck soil is abundantly demonstrated by the fact that it
held all of the Ioo cubic centimeters of sulphate of ammonia
solution, and by the further fact that it held 90.9 per cent of
the sulphate of ammonia,, even after an additional 1oo cubic
centimeters of distilled water had been passed through it.
These experiments emphasize, very forcibly, the fact that
the coarser the soil and the less organic matter it contains, the
more rapidly the water, and with it plant food, gets away, and
it will perhaps make clearer to us the conditions which exist
in the pineapple districts. There we have a very coarse soil
composed of almost pure sand, through which water runs
almost as it would run through a pile of stones, carrying much
of the soluble plant food with it.
LOSS OF PHOSPHORIC ACID AND POTASH.
Another experiment which is interesting as showing how
rapidly soluble fertilizers are leached out of sandy soil, was
carried out with a sample of soil sent to the Station by Mr.
E. S. Hubbard of Federal Point, Florida.










28 Bulletin No. 87.

In his letter commenting on the condition of the soil Mr.
Hubbard said: "In growing Irish potatoes here, heavy rains
of say two or three inches at a time, between the time of plant-
ing and the tops reaching six inches in height, have a detri-
mental effect of twenty or thirty per cent on yield, even where
surface drainage is good and water stands only limited time
in the furrows.
"Now this may be due to leaching of fertilizers or pack-
ing of the soil so nitrification is hindered, or both, but I am
inclined to think the leaching of fertilizers is mainly responsi-
ble, especially of soluble phosphoric acid and potash, as
organic nitrogen is mainly used, and the potato tops are usually
large enough."
The experiment was conducted as follows: One hundred
grams of the air-dried soil had mixed with it one gram of
sixteen per cent acid phosphate, containing 15.5 per cent of
water soluble phosphoric acid. This was placed in a tube
similar to those used in the previous experiment, and to this
was added sufficient distilled water to bring it, as nearly as
possible, to the original moisture content, and to supply,
approximately, the equivalent of four inches of rain fall. This
was allowed to percolate through the soil, which required
about one-half hour for the major portion, though it was
allowed to stand and drain for twenty-four hours. Following
this, a quantity of water approximately equivalent to three
inches of rainfall was added and allowed to percolate through
as before, twenty four hours being allowed for its comple-
tion.
A third portion, equal in quantity to the second, was now
added and twenty four hours again allowed for complete
drainage. At the end of the period the phosphoric acid in the
three separate percolates was determined, due allowance being
made for the small amount of soluble phosphoric acid origi-
nally in the soil.
The results were as follows:
Ist percolate contained 37.8 per cent. of the phosphoric acid.
2d percolate contained 15.8 per cent. of the phosphoric acid.
3d percolate contained 6.9 per cent. of the phosphoric acid.
Total ............ 60.5 per cent. of the phosphoric acid.










Soil Studies I. 29

That is to say, the equivalent of ten inches of rainfall,
percolating through the soil during a period of three days, in
three different portions, removed 60.5 per cent of the soluble
phosphoric acid present in the soil.
A similar experiment was tried with another sample of the
same soil, using one fourth of a gram of high grade sulphate
of potash instead of acid phosphate. The results were as fol-
lows:
Ist percolate contained 67.3 per cent, of the potash.
2d percolate contained 17.3 per cent. of the potash.
3d percolate contained 6.o per cent. of the potash.
Total ............ 90.6per cent. of the potash.
The results of the experiment would seem to bear out Mr.
Hubbard's contention that the detrimental effects are due to
the loss of soluble phosphoric acid and potash by leaching. At
a time when these elements are most needed for making and
maturing the potatoes, perhaps one half or two thirds of the
quantity applied, has been thus lost.
While the results from the experiment show the loss to be
alarmingly large, it should be borne in mind that the condi-
tions in the field are quite different from these artificial con-
ditions, and that the actual loss in the field is probably not
so great; at the same time they do point to a rapid loss of
soluble fertilizers when the rainfall is excessive, and indicate
the desirability of making a rather small application at the
time of planting-of materials not too readily soluble-and
later, after the crop has started to grow, and the roots have
commenced to reach out into the soil, make one, or perhaps
two, more applications of materials containing fairly readily
available plant food.
The soil sent by Mr. Hubbard contains considerable or-
ganic matter mixed with the sand, and would probably be
classed as Portsmouth sand or Portsmouth sandy loam. It
is perhaps a fair representative of much of the soil that is
devoted to citrus cultivation.
The question then arises, what is there peculiar to clay
soils and other fine soils to enable them to hold plant food and
moisture, that is wanting in the pineapple, vegetable and citrus
soils of Florida?










