Some observations upon the effect of borax in fertilizers

Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices.

Dniuersity of Maine

Maine Agricultural Experiment Station

ORONO
BULLETIN 288 JUNE 1920

SOME OBSERVATIONS UPON THE EFFECT OF
BORAX IN FERTILIZERS.

CONTENTS

PAGE
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GI STOMMIGHON its, 5.4 6s = o8-Aag aed G Sacre, <i dh) oles slersne ary = Meets go
Hieldohservations on potatoes im} TQIOQm sd:swtrws .ylsiee sates 94
muy iw relation tomtestilizem (ised sta. 4 nih ie chee ain ey h 95
Greenhouse experiments with fertilizers containing borax 103
VMO TCM Wil OLATOES 5.2 eiencalevees hale cat pre ote te sis bis Betas chat ote 105
Results from greenhouse experiments with potatoes..... 107
Wionkaewath other CrOpS.t resis ee pice tiled aerios Gar seas 118
ERS ARES MMR ec o0 cauh ole. ane Thicit ae HemPEPe Hina Aulal Pies bos Able o's aa eR 118

MAINE
AGRICULTURAL EXPERIMENT STATION
ORONO, MAINE

THE STATION COUNCIL

PRESIDENT ROBERT J. ALEY, President
DIRECTOR CHARLES D. WOODS, Secretary
ORA LE ee Blorettion, Committee of
FRANK E. GUERNSEY, Dover, Boardtopl trustees

CHARLES S. BICKFORD, Belfast,

eo ee eer eres o cece reece cceo ee

Commissioner of Agriculture

EUGENE H. LIBBY, Auburn, State Grange
WILSON W. CONANT, Buckfield, State Pomological Society
FRANK S. ADAMS, Bowdoinham, State Dairymen’s Association

LEONARD C. HOLSTON, Cornish, Maine Livestock Breeders Ass’n.
WILLIAM G. HUNTON, Portland, Maine Seed Improvement Ass’n.

AND THE HEAps AND ASSOCIATES OF STATION DEPARTMENTS, AND THE
DEAN OF THE COLLEGE OF AGRICULTURE

THE STATION STAFF

CHARLES D. WOODS, Sc D. Director
ADMINIS- ESTELLE M. GOGGIN, Clerk
TRATION CHARLES C. INMAN, Clerk
MARY L. NORTON, Clerk
JOHN W. GOWEN, Pu. D., Biologist
KARL SAX, Biologist
BIOLOGY RAYMOND PEARL, Pa. D., Collaborator
MILDRED R. COVELL, Clerk
BEATRICE GOODINE, Laboratory Assistant
JAMES M. BARTLETT, M. S., Chemist
CHEMISTRY « ELMER R. TOBEY, M. S., Assistant
C. HARRY WHITE, Pu. C.,, Assistant
ENTOMOL- EDITH M. PATCH, Pa. D., Entomologist
OGY ALICE W. AVERILL, Laboratory Assistant
PLANT WARNER J. MORSE, Pu. D., Pathologist
PATHOLOGY DONALD FOLSOM, Pu. D., Assistant
VIOLA L. MORRIS, Laboratory Assistant
AROOSTOOK ( JACOB ZINN, Acr. D., Assistant Biologist
FARM E. RAYMOND RING, A. B., Superintendent
HIGHMOOR WELLINGTON SINCLAIR, Superintendent
FARM | HUGH C. McPHEE, B. S., Scientific Aid
ROYDON L. HAMMOND, Seed Analyst and Photographer
n, ef BD.
NOVA onal

BULLETIN 288

SOME OBSERVATIONS UPON THE EFFECT OF
BORAX IN FERTILIZERS.

W. J. Morse.
SUMMARY

Unexpected and material losses in the form of partial or
almost total crop failure occurred in 1919 on a large number of
Maine potato fields where the customary relatively large appli-
cations of commercial fertilizer were made. Injury to the parts
of the plants below ground was apparent early in the season.
In severe cases many plants failed to reach the surface of the
ground and those that grew had a characteristic appearance
differing from types of injury or disease previously observed.

Field studies, covering a wide variety of conditions, showed
that these losses were, for the most part, confined to the fields
where fertilizers manufactured by certain individual companies
were applied. Moreover the trouble appeared to be associated
with the potash used in the manufacture of these fertilizers, for
it did not occur where the no-potash fertilizers put out by the
same concerns were used.

The Station chemist found boron present in appreciable
amounts in these fertilizers wherever samples could be obtained
of those used on the fields where the type of injury in question
appeared. No definite cases of similar injury were observed
where it could be shown that borax-free fertilizers carrying
approximately similar amounts of nitrogen, phosphoric acid and
potash were applied.

Limited experiments have been made with pot cultures in
the greenhouse in which fertilizers containing borax were ap-
plied to potatoes, beans, oats, wheat and buckwheat.

With potatoes samples of 6 different lots of fertilizer sold
in Maine in 1919 were used. At the rate of application the
amount of anhydrous borax used varied from nothing to 38.6
pounds per acre, the most extensive trials being at the rate of
17.6 pounds per acre.

90 Marine AcricuLTURAL ExpERIMENT Station. 1920. a

The results of the greenhouse experiments to a large ex-
tent confirm the field observations. Potato plants in pots con-
taining no commercial fertilizer and those in pots to which a
borax-free fertilizer was added were free from injury. No
plants which received fertilizer containing borax escaped injury
in some form or other. In general the amount of injury varied
with the amount of fertilizer used, but the results were not uni-
from in this respect.

Except where the largest amount of borax was applied, the
type of injury in the greenhouse differed in some important
respects from that observed in the field. Killing of the tips
and margins of the leaves was characteristic of the greenhouse
potato plants. At the rate of 17.6 pounds of anhydrous borax
per acre the most severe leaf injury was obtained where the
fertilizer was mixed with the upper 6 inches of soil in the pot
or with the 3 inches of soil below the seed-piece and the plants
heavily watered. The larger applications of boron caused
greater root injury, more stunting of the plants and less tip and
marginal injury to the leaves.

An application of fertilizer in the drill equivalent to 4.4
pounds anhydrous borax per acre caused severe injury to beans,
while broadcasting the same fertilizer, applying the equivalent
of 8.8 pounds anhydrous borax per acre caused no apparent
injury to oats, wheat and buckwheat.

INTRODUCTION.

The soils of New England are particularly free from sub-
stances which are deleterious to plant growth. Hence the ap-
parent presence of some poisonous salt in the fertilizer used by
many potato growers in Maine in the season of 1919 presented
an entirely new problem to the farmers and the fertilizer trade
and to the students of plant diseases as well.

Certain difficulties had been experienced in the use of chem-
ical commercial fertilizers coincident with the partial and later
the total disappearance on the market of European potash as the
result of the war. Partly because experiments conducted by this
Station and partly because the experience of certain practical .
growers had shown that on the Caribou loam, the most extensive
and best type of potato soil in the State, the potash content of
the fertilizers could be reduced materially without greatly les-
sening the potato crop, but more on account of the fact that

Tue Errect oF BorAx IN FERTILIZERS. 91

potash was high in price and was for the most part unobtain-
able, a large amount of no-potash fertilizers were used for the
first time in 1916. Most frequently these contained 5 per cent
of ammonia and 10 per cent of available phosphoric acid and
were known as 5-10-0 goods.

