The effect of manganese compounds on soils and plants ..

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THE EFFECT OF
MANGANESE COMPOUNDS ON SOILS
: AND PLANTS

A. THESIS

PRESENTED TO THE FACULTY OF THE GRADUATE, SCHOOL

OF CORNELL UNIVERSITY FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

BY

EUGENE. PEYTON DEATRICK

SEPTEMBER, 1917

Reprinted from Memoir No. 19, February, 1919, of Cornell University Agricultural
Experiment Station

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Tae. EFFEC? OF
MANGANESE. COMPOUNDS ON SOILS
AND PLANTS

A THESIS

PRESENTED TO THE FACULTY OF THE GRADUATE SCHOOL

OF CORNELL UNIVERSITY FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

BY

EUGENE PEYTON DEATRICK

SEPTEMBER, 1917

Reprinted from Memoir No. 19, February, 1919, of Cornell University Agricultural
Experiment Station

a ay Fe a ey (ORE SET

CONTENTS

PAGE
MME MEEAIUING NEE Is icy: gale a) sts Alo so a eae Dee Meee wae a eee 371
Menenments- with water eulgures 25.0600) bo. den dha ees atl
Papeniments with soil cultures... oo vei. fabs len Wee Peesaedee 374
Experiments with soil fungi and bacteria..................... 307
“NT DIST th oR ee ee Ee De ae ON ad AS SE oe 378
MIRE RIE HUIS WOOTEN (28 ole GOP Shs og, bea oid Saher we as eae Sh Wao aL 379
SAE TOUTTORON CUUOY sx oso. eds ee oe ate & ae ee eae 379

Effect of manganese compounds on wheat seedlings grown in
Pe PSMCILUIAIE A AE 0s Sv sne sho Rs. 2 So Wer ete Adah. oo ee 379
Effect of manganese compounds on wheat grown in soil........ 383
Manganese content of yellow leaves..................00 2.0005. 387
Relation of manganese to the oxidizing power of soils.......... 388
PARTON Ol WMAMPAMESE. 5 {2.0.62 Seid a ca a's Sa gre ooh a oes Pave eck! 390
“ELST STIG TLS ans 010090 25°00: A aa ae ee 393
Effect of manganese sulfate on soil bacteria................... 395
Area MADERUTUUG GARE 9s cates tea 'st ace raed apn bse asta ty ae te rae ae ee 396
PEt AMG eeu Pe tal Gene Uae tetee Crane « anal eee 397
SSRIS. Te TORE Sen ie Olen a Pe Re ao Rc aed Acne Peer Be 398

MRT PL OPNT CER ste eso tee el oe tic a le ee a he 399

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THE EFFECT OF MANGANESE COMPOUNDS ON SOILS AND
PLANTS

Oh Some BaNOR: BQ: BARU aI MOS eae sO AMe Se
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THE EFFECT OF MANGANESE COMPOUNDS ON SOILS AND
PLANTS

EK. P. Dratrick

Experimental evidence has shown that phosphorus, sulfur, potassium,
calcium, magnesium, iron, carbon, hydrogen, oxygen, and nitrogen are
essential to the normal growth and development of plants. Other elements,
including manganese, are almost universally found in soils and plants,
and this fact has led some investigators to assume that they perform
important physiological functions. The weight of evidence, however,
seems to indicate that the benefit following applications of a manganese
compound to soil is due to its stimulative, indirect action either on the
plant or on the soil, and manganese is therefore usually designated as
a catalytic fertilizer.

The investigation here recorded was undertaken for the purpose of
acquiring information regarding the specific effect of manganese com-
pounds in increasing plant growth; in other words, to determine whether
manganese is a direct plant stimulant, whether it increases the available
food supply in the soil, or whether both these factors are operative. The
direct stimulative or deleterious effect of a substance on plant growth
may be determined by growing the plant to be studied in water cultures
vf a pure nutrient solution. When the same kind of plant is grown in
soil to which the substance to be studied is added, the effect is usually
very much modified. In the soil culture the action must be considered
as the sum of the effects directly and indirectly on soil and plant.

REVIEW OF LITERATURE
Experiments with water cultures

The effects of manganese on plants have been studied by growing
seedlings in distilled water alone, and in distilled water to which nutrient
salts were added.

Working with the distilled water cultures, investigators have observed
both stimulative and toxic effects. Loew and Sawa (1902-03)! found
that in the presence of manganese in toxic quantities the leaves lose their

1Dates in parenthesis refer to Literature cited, page 399.

371

372 EK. P. Dreatrick

turgor and dry up, and no trace of new rootlets is apparent. In a solution
containing 1000 parts per million of manganese sulfate, the leaves of
barley plants faded to yellow and then turned brown. These investi-
gators found also that barley became chlorotic and the roots turned
brown in solutions containing only small quantities of manganese.
McCool (1913) noted that a solution containing 15 parts per million
of manganese in the form of chloride is injurious to field peas, and that
a solution containing 30 parts per million prevents root growth entirely.
Miss Brenchley (1914) found that manganese when present in strong
concentrations exerts a toxic influence on higher plants.

On the other hand, several investigators have obtained plant stimulation
in distilled water cultures containing small quantities of manganese.
Micheels and De Heen (1906) obtained a pronounced stimulation in
colloidal solutions of manganese. McCallum (1909) reported an accelera-
tion of tuber formation when potatoes were treated with a solution of
manganese chloride. Montemartini (1911), altho finding marked differ-
ences in the sensitiveness of plants, obtained increased growth with all
plants used in his experiment. McCool (1913) found slight stimulation,
as shown by length of the roots of pea seedlings, but the leaves showed
no effect.

The effects of manganese in solutions containing nutrient salts are
similar to those obtained with distilled water cultures, but experiments
show that the nutrients greatly reduce the toxicity of the manganese.
McCool (1913) found that this reduction of toxicity is proportional to
the concentration of the nutrient salts.

