SOME EFFECTS OF BORAX UPON THE GROWTH, APPEARANCE
AND CHEMICAL COMPOSITION OF CERTAIN PLANTS.

■by
GILBERT R. MUHR
T
w
»**EW
ao«w
ft

A THESIS
Submitted to the Graduate School of Michigan
State College of Agriculture and Applied
Science In partial fulfilment of the
requirements for the degree of
DOCTOR OF PHILOSOPHY

Department of Soils
1940

ProQuest Number: 10008225

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ACKNOWLEDGMENTS
The author wishes to express his appreciation
to Dr. R. L. Cook for his assistance through-cut the
course of this investigation.

He also wishes to

thank Drs. C. E. Millar and C. H. Spurway for their
constructive criticisms in the preparation of the
manuscript and the American Potash Institute, Inc.,
of Washington, P.C., for its fellowship which made
this investigation possible.

TABLE OF CONTENTS
Introduction............. . .................................. 1
Laboratory Procedures ....................................

3

Soil Fixation of Boron
Type of F i x a t i o n ......................................... 3
Rate of F i x a t i o n ........................................ 30
Symptoms of Boron Starvation and the Effect of Borax on
the Yield and Chemical Composition of Several Crops . . .

34

Symptoms of Boron Starvation .......................... 36
The Effect of Borax on Yields and the Chemical
Composition of Several Crops ..........................

36

Discussion.................

50

Summary and Conclusions ..................................

53

Literature Cited............

56

SOME EFFECTS OF BORAX UPON THE GROWTH, APPEARANCE
AND CHEMICAL COMPOSITION OF CERTAIN PLANTS.
INTRODUCTION
In the last decade the roles played in the development
of plants by a number of elements occurring in them in small
quantities have been undergoing rigorous investigation.

The

importance of several of these elements in plant growth has
been universally admitted.

Prominent among them is boron.

As far back as 1857, Wittstein and Apoiger (33)
obtained from the ash of the seeds of a certain Abyssinian plant
a crystalline substance answering to the test for boric acid.
Since that time, with the help of improved methods of analysis,
boron has been found to be present in the ash of most plants.
The presence of boron in plants is not entirely accidental as
small amounts are essential for proper development.
The exact role played by boron in plant nutrition is
not yet definitely established.

Many investigators, however,

have shown that its absence results in an internal breakdown
of the plant cells and finally death of the plant.
The general method for the study of the effects of a
simgle element in plant growth involves the use of nutrient
solutions.

These solutions contain the salts of the essential

nutrient elements —

nitrogen, phosphorus, sulphur, potassium,

-2magnesium, calcium,
elements.

iron and small quantities of the minor

Through the use of these solutions it soon became

obvious that the quantity of boron necessary for normal
growth varied with different plants.

Moreover, the quantity

of boron available to plants, a factor of great importance,
has been shown to have no significant correlation with the
amount of boron in the soil (6).
While the need of boron for plant growth has been
receiving considerable attention, fewer investigators have
been concerned with the specific effects of boron within
the plant and its relationship to other elements.

It is

the purpose of this investigation to study the nature of
boron fixation by the soil and to consider the effects of
borax on the growth, appearance, and chemical composition
of certain plants.
From the standpoint of fertilizers the form in which
boron is most readily procurable and, at present, least cost­
ly is granulated borax (Na^B^O^.lOH^O).

This compound, contains

11.34 per cent boron.

LABORATORY PROCEDURES
Standard laboratory methods were used in the chemical
analyses of plant tissue.

All analyses were made on tissue

dried in the oven at 65°C.
Boron was determined by the Berger-Truog method (l).

-3Calcium and magnesium were determined on the same ash
samples;

calcium by titrating the oxalate with standardized

potassium permanganate and the magnesium by the gravimetric
pyro-phosphate method.
Iron was determined by titrating the ferric ion with
a dilute standardized titanium trichloride.
A modified Gunning procedure was used to determine
nitrogen.
Potassium was determined by the chloro-platanic method.

I.

SOIL FIXATION OF BORON
Type of Fixation

It has been reported tha,t boron deficiency occurs
more frequently in alkaline than in acid soils (4,14,15)
and that over-liming may produce boron starvation (20,21 ).
Ferguson and Wright (11) have pointed out that the
fixation of boron in the soil by lime may happen in one of
three ways.
(1) “Lime may fix boron into some insoluble or slightly
soluble form.
(2) "Lime increases the pH of the soil and thereby may
reduce the ability of the root to absorb boron.
(3) "Lime may stimulate the growth of soil micro­
organisms until there is competition between them
and the plant for the supply of boron."

-4.
In a report by Cook and Millar (6 ) some factors affect
ing boron availability have been pointed out.

The growth and

appearance of soybean plants were used as a measure of the
availability of boron, as these plants exhibit very plain and
dependable symptoms of toxicity when a small excess of boron
is present.

It was assumed when borax is applied to soils in

fairly heavy quantities and the soybean plant is not injured,
that some constituents of the soil render the boron unavail­
able to the plant.
The boron toxicity symptoms of soybeans are first
noticed about ten days after the plants emerge from the soil.
Yellowish brown spots form near the edges of the leaves, as
illustrated by Figure 1.

The cotyledons turn yellow and drop

Figure 1.
Soybeans showing yellowish brown
spots near the edges of the leaves,
characteristic of boron toxicity.

-5off earlier on the plants injured by borax.

An excessive

quantity of borax also causes a rapid development of new
leaves at the top end of the stem and a premature death of
the base leaves.
From the yield data (See Table 1.) taken from the
above mentioned report, the following conclusions were drawn.
(1) “Calcium and magnesium carbonates were very
effective in fixing borax into forms not
available to soybeans.

Sodium carbonate had

no effect on the availability of borax.
(2) “Calcium and magnesium sulphates were partially
effective on Hillsdale soil in fixing borax
into forms not available to soybeans.

The

They

had no

effect on Warsaw soil. Sodium sulphate

had no

effect on either soil. ”

soybean plants whose yield data and toxicity

symptomsmade It oossible

to draw the above conclusions,

were

analyzed to study the relationship between plant composition
and soil factors affecting boron fixation.
The plants from each replication were dried, ground
to pass through a 1 mm. sieve and then combined to form
composite samples.
The soybeans were grown on two soils: Hillsdale B
horizon and Warsaw sandy loam.

These soils were placed in

1-gallon glazed earthenware jars and soybeans were planted
immediately after the application of the nutrients.

The

treatments are stated in terras of equivalents per acre.

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Soil

Table

1. The effect of borax-*- upon the percentage decrease in yield and the
boron, calcium, magnesium and nitrogen contents of soybeans grown upon
variously treated pots of Hillsdale B horizon and Warsaw sandy loam soil

-6-

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-70 n the Hillsdale B horizon the following were included, with
and without borax at the rate of 10 pounds:

CaCO^, 4 tons;

CaS04 , 1 ton; MgCO^, 4 tons; and N&2SO4 , 5 tons.

The Warsaw

sandy loam soil received double the above rate of CaSO^,
MgS04 , NagSO^ and borax,

and the same applications of CaCO^,

Mg CO-j and NagCO^.
Boron - As indicated in Table 1, the CaCO^ and
MgCO^ lowered the plant intake of boron.

Where no borax had

been applied to Hillsdale B horizon the boron content of the
dried plant tissue was lowered from 27 to 18 ppm. by both
CaCQ^ and MgCC^.

Where borax had been applied the decrease

in boron content as a result of the application of these
liming materials was from 90 to 50 and 57 ppm ., respectively.
Similar changes were also observed in boron content of the
plant tissue grown on Warsaw soil receiving applications of
GaCOg and MgCO^.
The boron content of the plants from cultures receiv­
ing the NagCO^and NagS04 treatments varied only slightly with
respect to the check.