A “new potato disease” made its appearance in July of that
season. The foliage of the affected plants, instead of being a
normal, healthy dark green, showed first a peculiar bronzing
and yellowing. As the disease progressed the plants had, on
casual inspection, much the appearance of potatoes just previ-
ous to ripening. In the final stages the leaflets hung limp and
the entire plant wilted. Usually discolored areas appeared on
various parts of the stems. A very characteristic feature of the
trouble was the formation of a dry, discolored, spongy area
which involved the whole stem just at the surface of ta€e ground.
Following this discoloration of the basal portions of the stem
the tissues would dry out, the stem would become hollow at that
point and the plant would fall over. Cross sections of the stem
sometimes showed a discoloration of the water or food conduct-
ing vessels.

When the trouble first appeared in 1916 there was some
reason to suspect that it was of a parasitic nature. The various
lesions scattered over the stems were of a light brown or red-
dish brown color and later usually showed a lighter colored cen-
ter. A number of different fungi were found to be associated
with the lesions, but most frequently the lighter colored portion
would be studded over with the fruiting bodies of a fungus of
the genus Phoma. Repeated attempts to reproduce the disease
in healthy plants by inoculation with cultures of this and other
fungi isolated from spots on potato stems obtained from dif-
ferent parts of the State resulted in failure. This seemed to
disprove the theory of a parasitic cause of the disease.

It was soon discovered that this so-called “new disease” oc-
curred only where the 5-10-0 fertilizers were used and there, in
destructive amounts, it was largely confined to the poorer types
of soil. Even small amounts of potash in commercial fertili-
zers or the application of relatively small amounts of stable
manure in addition to the 5-10-o fertilizer would correct the
difficulty. Later experience fully confirmed the conclusions

92 MAINE AGRICULTURAL EXPERIMENT STATION. 1920.

reached in 1916 that the fundamental cause of this trouble was
lack of potash in the fertilizer.*

These experiences led Maine potato growers to demand
that the manufacturers supply them with fertilizers containing
potash. The manufacturers met this demand as far as possible,
using various American sources of this material, but it was not
till 1919 that relatively large amounts of such fertilizers were
sold which contained potash in amounts at all comparable to
that used before the war. The so-called Searles Lake deposits
in California being the largest and most promising source of
American potash were naturally used in many cases. These de-
posits are not pure potash salts but contain mixtures of other
materials, including compounds of boron. Certain samples
of this potash, used in the manufacture of fertilizer that came to
the attention of the Station in 1919 contained the equivalent of
from 5 to 10 per cent of sodium biborate or borax.

No attempt will be made to discuss in this publication the
general problem of the effect of boron or its compound borax
upon plant growth or to review previous literature upon this
subject. It may be said, however, that it is only within a very
short time that it has even been suspected that the small amounts
of borax that have been found in the fertilizers under considera-
tion would prove so toxic to farm crops as now appears to be
the case.

Neither is an attempt made to discourage the use of Amer-
ican potash, provided it can be produced cheaply enough so that
American farmers can afford to use it and provided it can be
sufficiently freed from deleterious impurities so that it can be
used with safety. The experiences of the past few years sim-
ply serve to emphasize the importance and even the necessity
for all concerned to unite in supporting, in every way possible,

*For some reason, possibly due to more general use of stable ma-
nure, this trouble did not attract much attention in southern New Eng-
land till later. In 1918 it was sufficiently common in southern Connecti-
cut and on Long Island and surrounding territory to cause much com-
ment and alarm. Here again there was a strong tendency to look upon
it as a parasitic disease with Phoma as the causal fungus. On the other
hand Dr. Geo. P. Clinton, after a thorough canvass of the situation
seems to have reached, in part, similar conclusions as to the fundamental
cause, as were obtained in Maine. (See Potato Magazine Vol. 1, No.
12, June, 1919. Prematuring and Wilting of Potatoes, G. P, Clinton.)

Tue Errect or Borax IN FERTILIZERS. 93

any movement which has for its object making American agri-
cultural and manufacturing interests partially or wholly inde-
pendent of foreign sources of potash. In this connection it may
be said that the company principally interested in marketing
potash from the Searles Lake deposits states that with improvec
methods of refining they are now putting out a potash in which
the amount of borax is reduced to less than one per cent.

Some Practices FoLLowED By Maine Potato GROWERS.

Methods of growing the potato crop vary considerably in
different parts of the country. It may, therefore, assist the
general reader if a brief statement is made relative to certain of
the practices followed in Aroostook county where most of the
observations were made upon the effect of borax in fertilizers.
While there are numerous variations, potatoes usually follow
clover in a 3-year rotation, in which oats constitute the third
crop. While some stock is kept, the great majority of potatoes
are grown upon chemical fertilizers supplemented by humus
obtained from clover sod alone or from this and “second-crop”
clover plowed under the fall before.

In the last 20 or more years the amount of commercial
fertilizer used has gradually and quite materially increased until
now an application of 2000 pounds per acre is not an uncom-
mon practice and some growers use more than this. With few
exceptions this fertilizer is all applied in the drill at planting
time. Some planters distribute it above the seed-piece and some
below. Those planters in most general use do not deposit the
fertilizers in direct contact with the seed-piece, but close to it
and not mixed very much with the soil.

Formerly, when potash was relatively low in price, it was
not uncommon to apply fertilizers containing as high as 10 per
cent of this ingredient. A 4-6-10 was one of the mixtures pop-
ular with Maine potato growers in 1914 and for some years
previous. The samples collected by the Bureau of Inspections
of the State Department of Agriculture and analyzed by the
Station chemists show that the amount of potash in the special
potato fertilizers had dropped to 4 per cent or lower in 1915.
In 1916 only a few samples of 4-per cent goods were found.
For the most part the fertilizers found that year contained one

94 MaINne AGRICULTURAL EXPERIMENT StaTION. 1920.

or two per cent of potash and many none at all. Conditions
improved somewhat in 1917, there being more evidence of 3 and
4-per cent goods. A still greater proportion of the 1918 samples
were of the 4-per cent potash grade, while in 1919 some 6-per
cent goods were found. With the reduction in the amount of
potash used in potato fertilizers sold in Maine during the last
5 years there has been a tendency to increase the amount of
phosphoric acid, not because experience had indicated any need
for this, but apparently because it was the cheapest and most
plentiful fertilizing material that the manufacturers could ob-
tain.