According to Miss Brenchley (1914),

the Rothamsted experiments supported Aso’s work on the action of manganese sulphate
on barley, concentrations of the salt above 1/100,000 having a retarding influence on the
growth, the roots being coloured brown and the leaves also showing discolouration. At an early
stage in growth the lower leaves of the plants receiving the most poison began to be flecked
with brown spots.
A solution containing 1350 parts per million of nutrient salts and 770
parts per million of manganese in the form of sulfate, reduced the yield
31 per cent. A solution containing but 0.01 of this amount of manganese
developed brown roots after four weeks and reduced the yield 3 per cent.
In lower concentrations manganese was decidedly stimulative. Aso
(1902-03) found that manganese stimulated the growth of a number of
plants. The solutions which he used contained 0.5 per cent of nutrient

‘

Tue Errect oF MANGANESE COMPOUNDS ON SOILS AND PLANTS 373

salts and 0.02 per cent of manganese sulfate in one series, and 0.05 per
cent of nutrient salts and 0.002 per cent of manganese sulfate in the
other series.

Tottingham and Beck (1916) reported increased yields of wheat grown
in nutrient solutions containing small quantities of manganese chloride.

Various views are held regarding the cause of the stimulation on the
one hand and of the toxicity on the other. Loew and Sawa (1902-03)
suggest that the stimulation by manganese is related to the oxidation
of toxic substances within the plant leaf. They assert that certain noxious
by-products are formed in the leaf, and that in reality sunlight retards
growth. They state: “It is in the absence of light that growth
proceeds and the products of the sun’s work are chiefly consumed.”
Protoplasm oxidizes the carbohydrates formed, while the noxious by-
‘products, probably members of the benzene group, are oxidized by enzymes,
whose action is increased by the presence of manganese.

Many investigators find that the action of enzymes is in some way
related to the presence of manganese. Kastle (1910) writes at length
on manganese in its relation to the oxidizing ferments. It has been
shown by Bertrand, he states, that the oxidizing power of laccase (from
lucerne) is associated with the manganese content. He regards this
element as the co-ferment, or activator, of laccase, just as hydrochloric
acid is the co-ferment of pepsin. The oxidation of organic compounds,
such as hydroquinon, by the oxygen of the air, is accelerated by the
presence of manganese and varies with the form of the salt, being greater
with the salts of the organic acids. These salts are ‘‘ most easily hydro-
lyzable”’; thus,

R’Mn + HOH = R”H, + MnO.

The manganous oxide formed is “ spontaneously oxidizable.” In this
oxidation, “ molecular oxygen is split into two atoms, one of which com-
bines with the manganous oxide to form the peroxide, the other going to
oxidize the hydroquinon ’’; thus,

MnO + O2 = MnO; + O, and

C,H, (OH)2 -- O = C.Hs02 -+- HOH.
In the presence of an acid, R’’H: is unstable and is capable of oxidizing

more hydroquinon. Thus the manganese salt is regenerated. “ Accord-
ing to this conception the manganese would be the really active element

374 E. P. DEeatrRick

of the oxidase, so far as the activation and transfer of oxygen is con-
cerned, whereas the acid albuminoid radicle would impart to the ferment
its other properties, such as its conduct toward heat, solubility, ete.”

Manganese has been found to activate animal ferments. Considerable
work has been done on the oxidizing power of colloidal solutions of
manganese, which are described by Kastle as artificial ferments.

The reports of numerous investigators indicate that a relation exists
between the presence of manganese and the production of chlorophyll.
Van Dam (1907) states that seeds soaked in a solution of manganese
sulfate yield plants which develop greener leaves than normally. Jadin
and Astrue (1912) report that manganese constantly occurs in the ash
of plants and that the chlorophyll-bearing parts contain the greatest
proportion of this element. Mameli (1912) found that chlorophyll is
produced in some of the lower plants only when manganese is added
to the nutrient media. Pugliese (1913) states that there is an optimum
ratio for iron and manganese, which he gives as 1:2.5. Mazé (1914)
has described a special type of chlorosis due to the lack of manganese;
a large amount in the plant also causes chlorosis. Gile (1916) is of the
opinion that ‘“‘ manganese chlorosis may be due in part to a deficiency of
iron in the plant, induced by the action of manganese in the plant or
in the soil, and in part to a direct toxic action of the manganese.”’ Johnson
(1917) finds that the toxic effect of manganese on pineapples appears
to be ‘‘ due to a depression in the assimilation of iron,” and has worked
out a commercially successful method of cous the toxic effect
by supplying iron thru the leaves.

Experiments with soil cultures

A large number of experiments are reported in which manganese salts
have been applied to soil as a fertilizer. The results are somewhat ¢on-
tradictory.

Von Feilitzen (1907) found that manganese sulfate did not increase
the yield of oats perceptibly. Pfeiffer and Blanck (1912), after experi-
menting with various salts and plants, decided that their results were
not conclusive. They state that, while increased yields were occasionally
obtained, the salts of manganese should not be recommended for general
use as a fertilizer. This opinion is held also by Sullivan and Robinson
(1913), who advised that manganese should not be used ‘in any way

Tue ErrectT oF MANGANESE COMPOUNDS ON SOILS AND PLANTS 375

other than in experimentation and as a fertilizer complementary to the
usual chemical fertilizers.” Masoni (1916) experimented with several
manganese salts. Althothe chloride and the sulfate seemed to give
a certain advantage, he believed the results were too small to indicate
definitely the specific effect on the growth of the plants tested. Ehren-
berg and Schultze (1917) state that experiments covering several years
show that under many sorts of conditions neither a favoring nor an inhibi-
tory action of manganese compounds on the growth of plants is de-
monstrable. At the Woburn station, however, Voelcker (1904) observed
that manganese iodide, applied at the rate of 50 pounds to the acre, was
very toxic to the growth of barley.

On the other hand, some surprising results have been obtained from
the use of manganese salts. Javillier (1908) states that comparatively
small quantities of this element have been sufficient to increase the yields
of certain crops from 25 to 50 per cent. He believes there is no doubt
that manganese compounds, particularly the sulfate, may be used advan-
tageously as a complementary manure. Loew and Honda (1904—05) report
an increase of 50 per cent in Cryptomeria japonica from fertilizing with
manganese sulfate. With the use of the same salt Ray and Pradier (1909)
were able to increase the yield of apricots 23 per cent. Bartmann (1910)
cites Marre as having secured an increase of 60 per cent in some crops.
Numerous other investigators have reported data indicating that man-
ganese is a fertilizer of decided value.