Where borax had been applied to the

check, NagSC^ and NagGO^ treated pots,

the boron content of

soybean plants increased from about 25 to 90 ppm. in both
soil types, as compared with the plants not receiving borax.
The action of MgSO^ and CaS04 with respect to the
boron content of the soybean plant is not consistent in the
two soil types.

Neither treatment had any influence on

either soil type with respect to the boron content of the
plant where borax had not been applied.

Where borax was

-8applied to the pots of Hillsdale B horizon soil, the plants
contained less boron than did those from the same treatment
on the check pots.

CaS04 and MgSO^ treatments in comparison

with the check pots lowered the boron content of the dry plant
tissue from 90 to 77 and 75 ppm., respectively.

The plants

grown on similar treatments in the Warsaw soil showed only
slight deviations from the check.
The data in Table 1 also indicate that wherever boron
caused a decrease in yield the boron content of the plant
tissue increased substantially.

Treatments which entirely

or partially prevented borax from decreasing the yield also
decreased the boron content of the plant tissue.
Calcium - Toxic

quantities of boron seemed to

have very little influence onthe content of calcium in
plant

tissue.

However,

borax

contained slightly more calcium than normal ones.

the

those plants which were injured by

Plants from treatments which

showed no decrease in yield

by the application of borax showed no significant change
in calcium content.
While the observation has no connection with borax,
it is interesting to note,

especially with respect to the

plants grown on Hillsdale soil, that calcium and magnesium
contents of the tissue were considerably higher where their
respective carbonates were used, over where their respective
sulphates were used.

This seems to fit in nicely with Jenny*s

(16) idea of contact feeding.

Although greater concentrations

of the carbonates were used the solubilities of the sulphates

-9are considerably higher*
Magnesium - In general the magnesium content of
the soybean was not altered by an injurious application of
borax*
Nitrogen - As shown in Table 1, there was an
increase in nitrogen content in the tissue of those plants
injured by boron, grown on the Hillsdale B horizon*

Little

change was found in any of the plants grown on the Warsaw
soil*
Discussion - In general plants Injured by borax
were higher in boron,
ones*

calcium and nitrogen content than normal

These differences were much more apparent in tissue of

the plants grown on the Hillsdale B horizon than those grown
on the Warsaw soil.

The soil factors which prevented boron

toxicity symptoms and reduction in yield are correlated with
low boron content within the plant tissue.

This is further

proof that the boron was changed to a form not available to
the soybean plant.

In an article (7) recently presented for publication,
of which the writer is co-author,

three factors were found to

influence the fixation of boron.

These are active calcium^,

organic matter and clay content of the soil.

These factors

were determined by growing soybeans in nine different Michigan
soils.

These soils were selected because of their wide vari­

ation in texture, reaction and organic matter content.
^"Active calcium was determined by leaching 10 gms. of
soil with acidified ammonium acitate.
The calcium thus de­
termined was that in the exchangeable form and as carbonates."

-10The treatments on each soil type Included borax at the
rates of 0, 10 and 20 pounds per acre.
replicated three times.

All treatments were

Adequate quantities of all nutrient

elements, with the exception of boron, were applied to ea.ch
pot.

Ten soybean seeds were planted in each pot and the

seedlings thinned to six plants shortly after they emerged
from the soil.

The effect of borax on the growth and ap­

pearance of the soybeans varied with the soil type.

For

example, plants grown on Thomas sandy loam soil made a greater
growth as a result of both the 10 a.nd 20 pound supplications of
borax, while the soybeans grown on the Fox sandy loam were
seriously injured by the 10 pound application.

In order to

understand what constituents of the soil cause boron to become
unavailable in one soil and not in another,
analyzed.

several soils were

No single soil constituent seemed to correlate with

the relative

yields^.

From the data it soon became evident

that several

soil constituents played a role in preventing

applied borax from proving toxic to soybeans, and in order to
explain, wby borax proved toxic on one soil and beneficial on
another it was necessary to consider the relative quantities
in the soil of all three constituents - active calcium,
organic matter and clay.

In order to group all three soil

constituents into one factor which would be indicative of the
response of soybeans to applied borax, relative amounts of
each constituent were determined.
soil has the
sBased on

For example,

since Thomas

greatest organic matter content - 14.01 per cent the yield from the soil without borax - as 100.00.

-li­
lts relative organic matter factor is 100.00.

Warsaw soil,

containing 4.65 per cent organic matter has a relative factor
of 33.19 or 33.19 per cent as much organic matter as the
Thomas soil.

Likewise, for each of the soil constituents,

as indicated in Table 2, a relative figure was determined.
A soil factor was determined for each individual soil
by averaging the relative amounts of the three soil con­
stituents.

This soil factor gives a very good index as to

how soybeans would respond to greenhouse applications of
borax.

For each application of borax the relative yields

on the nine soils and the corresponding soil factors give
a very high correlation (r « 0.967 for the 10 pound applic­
ation and r * 0.974 for the 20 pound application.).

The

conclusion drawn from this work is stated as follows.
"Inverse and very high correlations were found to exist
between the availability of boron, applied as borax, to
soybeans and the active calcium organic matter and clay
contents of nine soils.

From such correlations it was pos­

sible to construct lines of best fit which may be used for
soybeans grown in not cultures of an unknown soil.

The

prediction thus may be useful in making recommendations re­
garding the field use of borax on that particular soil."
Soybeans grown In the above experiment were dried,
composited, ground to pass through a 1 mm. sieve and ana­
lyzed.

The results of the analyses are found in Table 2.

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-13,Boron - The boron content of the soybean tissue
was markedly increased through the application of borax.
However,

the rate of increase, the content of the boron in

soybean plants grown on the various soil types and the re­
sponses in yi_eld varied considerably with the soil type.
The Thomas soil, having a pH of 7.5 and an organic matter
content of 14.01 per cent, grew soybeans which were the low­
est in boron content.

This soil, while showing the greatest

response to borax in yield, failed to show a great increase
of boron in the tissue.
The Fox soil which was very acid and low in organic
matter content grew plants which were high in boron and with
the application of borax the amount in the tissue increased
from 60 to 150 ppm.
In general the plants grown on soils which have a
high soil factor were lower in boron content than those plants
which were grown on soils with a low soil factor.

The amount

of boron In the plant tissue was directly influenced by the
soil conditions which prevented toxicity symptoms and re­
duction of yields.
A definite correlation can be noted between response
of the soybeans to borax and the amount of boron in the plant
tissue.

When the boron content of the plant tissue, on the

dry basis, reached approximately 30 ppm. yields were not
further increased.

The toxic range was not reached until the

plant tissue contained between 50 and 60 ppm. of boron.

-14Calcium - The calcium content of the soybean
plant was influenced slightly by borax applications.

There

is a tendency for higher calcium content In those plants
which were injured by borax.

This is especially apparent in

the soybeans grown on Berrien soil.

The calcium content of

soybeans grown on this soil was increased from 1.76 to 2.10
per cent by an application of 20 pounds per acre.
trast,

In con­

the soybeans grown on Thomas soil seemed slightly low­

er in calcium content although the calcium content was not
markedly altered by the borax.
Iron - According to the data, borax did not
affect the iron content of the soybean plant.
Nitrogen - As indicated in Table 2, the nit­
rogen content of the soybean tissue apparently was not
altered by the boron content until the amount of boron in
the plant tissue reached the toxic quantity.

For example,

the plants from the Berrien soil were Increased from 2.20
to 3.10 in per cent of nitrogen by an application of borax
equivalent to 10 pounds per acre.

This change was accompanied

by a decrease in yield from 11.5 to 8.4 gms. per pot.

How­

ever, the plants grown on the Wisner soil showed no signs
of toxicity and no reduction in yield from borax.

The

nitrogen content of the dry tissue of the plants grown on
this soil did not vary with borax treatments.