30 Bulletin No. 87.

THE ABSORPTIVE POWER OF THE SOIL.
CHEMICAL ABSORPTION.

The researches of Way and other eminent investigators
have shown that most soils have an absorptive power with
reference to plant food. (It should be borne in mind that the
term "absorptive power" as used here, has reference to a
chemical change, and not to physical absorption as when a
sponge absorbs water.)
In the case of phosphoric acid this is not difficult to explain,
as the acid forms insoluble compounds with the iron, lime and
magnesium, which are present in most soils, and is in turn
rendered slowly available by the action of the solutions con-
tained in the roots of the plants.
As to the absorption of the alkalies, the explanation is not
so simple, since nearly all their compounds are readily soluble
in water.
Since most soils consist of sand, clay and organic matter,
"Way went to work to determine which of these constituents
had the power of fixing or absorbing the alkalies. Without
describing in detail his methods, it will suffice to say that he
showed that clay does possess absorptive properties, while
pure sand does not, and that organic matter is not essential
to this process.
Having shown that clay was the main constituent in soils
causing the absorption of alkalies, Way next tried to trace out
the particular compound which caused the absorption, and
finally succeeded in producing a hydrated silicate of aluminum
and soda which exhibited displacement and absorptive prop-
erties very similar to those shown by the soil. Then Eichorn
hit upon the idea of trying natural hydrated silicates or
zeolites and found that they exhibited the same power as
Way's artificial ones. That is to say the absorption of the
salts of the alkalies is due chiefly to the presence of zeolitic
materials, a group of minerals which is quite abundant in clay.
That this is true is shown by the fact that when clay is
deprived of these zeolitic materials, it loses its power of
absorption or fixation.
It has been shown that humus, too, possesses this power,










Soil Studies I. 31

the union in this case taking place between the minerals in the
fertilizers and the organic acids formed by the decay of the
humus in the soil, the resulting product being humates.
PHYSICAL ABSORPTION.

There is besides this purely chemical absorption of salts
by the soil, a physical absorption which is illustrated by the
organic matter of a muck soil absorbing water containing dis-
solved salts. Even sand will mechanically hold back a limited
amount of dissolved salts, but the amount is in proportion to
the fineness of the sand.
RAPIDITY OF ABSORPTION AND SOLUTION.
The absorptive power of clay soils has been further demon-
strated by the recent work of Schreiner and Failyer,a of the
Bureau of Soils. They passed successive portions of a solution
of monocalcium phosphate containing 200 parts of PO4 per
million, slowly through a column of clay soil contained in a
tube, and found that the phosphate was absorbed rapidly at
first and then more slowly as the total amount already ab-
sorbed increased, and this absorption continued slowly, even
after large quantities of the solution had been passed through
the soil. They found, too, that absorption was less with sandy
loam than with either clay or clay loam. They further showed
that if distilled water is afterwards passed slowly through
this same soil, the absorbed phosphate is taken out rapidly at
first, and then slowly until a stage is reached where the
amount removed is almost constant, and the concentration is
approximately the same as the percolate from the original
soil, although a large quantity of the absorbed phosphate still
remained in the soil. Their experiments with potassium
gave results showing the same general tendencies. Their'final
conclusions are, that the concentration of the phosphate in
the soil solution is practically the same whether the soil con-
tains a large or a small quantity of absorbed phosphate, and
that it is this absorptive power of the soil which controls the

a The Absorption of Phosphates and Potassium by Soils, by
Oswald Schreiner and George H. Failyer, Bulletin 32, Bureau of
Soils U. S. D A.