A number of investigators, including Nagaoka (1906-08), and Skinner
and his co-workers (1914, 1916), report data which are apparently con-
tradictory. Nagaoka (1906-08) reported that in 1902 manganese sulfate
applied at the rate of 70 pounds to the.acre, increased the yield of rice
37 per cent; the following year the residual effect was considerable; in
1904 the season was “ exceptionally favorable,’ but the treated plats
again surpassed the checks; in 1905 the experiment was repeated, but that
year the yield was greatly decreased. Skinner and Sullivan (1914)
reported their work on the action of manganese in soils; they found that
the growth of wheat was increased when various salts were added to a
soil described as an unproductive sandy loam, while on a productive loam
the salts had no stimulating effect.

Further experiments were reported by Skinner and Reid (1916), who
state that “in a six-years field test of manganese sulphate used at the

376 EK. P. Dratrick

rate of 50 pounds per acre on an acid silty clay loam, its effect each year
was not beneficial to the crops grown.” During the following years of
experimentation the yields of the crops were increased. The soil had been
found to be very acid, and large quantities of calcium carbonate were applied.

It appears that the reaction of the soil is a determining factor in the
action of manganese. Nagaoka (1906-08) notes that the soil increases in
acidity with the continued application of manganese sulfate. Rousset
(1909) cites Malpeaux as securing contradictory results with both the
sulfate and the chloride of manganese, but favorable results with the
carbonate and the oxide applied in combination with marl.

Some results have been obtained, however, which point to a decreased
stimulation when manganese is applied with some form of calcium.
According to Uchiyama (1907), ‘“‘ A manurial mixture of a nearly neutral
reaction, exerts the best effect. Manures of decisive alkaline or acidic
nature on the other hand are not so favorable, since the former interferes
with the effect of the manganese salt, while the latter are not suitable
for the growth of most plants.’”’ Chittenden (1915-16) observed the same
effect; he states that in two out of three cases manganese sulfate alone
increased the yield, while the addition of lime to the manganese sulfate
decreased the yield.

Many of the apparently inconsistent reports are explainable when
complete data regarding the experiment are available. Some of the
applications are too low. Others, as that of Crochetelle (1913), who
applied an excessive amount (2000 pounds to the acre) of manganese
sulfate to a “ calcareous clay,’ are high yet stimulative.

References to the change which manganese compounds may undergo
when added to soils are numerous. Nottin (1912) found that manganese
is adsorbed like potassium or ammonia, and is precipitated by calcium
carbonate and organic matter; the demanganization of water by calcium
carbonate, and the precipitation of manganese found in dolomitized lime-
stones, indicate that, in alkaline soils at least, the soluble salts of man-
ganese are changed to oxides. In the soil solution, manganese probably
occurs in the form of the bicarbonate, as Vincent (1916) concludes.
Regarding solubility, Masoni (1916) states that the organic acids are
particularly active in dissolving manganese. He claims that the behavior
of the carbonates, sulfates, and oxides of manganese may be explained
as phenomena of hydrolysis and of successive oxidation and reduction.

THE EFFECT OF MANGANESE COMPOUNDS ON SOILS AND PLANTS 377

According to Schreiner, Sullivan, and Reid (1910:37), ‘ soils may have
practically the same amount of manganese and still vary greatly in oxidiz-
ing power, so oxidation in soils, if due to manganese, depends on the nature
of the manganese as much as on the amount.’”’ The salts of manganese
added to soils which were low in this element and had “ very little oxidiz-
ing power,” did not increase their power to oxidize aloin. Experiments to
learn the effect on oxidation of the addition of hydroxy acids and salts to
manganese compounds in the soil, led these authors to state (page 56 of
reference cited): ‘This oxidation appears to be mainly nonenzymotic,
the result of interaction between inorganic constituents and certain types
of organic matter. It may also be brought about by organic matter in
a\state of autoxidation and by inorganic oxygen carriers, such as man-
ganese and iron. Both processes activate oxygen.”

According to Sullivan and Reid (1912:28), “‘ That the catalytic power
of the soil is correlated to some degree with the manganese content of
the soil is evident.’”’ A comparison of soils of varying manganese content,
and the failure of the addition of manganese salts to increase the catalytic
power of soils that were poor catalyzers even tho the content of manganese
was high, led these investigators to state that factors other than the “ total
amount of manganese must be the determinants.” They suggest that
either the nature of the manganese compound or the nature of the associ-
ated organic matter is more important than the amount of manganese.

Experiments with soil fungi and bacteria

Altho the experimentation is meager, the weight of evidence supports
the conclusions of Bertrand (1909) that manganese stimulates the growth
of fungi. Loew and Sawa (1902-03), however, found no stimulation, and
they have written at length on the difference of the behavior of manganese
on the growth of phanerogams.

Kelley (1912) concluded that nitrification took place more rapidly in the
soil high in manganese, while ammonification was about equal in soils
ef either high or low manganese content. Leoncini (1910) and Montanari
(1914) have found that manganese increases the activity of nitrifying
bacteria. :

Brown (Brown and Minges, 1916) applied various salts of manganese
to soil cultures, and concluded from his data that “if manganese salts

in small quantities increase crop yields on a soil, that increase may be _

378 E. P. Deatrick

due in part at least to a beneficial effect on ammonification and _ nitrifica~
tion.” If, on the other hand, the salts “ restrict crop growth, that restric-
tion may be due in part to a depression of bacterial activity.”

Greaves (1916) has recently published his results. He states that with
the possible exception of the chloride, all the manganese salts tested were
strong stimulants to the ammonifying organisms of the soil. At maxi-
mum stimulation, 25 per cent more ammonia accumulated than in the
normal soil.

Olaru (1915) states that the nitrogen-fixing power of bacteria from
legumes is greatly increased by manganese. Gregario (1916) finds that
mannitol bouillon containing 60 parts per million of manganese in the form
of the chloride and inoculated with Bacillus radicicola fixes three times as
much nitrogen as do the checks; a concentration of 200 parts per million
retards the fixation. Furthermore, he finds that Clostridium pasteur-
zanum, which normally is not a free fixer, becomes capable of fixing nitrogen
in the presence of manganese. Similar results have been obtained with
Azotobacter chroococcum.