It is interesting to note that, in spite of these wide varia-
tions in the composition of the fertilizers used, no general com-
plaints have been made by the potato growers, previous to 1919,
of ill effects from their use, except where 5-10-0 or similar mix-
tures were used, although in 1918 there was some undercurrent
of feeling that the results obtained from goods carrying Ameri-
can potash were not quite up to expectations. While it is an
open question whether such excessive applications of potash as
are made when 2,000 pounds of fertilizer per acre are used, con-
taining 10 per cent of this material is necessary or wise, the re-
sults obtained from the practice previous to 1914 were such as to
convince many practical potato growers that it was good business.
The only bearing that the question has on the matter under con-
sideration is that it serves to emphasize the fact that even exces-
sive applications of the type of potash used prior to 1914 resulted
in no dissatisfaction on the part of the users.

FIELD OBSERVATIONS ON INJURED Potato FIELDS IN I9QIQ.

Early in July 1919 rumors began to reach the Station that
some fields of potatoes in Aroostook County were not showing
normal germination and growth. Definite complaints began
to be received about the middle of July by both the State De-
partment of Agriculture and the Experiment Station. The
Director of the Station, and the Chiefs of the Bureaus of In-
spections and Seed Improvement of the State Department at
once decided to make a joint, personal investigation of the sit-
uation. As a member of this party the writer spent ro days in
the field studying conditions at that time. During the remainder

Tue Errect oF BorAx IN FERTILIZERS. 95

of the growing season considerable attention was given to sim-
ilar field studies in various sections of the State.*

It soon developed that the trouble was confined largely to
the fertilizers manufactured by certain individual companies
and, as far as the writer observed, to the brands put out by
these companies which contained 4 or 6 per cent of potash.
Wherever samples could be obtained of the goods used, the
analyses made by the Station chemist showed the presence of
borax in appreciable amounts. It later developed that borax
might be present in a fertilizer from other sources, from mix-
tures of nitrate of potash and soda for instance, but in the field
observations under consideration the trouble seemed always as-
sociated with the potash used. For example, some fields were
seen where a part was planted with a fertilizer containing pot-
ash, and another part planted with a no-potash fertilizer put
out by the same concern. The plants where the last named
material was used appeared strong and vigorous when examined
the latter part of July, while those where the potash goods were
used showed various degrees of what will be described as borax
injury.

NATURE AND AMmouNT oF INJURY OccuRRING oN Porato
FIELDS AND Its RELATION TO THE FERTILIZER USED.

Although the type of injury may differ, as will be pointed
out later, the presence of even small amounts of borax in a fer-
tilizer when such fertilizer is applied at the rate of a ton per
acre has a very marked effect on the potato plant, both in the
field and in the greenhouse. In the field the casual observer
first notes, in severe cases, a stunted appearance of the plants,
with an abnormal number of “skips” or failures to germinate.
Such a field is shown in the foreground of Fig. 14. Note the
vigorous growth and even stand of the plants in the background.
This portion of the field was planted three weeks after the first.

*The writer was especially fortunate in being able to inspect a large
number of these fields in company with Dr. George H. Pethybridge,
Economic Botanist to the Department of Agriculture and Technical In-
struction for Ireland, Dr. A. D. Cotton, Mycologist to the Ministry of
Agriculture and Fisheries, London, and Mr. E. J. Wortley, Director of
Agriculture, Bermuda, all of these gentlemen being potato-disease spec-
lalists of international reputation.

96 Marne AGRICULTURAL EXPERIMENT StaTIoNn. 1920.

A 4-8-6 fertilizer was applied in the same manner in each case,
but different lots obtained from different manufacturérs were
used.* Equally striking differences were observed from the use
of these two fertilizers on the same field, using the same seed
planted the same day. All injury disappeared at the exact point
where one fertilizer ran out and the other was placed in the
planter.

On severely injured fields, like that mentioned above, a close
inspection revealed the fact that there were few normal plants.
At the time when the plants on uninjured, near-by or adjoining
fields were for the most part strong and vigorous and nearly
covered the ground, those where the injury occurred presented
a very striking contrast. An occasional plant might be found
which approached normal appearance, but for the most part
those that came were weak and sickly looking, many being only
two or three inches high. An intertesting fact was noted that
many of these stunted plants blossomed at the same time as
healthy plants of the same age.

The foliage of the injured plants, where borax was present
in the fertilizer, had a characteristic appearance. There was
considerable yellowing of the leaves, more particularly of the
margins. This was most prominent on the more dwarfed and
more severely injured plants. The yellowing was of a bright
golden color, and not the pale, sickly yellowing usually present
in plants that are normally or prematurely ripening. In the
milder cases the abnormal color was restricted to the extreme
edges of the leaves. In fact, as field observations progressed,
the appearance of this very narrow band of yellow at the mar-

*Unfortunately samples of these two lots of fertilizer could not be
obtained for analysis. The only evidence that the differences shown on
the adjoining portions of this field was due to the presence of boron in
one of the fertilizers used is that wherever it was possible to obtain
samples of the same brand of fertilizer where it had been used on fields
that showed similar injury, these samples contained borax in more than
appreciable amounts. On the other hand no samples of the other brand
were found which contained any borax. Only one complaint was re
ceived where any of the goods manufactured by this concern were used
Here no sample could be obtained. The writer examined the field in
question and, while it was seen too late in the season to form an accurate
opinion, was not convinced that the owner’s contention that he had a
case of borax injury was correct.

97
}
gins of the leaves, particularly the lower ones, came to be looked
upon as an important diagnostic character in cases of suspected
borax injury, where the effects were not sufficient to produce
serious stunting and failures to germinate. In severe cases the
leaves themselves were frequently narrowed and in certain in-
stances the smaller leaves at the top were noted as folded up-
ward on the mid-rib.

Tue Errect oF Borax IN FERTILIZERS.

Fic. 14. Two different brands of 4-8-6 fertilizer were used on this
field. The portion shown in the background was planted 3 weeks later
than that where the weak, scattered plants occur. See foot-note on p. 96.

On many borax injured fields, for the most part planted
during the last two weeks in May, a marked change began to
take place about the first of August. The plants which sur-
vived started to grow and, as a result, many of the more marked
symptoms of the trouble as already described either disappeared
or became masked by the growth of the plant. This apparent
recovery is explained on p. 100. The only borax injured potato
field that the writer was able to visit at regular intervals
throughout the season, indicated that this improvement in the
condition of the plants came too late to materially aid in pro:
ducing a crop. This seemed to be the general opinion of owners
of fields which showed similar conditions.

98 MAINE AGRICULTURAL EXPERIMENT STATION. 1920.

The parts below ground showed other striking evidences
of injury. The nature of this injury varied somewhat with the
type of planter used, that is, whether the planter deposited the
fertilizer above or below the seed piece. It also varied with the
-amount of borax-containing potash which was applied. For
example, the injury where a 4-8-6 fertilizer was used was more
‘severe, as a rule, than where the same amount of 4-8-4 goods
from the same manufacturer was applied.

As might be expected some of the worst cases of injury
observed were those where the fertilizer was deposited above
the seed piece and the stem of the plant had to grow up through
it. On one such field in particular there was a large amount of
browning of the stems in the region of the fertilizer. Many
cases were found where the stem was entirely cut off and in
some instances it had sent out new branches from below, which
in turn might or might not be cut off. Injury to the stems be-
low ground also frequently occurred where the fertilizer was
deposited below the seed piece but this was more often close
to the base or point of attachment of the stem.