32 Bulletin No. 87.

concentration of the phosphate in the free soil moisture. That
is to say, they hold that the application of an excessive amount
of a phosphatic or potassium fertilizer would not materially
increase the concentration of the phosphatic or potassium
salt dissolved in the free soil moisture.
But if this extra amount of fertilizer does not increase
the concentration of the soil solution, then what becomes
of it? In a soil possessing absorptive properties, much of it
would undoubtedly be absorbed, and held in a condition to
be released when the root systems of the plants, feeding upon
the plant food in the soil moisture, have sufficiently reduced
the concentration of this moisture. If, however, as is the
case with the pineapple soils, this absorptive power is want-
ing, or is present only to a limited extent, then the only logi-
cal conclusion is that this extra amount-this over dose-of
phosphate and potassium, will be carried down out of reach
of the plants by the first rain that falls.

IMPORTANCE OF THE ABSORPTIVE POWER OF THE SOIL.

The importance of this absorptive power can scarcely be
over-estimated.
Huston and Goss, formerly of the Indiana Station, have
pointed out that by means of this power those mineral ingre-
dients of plant food of which most soils contain but little, refer-
ring more especially to phosphoric acid and potash, are held in
a form too insoluble to allow of rapid loss by drainage, and
still soluble enough to answer the needs of vegetation, pro-
vided the store is large enough. This cannot, however, be
said to apply to nitrogen in the form of salts of nitric acid,
since nitrogen in this form cannot be absorbed, but here
nature has made a wise provision for this element by binding
it in the form of organic bodies which nitrify but slowly, and
by supplying each year a small amount from the atmosphere.
Huston and Goss conclude their discussion of the importance
of soil absorption with the following statements:
"By means of the absorptive power of soils the farmer, if
he puts on an excess of potash and phosphoric acid as a fer-










Soil Studies I. 33

tilizer, does not lose it, but is able to reap the benefits from
it in the next year's crop. If it were not for this power, the best
method for applying fertilizers would be a much more com-
plicated problem than it is at present, as it would be necessary
to apply them at just the proper season, and in nicely regu-
lated amounts to insure against loss."

PINEAPPLE SOILS LACKING IN ABSORPTIVE POWER.

Of course Huston and Goss did not have in mind such
soils as the East Coast pineapple soils when they wrote this,
for we have there just the conditions which they say would
make the problem of fertilizer application much more com-
plicated than it is, and make it necessary to apply the fertilizers
at just the proper season and in nicely regulated amounts to
insure against loss.
We have there a soil which is practically devoid of clay
and therefore of zeolitic materials; which contains only
traces of iron, lime and magnesia, and a comparatively small
amount of organic matter, but which is on the other hand,
98 to 99.5 per cent. insoluble matter-much of it being very
coarse sand-hence there are wanting nearly all those proper-
ties which in ordinary soils would effect the absorption of
soluble plant food. As a consequence the amount actually
available for the plants probably cannot much exceed that
which they make use of soon after the application is made, or
before the falling of a heavy rain, and that which is mechani-
cally held, and this last is undoubtedly small where the sand is
so coarse, and where there is so little organic matter.
Even organic fertilizers such as bone meal, cottonseed
meal, dried blood and castor pomace, are slowly converted
into soluble forms in the soil, and on account of the almost
entire absence of those substances which produce absorption
phenomena (a binding of soluble plant food) a large part of
this soluble plant food, if not seized upon at once by the plant
roots, probably goes down with the first rain.










34 Bulletin No. 87.

VALUE OF SLOWLY AVAILABLE MATERIALS FOR SUCH
SOILS.