Naftel (21) has reported that boron fixation by over­
liming is due to the stimulation of growth of soil micro­
organisms resulting In the available boron being largely used

-15in building the bodies of the organisms.
Dunklee

MIdgley and

(20) on the other hand report that the fixation is

chemical rather than biological.
As a means of obtaining further information on the
idea of fixation through cell metabolism an experiment was
set up to determine whether a stimulation of soil micro­
organisms by means other than lime would decrease the avail­
able boron In the soil.
Soybeans were grown in 1-gallon glazed earthenware
jars each filled with 5 kgms. of Warsaw sandy loam soil.
This soil, with a pH of 6 .0 , is not too acid for bacterial
development but is sufficiently acid so that added lime fixes
applied borax.

Four soil treatments in sets of six Included

a check and applications of CaCO^, equivalent to 8 tons per
acre, CaSO^ equivalent to 4 tons per acre, and sucrose
equivalent to 18 tons per acre.

To three of each set of six

pots borax was applied at the rate of 20 pounds per acre.
Adequate quantities of nutrient elements, with the exception
of boron, were applied to all pots.
Ten seeds were planted In each pot and the seedlings
were thinned to six plants shortly after they had emerged
from the soil.

The moisture content was kept uniform by

frequent additions of distilled water.
Results.
shown in Table 3.

The results of this experiment are

It will be noted that sucrose failed to

reduce the toxic effects of boron as the yields on pots

-16receiving borax v/ere decreased 17.4 per cent.

This is

practically the same decrease in yield as was caused by borax
In the check pots.
Table 3. The effects of CaOCu, CaSO^ and sucrose
on the fixation of boron as indicated by yields
of the entire soybean plants, grown in Warsaw
sandy loam pot cultures.

Treatment
None
GaC0 3 , 8 tons
CaSO^, 4 tons
Sucrose, 18 tons

Degree of toxicity and percentage de­
crease in yield as a result of applying
borax"1 after the treatment indicated.
Toxicity
Yield decrease
Very serious
None
Medium
Very serious

19.4
0.0
9.4
17.4

^Equivalent to 20 pounds per acre.
The CaSO^ reduced the toxicity of borax and this
evidence tends to verify the conclusions drawn from the data
in Table 1.
No toxicity symptoms or other harmful effects were
apparent on the plants grown In the limed pots receiving
borax.

This observation is supported by the fact that the

yield was not altered in comparison with that of similarly
limed pots not receiving borax.
As the presumably Increased number of organisms caused
by the addition of sugar to the culture did not change the
applied boron Into some form not injurious to soybeans,

it

seems Ibgical to assume that the role of lime is not simply
that of stimulating the micro-organisms but that it plays

-17another altogether different role in fixing boron into an
unavailable form.
From the data given It appears that the causes of
boron fixation in the soil are quite complex.

First, CaCO^

rendered the boron unavailable and nontoxic to soybeans but
NagCO^ failed to prevent boron from being toxic, making it
appear that fixation was not influenced a great deal by pH.
However, CaSO^ only partially reduced the toxic effects of
borax indicating that fixation was not entirely due to the
calcium ion.

As the fixation of boron appeared not to be

biological in nature,

it became apparent that pH must have

some indirect effect upon this tie-up.

In order to confirm

this idea an experiment was set up to attack the question
from a different angle.

It was thought that If pH has any

influence on the unavailability of boron In an alkaline soil
some treatment which would lower the pH should make the soil
boron more available to the plant.

With this idea in view

the following investigation was made.
Sugar beets were grown in 2-gallon glazed earthenware
jars filled with 8 kgms. of Thomas sandy loam soil taken from
the area shown in Figure 2.
contains free carbonates.

This soil has a pH of 7.5 and
It has repeatedly shown responses

to borax treatments in greenhouse cultures.
By laboratory experiments the amount of sulphur neces­
sary to lower the pH from 7.5 to 6.2 was determined to be
approximately six and one-half tons per acre.

Sulphur was

thoroughly mixed at this rate into the soil of four of a series

-18-

Figure 2 . An area of Thomas sandy loam
soil near Unionvllle, where practi­
cally all the beets showed heart rot
symptoms.
of eight pots.

To two of each set of four pots borax was

applied at a rate equivalent to ten pounds per acre.

All

other nutrient elements were applied in adequate quantities.
Four sugar beet plants were transplanted into each
pot soon after they had emerged from the quartz sand in which
the seeds were germinated.

The moisture content of all the

pots was kept uniform by frequent additions of distilled
water.
Results - As shown by the data reported in
Table 4, all plants grown in cultures without boron or sul­
phur were affected with heart rot, while all plants receiv­
ing either boron or sulphur produced healthy plants.

In the

-19
Table 4 . The effect of sulphur and borax on heart rot
occurrence and the yield of sugar beets grown on
Thomas sandy loam pot cultures.
Treatment
Base
Nutrients
Control

Without boron
With boron

Sulphur

Without boron
With boron

Plants
showing
heart rot
%
100
0
0
0

pH
8.0
8.0

Green Wt. per pot*
Tops
Roots
gms.
gms.
24.7
65.2
35.1
125. 3

6.2
6.2

34.7
37.5

130.4
164.0

* Average of two replications.
series not treated with sulphur, boron applied as borax at
the ra,te of ten pounds per acre increased the yield of roots
from 24.7 to 35.1 gms. per pot, and the yield of tops from
65.2 to 125.3 gms. per pot.

In a like manner,

sulphur ap­

plied at the rate of six and one-half tons per acre and with­
out borax increased the yield of roots from 24.7 to 34.7 gms.
per pot and the yield of tops from 65.2 to 130.4 gms. per
pot.

Thus the effect of the application of sulphur in lower­

ing the pH from 7.5 to 6.2 must have liberated boron to the
extent that the yield was increased in comparison with that
obtained from the application of ten pounds of borax.
The application of both sulphur and boron had no
advantage over either boron or sulphur alone.

The yield of

tops of the plants grown in the sulphur pots was increased
from 130.4 to 164.0 gms. per pot by an addition of borax,
although the root increase was only 34.7 to 37.5 gms. per
pot, the latter figures being entirely within experimental
error.

-20Such data would indicate that pH does play a major
role in the fixation of boron, but, as indicated by the yield
data in Table 1, pH is not the only factor influencing the
availability of boron.

As far as lime is concerned in the

fixation of this element,
First,

Its effects really are two fold.

It raises the pH of the soil and secondly furnishes

the calcium ion, both of which seem essential in fixing
boron into an unavailable form.

Rate of Fixation
A number of investigators (2,3,26,34) have reported
that toxicity of boron on sensitive plants has been lessened
considerably by delaying the planting date several weeks
after application of the borax.

Two reasons for this have

been suggested.
(1) Some of the readily soluble borax has been leached
out of the immediate reach of the young plants.
(2) A large portion of the borax has been changed over
to some less soluble form and therefore is less
available to the plant.
An experiment was started late in the fall of 1939 to
determine the fixing capacity of Thomas sandy loam soil for
boron.

The usual procedure for the application of nutrients

to pot cultures had been carried out but as the length of
day was very short it was considered advisable to wait until
the following spring to plant the soybeans.

Accordingly,

the pots were covered with wax paper and the date of planting

-21postponed for approximately six months.

The treatments in­

cluded applications of borax at the rates of 0, 30, 40, 80
and 100 pounds per acre.
In the spring ten seeds were planted in each 1-gallon
pot and the seedlings thinned to six soon after emerging from
the soil.

Their growth was observed and the length of time

necessary for the appearance of toxicity symptoms noted.
Little or no indication of toxicity was noticed on the
soybean plants until about 30 days after the plants had emerg­
ed from the soil.

At this time a few symptoms were apparent

on the plants which received the 100 pound application of
borax.

The remainder of the plants, as indicated in Table 5,
Table 5. The effect of borax on the yield
of the entire plant and the toxicity
of soybeans grown on Thomas sandy loam
pot cultures planted six months after
application.