The lesions somewhat resembled those caused by Rhizoc-
ttonia, but were invariably much lighter brown in color and were
more likely to entirely encircle the stem. Rhizoctonia may or
may not be present as a complicating factor, but there is plenty
of evidence in the line of field observations which indicate that
neither it nor any other parasitic fungus is a material factor in
the production of stem lesions which are attributed to the pres-
ence of borax in the fertilizer used. For example, the owner
of the field shown in Figure 15 used a fertilizer containing
borax up to the point where the stake is placed in the row. At
this point he changed to another brand of fertilizer of the same
formula but which contained no borax, and immediately con-
tinued planting. The plants on the left showed all the typical
symptoms of severe borax injury described above and numbers
of them selected at random showed the stem browning and in-
jury in practically every case. On the other hand the plants
of the portion of the field at the right of the stake, where the
other fertilizer was used, were normal in appearance, nearly
covered the ground at the time the record was made, and showed
no evidence of injury to the parts below ground.

Fic. 15. A fertilizer containing borax was applied to the left-hand
portion of this field. The stake in the row at the center marks the point
where the owner changed to a fertilizer of the same formula, but con-
taining no borax.

Fic. 16. A 3-6-6 fertilizer, with a smaller amount of 5-10-0 applied
Jater, was used on the two and a fraction rows beginning with the point
marked with the hat and ending at the point where the stake is placed.
The potatoes on either side were fertilized with 5-10-0 alone. See p. 102.

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Fic. 17. The plants on the left received a small amount of fertilizer
containing borax. Those on the right received no fertilizer. See p. 103.

Fic. 18. This illustrates the appearance of many of the badly injured
fields during the latter part of July.

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THe Errect oF BorAx IN FERTILIZERS. 99

Fic. 19. Bad cases of borax injury in the field. This represents the
entire growth made by the plants in three months. Note that the root
system is almost entirely destroyed. Compare with Fig. 21.

Browning and killing of the roots was a very prominent
sign of the trouble, being more pronounced in the case of the
badly dwarfed plants. This condition is well illustrated by
Figure 19 from a photograph made on August 13. It will be
noted that in spite of the fact that the seed pieces had been
planted nearly 3 months the plants had made practically no
growth above the surface of the ground. The roots had been
killed off at the base and there were no roots present at the
nodes of the stem, where it was covered with soil, as would nor-
mally be the case. Of the roots at the base of the stem, whether
the fertilizer was applied above or below the seed peice, fre-
quently nothing remained but a tuft of dried, brown stubs.

Seed-pieces in direct contact with the fertilizer often
showed a burning and erosion of the cut surfaces. In general,
however, the presence of borax seemed to have a preservative

100 Maine AGRICULTURAL EXPERIMENT Station. 1920.

effect on the seed-piece, since there was a marked absence of
decay in the latter where fertilizers were used which contained
it in considerable quantities.

Plants which survived till the middle of the summer usu-
ally began to put forth roots from the stem close to the surface
of the ground or in the region most remote from the point of
application of the fertilizer.* These plants, if they had not
been too severely injured, then began to grow fairly rapidly as
the result of the partial establishment of a new root system in
the hilled-up soil, out of contact with the fertilizer. As has
already been stated the yellowing and other evidences of injury
disappeared more or less completely with the new growth. This
belated or secondary growth of the injured plants tended also
to obscure the number of missing hills and thus improved the
appearance of the affected fields generally. Such of these fields
as it was possible to observe from time to time during the season
proved very deceptive to those who were not familiar with their
history. The yields of tubers were far from what might be
expected from the appearance of the partially recovered plants.
One field in particular, which the writer had under observation
during the latter part of the growing season, showed marked
improvement during August and September, but the owner ob-
tained only about one-third of a normal yield. The fertilizer
used carried 0.88 per cent anhydrous borax and at the rate used
was equivalent to an application of 17.6 pounds of anhydrous
borax per acre.

The above description of the injury to potatoes in the field
and attributed to the presence of borax in the fertilizer used,
applies more particularly to the severe cases. All gradations
between this and fairly normal plants might be found on the
same field. A few mild cases of injury were seen where it was
rather difficult to decide whether or not the trouble was due to
the presence of borax in the fertilizer. Some of these were

*For the benefit of those who are not familiar with the cultural
practices followed with potatoes in Maine it may be said that it is cus-
tomary to cover the plants with a horse hoe as soon as they begin to
break ground. This is repeated when the plants begin to appear a sec-
ond time. Hence a considerabe ridge or hill is already formed from
the surface soil, well above the seed-piece and fertilizer, before the plants
finally come up.

Tue Errect or BorAX IN FERTILIZERS. 101

seen so late in the season that most of the prominent symptoms
had disappeared. None of these were classed as borax injury
unless fairly conclusive evidence such as the characteristic stem
and root burning could be obtained. In this connection it may
be said that in every one of such mild or doubtful cases where
field observations gave presumtive evidence of borax injury and
samples of the fertilizer could be obtained the samples were
found by the chemists to carry borax in appreciable amounts.

No attempt has been made by the present writer to secure
data as to the yields on any considerable number of fields where
borax injury occurred, but numerous cases have been reported
where the yields were not over half or one-third of a normal
crop and some of the more severely injured fields would hardly
produce a sufficient crop to pay the cost of harvesting.

The early part of the growing season of 1919 in Aroostook
county was quite dry. In a few instances much less injury was
observed on the lower and less thoroughly drained portions of
the fields. In one case the owner planted part of a field a few
days before a heavy shower and finished the remainder of it
after the rain. Much less injury occurred on that part of the
field planted after the rain. Since borax is readily soluble, these
observations suggested that it was carried away by the soil
water and that in seasons of ordinary rainfall in June much
less injury from borax might be expected. Other observations
indicated that more thorough mixing of the fertilizer with the
soil than is commonly practiced would prevent or materially re-
duce the amount of injury. In the greenhouse experiments
described later an attempt was made to test these theories and
it will be seen that they were not wholly confirmed.

In studying conditions in the field it soon developed that
there was sufficient evidence of a general nature to convince the
average person that the trouble under consideration was associ-
ated with the fertilizer applied, moreover, that it was in some
way connected with the potash used in the fertilizer in most
instances. On the other hand many individual cases of them-
selves, when considered alone, fell far short of actual proof of
this, or of proof approximating that which can be obtained
through experimental evidence. However, a few fields of
potatoes were found which provided conditions approaching

102° MAINE AGRICULTURAL EXPERIMENT STATION. 1920.

those which might be selected under actual experiment. Two of
these will be described by way of illustration.