Nevertheless there is under such circumstances an advan-
tage in using slowly available forms over the readily soluble
forms, for while they are thus being made available, the plants
are being benefited, and the excess to be carried away by
percolation is not so great.
I believe one of the merits of slag phosphate, for use on
sandy soils, lies in its somewhat insoluble, but nevertheless
slowly available form of phosphoric acid. When applied from
year to year, a small amount is being rendered available all
the time, and at the same time no very great amount is lost
by percolation. I further believe that if we could get a more
slowly available form of potash for such soils, the problem
of fertilizing pineapples would be simplified and the expense
reduced. The good results obtained with tobacco stems might
possibly be attributed to the fact that the potash becomes
slowly available, and thus in the end is nearly all taken up by
the plant.
PLANT FOOD AND CAPILLARY ACTION.
But some one asks, may not much of this lost plant food
be recovered and brought within reach of the roots by the
capillary action of the soil moisture?
If the soil were a clay or a clay loam the answer would
certainly be in the affirmative, but in such coarse sandy soils
the conditions are very different. It is a well known physical
fact that when three tubes of different internal diameters are
placed open end in water, the water will rise highest in the
smallest tube, that is, the smaller the tube, the greater the
capillary action. So with the soil, the finer the particles the
greater the capillary action, and as the particles of sand com-
posing the pineapple soils are very large in comparison with
the particles that make up clay soil, so the amount of water,
and hence of plant food, brought up from a deep soil by
capillary action is correspondingly smaller. Hence it is that
plant food when once lost in the waters of the sub-soil, are
recovered but slowly and with great difficulty by capillary










Soil Studies I. 35

action. This was well illustrated by another experiment con-
ducted in our laboratory.
Over the end of a glass tube of about 3-4 inch internal
diameter, was tied a piece of muslin cloth, and in the tube
was placed the pineapple soil to a depth of 12 inches. The
tube was then suspended so that the end over which the
cloth was tied just touched the surface of distilled water
contained in a beaker. At the end of three days the highest
point at which the soil had been moistened by capillary water
was 3 3-8 inches. The same experiment was tried with the
Columbia county soil, and the South Carolina clay soil with
the result that at the end of the three days the Columbia
county soil was moistened to a height of 8 3-8 inches, and
the South Carolina clay soil to 7-8 inches. In each case the
tube was weighed with the dry soil, and again at the expir-
ation of the three days. The pineapple soil retained Sq
grams of water, the Columbia county soil 23.4 grams, and the
South Carolina clay 27.2 grams or a little more than three
times as much as the pineapple soil. This indicates very
clearly the difference in capillary action. In the pin apple
soils the grains are large and as a consequence many of the
spaces between them are too large for capillary spaces.
To illustrate in another way, if you could put these grains
of sand together into the form of a lamp wick, you would
still have a very poor medium for lifting oil, but if the wick
be made of fine particles of asbestos, which is also a mineral,
the oil is raised without difficulty and a good flame is the
result.
SOME REMEDIES SUGGESTED.

WITH ESPECIAL REFERENCE TO PINEAPPLE SOILS.

Then is it possible to do anything to prevent this great
loss of plant food?
Certainly it is not possible and perhaps not desirable to
convert the sandy soils into clay soils, nor even to mix with
the sand a small percentage of clay.










36 Bulletin No. 87.

I will mention a few ways that have suggested themselves
to me.
(I.) By increasing the amount of organic matter in the soil.
It is a well established fact that organic matter acts as a
sponge to hold moisture, and in holding water it will hold
plant food. This was well illustrated in the experiment with
the muck soil. One hundred and fifty grams of an air dry
muck soil retained over Ioo grams of water, and 90.9 per
cent, of the sulphate of ammonia. Whereas the same weight
of the pineapple soil retained only 30 grams of water and
5.77 per cent. of the sulphate of ammonia. Old pineapple
plants and other organic matter might be allowed to decay on
the fields instead of being burnt. Other ways will doubtless
suggest themselves to those interested. Of course the pine-
apple grower cannot resort to cover crops such as velvet
beans, cowpeas, beggarweed etc., as can the man who grows
oranges or ordinary field crops.
(2.) By the use of windbreaks.
Currents of dry hot air passing over the fields cause the
surface moisture to evaporate rapidly, thus to a certain degree
breaking the chain of capillary moisture.