Treatment
Check
30# Borax
40#
w
80#
"
100#
"

Yield
per pot*
gms.
11.3
10.3
11.1
9.8
8.4

Toxicity
None
n
«
«
Slight

^Yields are averages of two replicates.
did show a slight depression in yield.
The data in Table 5 seemed rather strange since
symptoms of toxicity had been observed when 20 pounds of
borax had been applied on the same soil in an earlier exper­
iment.

Therefore a new series of pots was set uo to see

how much injury to soybeans might occur on the same soil when

-22the soybeans were planted immediately after the borax applica­
tions were made*
In a new series soybeans were again grown in 1-gallon
glazed earthenware jars filled with 4 kgms. of the Thomas
sandy loam soil.

The usual applications of nutrient elements

with the exception of boron were applied to the soil.

The

duplicated treatments included 0, 10, 30, 50 and 100 pound
applications of borax.

Immediately after the application of

the nutrients, the usual procedure of planting was followed.
The plants were thinned to an even stand and their growth and
appearance noted and recorded.
A few days after the removal of the first crop of soy­
beans, the soil in each pot was removed, remixed and replaced
in the p o t .

A second crop of soybeans was planted on the

soil approximately two months after the application of the
borax.

An even stand in the pots was again maintained and

the effects of borax noted.
As shown in Table 6 , the plants seeded immediately
after the application of borax showed marked signs of
toxicity.

About ten days after emerging from the soil, the

toxicity symptoms were first observed.

The pots with the

heavy applications of borax showed the first symptoms, which
soon became very marked and the plants made a spindling grow­
th

and almost died.

The yields from pots which received more

than 20 pounds of borax per acre were greatly decreased while
those from the pots which received 10 pound applications were
slightly increased, from 26.5 to 28.1 gms. per pot.

The 100

-23Table 6 * The effect of various quantities of borax
and the time of planting, on the toxicity of
soybeans grown in Thomas sandy loam pot cultures.
Treatment
___________
Check
10# Borax
20#
M
50#
11
100#
H

First .Cr.pp5.
— Se.cond ,Crop5
Yield1_Toxicity______ Yield1 Toxicity
gms.
gms*
26*5
None
15.2 None
28.1
»
15.8
»'
23.5
Slight
16.3
"
9.1
Serious
8.9 Slight
4.5
Very serious
7.2 Serious

pYields are averages of two replicates.
rPlanted immediately after applications of borax.
^Planted two months after the application of borax.
pound application caused a decrease in yield from 26.5 to 4.5
gms. per pot.

The trend in yields decreased inversely as the

rate of application increased from 10 to 100 pounds.
The second crop of soybeans failed, as indicated in
Table 6 , to show any toxicity signs on the pots receiving
borax at the rates of 10 and 20 pounds per acre.

The yields

of the soybeans receiving these applications were slightly
above those of the check pots.

The soybeans that received

borax at the rates of 50 and 100 pounds per acre showed
toxicity signs and reduction in yields.

In neither case,

however, were the toxicity symptoms or reductions in yield
nearly so severe as in the first crop.

The 100 pound applica­

tion reduced the yield 83 per cent for the first crop and only
52 per cent for the second.
These experiments, while not quite identical in set­
up, indicate very clearly that the fixation of boron on the
soil studied is not instantaneous but a rather slow process.

•“3 4-

II.

SYMPTOMS OF BORON STARVATION AND TFF EFFEOT OF
BORAX ON THE YIELD AND CHEMICAL COMPOSITION OF
SEVERAL CROPS

Plant symptoms have been used for a long time to indi­
cate the lack or over-supply of certain nutrient elements with­
in the soil*

While it is impossible to distinguish all plant

needs toy certain characteristic starvation or toxicity symptoms
no one denies their value in solving plant nutrition problems.
This is especially true in case of the minor elements* since
the quantities of these elements compose such a small fraction
of the soil and the quantity necessary for normal plant g;rowth
is so extremely small.

Furthermore, chemical analyses may

fail to differentiate between the available and non-available
forms of the minor elements and for that reason may not al­
ways give an accurate indication of the response plants may
makd to an application of the minor elements under considera­
tion.

A study of plant symptoms followed by soil and plant

analyses should give the most accurate insight into the in­
dividual requirements of soils for proper plant development.
In order to determine what characteristic symptoms
are correlated with boron starvation and to secure plants
for analysis, a number of plants were grown in greenhouse
cultures.

These were also supplemented in a few cases with

plants from field plots.

Certain plants which showed def­

inite boron starvation symptoms were analyzed.

All these

analyses were made to see if any correlation exists between
the quantity of certain elements in the plant and the
starvation symptoms.
Methods for greenhouse studies pertaining to Part II
of this thesis have very much in common.

To avoid repetition,

the general greenhouse experimental procedure may be summariz­
ed as follows.

The crops were grown in glazed earthenware

jars filled with either Thomas sandy loam or quartz sand.
Adequate quantities of all nutrient elements with the excep­
tion of boron were supplied in all cases.
per 1-gallon jar and per acre —

These quantities —

are stated in Table 7.

Table 7.
The quantity of ea.ch nutrient element applied
to greenhouse pot cultures and its equivalent in
pounds per acre.
Urns, per
gal. pot

lbs. /
acre

Nutrient

1FeP04

1.00

500.0

MnS04 .4Hg0

0.008

4.0

1CaHP04 .2H20

0.50

250.0

CuS04

0.005

2.5

kno3

0.50

250.0

NaCl

0.005

2.5

C & (N03 )g •4HgO

0.25

125.0

Zn SO^

0.005

2.5

MgS04 .7HgO

0.25

125.0

Nal

0.001

0.5

Al2 (S04 )3.Hg0

0.0125

0.144

72.0

Nutrient

6 .3

2Ca(HP04 )2

lbs./
Gms. per
. gal. pot . acre

Applied separately as dry salt to sand culture.
^Applied separately in solution to Thomas sandy loam pot
cultures.
Uniform moisture relationships were maintained in all jars by
frequent weighing and addition of distilled water.

-26The number of plants within the jars was kept uniform
for each individual crop by early thinning or by direct trans­
planting.

The quantity of borax applied varied with the crop

under study.
At harvest time the plants were dried in an oven at
65°G. and ground to pass through a 1 mm. sieve.
Insufficient tissue in many cases limited the number
of analyses that could be made.

Symptoms of Boron Starvation
Sugar Beets - The boron starvation symptoms of the beets
have been reported in an earlier article (4) as follows.
symptoms are first noticed.

"Leaf

These are illustrated by the

plants in the greenhouse pot cultures as shown in Figure 3.

Figure 3. A large number of small leaves
some twisted and abnormally shaped,
indicate boron starvation.

I

-27The blackened and checked petioles are positive signs of
the heart rot.

Shortened and twisted petioles and large

numbers of small leaves are also reliable signs.
MAn insufficient supply of boron results in a
breakdown of the tissue in certain portions of the plant.
In the sugar beet the death of the growing center of the
crown and the production of such beets as shown in Figure
4 have resulted in the name heart rot.

Later in the season

Figure 4. After the fa-11 rains start, new
leaves often co rag out from around the
dead heart.
These leaves may soon
die or may attain full growth, accord­
ing to the condition of the beet.
some beets send out a large number of leaves from around
the edge of the crown.

These leaves may die after reaching

the stage shown in Figure 4, or they may continue to grow
until harvest time when they practically cover the dead heart.

-28"All sugar beets suffering from an insufficient supply
of boron do not exhibit the same symptoms of deficiency.
Some show leaf symptoms only, while others suffer breakdown
of the root tissue. 11
Canning Beets-— Red beets grown on boron deficient
soils show definite starvation symptoms.

These symptoms

have been described in several previous articles (5,17,22,29).
The outstanding signs of boron deficiency in red beets
occur within the root and has been termed "internal black
spot1' (30).