Mr. A. on one side of a field of several acres applied a
3-6-6 fertilizer at the rate of 1700 pounds per acre, all in the
drill at planting time. Next to this, a section of the field was
planted with 1300 pounds of the 3-6-6 goods per acre in the
drill, with 500 pounds of a 5-10-0 fertilizer applied later on top
of the row. Next came 4 rows with 1700 pounds per acre of
5-10-0 applied in the drill at planting time. Then following
were two and a fraction rows with 1300 pounds per acre of
3-6-6 in the drill at planting time and with 500°pounds of 5-10-0
on top of the row, the same as the second section of the field
described. The remainder of the field was planted with 5-10-0
goods at the rate of 1700 pounds per acre in the drill at plant-
ing time. ;

When examined first on July 21 the plants where the 5-10-0
fertilizer was used alone were, on the average, strong and vig-
orous. Where the 3-6-6 fertilizer was used alone or in com--
bination with the 5-10-0 goods there appeared, in addition to
numerous “skips” or failures to produce plants, the character-
istic stunting of the plants, with yellowing of the leaves, more
especially at the margins, and varying amounts of injury to the
parts below ground. The injury was more pronounced where
the 1700 pounds per acre of the 3-6-6 fertilizer was applied in
the drill at planting time than where only 1300 pounds of this
fertilizer was used at that time and 500 pounds of 5-10-0 was
applied later.

Figure 16 is from a photograph of the two and a fraction
rows which received 1300 pounds per acre of the 3-6-6 in the
drill and 500 pounds of the 5-10-0 later. On either side are
rows of plants which had 5-10-0 alone at the rate of 1700 pounds
per acre in the drill. The barrel stave in one row indicates
where one fertilizer gave out and the other began.

Mr. B. had a field of 44 acres of potatoes, on which he
applied a 4-8-4 fertilizer in the drill. He began to plant using
this at the rate of 2400 pounds per acre. Later he cut the
amount down to 2000 pounds per acre. Then seeing that he had
an insufficient amount of fertilizer to finish the piece, and being
unable to secure an additional supply, he reduced the amount
from time to time till he reached the minimum that the planter

Tue Errect or Borax IN FERTILIZERS. 103

would apply. Finally he ran out of fertilizer and finished the
piece without any.

It was impossible to locate with any degree of accuracy
where all of these changes in the amounts of the fertilizer ap-
plication were made on this field, but one had no difficulty in
locating the exact point where he began to plant with no fer-
tilizer at all. The plants where no fertilizer was used were
more vigorous and uniform than those on any other portion of
the field. The contrast between the appearance of the plants
where no fertilizer whatever was used and those next to them
that received only a small amount of fertilizer is shown in Fig.
17

Fig. 18 is a fairly representative illustration of the condi-
tions observed on this field and numerous others during the lat-
ter part of July, 1919.

Where the larger amounts of fertilizer were used there
were many missing hills. The plants averaged small and weak
with yellowing of the margins of the lower leaves. The smaller
leaves at the tops of the more stunted plants were folded to-
gether. Not much stem injury was noted at the time of obser-
vation, but frequently the stems were found to be those which
had branched up from below where the original stems had been
killed below ground and had entirely disappeared.

The injury appeared in different degrees on all parts of
the field to which the fertilizer was applied, but with each de-
crease in the amount of application it was evident that there
was a corresponding decrease in the amount of injury produced.
In a few instances the differences between adjoining sections of
the field were sufficiently marked to indicate the probable point
where the changes were made on the planter to reduce the
amount of fertilizer application.

GREENHOUSE EXPERIMENTS WITH FERTILIZERS CONTAINING
Borax.

The close relation between the presence of borax in the
fertilizers used and the injury which occurred on many potato
fields, as shown by the observations made during the summer
of 1919, led to the planning of certain greenhouse experiments
with fertilizers, with and without borax, using potatoes, beans,

104 MaIne AGRICULTURAL EXPERIMENT STATION. 1920.

oats, wheat and buckwheat. The results reported here are those
obtained from what from the first have been regarded as pre-
liminary studies, but it is believed that they are of sufficient sig-
nificance to be of value as a matter of record at this time.

These preliminary experiments possess certain limitations,
some of which will be mentioned. While, as will be seen, the
results with potatoes and beans were quite striking and uniform,
a larger number of pots for each individual treatment would
have been better. The relatively smal! number of pots used
was partly due to the limitations imposed by lack of greenhouse
space, but more particularly in the case of potatoes it was due
to the fact that at the time the work was begun, October 3, it
was difficult to secure a sufficient amount of satisfactory seed
potatoes in condition for immediate germination. While the
results show that fertilizers containing borax produced varying
amounts of injury to potatoes and that such injury did not oc-
cur on plants in pots containing borax-free fertilizer or in pots
containing no fertilizer, they do nof show conclusively that
borax is the sole and only factor involved. They furnish very
strong presumptive evidence that this is the case. There are
also certain objections that might be raised to the method used
in applying water to the pots.

Plans were made whereby it was intended to repeat and
amplify these experiments to meet the objections enumerated,
as far as the limitations of greenhouse space would permit. It
was then found that the Directors of the other Agricultural
Experiment Stations in New England, New York and New
Jersey were interested in joining in conducting a cooperative
greenhouse experiment on a relatively large scale in which the
effects of the presence of different amounts of borax in fertili-
zers when used on potatoes, corn and beans would be determined.
Arrangements were perfected whereby this work was begun
about February 1, the final plans being prepared by the Director
of the Maine Station and the writer. To Mr. J. R. Neller of the
New Jersey Station, an expert in pot culture, was assigned the
responsibility of carrying out the details of these cooperative
experiments, which are now in progress in the Vermont Station
greenhouses.

As soon as the plans mentioned above were perfected, werk
along similar lines was discontinued at Orono. The fcilowing

Tue Errect oF BorAX IN FERTILIZERS. 105

concerns only the results previously obtained in the preliminary
experiments at this Station, or between October 1, 1919, and
about January 15, 1920.

WORK WITH POTATOES.

Soil. The soil used for potatoes was a medium heavy
loam which had been under cultivation for many years, being
used each year for garden purposes. In recent times it has
had an application of barnyard manure on alternate years and
commercial fertilizer applied yearly. It was taken directly
from the garden and placed in pots in the greenhouse.

Kinds of fertilizers used and amounts applied. Six differ-
ent brands of fertilizers, made by five different concerns and
sold in Maine in 1919, were used. In every instance the ap-
plications of all fertilizers to pots containing potatoes were made
at planting time and as nearly as possible at the rate of 2,000
pounds per acre. The usual fertilizer analysis of each lot had
been made by the Station chemists, including a quantitative de-
termination for borax. These results and certain other data,
including the number of pounds of anhydrous borax used when
the several fertilizers are applied at the rate of 2,000 pounds
per acre, are shown in tabular form.

Table Showing Composition of Fertilizers Used.

Per cent of Pounds of anhy- |

Station No. Composition anhydrous drous borax per Number of
borax acre pots used

5549 4-8-6* 0.88 17.6 20

5389 4-8-6 0.85 7.0 4

5518 3-6-6 0.93 18.6 4

5536 3-6-6 1.44 28.8 4

5513 4-8-6 1.93 38.6 4

5409 4-8-6 0.00 00.0 4

Checks, no fer-
tilizer — —— —- 4

*The figures in this column represent approximately the per cents of ammonia,
available phosphoric acid and potash respectively.