(3.) By the addition of lime to the soil.
In some soils lime tends to produce a flocculent effect (a
binding together of the minute particles into flakes) which
condition makes the soil more retentive of moisture.
In a sandy soil the tendency would be for the lime, after
it has been carried down a short distance, to begin to cement
together the grains of sand and thus form a layer somewhat
impervious to the downward movement of water, thus pre-
venting to some extent, the loss by leaching. In using lime,
however, care must be exercised that it be not used in such
a way as to cause the loss of ammonia from other materials,
sulphate of ammonia for example.

(4.) By using fertilizing materials which become slowly
available.
For such a crop as pineapples, where the plants remain in
the ground from year to year, there would seem little reason









Soil Studies I. 37

for using quickly available materials, except say for the first
eighteen months, to get the plants started, even had we a soil
that was capable of absorbing and holding the plant food.
After a certain amount of these slowly available materials
have been added to the land some plant food is being rendered
available all the time, and as the roots are there ready to util-
ize it, not so much is lost by seepage to the soil waters
below. It seems to me, too, that this same reasoning might
apply to the fertilization of orange trees.
(5.) By shading.
Shading undoubtedly tends to conserve soil moisture, and
if we can retain moisture near the surface, it means more
moisture and with it more plant food brought up from the deep
sub-soil by capillary action. This latter fact is demonstrated
in the alkali regions of the west. As soon as they begin to
irrigate land that is impregnated with alkali, the alkali com-
mences to rise through capillary attraction from a subter-
ranean source and in many instances completely destroys nearly
all kinds of vegetation.

(6.) By smaller and more frequent applications of fertilizers.
In the light of the evidence before us, I am strongly in-
clined to the belief that it would be economy to fertilize pine-
apples from four to six, instead of two to three times a year.
I am aware that this is not in accord with recommendations
made in our recent bulletin on pineapple fertilizer experi-
ments, but at the time those recommendations were made,
we had not discovered that such a large percentage of the
plant food applied to pineapple soils, was unaccounted for.
If the farmer should give to his horse at one time, food
enough to last it one week, he would expect much of it to
be wasted; so if you give to your pineapple plants soluble
food enough to last them six months, and there is nothing in
the soil to bind or absorb this plant food, so that it can be given
out gradually as the plants can utilize it, there must necessarily
be much loss.
Reasoning along the lines indicated, I am of the opinion
that in the case of pineapples, 2000 pounds of fertilizer ap-










38 Bulletin No. 87.

plied at intervals of two or three months would be as effective
as 3500 pounds of the same material in two applications.
There is of course the difficulty that the extra expense of
frequent applications might overbalance the cost of the extra
amount of fertilizer required with the less frequent applica-
tions.
This could be determined by an experiment and would
doubtless prove to be a profitable field for investigation along
other lines than pineapple growing.

SOILS PRODUCING GENERAL FARM CROPS.

When we come to soils producing general crops, the prob-
lem of fertilization is not quite so complicated. Here it is
possible to maintain the fertility by practicing rotation of
crops, by the more extensive use of stable manure, and by
growing cover crops such as beggarweed, cowpeas, and velvet
beans, all of which make excellent feeding materials and at
the same time are very effective soil renovaters.

MORE HUMUS NEEDED.