These spots are irregular in shape and usually

occur near the surface but occasionally in the central
portion of the beet.

The breakdown is generally found in

the lower portion, but In extreme cases it may extend through­
out the beet.
texture.

The spots are dark in color and corky in

The spots are not altered greatly by cooking and

present an unsightly appearance in the sliced beets.

Beet

roots of boron deficient plants are usually rather flattened
in shape and less symetrical than are the normal beets.
In general the leaf symptoms are similar to those
observed in sugar beets.
twisted;

The leaves are distorted and

one side of the leaf develops faster than the other,

giving the appearance of a half-spiral.

The concave side of

the oetiole displays a characteristic cross-checked appearance.
The affected leaves die and drop off early, while new
leaves continue to develop from the center of the crown.
extreme cases the beet takes on a rosette appearance,
numerous small leaves around the crown.

with

In

-29Htfhile the deep, unusually red color of the leaves of
red beets is not always indicative of boron starvation, it
is found in association with the above symptoms*
Mangels - Boron deficiency symptoms of mangels are very
similar to those of sugar beets.

The checking of the petioles

is not quite so prominent in mangels as in sugar beets, but
the shortened, twisted and deformed leaves are very common and
numerous small leaves appear at the lower edges of the crown.
The new leaves are generally at right angles to the crown and
give the plant a flattened appearance.
The roots in the pot cultures all showed internal
breakdown of the tissue as illustrated in Figure 5.

Figure 5. The effect of borax on the growth
and quality of mangel roots grown in
sand cultures*
Left - 2.5 pounds of borax per acre.
Right - No borax.

Cankers

-30have also been noticed in roots from fields where top
symptoms have indicated boron deficiency.
Rutabagas - The leaf symptoms of rutabagas are less
marked than are those of the sugar beet.

Some of the leaves

die prematurely but there are fewer deformed leaves than are
found on either sugar beets or mangels.
The most pronounced symptoms are found in the root.
As is true in most cases of boron deficiency in root crops
there is an internal breakdown of the tissue.
cankers, however,

Instead of

the root develops a "water-core” or "brown-

heart" condition which appears as dark brown water-soaked
areas in the central portion of the root*

These areas may

vary from small spots to areas comprising most of the interior
portion of the root.
Turnips - Other than growth, little difference as a
result of boron application could be noted in the tops of the
turnips.

The roots of the plants growing in soil to which no

borax had been applied were less elongated than were the nor­
mal plants.

Only a few small spots indicated a condition

similar to that reported as "brown-heart"•

McLeod (19) re­

ports that "brown-heart" is not usually found until the root
exceeds Z inches in diameter.

This probably explains why the

turnips grown in the greenhouse failed to develop this con­
dition.

Coulson and Raymond (8) described the external

symptoms as roughened skin on the roots and the development
of yellowish, mottled and distorted leaves.

Davis and

-31Ferguson (9) report the internal symptoms of the root with
"brown-heartn as a darkened, water-soaked condition of the
tissue which may develop into a hollow center*
Radishes - No leaf or root symptoms of boron starv­
ation other than size could be noted in the radishes grown
on pot cultures.

However, Wolf (33) reoorts checking of the

petioles, a condition similar to sugar beets, and Truniger
(3?) found that radishes grown on pot cultures without borax
had characteristic woody cankers on the sides of the roots.
Chicory - When starved for born this plant made only
a stunted growth.

Many of the leaves were twisted and the

petioles and midribs of the leaves were weakened.

As a

result of this condition some of the leaves were broken and
those not broken failed to stand as erect as did the leaves
of normal plants.

A very pronounced reddening occurred in

the leaves of boron starved plants*
The roots of the normal plant, as indicated in
Figure 6, were much larger and contained a more fibrous
root system.

No internal break-down of the tissue could

be noticed in any of the roots.
Barley - The barley plants showed very little differ­
ence in growth until the plants started to head, except for
a slightly heavier growth in the borax treated pots.

The

time of heading, as indicated in Figure 7, was hastened
about ten days by the borax application.

The pots receiv­

ing the heavier application headed first and those receiving

:

:

.,

.......

Figure 6. The effect of borax on the browth of
chicory roots in sand cultures.
Left - 3.5 pounds of borax per acre.
Right - No borax.
—« ■ i

Figure 7. The effect of borax on the growth of
barley in Thomas sandy loam pot cultures.
Left - No borax.
Center - 2.5 pounds
of borax per acre.
Right - 5 pounds of
borax per acre. Note the difference in the
heading.

-33the lighter application followed in order.

Some of the plants

in the untreated pots failed to produce heads and some plants
which did produce heads were stunted and little grain was
formed.
Wheat - The only noticeable effect of the borax upon
the growth of the wheat was the time of heading.

The wheat

in the pots receiving borax headed a few days sooner than
those plants not receiving borax.
Corn - No early effects of borax on the growth of
corn were noticed.

However, when the tassels started to shoot,

the leaves of the plants grown in pots without borax were ting­
ed with red.

The normal plants were larger, as illustrated in

Figure 8, and failed to show to any degree the red color in
the leaves*
The deficient plants were slower in tasseling than
the normal ones.

The symptoms of streaking of the leaves as

reported by van Overbeck (28) were not noticed in these
plaints.
Dandelions - Dandelions were transplanted from the
college campus into pots filled with Thomas sandy loam soil.
Three plants were placed in each pot.

Treatments, a check

and borax at the rate of 5 pounds per acre, were each re­
plicated four times.
The plants receiving borax made a more luxuriant
growth and the leaves stood more erect than was the case
with plants starved for boron.

As indicated in Figure 9,

borax influenced the blossoming and seed development of the

-34-

Figure 8. The effect of borax on
the growth of corn in Thomas
sandy loam pot cultures*
Left - No borax.
Center - 5 pounds of borax
per acre.
Right - 10 pounds of borax
per acre.

-35-

Figure 9.
The effect of borax on the bloom­
ing of dandelions in Thomas sandy loam
pot cultures.
Left - No borax.
Right - 5 pounds of borax per acre.
plants.

Shortly after transplanting some of the plants in

the borax treated pots started to bloom.

While the time of

blooming of these plants was not uniform every plant re­
ceiving borax blossomed quite profusely.

In contrast, not

one of the twelve plants without borax blossomed.

-36The Effect of Borax on Yields and the Chemical
Compos it ion of Several Crops.
Numerous investigators (4,8,9,19) have reported in­
creased yields of sugar beets, mangels, turnips and rutabagas
as a result of applications of borax.

Cook and Millar (4-) have

reported higher percentages of sugar in normal sugar beets than
in those suffering from heart rot.

Improved quality of canning

beets, cabbage, cauliflower and celery has been reported (5,29,
10,11,23) to be the result of applications of borax on soils de
ficient in this element*
Some writers (12,31) have reported better growth and
larger yields of alfalfa and clover as a result of borax ap­
plied in pots and in the field but it seems that plants belong­
ing to the family graminaceae need very little boron and do not
respond readily to applications of borax.
Various explanations have been advanced for the
physiological breakdown in the tissue of many plants suffering
from boron starvation.

Schmidt (24) has advanced the opinion,

based on experimental data, that plants suffering from insuf­
ficient boron assimilate more nitrate nitrogen than is needed
and that the cells break down as a result of the high nitrate
concentration.

It has also been mentioned that the function

of boron is to act as a regulator of the permeability of the
plasma membrane in controlling; the intake of certain ions.
To furnish more information on the response of various
crops to borax and to throw more light on the relationship
which may exist between the intake of boron and other elements

-37into the plant the following pages are devoted to a report of
the yields of crops grown for the purpose of studying plant
symptoms.

Attention is also given to the effect of borax, ap­

plied to the soil, on the content of boron,

iron, nitrogen,

potassium, calcium, and magnesium in the dried plant tissue.
SUGAR BEETS
Sugar beets were grown in pot cultures of Thomas sandy
loam soil.