Summary

Much of the evidence in the foregoing reports is contradictory. The
results would be more intelligible if complete data regarding the experi-
ments were given. The applications of manganese salts to soils have been
made without any apparent consideration of the type of soil. Such
factors as soil type, the presence of calcium, and the crop to be grown,
are factors that determine the action of a given application. Large
applications on a sandy loam are detrimental, while the same applications
on a clay loam or on a soil high in calcium would in all probability be
stimulative.

The role of calcium seems to be a complex one. If the manganese
were stimulative in the soluble form, the addition of calcium would pre-
cipitate the manganese and prevent the stimulation. [f, on the other
hand, the manganese were present in such concentration as to be toxic,
the addition of calcium would be beneficial, not only by causing precipi-
tation of the manganese but also by increasing the oxidizing power of
the soil by such precipitation.

Altho the evidence is in many respects inconclusive, the following
statements seem to be justified by this review:

1. Manganese is universally distributed in small quantities in soils and
plants.

Tae Errect or MANGANESE ComMpouNpDs ON SorLts AND PLANTS 379

2. The majority of experiments indicate that, as Miss Brenchley (1914)
states, “manganese exerts a toxic influence upon the higher plants, if
it is presented in high concentration, but, in the absence of great excess
of the manganese, compounds, the poisoning effect is overshadowed by
a definite stimulation.”’

3. The toxicity of manganese is reduced by nutrient solutions and by soil.

4. Manganese compounds have been associated with the catalytic
power of soils and with the oxidizing power of soils and plants. Com-
paratively large yields have been obtained with manganese fertilization
under neutral or alkaline soil conditions, and the yields have been cor-
related with the oxidizing power of the soil. The stimulation of plants
has in part been explained as due to increased activity in the metabolic
processes within the leaf.

5. A stimulation of the ammonification and nitrification in soils has
also been reported.

EXPERIMENTAL WORK
Scope of present study

In order to test the effect of manganese salts on the growth of plants,
the weight of wheat seedlings grown in manganese solutions of varying
concentrations (both in the presence and in the absence of nutrient salts)
was compared with the weight of plants grown in cultures containing no
manganese. The concentrations producing stimulation were then used
as a basis for the applications in the experimental work conducted to
test the manurial value of manganese when applied to soils. Dunkirk
silt loam was treated with various manganese salts and planted with
wheat. An attempt to explain the results obtained led to a study of the
oxidizing, ammonifying, and nitrifying powers of soils treated with salts
of manganese.

Effect of manganese compounds on wheat seedlings grown in water cultures

Wheat seedlings (Jones’ Paris Prize 106-43) from seeds germinated in
running tap water were allowed to attain a growth of about eight centi-
meters, and were then transferred to culture containers. These were
salt-mouth bottles of a capacity of 250 cubic centimeters, fitted with
four-holed corks and wrapped in black paper. Each series was set up

i

380 E. P. DEeatrRick

in quadruple and was run for a period of two or four weeks. The nutrient
solutions were made up from the following formulae:

Salt. “Caletinatnantvetie: Pi cae ec a woke + oo cee 27 grams
Salt 2; Miaenestum sullate tei ie cau eee eee so ee 6 grams
Salt 3. Potassium phosphate (monobasic)..... 15 grams
Salt 4.) Pereve'saliate con xO Sea 6.) 0. 5-aram
Salt 5: Potassnim chlorite #2447 Rees ee ee 7.5 grams

Salts 1 and 5 were dissolved together in 3 liters of water; salt 2 was
dissolved in 14 liters, as was also salt 4, and both of these were mixed
with salts 1 and 5. To the mixture was then added salt 3, after it had
been dissolved in 3 liters of water. The total quantity was then increased
to 10 liters by adding 1 liter of water. This solution contains 4656 parts
per million of salts.

The wheat seedlings were placed in cultures containing 10, 20, 100,
200, 400, and 1000 parts per million of manganese in the form of manganese
sulfate, and were harvested after remaining in the greenhouse for four
weeks. The results are given in table 1:

TABLE 1. Wueat Srerepiincs (ENDOSPERMS NOT REMOVED) GROWN IN SOLUTIONS OF
MANGANESE SuLFATE. No Nutrients PRESENT

Length Weight of four plants Total f
Parts per million (in centimeters) (in grams) dry Relative
of manganese = weight weights
Leaves Roots Leaves Roots

Ole Ses Perens: Le / 18.2 .0784 .0514 . 1298 100
IQUE Sek ee corte 10.6 10.3 .0940 .0460 . 1400 108
On PRA ae ae bats 5.6 .0967 .0319 . 1286 99
LOOM A CAE eR aie 10.6 4.2 .0658 .0211 0869 67
DO ner terane rs mee eae 12.4 4.6 0873 .0163 . 1036 80
ANOS ESCA eee eke 10.9 Bed .0770 .0222 .0992 76
1000 eee: 9.8 3.8 .0641 .0171 .0812 63

As shown in table 1, solutions of manganese sulfate containing no nutri-
ents were found to be toxic. All the manganese cultures, at the termina-
tion of the experiment, might be characterized as dead or dying. There
was no great increase in growth, if any increase at all, even in the lowest
concentration. The total dry matter was reduced in all cases except
with a concentration of ten parts per million. The first symptom of the
toxicity of manganese is the yellowing of the tips of the lower leaves.

THE Errect oF MANGANESE COMPOUNDS ON SorLs AND PLANTS 381

Then bleaching occurs in small patches, which redden, dry, and turn brown.
The intensity of this chlorotic condition decreases with the decrease in
the concentration of the manganese. The roots of the plants grown in
concentrations of 1000 parts per million turned brown in spots, especially
at the tips, within four days. This browning occurred on the roots
of all the plants except the checks, the length of time before the browning
appeared being proportional to the concentration of the manganese.