The constant cultivation of land in corn and cotton tends
to exhaust not only the mineral plant food, but also the humus
which has such a good effect in conserving soil moisture and
with this, the soluble plant food.
It is entirely safe to say that a more liberal use of stable
manure and green manure crops in the corn and cotton coun-
ties of Florida will produce surprising results in the way of
improving the texture of the soil and its capacity to absorb
moisture and plant food.
But here also, as in the pineapple and orange districts, the
soil is composed chiefly of sand which is open and porous, with
only a very small percentage of clay, and the tendency is for
the soluble plant food to be leached out rapidly when there is
much rain. It is therefore very desirable that the fertilizer be
applied just as near the time that the plant will need it as
possible, and in several small amounts rather than in one
large application.








































I - '


I '.






















Photo. by H. H. Hume.

ROOT SYSTEM OF THE BEGGARWEED, SHOWING NITROGEN-
GATHERING NODULES.










40 Bulletin No. 87.

A DOUBTFUL PRACTICE.

The custom of putting the fertilizer in the ground some-
time before the cotton is planted is questionable to say the
least, for should there come heavy rains before the cotton
begins to grow, undoubtedly much of the fertilizer is leached
away beyond the reach of the roots of the plant. It would
unquestionably be better to distribute at least a part of the
fertilizer along side of the rows after the cotton is up. This
could be done as a part of the cultivation, thus increasing the
expense but slightly, and would place the fertilizer within
reach of the plant roots at a time when it is needed.

THE ABANDONMENT OF SOILS.

Prof. Milton Whitney in testifying before the U. S.
Industrial Commission in 1901a, on the causes of the abandon-
ment of soils, made the following statements:
"The exhaustion of the soil is due, in my opinion, to
changes in the chemical and physical properties of the soil
rather than to any actual extraction of plant food.
"A soil to be productive must render annually, as the
crop needs it, a sufficient amount of food material in a form
available to the plants. As a matter of fact soil is a difficultly
soluble substance, composed mostly of silicates and aluminates,
or difficultly soluble compounds of silica, alumina, potash,
soda and lime in various forms. Through atmospheric agen-
cies, largely, these compounds are rendered more or less
readily available to plants.
"A fertile soil is one in which the weathering effects come
in at such times and to such an extent as to render available
to plants a sufficient amount of this plant food. If that
weathering does not take place and the food material is not
brought into a condition in which it is available to the plants,
the land is as poor as though it actually contained no plant
food.
"I have never in my experience seen a case in which one
could say with any degree of certainty or even of probability

a Exhaustion and Abandonment of Soils, Report No. 70 U. S.
D. A. Testimony of Milton Whitney before Industrial Commission.










Soil Studies I. 41

that exhaustion was due to the actual removal of plant food.
It is perfectly safe to say that the conditions of the so-called
wornout soils in the south is due, not to an actual extraction of
plant food, but to the chemical condition in which it now is,
in which it is unavailable to plants, and that the restoration
of the fertility of that land must be, not necessarily in the
addition of plant food to the soil, but in bringing about such
changes in the physical conditions or in the chemical combi-
nations as will encourage that natural weathering of the soil
which brings the plant food into a condition in which the
plant can get its support."
FLORIDA SOILS DIFFER FROM THE GENERAL TYPE.

There is undoubtedly much of truth in the above, but it is
doubtful if all the statements made here will hold true in the
case of many of the Florida soils, where there is such a small
proportion of those materials, which in a clay soil, would yield
soluble plant food under the influence of the natural weath-
ering processes, and where the loss by seepage is so great.
However, there can be no question about the importance of
improving the physical condition of the soil in very many
cases, and there is no better way of doing this than by keeping
stock and growing green manure crops as mentioned before.
In this connection Professor Bailey of Cornell says: "A
sandy soil may also be seriously impaired for the growing of
any crop, if the humus, or decaying organic matter, is
allowed to burn out of it. It then becomes leachy, it quickly
loses its moisture, and it becomes excessively hot in bright
sunny weather."
THE BALANCE MUST BE KEPT UP.
If we continue to remove annually, as much or more plant
food as we apply, which is often the case in the growing of
corn and cotton, and do not rotate crops or use other means
of renovating the soil, we cannot expect to maintain its fer-
tility; and if the farmer who produces general crops would get
the most out of his soil, he must cultivate fewer acres, and
make these few of better quality. If it pays the fruit and
truck grower to thoroughly clear and prepare his land, and