Various elements were separately omitted from

some nutrient solutions supplied to the cultures and doubled
in concentration in others.

Borax was supplied at rates of

10 and 30 pounds per acre, respectively.

The effect of the bor­

ax on growth was determined by weighing; the roots and tops at
harvest time.

The samples were saved for chemical analyses.

To supplement the analyses made on plants grown in
greenhouse cultures, field samples from the same soil type
were analyzed.

These were gathered according to the appearance

or non-appearance of heart rot symptoms.

The beets with heart

rot were selected from the area shown in Figure 1, and the
normal beets from another area in the same field.
Yields
In the Thomas sandy loam pot cultures borax, applied at
the rate of 10 pounds per acre, prevented heart rot and in­
creased the yield of roots from 48.7 to 90.4 gms. per pot and
the yield of tops from 109.0 to 131.4 gms. per pot.

The 20

pound application of borax resulted in a slightly greater
yield of tops but a smaller yield of roots than was obtained as
a result of the 10 pound treatment.

-38Composition
The effect of boron starvation on the composition of both
the tops and roots of sugar beet plants is shown by the data re­
ported in Tables 8 and 9.
Boron - The boron content of the dried tops of the beets
grown in pot cultures was increased from 10 to 20 ppm. by the 10
pound application of borax and from 10 to 24 ppm. by the 30
pound application.

Likewise the roots from the plants which had

received borax contained more boron.

The increase in boron con­

tent was from 10 to 14 and 15 ppm. for the 10 and 20 pound ap­
plications, respectively.
The data obtained from the analyses made on field samples
show close resemblance to those obtained from the greenhouse
sample analyses.

The boron content of the dry tissue of field

grown beets having heart rot was 10 ppm., identical with that
of similar beets produced in pot cultures.

The dried tissue of

normal beets produced in the field contained 13 ppm. of boron
as compared to 15 ppm. in the dried tissue of beets grown in
pot cultures which had received borax.
Iron - The iron content of both roots and tops of the
sugar beets grown in the green house pot cultures was consider­
ably higher in the plants which were low in boron content.

The

iron content of the dried roots was decreased from .033 to .013
per cent by a borax application equivalent to 10 pounds per acre.
Marked differences were found in the iron content of
field grown beets.

That of the dried tissue from beets showing

symptoms of heart rot was .028 per cent as compared to .011 per
cent in the tissue of normal beets.

-39-

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-40Potassium - Field grown sugar beets with heart rot were
lower in potassium than were normal beets*

These results vary

from those obtained from greenhouse cultures in which there
was no apparent change in the potassium content as a result of
the application of borax*
Nitrogen - Boron starvation in the plant was accompanied
by a higher content of nitrogen in both the roots and the tops.
In the pot cultures an application of borax at the rate of 10
pounds per acre decreased the content of nitrogen by .14 per
cent in the dried roots and by .66 per cent in the dried tops.
The doubled application of borax did not cause a further decrease
in the nitrogen content of the dry tissue.
In the field samples the beets showing heart rot symptoms
contained .63 per cent more nitrogen in the dried tissue than
did the normal ones.

The percentage of nitrogen in the field

samples was higher than in the pot-culture samples.
Calcium and Magnesium - The 10 pound application of borax
produced only slight changes in the calcium and magnesium con­
tents of the sugar beet plants grown in pot cultures.

The data

indicate, however, a general trend toward higher percentages of
these elements in plants grown in a medium containing an in­
sufficient supply of boron.

This trend is quite evident in the

samples obtained from the field.
CANNING BFFTS
Canning beets, otherwise spoken of as "garden beets",
were grown in Thomas sandy loam pot cultures.

Three pots re­

ceived complete nutrient solution including borax at the rate

-41of 10 pounds per aore and three others received nutrient sol­
ution

from which the borax had been omitted.

The effect of

borax was determined from the weight of the roots

and tops at

the end of 65 days from the date of planting and from analyses
made on the dried tissue of the roots and tops.
The effect of borax applied in the field on this crop
was determined from random samples selected from plats included
in an

experiment conducted on Emmet sandy loam by Cook and

Millar (5).

The

different farms.

samples were selected from eight plats on two
Four of the eight plats received borax ap­

plied broadcast at the rate of 40 pound's per acre and the other
four received no borax.

The percentages of beets in the random

samples showing signs of boron starvation,

internal black soot,

were determined by slicing the samples.
Yields and Black Spot Occurrence
As shown by the data presented in Table 10 the growth
of the garden beet in pot cultures was greatly stimulated by
Table 10, The effect of borax on the yield of
canning beets and on the boron and nitrogen
content of canning beet tope grown in pot
cultures of Thomas sandy loam soil.
Treatment
0# Borax
10# Borax

♦Yield /pot
Roots
Tops
2.5
7.3

7.9
14.9

Boron
ppm.
7.5
27.5

Nitroeen
f°
1.78
1.45

* Average of three replications.
the application of borax.

The yield of roots was increased

from 2.5 to 7.3 gms. and that of the tops from 7.9 to 14.9
gms. per pot by a 10 pound application.

Borax applied in the

-42field at the rate of 40 pounds per acre was very effective in
reducing signs of boron starvation.

The data reported in Table

11 show that this reduction was from 54.30 to 5.96 per cent.
Table 11.
The effect of borax on the occurrence
of internal black spot and the boron and
nitrogen content of canning beets grown in
Antrim county.
Treatment

Beets showing*
internal black soot

Boron
ppm.

54.30
5.96

17.3
19.9

0# Boron
40# Boron

Nitrogen
1o
2.01
2.02

Composition
Boron - The boron content of the dried tops of canning
beets grown in Thomas sandy loam pot cultures was increased from
7.5 to 27.5 ppm. by an application of 10 pounds of borax per acre
Considering the low level of boron in the tissue of the untreated
plants the increase seems highly significant.
Applied in the field on Emmet sandy loam an application
of borax at the rate of 40 pounds per acre increased the boron
content of the dry tissue from 17.3 to 18.9 per cent.

This

difference is slight compared to that obtained in the beets grown
in pot cultures.

The difference in results obtained in the two

experiments may be the result of leaching which occurred in the
field.
Nitrogen - The nitrogen content of the dried tissue of
beets grown in pot cultures was lowered from 1.78 to 1*45 per
cent by an application of 10 pounds per acre of borax.

No

differences occurred in the nitrogen contents of beets grown in
the field experiments.

-43MANGELS
Mangels were grown in sand cultures with and without borax#
The rate of borax application was equivalent to 2#5 pounds per
acre.

The treatments were replicated four times.
Yields
As indicated in Table 12 borax applied to mangels grown

in sand cultures at the rate of 2.5 pounds per acre increased
the yield of tops from 4.2 to 8.7 gras, and of roots from 7.8 to
22.6 gms. per pot.
Table 12. The effect of borax on the yield and
boron, nitrogen and iron content of sugar
beets grown in sand cultures.

Treatment
0# Borax
2*5# Borax

♦Yield/pot
Roots:Tops
7.8
22.6

Boron ppm.
Roots:Tops

Nitrogen
Roots:Tops

Iron %
Roots:Tops

7.5 17.5
10.0 50.0

1.36 1.53
1.02 1.35

.014 .035
.011 .029

4.2
8.7

♦Average of four replications.
Composit ion
Boron - The boron content of the dry top tissue was in­
creased from 17.5 to 50.0 ppm. and that of the dry root tissue
from 7.5 to 10.0 pom.
Nitrogen - In the dry tissue of the mangel, nitrogen was
decreased from 1.63 to 1.35 per cent in the tops and from 1.36
to 1.02 per cent in the roots.
Iron - The iron content of the dry mangel tissue decreased
from .035 to .029 per cent in the tops and from .014 to .011 per
cent in the roots with an application of 2.5 pounds per acre of
borax.