The toxic effect was not so great in cultures of manganese sulfate con-
taining nutrient salts (4656 parts per million) as in pure solutions, as is
shown in table 2:

TABLE 2. MANGANESE SULFATE ADDED TO NUTRIENT SOLUTIONS CoNTAINING 4656 Parts
PER MILLION oF NUTRIENT SALTS

Length Weight of four plants Total
Parts per million (in centimeters) (in grams) d, 2 Relative
of manganese 1 weights
weight
Leaves Roots Leaves Roots
oe ye eee, 19.4 12.0 1713 .0742 . 2455 100
HOt etre des tis 17.8 15.4 .2951 . 2033 .4984 203
MMe ects cicidbie ate « 19.2 15.6 . 2668 .1781 4449 181
OP sisi ciacdes PEP 14.0 2383 . 1294 38677 150
PUN states sles soc > 20.5 12.8 . 2250 . 1052 . 3302 135
410.0) iS eon eae 20.7 9.3 ..2020 .0780 . 2800 114
TINO en yecnepe tre eee 16.0 5.9 .1581 0459 . 2040 83

This demonstrates the ameliorating effect of the nutrient salts in over-
coming or reducing the toxicity of a plant poison. At 1000 parts per
million the total dry matter was reduced, but it equaled the check at
400 parts per million and increased with a decrease in the concentration
of the manganese. The yellowing of the tips of the leaves at 1000 parts
per million commenced in nine days. The browning of the roots was not
observed in any of the cultures except those of greatest manganese content.

A second series of cultures was run in which the chloride, the carbonate,
and the dioxide of manganese were used in addition to the sulfate. The
seedlings of the first series, reported as having grown in solutions con-
taining no nutrient salts, were in reality not grown in the absence of other
elements. That the effect of the storage food in the endosperms is a
factor in work of this nature, is suggested by McCool (1913), who states:

Pea seedlings [cotyledons not removed] that have been grown for ten days in distilled
water, tap water, and full nutrient solution, respectively, are much more resistant to the

382 E. P. Dratrick

poisonous influence of manganese than those that are transferred from germinating pans
and placed immediately in solutions of manganese. The nature of the medium used in this
preliminary treatment — that is, whether distilled water, tap water, or full nutrient solution —
has no visible effect on the resisting power of the plants.”

The seeds in this second series, consequently, were germinated as before,
but when the seedlings were about eight centimeters high the endosperms
were pinched off. This was done to eliminate as much as possible the
influence of the storage food. The concentration of the nutrient solution
was but one-fifth of that used in the previous series of cultures.

The average dry weight of the wheat seedlings at the time of setting
up the cultures was determined, so that the effect of the manganese solu-
tions might be the more accurately ascertained. The results are given
in tables 3 and 4:

TABLE 3. Wueat SrEepiincs (ENDOSPERMS REMOVED) GROWN IN SOLUTIONS OF
MANGANESE Satts. No Nutrients PRESENT

Increase
Average or decrease _ Relative
Parts per million of manganese dry weight | im weight | increase or
(grams) during the | decrease in
two weeks weights
(grams)
Oi Saez: RERERER SE Ie ANE ee .0319 .0025 100
Manganese sulfate
1k ST Ee CO OE rn eee 0336 .0042 168
Baal ROS SS: AIR Ee SIRES LR Oe eee ee ne 0304 .0010 40
LO ij eek er tee RARE: See RU eT ae eee .0298 .0004 16
LOO A 25.3. ee Pe he eR ee eee een .0309 .0015 60
LQOO eA So PERRO PRE elo are .0258 —.0036 —144
Manganese chloride
A 53 5 5-a Cee ae e . 0352 .0058 232
SECA ETS SPARE AS ac Re oS .0342 .0048 192
TOE A, SEG Pg OR Se Ae ONE ee .0832 .0038 152
LO ee AE ek Reyer ee Sa eee ea .0309 .0015 60
OOO We Sh tian wou coger ae EU ann ane aes .0252 — .0042 —168
Manganese carbonate
MS a, ee eat ORT Ce ey .0322 .0028 112
Ba ah etek Viney nla, ot Lal An Re pee Ra .0350 .C056 224
LOTS |e osieeis RO EBERLE CE LR Oe Cee ee .0297 .0003 12
LOO Se AES a eg ie OOS: G) ea 0349 0055 220

ee

Tue Errect oF MANGANESE COMPOUNDS ON SOILS AND PLANTS 383

TABLE 4. MancGanrse Satts Appep To Nutrient SoLutions ContTarnine 961 Parts
PER MILLION oF NUTRIENT SALTS

Increase
ap Average in weight Relative
Parts per million of manganese dry weight | during the | increase in
(grams) two weeks weights
(grams)
Petts A ey Ares ee oe POS ules 0367 .0073 100
Manganese sulfate
De cals Rae GS a aan ne .0392 .0098 134
Dace Cob DA Sab O a Dee rare .0404 .0110 151
UO) oct cleat Pie BEES DU eee 0423 .0129 177
LO ee ee: c BOR AIE DOEIOE ok. Soe ae .0400 .0106 145
MUN PE ERIN Ss ee ees he bee .0368 .0066 96
Manganese chloride
eee ie OD Ds a. Sede afew ss .0385 .0091 125
Sep gute eh nalts AIPORT EAE HERS PGE eee .0419 .0125 171
UO. oe ee ot 26 Oe Spa ee eee ei .0395 .0101 138
HOD), eo a enceeacs Bl dah de Oc eR 0387 .0093 127
Be « angele catelae Gh enh a ea .0320 .0026 36
Manganese carbonate
Lh wed ob d bane ces AS Sees eco eee ee .0367 .0073 100
8D, oe etd B coon a dae et ee Seneca a .0376 .0082 112
Ws cope Cicer 2d ae ee .0387 .0093 127
SO. ee ee TE aes eer .0455 .0161 220

It will be noticed that by this procedure it has been possible to show

an actual decrease in the weight of the seedlings grown in the solutions

of highest concentrations of the sulfate and the chloride.

An examination of tables 3 and 4, giving the results of this series of
experiments, shows that these results agree in general with those of the
first series; that is, as the concentration of the manganese decreases, the
total dry weight increases. The figures show clearly the greater toxic
effect of the manganese in the absence of the endosperm. The results
here reported agree closely with those of Miss Brenchley (1914).

Effect of manganese compounds on wheat grown in soil

. The determination of the effect of a given factor when added to the

soil is complex. The effect of this factor on the growth of plants is but

384 E. P. DEATRICK

an indication of its resultant effect on the various activities in a complex
medium. It was therefore deemed advisable to determine, in the first
place, whether the addition of manganese sulfate to soil cultures inhibits
its power to function as in the case of water cultures. Consequently,
wheat was grown on soil to which manganese sulfate had been added in
varying amounts.