Variation in methods of application of fertilizer. As will
be seen by the number of pots given in the right-hand column
of the table, the most extensive trials were made with

106 MAINE AGRICULTURAL EXPERIMENT STATION. 1920.

fertilizer No. 5549 which, when applied at the rate of 2,000
pounds per acre, was equivalent to an application of 17.6 pounds:
of anhydrous borax per acre. With this fertilizer the 20 pots
were divided into 5 different lots of 4 pots each, according to
the method of application. In the first lot the fertilizer was:
thoroughly mixed with the upper 6 inches of soil in each pot.
In the second it was distributed in a strip about 3 inches wide:
across the pot (in a manner similar to the way it is deposited in
the row in the field by the planter) just below the seed-piece,.
but not in direct contact with it. In the third the fertilizer was:
distributed in a manner similar to the second, but just above
the seed-piece. In the fourth lot it was thoroughly mixed with.
the 3 inches of soil just below the seed-piece, while in the fifth:
it was thoroughly mixed with the 3 inches of soil above the
seed-piece.

With each of the remaining 5 fertilizers, namely, Nos. 5389,
5518, 5536, 5513 and 5400, only 4 pots were used, representing
two pots each of the second and third methods of application
described for No. 5549. Four other pots were planted with
potatoes without adding any fertilizer. These and those in
which fertilizer No. 5409 was used, which contained no borax,
were introduced as checks.

Seed tubers used. There were available a small amount of
tubers which had been produced in pots in the greenhouse, har-
vested in the early summer and stored in a cool basement. These
were firm and vigorous and some were just beginning to sprout
at the time of planting. A half of a tuber was placed in each
pot, care being taken to distribute the halves so that no two
would have the same fertilizer treatment.

Depth of planting. In all cases the distance was 3 inches
from the top.of the seed-piece to the top of the soil after plant-
ing. Wherever the fertilizer was distributed in drills above or
below the seed-piece without mixing with the soil, a thin layer
of soil was placed between it and the seed-piece.

Watering. All of the pots which were 10-inch and of the
ordinary unglazed type, were placed on benches with saucers
underneath. One-half of all of the pots, representing the dif-
ferent methods of application of the various fertilizers, were
kept heavily watered, while the other half had a scanty water
supply or were kept as dry as possible and still have them moist
enough for growth. As a rule this required about 300 and 150

Tue Errect oF Borax IN FERTILIZERS. 107

cc. of water respectively per pot daily. All of the water was
applied in the saucers, thus making the water current always
upward through the soil in the pot.

Temperature. The temperature control was set at about
70 degrees F. during the day and from 50 degrees to 55 degrees
F. during the night. During the night of December 15 on
account of the failure of the University heating plant to fur-
nish sufficient steam the temperature fell to the danger limit
and some of the plants nearer the walls of the house were frozen.
This seriously interfered with certain features of the work and
made it impossible to make some desired photographic records,
but it did not materially affect the final results and conclusions.

Records. While changes in the appearance of individual
plants were noted as soon as they appeared, detailed records of
the growth and appearance of each plant were made weekly. At
the close of the experiment all plants were removed from the
pots and the root systems separated from the soil as carefully
as possible and examined for injury.

RESULTS OBTAINED FROM GREENHOUSE EXPERIMENTS WITH
POTATOES.

Except for some mosaic the unfertilized check plants re-
mained perfectly healthy till they were removed from the pots
3 months after planting. The plants in the pots containing the
borax-free fertilizer No. 5409 were entirely free from any evi-
dence of fertilizer injury or disease. This entire lot was in-
cluded in the few plants which were badly injured by frost.
However, all of the other plants which developed borax injury
had shown it, in marked degree, some time previously. Of the
4 pots fertilized with No. 5409 one was about g inches high and
the other 3 about 15 inches high when killed by frost on Decem-
ber 15. Unfortunately no photographs had been taken to show
their appearance at that date. All that can be said is that at
this time the health and vigor of these 4 plants showed a marked
contrast to the other 40 in the experiment, including the un-
fertilized checks.

No plants which received fertilizer containing borax es-
caped injury in some form or other. In general the amount of
injury varied with the amount of borax present in the fertilizer

108 Maine AGRICULTURAL EXPERIMENT StaTIon. 1920.

nESPsin Sm al

a:
E
Ff

Fic. 20. These two plants were photographed about two weeks after

appearing above ground. The fertilizer used in pot 32 carried a relatively
high percentage of borax, while that applied to pot 44 contained no borax.

‘See p. 109.

Fic. 21. This represents the total growth made in the greenhouse in

three months by one of the plants fertilized with No. 5513, equivalent to
38.6 pounds of anhydrous borax per acre. Compare with Fig. 19.

Tue Errect or Borax IN FERTILIZERS. 109

used, but the results were not entirely uniform in this respect.
As might be expected the most severe injury occurred with
fertilizer 5513 where the amount of anhydrous borax applied
was equivalent to 38.6 pounds per acre. The 4 plants in this
series were much stunted and yellowed, although those having
the fertilizer applied above the seed-piece finally made a partial
recovery and attained a height of 7 and 12 inches respectively in
3 months time. The early condition of the last mentioned or
larger plant is shown in Fig. 20, pot 32. At that time it was
weak and yellowed. The plant in pot 44 was grown on fertil-
izer No. 5409 which contained no borax. The two plants ger-
minated within two days of each other and were about two
weeks above ground when the photograph was made. The two
plants where fertilizer 5513 was placed below the seed-piece
-made very little growth. At the end of 3 months one consisted of
simply a rosette of small leaves just at the surface of the soil.
See Fig. 21. The other was only 3 inches high.

The amount of injury obtained with fertilizer No. 5389
where the application of anhydrous borax was equivalent to 7
pounds per acre was somewhat surprising. Not only was there
some stunting and yellowing of the plants where the fertilizer
was applied below the seed-piece, but a considerable amount of
the type of injury next to be described was present on all of
them.

THE MOST COMMON TYPE OF INJURY TO POTATOES IN THE
GREEN HOUSE.

While some of the plants in the greenhouse, more particu-
larly in the case of heavy applications of borax, showed the
yellowing and a stunted, shrubby appearance similar to that
characteristic of plants in the field where borax was present
in the fertilizer used, this was not general. Yellowing was more
or less in evidence in a number of cases when the plants were
young but this usually disappeared as they became older. Quite
a different type of injury occurred, without exception but in
varying degree, upon all plants which were grown in pots con-
taining a fertilizer which carried borax.