-44RUTABAGAS
Field samples of rutabagas were selected according to
boron deficiency symptoms from a Brookston clay loam soil located
near Ionia, Michigan*

Normal plants and those showing symptoms

of boron starvation, brown heart* were selected from the same
field*
Compos ition
Boron - As indicated in Table 13, the normal rutabaga
plants were higher in boron than were the deficient ones.

The

dried tops of normal plants contained 10 ppm. more of boron than
did the deficient tops and the dry root tissue from normal plants
contained 5 ppm. more than did roots with brown heart.
Table 13. A partial analysis of normal and boron
deficient rutabagas grown on Brookston clay
loam.
Symptoms
No rmal
Boron deficient

Boron ppm.
Roots:Tops
15
10

30
20

Nitrogen ?~ Iron
Roots:Tops Roots:Tops
3.15 3.19
2.23 2.43

.036 .338
.078 .499

Nitrogen - The nitrogen content of the normal plants was
lower than that of those starved for boron.

The difference on

the dry basis was .08 per cent in the case of the roots and .34
per cent in the tops•
Iron - The iron content of the rutabagas showing brown
heart was more than double that of the normal plants.

The

dried tops from the infected roots contained ,497 per cent iron
while the dried tops from normal roots contained only .328 per
cent of iron.

The roots contained less iron than the tops, but

-45the same relationship between/ iron content and the deficiency
symptoms held.
The results of these analyses show rather conclusively
that the symptoms present in the rutabaga roots were really
those of boron starvation.
TURNIPS
Turnips were grown in Thomas sandy loam pot cultures.
Treatments consisted of a check and borax equivalent to 5
pounds per acre.

Treatments were replicated two times.
Yields

As indicated in Table 14 an application of borax,
equivalent to 5 pounds per acre increased the yield of both the
tops and the roots of turnips grown on Thomas sandy loam pot
cultures.

The yield of roots was increased from 44.2 to 49,3

gms. per pot and the yield of tops from 54.7 to 66.0 gms. per
pot.
Table 14.
The effect of borax on
the yield of turnips grown on
Thomas sandy loam pot cultures.
* Yield
Roots
Tops
gms •
gms.
44.2
54.7
0# Borax
49.3
66 •0
5# Borax
’•'Average of two replicates.

Treatment

RADISHES
Radishes were grown in Thomas sandy loam pot cultures.
Treatments consisted of a check and borax apolied at the rate
of 5 pounds per acre.

Each treatment *was replicated two times.

-46Yields
The effect of borax on the yield of radishes is indicat­
ed in Table 15*

An application equivalent to 5 pounds of borax

per acre caused the yield of radish roots to increase from 31*5
to 53.9 gms. per pot.

A small increase in the yield of tops

accompanied the increase in yield of roots.

*Yield gms.
Roo ts:Tops

Treatment
0# Borax
5# Borax

53.9 31.5
57.7 53.9

p
p I
B
*!

Table 15.
The effect of borax upon the yield and partial
analysis of radishes grown on Thomas sandy loam pot
cultures.
Boron
Roots: Tops

Nitrogen %
Roots:Tops

Iron °(o
Roots:Tops

17.5 30.0
30.0 37.0

3.88 4.25
2.52 4.08

.064 .033
.043 .023

^Average of two replicates.

"

Composit ion
Boron - As indicated in Table 15, the borax treated
plants were higher in boron content than were those not treated
with the salt.

The boron content of the dried root tissue was

raised 2.5 ppm. and that of the tops 17.0 ppm. by this small
applicat ion.
Nitrogen - The nitrogen content of both the tops and roots
of radishes was decreased by borax.

This decrease in the dried

tissue of the roots was .36 per cent and in the dried top tissue
it was .31 per cent.
1 rc>n - The iron content of the radishes not receiving
borax was higher than that of those receiving borax.

The per­

centage of iron in the dried tops and roots was decreased from
.032 to .023 per cent and .064 and .043 per cent, respectively,
by an application of borax equivalent to five pounds per acre.

-47CHICORY
Chicory was grown in quartz sand cultures*

The treat­

ments consisted of a check and an application of borax at the
rate of 3.5 pounds per acre.

All treatments were replicated four

t imes.
Yields
An application of borax at the rate of 3.5 pounds per
acre increased the yield of chicory roots from 29.5 to 33.4 gms.
and the yield of tops from 15.6 to 19.6 gms. per pot.

The data

are reported in Table 16.
Table 16. The effect of borax on the yield and
analysis of chicory grown in sand cultures.
Treatment

*Yield sms. Boron ppm.
Roots:Tops Roots:Tops

0# Borax
3.5# Borax

24.9 15.6
32.4 19.6

7
9

14
28

Nitrogen io
Roots:Tops

KaO i
Roots

Iron %
Roots

0.34 1.15
0.24 1.07

1.32
1.17

.014
.011

♦
A.r/a
1 -i Cl4-^ <=
* Average
of four replicates.
Boron - The borax increased the boron content of the dried
chicory roots only slightly but doubled the boron content of the
dried leaves.

The increase was from 14. to 28. ppm.

Nitrogen - The nitrogen content of the roots and tops of
the chicory plant was decreased by the borax application.

The

decrease in the nitrogen content of the dried roots was from .34
to .24 per cent and that of the tops was from 1.15 to 1.07 per
cent •
Potassium and Iron - The potassium and iron contents of
the chicory roots were likewise decreased by the 3.5 pound ap­
plication of borax.

On the dry basis this increase amounted to

.15 per cent for potassium and .003 per cent for iron.

-48BARLEY
Barley was planted on Thomas
applied atthe rates of 3.5 and 5.0

sandy loam soil andborax

was

pounds per acre. Each treat­

ment was replicated three times.
Yields
The effect of borax on the yield of the entire barley
plant is shown in Table 17.

Applications of borax equivalent

to 2.5 and 5.0 pounds per acre, respectively,

increased the yield

of barley from 3.2 to 4.6 and 4.9 gms. per pot.
Table 17. The effect of borax on the
total yield of the barley plant
grown in Thomas sandy loam pot
cultures.
Total yield
of plant*
gms .
3.2
4.6
4.9

Treatment
0# Borax
3.5# Borax
5.0# Borax

♦Average of three replicates.
m-IEAT
Winter wheat was planted in the fall in Thomas sandy
loam pot cultures.

The jars were left in a screened room,

without glass and adjacent to the greenhouse, until mid-winter
when they were moved into the greenhouse.

The treatments con­

sisted of borax at the rates 0, 3.5 and 5.0 pounds per acre,
replicated three times.
Yields
The borax resulted in slightly increased yields as shown
by the data reported in Table 18.

The pots receiving borax at

the rate of 2.5 pounds per acre yielded 3.0 gms, per pot more than

-49did those which received borax at the rate of 5 pounds per acre*
The 5 pound per acre application may have been too much for the
crop.

That the small increase in yield recorded for the 2.5

pound per acre application of borax is not entirely due to
experimental error is indicated by the fact that the wheat which
received borax headed before that grown without borax.
Table 18.
The effect of borax on
the yield of the entire wheat
plant grown in Thomas sandy loam
pot cultures.
Yield *
gms. per pot

Treatment

18.8
20.8
19.3

0# Borax
2.5# Borax
5.0# Borax

CORN
Corn was grown in 2-gallon jars filled with 8 kgms. of
Thomas soil.
per acre.

Borax was applied at the rates of 5 and 10 pounds

The treatments were replicated three times.
Yields

As indicated in Table 19, borax applied at the rates of
5 and 10 pounds per acre increased the yield of the total corn
plants from 86.5 to 103.5 and 117.4 gms. per pot, respectively.
Composit ion
Boron - The boron content of the dried corn plants, roots
and tops, was increased from 5 to 15 ppm. bv an application of
5 pounds of borax per acre and from 5 to 18 ppm. by an ap­
plication of 10 pounds per acre.
Nitrogen - The nitrogen content of the corn was not alter­
ed by applications of borax.