In this, as well as in other soil experiments, the soil used was Dunkirk
silt loam, obtained near the experimental plats of Caldwell Field. The
results of the chemical and mechanical analyses are given in tables 5
and 6, respectively:

TABLE 5. Cuyemicat (BuLK) ANALYsIS oF DuNKIRK Sitt Loam

Surface Subsoil

Constituent determined 1 to 12 inches | 12 to 24 inches
(per cent) (per cent)

INGiro em q(IN)) Sik ieee rs: Leia bc PAIN spunea ay aa aoa 0.186 0.082
Oreanievearbony(G)Aiere iy 2 0 NE oe ae eer sla a be as 1.670 0.440
CarbonvGioxde(COn) eer sk, cree ee ein ie eee en Trace 0.260
Calctum oxide (CaO). 20 ec. ss ee eee! 0.430 0.830
Maenesiimy oxide, (MpO)eoh .. 9 ee nee ee 0.450 0.690
Potassium-oxide (K20) 624; i ee a ye eee 1.740 2.110
Sodium oxide <(NigtsO)s"05. ve eee Lenco tee We 1.090 1.280
Phosphorie;anhydride ((P:O:): see. aa ee eee 0.123 0.126

Manganese oxide ((Nin3z04)... 2 tere oe ee ee 0 0

TABLE 6. Mercuanrcat ANAtysis oF DunxkrirK Sitt Loam

Per cent
Rune travel et .e.4 5 HORA EL iO RU de Beas Ree nk ey ect ee re 0.5
area SANG.) ion ate yoy lien. cmnge al BT sie sk Pee ce Dees an eee ee 0.8
Medium sangha i or yc vice oa he Meee clear eae Poe eS Se ee an ee 0.6
BING SANG oi Se RS RETR RETA gS OE eerie a ee 2:7
WervVaniInersandoc 8:0 lah ie ge sa ed dl lead AR 9.5
1g ae Le OR DiI Tie MW hie ES oF hE oo 67.3
Glave ee ee dk ESSE EE BG oe Ok oo ee ep er eeneen ene rene 18.6

The soil was procured in quantity, was allowed to partially dry out in
the air, and was then passed thru a 2-millimeter sieve. After treatment
with manganese sulfate the soil was placed in small wire baskets, 350

r eee

Tue Errect or MANGANESE COMPOUNDS ON SOILS AND PLANTS 385

grams to a basket. The baskets were paraffined and a sand mulch was
placed on the surface. Six baskets of each treatment were set up, four
of which were planted with wheat seedlings about 10 centimeters high.
There were four seedlings in each basket. The baskets were carried to
the greenhouse, where they remained for a period of three months. Dur-
ing that period they received such applications of distilled water, from
time to time, as would bring the soil up to the original moisture content
of 25 per cent (dry basis). On May 3, 1916, the crop was harvested,
and the plants were dried, weighed, and analyzed for manganese. The
results are given in table 7:

TABLE 7. Wuerat Grown ror THREE Montus on DunkKIRK Stut LoAM TREATED WITH
MANGANESE SULFATE

Average weight :
Parts per million of manganese added _ of seedlings Relative
in each culture weights
(grams)

De gd o28 cecece WSN Gt REI, CIES cc IA en a oe 2.70 100
OMS trey te 6 Be oe il oon cae eigen’ 3.25 120
EMD) «eo eoplin Bic A CUO SABES RIERA OEIC NEC ike 2.80 104
So MEME Teter Mr SAPONINS LS nt kis iaghed os tare, eels 1.94 72
LUND). Sass lolabae oP Sie Sea Ee DIS DE Ee ieee a nea one 2.05 76

An examination of the relative weights shows that the manganese is
at least not prevented entirely from stimulating plant growth when it
is added to soil. The stimulation at 10 parts per million was appre-
ciable.

Another set of cultures was arranged on December 12, 1916. Two kilo-
grams of air-dry soil, to which the various quantities of manganese sulfate
were added, was placed in wire baskets. These baskets then received a
coating of paraffin and a sand mulch. Seven of the baskets received an
application of calcium carbonate at the rate of 20,000 parts of CaO per
million of soil. The soil was seeded to wheat and the moisture content
was raised to 25 per cent (dry basis), where it was kept by the addition
of distilled water from time to time. One month later the seedlings were
thinned to five to a basket, and these were allowed to grow for seven and

386 E. P. Deatrick

one-half months. The crop was harvested on July 3, 1917. The yields
obtained are recorded in tables 8 and 9:

TABLE 8. Wueat Grown For SpvEN AND One-Hatr Montus on Dungrek Srur Loam
TREATED WITH MANGANESE SULFATE

Weight of straw Weight of grain
Parts per million of manganese added
Average : Average -
(ann) Relative Grae Relative

Uta as eR eal Net Medes einai ai tacl dR 5.6 100 2.0 100
LO es ey Rt ON eto CTE re ee ee eee ee 5.0 89 4.0 200
75 aN RRP OPNS SAREE pera | hn ds as Deal 102 4.1 205
SOR SiR ee EME Ae Ceremeeeen ave ete 3.5 62 273 115

TABLE 9. Wueat Grown For SEVEN AND One-Hatr Montus on Dunxrek Sitt Loam
TREATED WITH MANGANESE SULFATE AND 20,000 Parts per Minion or Caucrum Car-
BONATE

Weight of straw Weight of grain
Parts per million of manganese added x a
Average : verage :
en) Relative (grams) Relative

Ox es a a ae ee eee ae ee 17 100 US {/ 100
LON Se toe oe Oe ne Pee ee 4y5 265 2.0 118
DS IN led Bin he ae Zs Re gs a 4.9 288 1.8 106
Ly | pea pe agen aa Sr OE Piece SEE St a, 5.0 294 2 123

The effect of the manganese in these cultures is not apparent when
the yields are considered. Practically all the yields of the soil treated
with manganese are somewhat higher than those treated with calcium.
The yield for the calcium carbonate check is strikingly low, for which no
reason can be assigned by the writer. Greater differences, however, than
those that appear in the data of table 9, were noted at an earlier stage
of growth. It was observed that a majority of the manganese plants
headed before the calcium-manganese plants did. In this respect it
would seem that the calcium had interfered with the action of the
manganese,

Tue Errect oF MANGANESE Compounps on SoILs AND PLANTS 387

Other investigators have stated that the effect of manganese on yield
is not marked. While Bertrand (1909) notes that the favorable results
of manganese are not apparent until harvest time, Miss Brenchley
(1914) states that there is a retarding effect on the ripening of the grain
but not on the yield. Takeuchi (1909-13) reports that the control plants
of flax were behind the manganese plants in growth and flowering. Aso
(1904-05) found that rice treated with manganese flowered four days earlier
than did the checks. Salomone (1907) states that the stimulation of the
vegetative portion of plants is greater than that of the grain. Comparison
of the data in tables 7 and 8 shows that greater differences in the yields
were obtained when the plants were harvested before they matured.