This type of injury was characterized by death and drying
out of the tips and margins of the leaflets. The injury first

110 MAINE AGRICULTURAL EXPERIMENT STATION. 1920.

appeared on the basal leaves and afterwards on the upper ones,
and almost without exception was noted on the tips of the leaf-
lets first and then on the margins. While the whole margin might
be affected, the trouble was more severe and appeared first on
the half of the leaflet nearest the tip. In like manner the ter-
minal and first two lateral leaflets were attacked first and were
more severely affected. Fig. 22 shows a plant all of the
leaves of which are affected in this way. The injury was first
observed between two and three weeks after the plant came up
and the photograph was made six weeks after that. At that time
the two lower leaves had fallen and two more were about ready
to fall.

Fic. 22. Type of injury most common in the greenhouse. The tips
and margins of practically all of the leaves are affected. See also Fig.
ZO pee lili7e

The age of the leaf seemed to be a determining factor. A
lower leaf might be badly affected while the leaves from a young

Tue Errect oF BorAx IN FERTILIZERS. 111

shoot formed in its axil would appear entirely healthy at the
same time. However these leaves from the younger shoots
nearer the base later showed the same marginal injury.

The dead tissues suggested more of an olive tinge than a
browning. A comparison with standard color charts failed to
match any shade or tint of brown except possibly in the case of
the first appearance of the injury on the tip of a leaflet. The
color was difficult to match and about the best description that
can be given is that it resembled most closely what might be ex-
pected where a potato leaf had been killed rapidly and quickly
dried with little yellowing.

The appearance of the affected leaves seemed to indicate
simply a progressive death and drying out of the tissues. While
there was a fairly sharp line of demarkation between the
diseased and healthy portions of the leaves, the latter near this
line usually showed more or less fading out of the normal green
color to a lighter green or even a yellowish tinge. In advanced
stages the leaf-blades themselves would become yellow, soon fol-
lowed by the dropping of the leaf. Some of the more severely
injured plants lost all of their leaves before they were dug up
early in January.

In some instances there was a suggestion of what has been
called “tip-burn” of the potato. However, there is no reason for
confusing this tip and marginal injury on greenhouse plants,
resulting from borax applied to the soil with the fertilizer, with
the usual forms of the tip-burn in the field. It occurred under
relatively humid conditions, at a time of the year when sunlight
was at its lowest intensity, and in greater degree on the plants
supplied with an abundance of moisture. The plants were en-
tirely free from insects of all kinds.

Several facts, taken together, strongly suggest that this tip
and marginal injury is the direct result of the accumulation of
compounds of boron in the tissues affected. Droplets of liquid
were constantly observed upon the tips and margins of the
leaflets of potato plants grown in the greenhouse particularly
at the times when no other explanation could be given for their
presence, except that they exuded from the leaves themselves.
Moreover faint traces of a whitish deposit were repeatedly
seen on these leaves in the same locations after the droplets had
evaporated. This condition was found to be common and was

112 MAINE AGRICULTURAL EXPERIMENT STATION. 1920.

in no way restricted to plants grown in pots containing borax
or to plants included in the experiments under consideration.

The size and rapidity of growth of many of the plants which
showed this type of injury in marked degree, particularly those
which were heavily watered, indicated considerable root growth
and this was confirmed by later examination. Likewise plants
which suffered severe root injury and stunting as the result of
heavy applications of borax showed relatively smaller amounts
of the tip and marginal injury. Therefore it seemed reasonable
to suppose that compounds of boron were being taken up by the
roots, were being carried along with dilute solutions of food
materials and deposited in the leaves. Since there is constant
evaporation of water from the leaves and a fairly constant cur-
rent of water from the roots upward through the stems and con-
tinuing through the leaves to the margins of the latter, it would
seem that any materials or salts brought along in solution in this
transpiration current, which were not used by the leaves in the
manufacture of food materials for tissue building or for storage,
would tend to concentrate most at or near the margins and that
this concentration would be greater in the older leaves. A suf-
ficient concentration of any poisonous material would result in
the death of the tissues at that point.

To test the above assumption with reference to boron in
the plants in question some of the dead margins of the injured
leaves were removed with scissors. At the same time an ap-
proximately equal amount of the margins of healthy leaves was
obtained from plants which were grown upon fertilizer No: 5409
which contained no boron. These were tested qualitatively by
the Station chemist on December 3, or two months after the
tubers were planted. The sample from the injured leaves gave
a positive test for boron while that from the healthy leaves gave
a negative test.

RELATION OF THE TIP AND MARGINAL INJURY OF THE LEAVES TO
THE METHOD OF APPLICATION OF THE FERTILIZER AND
WATERING.

Based upon the larger series of pots with fertilizer 5549
where the applications of anhydrous borax were equivalent to
17.6 pounds per acre, fertilizer applied below the seed-piece,

Tue Errect oF Borax IN FErTILIzers. 113

whether mixed or unmixed with the soil, caused greater tip
and marginal injury than where it was applied above the seed-
piece. Mixing fertilizer with the soil resulted in greater leaf
injury, unless it was mixed with the soil above the seed-piece.
Abundant watering increased the amount of leaf injury. Stated
in another way, the most severe leaf injury was obtained where
the fertilizer was mixed with the upper 6 inches of soil or with
the 3 inches of soil below the seed-piece and the plants heavily
watered.

It will be remembered that with the remaining 5 lots, the
fertilizer was applied only in the drill, both above and below
the seed-piece. Half of the pots in each lot were abundantly
watered and the other half scantily watered. As has been
stated very healthy, vigorous plants were obtained with No.
5409 which contained no borax. The other 4 lots which rep-
resented varying applications of borax gave results in general
agreement, as far as they went, with those given above for No.
5549. The most severe injury of both types resulted from the
application of the fertilizer below the seed-piece, and abundant
watering—as a rule—produced more tip and marginal injury.

On account of the relatively small rainfall in Aroostook
county in June, 1919, the water supply for the plants, previous
to the appearance of the injury in the field, where most of the
more serious cases were seen, was largely from below upward.
A desire to duplicate field conditions as nearly as possible was
what led the writer, in planning the greenhouse experiments, to
decide to make all applications of water to the pots from below.
The results obtained indicate quite clearly that the method of
watering -adopted, materially influenced the relative amounts of
leaf injury which resulted from the variation in the methods of
fertilizer application. Continued watering from above has still
greater objections as it would have a tendency to carry the borax
away from the plants. Alternate watering from above and
below, such as was decided upon in the case of the cooperative
experiments now in progress, undoubtedly is the nearest ap-
proach to field conditions that can be obtained in the green-
house. It is granted that, in the confined conditions imposed
by the pot, there is less opportunity for the plant to escape from
the poisonous action of the borax, but in spite of this fact and
the objection to the method of watering mentioned above it is

114 Marne AGRICULTURAL EXPERIMENT STATION. 1920.

believed that these greenhouse experiments may serve as a fairly
accurate index of the relative amounts of the various forms of
injury which may be expected from the application of like
amounts of borax to potatoes in the field.

ROOT INJURY IN POTS.

The potato plants were all removed from the pots early in
January and an examination was made of the root systems.
While care was exercised to remove them in as nearly a natural
condition as possible it was extremely difficult to separate them
from the soil without breaking off many of the finer rootlets.
Hence the illustrations show the relative and not the absolute
conditions.