42 Bulletin No. 87.

fertilize and cultivate with much expenditure of thought, time
and labor, then the general farmer also will profit by these
measures, perhaps not to the same extent, but certainly in
the same proportion.
THE COMPOSITION OF SOME DIFFERENT TYPES OF
SOILS.
The following chemical and mechanical analyses of a few
typical soils are herewith given in tables I and II, for com-
parison.









TABLE I, COMPOSITION OF SOME TYPICAL SOILS.

RED RIVER AVERAGE OF
PINEAPPLE ORANGE COTTON COTTON VALLEY WHEAT 200 FERTILE
SOIL.a SOIL. b SOIL (FLA.I SOIL (TENN.) d SOIL., SOIL.f SOILS. g

Surface Sub- Surface Sub- Surface Sub- Surface Sub- Surface Sub- Mich. Md.
Soil Soil Soil Soil Soil Soil Soil Soil Soil l So Surface Surface
__ __ Soil Soil
Per Cent Per Cen Per Cent er Cent Per Cen er Cent Per CentPer Cent Per Cent 'er Cent Per Cent Per Cent Per Cent

Silica (SiO) ........... 99.073 99.104 96.395 99.341 97-510 98.170 88.434 86.533 63.070 49.58o 75.74 75.68 79-95

Potash (K20) .......... .006 .012 .014 .007 .oro .012 .380 .494 .540 .250 1.Io 1.52 .29

Soda (Na2O) ........... ................ .084 .50 .05 .080 .085 .301 .450 .480 .43 .65 .25

Lime (Ca O)........... .000 .001 .034 .022 Trace Trace .205 .152 2.440 7.450 1.38 .47 2.16

Magnesia (Mg O) ..... .009 .o01 .022 .o08 .020 .050 .246 .351 1.850 4.480 .56 .84 .55

ron a Alu (Fe ........... 62 .406 136 .o01 .678 .694 5.289 7.786 12.070 14.2oo 9.66 14.92 7.88

Phosphoric Acid (P- O) .012 .014 .018 .022 .032 .026 .071 .074 .380 .170 .33 18 .24

Sulphuric Acid (SO ... .000 .ooo .017 .009 Trace Trace .o18 .012 .Tr .100 .18 .08 .03

M moisture ............... .072 .068 .608 .1 4 75 .155 1.307 1.5oo ... .. .. .. 1.48 ..............

Volatile Matter......... .796 .0oo 2.306 .3o8 1.5I .890 3.6oo 2.557 15.550 6.220 7.50 3.96 7.00


B. Bulletin No. 60, Fla. Expt. Sta.. Pineapple Culture: T. Soil.
b. Unpublished Analyses, Fla. Expt. Sta.
SUnpublished Analyses, Fla. Expt. Sta.
,. Bulletin No. 3, Vol. X., Tenn. Expt. Sta., The Soils of Tcnn.
.Bulletin No. 30, Minn. Agrl. Expt. Sta.
Bulletin No. 70, Md. Agrl. Expt. Sta., The Chem. Composition of Mdli. Soils.
". Soils and Fertilizers. Harry Snvder.













TABLE II, MECHANICAL ANALYSES OF SOME TYPICAL L SOILS.