Manganese content of yellow leaves

Several investigators have reported that the yellow leaves of manganese
plants contain more manganese than do the green leaves. The leaves of
the plants grown on soil treated with manganese sulfate (page 385) were
analyzed for their manganese content by the colorimetric method described
in Bulletin 31 of the United States Bureau of Soils. The results are given
in table 10:

TABLE 10. Awnatyses or Leaves or WHEAT GROWN ON Sort TREATED WITH MANGANESE
SULFATE

Manganese (in parts per million grams
of dry matter) in

Parts per million of manganese added

| 5
Green | Yellow eee
leaves leaves : aves

USS een eg eR ee aT Trace Trace Trace
TL) ssa ath oo NR bee cee eae i a Re Trace Trace Trace
SS ae Re a Trace 3.8 P22
TANG. woes Gao Se Ce ee el ino 3.ol
TNO exc Claes tons ee Rak et aE ne pd aa a 1.95 125. 3.12

If Aso (1902-03) is correct in stating that the colorimetric tests for the
oxidizing enzymes showed that ‘“ the yellowish leaves of the manganese
plants gave reactions of higher intensity than the green leaves of the control
plants,” it seems that the intensity of these enzymes is proportional to

388 E. P. Dratrick

the manganese content of the leaves. Woods (1899) states: “It has
long been known that chlorophyll could be readily converted by oxida-
tion, into a yellow coloring matter, xanthophyll.”’ While a moderate
stimulation of the oxidizing power of the plant juices may result bene-
ficially, an excessive stimulation may result in the oxidation of the chloro-
phyll.

Relation of manganese to the oxidizing power of soils

In some eases the lack of fertility in a soil has been shown to be due to

the presence of certain organic substances injurious to plant growth.
Schreiner and Shorey (1909) found that when such soils are well aérated
they become productive. Schreiner, Sullivan, and Reid (1910:44) state
that the addition of manganese to soils promotes ‘ the most active oxi-
dation,” and “ by its strong oxidizing power ..... would render the
injurious material in the soil harmless or even beneficial and by the oxi-
dation of inert or rather stable organic matter might cause”’ a liberation
of plant food. <A brief study of the effect of manganese salts on the oxi-
dizing power of soils has therefore been made by the writer.

Portions of Dunkirk silt loam were sprayed with solutions of manganese
chloride, manganese sulfate, potassium permanganate and suspensions of
manganese carbonate, and manganese dioxide, in quantities such that
the manganese added was in the proportion of 10, 100, and 1000 parts
of manganese per million of dry soil. It was thought that by spraying
the soil a more uniform distribution of the manganese could be obtained.
Consequently the calculated amounts of the salts were added to sufficient
water to bring the soil to 25 per cent moisture content (dry basis). The
spraying was done with a simple atomizer, made with two pieces of glass
tubing of different bore and a wide-mouth bottle. It was found that the
physical condition of the soil was very good when the water was added
in this way. A determination showed that the moisture lost in the form
of mist and evaporation during the treatment was negligible. The soils
were stored in glass quart jars for about seven months.

To test the oxidation in the soil, 50 cubie centimeters of the following
solution was added to 10 grams of the air-dried soil in a centrifuge tube:

10 grams aloin
200 cubic centimeters N/10 HCL
790 cubic centimeters distilled water

THe Errect oF MANGANESE CoMPouUNDS ON SorLs AND PLANTS 389

The tube was shaken for exactly one-half minute and was then placed in
the centrifuge, which was started one minute after the solution was added.
At the end of two minutes the electric current was turned off the centrifuge,
and the speed was allowed to decrease gradually while a second test was
started. Five minutes after the aloin was added in the first test, a
portion of the supernatant liquid was poured into a colorimeter tube
and the depth of color was compared with that of a standard.

- This method will be found to differ considerably from that of Schreiner,
Sullivan, and Reid (1910). The oxidation in the soils reported was so
great that it was found necessary to use the method already described.
The difference between the two methods is indicated by the following:

| Schreiner,
Sullivan, Deatrick
and Reid
TMG D Gil Ho elergrere lb eat ares tae Aba a SOTO ne ra 2 to 3 hours 5 minutes
Concentration of aloin solution....................... 0.125 per cent 1.0 per cent
IGCCUMIIINOT ACen mee ane cso GANA astaeia cowie was C.H;OH HCL

The standard used in the writer’s experiments was a solution of aloin
which had been completely oxidized with either manganese dioxide or
nitric acid. The results were calculated on the basis of the oxidation in
the untreated soil as 100.

The oxidation of phenolphthalin (made by reducing phenolphthalein
with zine dust and sodium hydroxide) was also used as a means of testing
the oxidation in soils. The data are given in table 11. These figures
indicate definitely that the addition of manganese salts to soils increases
the power to oxidize organic matter such as aloin and phenolphthalin.
It appears that the salts which are the most effective are the perman-
ganate, the chloride, and the sulfate.

While the treatment with manganese dioxide seems to have interfered
slightly with oxidation, it has been observed that soils treated with pre-
cipitated manganese oxides, instead of the pulverized pyrolusite, oxidize
aloin readily. The oxidation in the air-dry soil from the field was very
weak. The increase due to the moisture treatment alone is very noticeable.
Since the soil contains no manganese, this is due to some other cause.