The plants which were grown upon fertilizer No. 5409,
free from borax, had long fibrous roots running to the bottom
and penetrating to all parts of the pots. Fig. 23 shows the root
system of one of these plants.

Fic. 23. Root system where borax-free fertilizer, No. 5409, was
used in pots in the greenhouse.

Tue Errect oF BorAX IN FERTILIZERS. 115

As might be expected the most severe root injury occurred
where the fertilizer was applied in drills, unmixed with the soil.
This was more pronounced in the presence of the larger amounts
of borax and showed a distinct correlation with stunting and
_ yellowing of the plants, or with the prevailing type of injury
which was observed in the field during the previous summer.
Fig. 21 shows a plant having a very severe type of injury where
practically the whole root system had been destroyed. It also
illustrates the entire growth made by this plant during a period
of 3 months. This was obtained with fertilizer 5513, or where
an application of 38.6 pounds of anhydrous borax was made
per acre.

Where the fertilizer was applied above the seed-piece the
injury was least near the base of the plant. Where it was ap-
plied below the seed-piece it was least near the surface of the
soil. Rather marked cases of these forms of root injury are
shown in Figs. 24 and 25. It will be noted that while a part

Fic. 24. Root injury to plant in greenhouse where fertilizer con-
taining borax was placed in the pot above the seed-piece unmixed with
the soil.

116 Marine AGRICULTURAL EXPERIMENT STATION. 1920.

_ seme

Fic. 25. Root injury in greenhouse where the same fertilizer as
was used on the plant, the root system of which is shown in Fig. 24, was
placed in the pot below the seed-piece unmixed with the soil.

of the roots which have grown out near the surface of the soil
from the stem shown in Fig. 25 have been killed, 3 long, fibrous
ones remain. In such cases the roots ran along near the surface
till the wall of the pot was reached. Then they passed down-
ward through that portion of the soil in the pot that was more
remote from the fertilizer. This condition, of course, only
obtained where the fertilizer was applied in the drill below the
seed-piece. It was exactly in accord with what was observed
repeatedly under like conditions in the field.

It may be of interest to briefly sketch the history of the
plant shown in Fig. 25. The seed-piece was planted October
3, using fertilizer 5513. The plant broke ground on November
18, but it was less than one inch high on December 1. (Plants
grown on 5400, carrying the same amounts of ammonia, phos-
phoric acid and potash, were from 8 to 14 inches high at this
time). By December 15 it was about 1% inches high, and was
3 inches high on January 1. At that time it had the curled,

Pe
a

THe Errect or Borax IN FERTILIZERS. 117

stunted and yellowed appearance similar to that of badly injured
plants in the field. Undoubtedly, if allowed to grow, it would
have shown the partial recovery that was observed with those
plants in the field which produced roots that started near the
surface of the ground and penetrated the soil remote from the
fertilizer.

Root injury was less severe where fertilizer was mixed
with the soil above and below the seed-piece than where it was
placed in drills above and below. Little or no root injury could
be found where the fertilizer was mixed with the upper six
inches of soil in the pots. However, as has already been stated,
it was where the fertilizer was mixed with the soil that most of

the tip and marginal injury of the leaves was obtained. The
root system of one of the plants where the fertilizer was mixed
with the upper six inches of soil is shown in Fig. 26. The ap-

»

Fic. 26. Root system of plant shown in Fig. 22. The fertilizer,
No. 5549, was mixed with the upper six inches of soil in the pot. The
root injury was slight but the leaf injury was marked.

118 ; MAINE AGRICULTURAL EXPERIMENT STATION. 1920.

pearance of the plant itself on January 1 is shown in Fig. 22.
The record states that at that time the margins of all leaves
were badly affected, the two lowest leaves had fallen and the
next two were about ready to fall.

It should be remembered that tests with fertilizer mixed
with the soil were confined to No. 5549, or with applications of
17.6 pounds of anhydrous borax per acre. Undoubtedly great-
er root injury from mixing fertilizer with the soil would have
been obtained if the samples carrying higher percentages of
boron had been used in this way.

WORK WITH OTHER CROPS.

The work of testing the effects produced upon crops other
than potatoes by fertilizers containing borax was only inciden-
tal, was planned simply as preliminary tests, and was conducted
upon too small a scale to be of much value. The results ob-
tained with beans in comparison with those obtained with other
crops were of such a striking character that it is desirable to
record them in detail. No. 5549 was the only fertilizer used,
and regular greenhouse potting soil was employed.

Beans. Three different varieties of beans were used. The
seed of two of them was produced in 1918 and the other in 1919.
Three eight-inch pots were used for each variety. Fertilizer
5549 was applied to two of these and nothing added to the third
pot which served as a check in each instance. The potting soil
contained an abundance of natural fertilizer.

The fertilizer was applied at the rate of 500 pounds per
acre in the drill, making an application of anhydrous borax
equivalent to only 4.4 pounds per acre. This fertilizer was dis-
tributed in a strip 3 inches wide across the soil in a nearly filled
pot, and covered with a thin layer of soil. In each pot 6 seeds
were evenly spaced in two lines directly over the strip of fertil-
izer, and then covered with an inch of soil.

All of the beans in the check pots germinated and produced
normal, vigorous plants, although those from the variety grown
in 1919 came more slowly. The behavior of the beans in the
pots containing fertilizer contrasted very strikingly with that
of those in the check pots. This was shown by a much delayed

119

Tuer Errect or Borax IN FERTILIZERS.

Le

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120 Maine AGRICULTURAL EXPERIMENT STATION. 1920.

or partial failure to germinate and a pronounced lack of green
in the leaves of all plants that did grow. In the case of the
variety where the seed was grown in 1919, only one plant in
each pot containing fertilizer appeared above ground and these
plants died almost immediately. In the case of the two varie-
ties from the 1918 seed one finally gave 100 per cent germination
in the presence of the fertilizer but the plants grew very slowly,
the leaves were stiff and of a pale, waxy color, entirely lacking
in chlorophyll. Their appearance as compared with the check,
pot 3, is well shown in Fig. 27. This is from a photograph
taken about 6 weeks after planting. Eventually all but one
plant in each of pots 1 and 2 of this series died. These two
plants slowly, but not wholly, developed a normal green color
and remained weak and stunted, although they were kept under
observation up to the time when the plants in the check pot
were practically mature. The series in which the third variety
of beans was used showed only 50 per cent germination in the
presence of the fertilizer and the history of the injured plants
was similar to that given above.

Oats, wheat and buckwheat. Series of pots similar to
those described for beans were used for planting oats, wheat,
India wheat, old-fashioned buckwheat and Japanese buckwheat.
Here the applications of fertilizer 5549 were made at the rate
of 1000 pounds per acre, broadcasted, or mixed with the upper
inch of soil in the pots. This would make the applications of
anhydrous borax 8.8 pounds per acre. No consistent differ-
ences could be noted either in gerinination of the seeds or in
the health of the plants growing in the pots which did or did not
contain the borax.