UQ r

V E





















c. Field Operations of the Bureau of Soils, 1904, U. S. D, A.
oC) u u > U) U
Per Cent P er Cen t. Per Cent. Per Cent.Per Cent. Per Cent. Per Cent. Per Cent.
Pineapple Soil, a ............... ........... .58 .36 19.32 43.72 33.6 .26 .6o .42

Orange Soil, b ............................ .59 Trace 5.96 37.90 47.35 5.00 .73 .25 1.24

High Pine Land, b .................. ......... 1.82 1.46 5.78 23.89 45.1I 18.42 .96 .38 1.56

Rich Heavy Hammock, b.................... 2.68 .82 2.48 19.60 44.15 19.07 3.35 1.19 4.48

Sea Island Cotton Soil, c ..................... ........ .40 10.40 23.10 49.80 12.50 2.40 ........ i.1Io

Cotton Soil, (Tenn.), d ..................... .36 .04 .19 .91 1.04 5.J9 60.28 15.38 13.15

Wheat Soil, (Md.), e ............................... .00 .27 .64 3.20 22.58 26.25 10.42 32.40


a. Bulletin No. 68, Fla. Agrl. Expt. Sta., Pineapple Culture, I. Soils,
'. Bulletin No. 13, Bureau of Soils, U. S. D. A.
c. Field Op-rations of the Bureau of Soils, 1904, U. S. D, A.
d. Bulletin No. 3. Vol. X, Tenn. Agrl. Expt. Sta., The Soils of Tenn.
e. Bulletin No. 70, Md. Agrl. Expt. Sta., The Chem. Composition of Md.
Soils.









Soil Studies I. 45

It will be instructive to compare the amount of silica,
potash, and phosphoric acid in the pineapple and orange
soils, with that in the wheat soils, and the average of two
hundred soils.
It is interesting, too, to note the difference in percentage
of clay in the pineapple and orange soils on the one hand,
and the Tennessee cotton and the Maryland wheat soils on
the other; that in the pineapple soil being forty two one hun-
dredths of one per cent, and that in the Maryland wheat
soil being thirty two and four tenths per cent. There is
also a wide difference in the percentage of coarse sand in
these two soils; that in the pineapple being nineteen
and thirty two one hundredths and that in the wheat soil
being nineteen hundredths. Here is a partial explanation, at
least, of the difference in the absorbing or binding powers of
the two soils.
A careful study of the tables will reveal other interesting
dissimilarities.
SUMMARY.
(i.) Most Florida soils are very deficient in plant food,
and also in those materials which, in clay soils, absorb or
hold for the future use of the plant, the food that is applied
in the form of fertilizers.
(2.) On account of the almost entire absence of these
binding materials, the loss of soluble fertilizers, by leaching, is
very great; the loss from this cause, on the pineapple fields
of the East Coast, being apparently, over 60 per cent. of the
amount applied.
(3.) These same Florida soils, however, under careful
cultivation and liberal fertilizing, produce abundant crops of
the fruits, vegetables and grains that are adapted to this
climate.
(4.) In order, therefore, that his operations may be
profitable, it is incumbent upon the Florida farmer and fruit
grower to pursue such methods of cultivation and fertilizer
application as will, so far as possible, prevent this loss.
(5.) It is possible to increase the power of sandy soils









46 Bulletin No. 87.

to absorb or bind plant food, and also their power of holding
moisture.
(6.) Some of the methods suggested for accomplishing
these results are the following:
(a) Increasing the organic matter in the soil. This may
be done by the use of green manure crops, cover crops, stable
manure and by the application of such miscellaneous vegetable
materials as may be available.
(b) The use of lime.
(c) Windbreaks.
(d) Shading.
(7.) Smaller and more frequent applications of fertili-
zers, and the use of somewhat slowly available materials
where rapid growth is not required, will enable the plant to
utilize more of the food materials before they are leached
away beyond the reach of the roots.
(8.) In soils where sand predominates to the extent that
it does in Florida, we need not expect to continue to gather
bountiful crops, if we remove with these crops as much, or
more, plant food as we apply. The balance must be kept up
and in addition some allowance made for loss by leaching.
(9.) Much may be done towards keeping up this balance
by careful economic methods, by rotation of crops and by the
application of fertilizers at a time when the plant is best able
to utilize them.
ACKNOWLEDGMENT.

I am indebted to Dr. E. W. Berger of the Department of
Entomology for helpful suggestions, and a careful reading of
the manuscript.





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