-50Iron - The iron content of the dried tissue of the corn
plant was decreased from .053 to .045 per cent by an application
of borax equivalent to 5 pounds per acre*

An additional 5

pounds of borax did not further decrease the iron content of the
dried tissue.
Table 19. The effect of borax on the yield*
and partial analysis* of corn grown on
Thomas sandy loam pot cultures.

Treatment
0# Borax
5# Borax
10# Borax

Yield of
Fodder
gins«
86.5
103.5
117.4

Boron
ppm.

Nitrogen
1o

5
15
18

1.30
1.26
1.18

Iron
$
.053
.045
.046

♦Average of three replications.
DISCUSSION
As the data in the preceeding sections indicate, most
plants that are deprived of boron, accumulate larger quantities
of calcium, nitrogen, magnesium, and iron.

The greatest dif­

ferences in mineral content between the normal and deficient
plants occur in the contents of iron, nitrogen, and boron.
Borax applied to boron deficient soils reduces the nitrogen and
calcium content of plants grown thereon provided there is an in­
crease in yield, but when toxic quantities of borax reduce the
yields the calcium and nitrogen contents of the plants are often
greater than those of the deficient plants*

-'Several investigat­

ors (13,13, 34,25) have reported higher nitrogen contents on a
number of crops over similar crops receiving sufficient boron.
Few investigations have been reported concerning the iron-boron
relationship•

-51The accumulation of calcium in boron deficient plants has
been reported by Shkolnik (25).

Some evidence has been present­

ed which indicates that deficient plants are low in potassium.
However,

the data reported in this paper leads one to believe

that potassium content is not greatly altered by response of
plants to boron.

Field grown sugar beets showing boron deficiency

symptoms were low in potassium, while chicory roots growing in
boron deficient greenhouse cultures were high in this element.
In no case was there a large difference in potassium content
■as a result of applications of borax.
Application of borax resulted in an increase in the boron
content of the tissue of all plants.

It was found also that

field samples of sugar beets, canning beets and rutabagas show­
ing boron deficiency symptoms contained less boron than did
normal crops grown in the same fields.
The data might lead one to believe that the function of
boron is to act as a regulator of the permeability of the plasma
membrane and control the intake of certain ions.

However, the

increased quantities of nitrogen, iron, and calcium in deficient
plants, may be entirely due to retarded plant development.

The

data regarding potassium, however, tend to disprove the latter
idea.
Boron appears to have definite functions within the plant.
Hoot cells of the sugar beet, canning be-t, rutabaga, turnip and
radish developed improperly and formed woody cankers or "brown
heart" if not supplied with a small quantity of boron.

The pre­

mature death of old leaves and the development of numerous small
leaves usually accompanies the development of woody tissue in

-53the root crops.
Cereals and other seed-bearing plants often fail to
blossom and develop fruit with insufficient supply of boron.
Lohnis (18) reports that wheat,

rye, and barley failed to pro­

duce fertile blossoms without small quantities of boron.

A

decrease in the blossoming of snap dragons has been reported to
be due to the lack of boron (13).

Improper development of

cotton buds has also been related to boron deficiency (36).
In the experiments reported here, corn, wheat, barley
and dandelions failed to develop seeds properly when boron was
lacking.
There is little doubt that different plants require
different amounts of boron for proper growth.

The amount re­

quired for wheat would hardly be sufficient for sugar beets.
It appears also that some plants may be far superior in their
ability to secure boron from the soil.

Soybeans, sensitive

to moderate applications of borax, require more boron in the
tissue on the dry basis than do sugar beets.

The dry tissue of

various crops grown on Thomas sandy loam pot cultures varied
in boron from 5 to 20 ppm. where borax had not been applied.
Applications of borax which may prove toxic for one crop may
hardly be sufficient for another.
SUMMARY AND CONCLUSIONS
Soybeans were grown in pot cultures of Warsaw sandy loam
and Hillsdale B. horizon.

The soil treatments consisted of

CaC03 , CaSC>4 , MgCOg, MgS04 , Na3C03 , NagSO^j. and a control with and

-53without borax.

These soybeans were analyzed by the author for

boron, calcium and nitrogen to determine the effects of these
treatments on the chemical composition of the plant.
Soybeans were grown in pot cultures of nine Michigan
soils.

Soil treatments included borax at rates equivalent to

0, 10 and 20 pounds per acre.

These were grown to determine the

soil factors influencing boron fixation.

The analyses of the

soybean plants from these pot cultures were made to determine
the influence of soil factors and the application of borax on
the content of boron, calcium, magnesium,

iron, and nitrogen in

the plant tissue.
To ascertain the effect of pH on the availability of
boron, sugar beets were grown on an alkaline soil.

This soil

previously failed to supply sufficient boron for the proper
development of sugar beets.

Four treatments consisted of a

check, borax equivalent to 10 pounds per acre, sulphur suffic­
ient to lower the pH from 7.5 to 6.2 and sulphur with borax.
In order to determine the rate of fixation, soybeans
were planted on Thomas soil at intervals of six months, two
months and immediately after the application of borax at rates
varying from 0 to 100 pounds per acre.
A number of crops - sugar beets, canning beets, mangels,
rutabagas, turnips, radishes, chicory, barley, wheat, corn and
dandelions - were grown on either a boron deficient soil or a
boron deficient quartz sand culture.

These crops were grown

to determine boron deficiency symptoms and to secure normal
and boron-deficient plant tissue for chemical analyses. Certain

-54crops were analyzed for boron, calcium, nitrogen, potassium,
magnesium and iron to see if any correlation exists between
the mineral content of these crops and the supply of available
boron in the soil.
The results of these experiments may be summarized as
follows:
1.

CaCOg and MgCOg applied to Warsaw and Hillsdale B horizon
reduced the boron content of the soybean tissue.

2.

NagCOg and NagSO^ applied to the above soils did not alter
the boron content of the soybean tissue.

3.

CaS04 and MgSO^ decreased the boron content of soybeans
grown on the Hillsdale B horizon where excessive borax
had been applied but did not alter the boron content
of the tissue where borax had not been applied.

4.

Accumulations of calcium and nitrogen accompanied an
excessive boron content in the plant tissue.

5.

The soil constituents, namely active calcium, organic
matter and clay content, which prevent applied borax from
becoming toxic to soybeans prevent boron from accum­
ulating in the plant tissue.

6.

Yields were increased with applications of borax until the
boron content of the plant tissue, on the dry basis,
reached 30 ppm*

7.

Boron becomes toxic to soybeans when the content of the
dry tissue exceeds 50 to 60 ppm.

8.

The magnesium and iron contents of soybean tissue were not
greatly altered bv toxic quantities of boron.

-559.

Sulphur equivalent to six and one-half tons per acre, applied
to Thomas sandy loam pot cultures, was as effective as
borax in controlling heart rot of sugar beets.

10

. Delayed

planting in Thomas sandy loam pot cultures, after

the application of toxic quantities of borax, reduced the
toxic effect of the borax to soybeans.

11 .

An insufficient supply of boron for root crops is usually
evidenced by breakdown in root tissue, distortion and
premature death of the leaves and the forming of numerous
small leaves.

12

.

Lack of sufficient amounts of boron for barley, wheat and corn
delayed heading.

13.

Dandelions with an insufficient supply of boron failed to
bloom.

14.

The tissue of plants deprived of boron was in most cases
higher in percentage of calcium, nitrogen, magnesium and
iron than was the tissue of plants grown in the presence
of sufficient boron.

15.

Borax applied to the soil in all cases increased the boron
content of the dried tissue of plants grown on the soil.

16.

Plants with characteristic boron deficiency symptoms were
relatively low in boron content.

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14*

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Pacific Coast