390 E. P. Deatrick

TABLE 11. Oxmation in Dunxiek Sitt Loam TREATED wiTH MANGANESE SALTS
(Tests made seven months after treatment)

Relative oxidati
Parts per million of manganese added Ne

Aloin Phenolphthalin

Oe HRA Ee ay oe She. GE Nae ee in eee Ne Ee 100 100

LOS ae eae Ct ED cel oe ecg ok 101 100
100 ae Re ole lo Oa Uh Eg is Sea a rd 136 120
1000) 2 FEE Ge eee ee es Renee es Cees 444 200
Manganese dioxide

Oe ee le eee | 93 100
10,0 Wamigiai Ress Ch PRI, Fa 3 ae nn ei bei 94 100
OOO 2. OPS ost Sie es Reman t: ee i» et eon iw. ee eR 95 100
Manganese chloride

LO eee sh PO ee ae arginine Aon ee eh ae 105 100
TODS Ho eo Le a ene re er ire nie eee ee 113 125
1000s. 20 See ee aN Se ee ery ete 171 167
Manganese carbonate
ieee ne Ne aes on CE peed y Cen be At, Gey Sakae 105 100
1100 ti Re ape ae eb 0 Cs See ROE atee 117 100
LOO ie. Usk Se ae eee re cle eke 128 142
Manganese sulfate

1 | PON ERR acumen ns 20 Nia at eo ac aee det 105 100
11 ire iar ee Mie ise AOS A i 3 oN a am tla aS all 136 130
1000: 3245. PRO EN Re eee a ee eee 233 172

Adsorption of manganese

It had been noted that soil to which manganese salts were added devel-
oped a power to oxidize aloin in proportion to the length of time that
the salt was in contact with the soil. In order to test this more accurately,
portions of soil, the moisture content of which had been held at 25 per
cent for seven months, were treated with solutions of manganese sulfate.
The data, given in table 12, indicate that oxidation does not develop at
once, but that it is greatest in the soil in which the manganese has been
present for the longest time.

Tue Errect oF MANGANESE CoMPOUNDS ON Sorts AND PLANTS 391

TABLE 12. Errecr or Duration or Contact or Sor with Manganese SULFATE, ON
THE OxipIzING PoWER OF THE SorL

Date when Date when

Parts per million of at eee Relative
manganese was oxidation was Phe ve
manganese added anidaal detarnaned oxidation
LO S2 8 omtea 82 DER OEE TIDe DRI eee April 3, 1916 November 8, 1916 100
LW.te cel cg ORI OTE OR Ne ane November 8, 1916 | November 8, 1916 100
Lia ager Get GES epee ee DOO aan April 3, 1916 November 8, 1916 185
NOC eae Ae ea ae November 8, 1916 | November 8, 1916 112

In order to test the adsorptive power for manganese, four percolation
cylinders were filled with Dunkirk silt loam, a kilogram to each cylinder.
The cylinders were labeled A, B, C, and D, respectively. To soils C
and D calcium hydroxide was added at the rate of 10,000 parts of CaO
per million of soil. Soils A and B were untreated. A solution of
manganese sulfate containing 1000 parts per million of manganese was
then percolated thru the soils after they had been saturated with distilled
water. Each successive 100 cubic centimeters of the percolate was
analyzed for manganese by the colorimetric method described in Bulletin 31
of the United States Bureau of Soils. The manganese content of the
percolates, expressed in parts per million, is given in table 13:

TABLE 13. Mancaness Content or MANGANESE SULFATE SotuTrion (1000 Parts PER
MIuiion oF MANGANESE) PERCOLATED THRU DuNKIRK Sitt Loam

Singocasive 100-ce. "portions Manganese content in parts per million

of percolate

A B (8, D
The igs 2 oe Cn Loe Oe Deen eee 0 0 0 0
Be se isle a ESE ee ee ar Trace 111 0 0
Lh etatae ee cugselle unk De tae ARN Dae a a etd a 62 286 0 0
Bota on COO RS gears eter a 500 400 Trace 0
Sek Sao eee i ee 625 417 62 Trace
1 Dy habe RAS ethene ae oa he ae ee 715 455 154 92
PDS ee Os 715 500 218 167
he OL AE RC aS ee epee 715 525 256 143
GME area mee rere ee cas 715 555 357 222
TP IE ea aS Oe one ee ee ea 770 475 357 91

392 E. P. Deatrick

The soils treated with calcium hydroxide precipitated more manganese
than did the untreated soils. In the case of soil C, one liter of the solution
was passed thru it before any appreciable amount of manganese appeared
in the percolate. On air-drying these soils, C and D were found to have
an intensive oxidizing power as compared with A and B.

Soils treated with 1000 parts per million of manganese in the form of
pulverized pyrolusite were found not to have a strong oxidizing power.
A solution of aloin, however, is rapidly oxidized when some of the pyrolusite
isadded toit. Colloidal manganese dioxide (from potassium permanganate
and hydrochloric acid, purified by decantation) oxidizes aloin immediately.
These phenomena, added to the fact that soils C and D developed the
oxidizing power immediately in the presence of calcium, have led the
writer to believe that the oxidation in soils due to manganese is due to
the presence of manganese dioxide. In a solution of a manganese salt,
manganic hydroxide is readily formed on the addition of an alkali. The -
formation of the oxide in soil to which a soluble manganese salt has been
added, is directly proportional to the lime content, that is, the basicity
of the soil. In the absence of an excess of an alkali form of calcium,
the formation of the oxide of manganese is slower, for the stability of the
soluble salts, as the sulfate and the chloride, is of course greatest in an
acid solution. The salts of the weak acids, however, are not so stable,
and when adsorption phenomena play a part, the salts are unstable even
in neutral media. Thus, if pure, fine sand is treated with a solution of
manganese citrate, this instability is soon demonstrated by the browning
of the sand. This has been found to be the case with sand so treated
and stored in a jar. On exposure to air, sand treated with the acetate
and the citrate has developed a sight brown color.

Schreiner, Sullivan, and Reid (1910) apparently tested their soils
immediately after adding the manganese salts. These soils were prob-
ably deficient in lime, and therefore the addition of manganese did not
increase oxidation. The increase noted when hydroxy acids were added
to these soils may have been due to the formation of the organic salt of
manganese and the subsequent precipitation of the oxide from the less
stable salt.

The formation of the dioxide, and the oxidation phenomena in soils
as described, are analogous to the formation of calcium manganite (CaO.

;
;

Tue Errect oF MANGANESE COMPOUNDS ON SOILS AND PLANTS 393

MnO.) and its use in the Weldon recovery process for the preparation of
chlorine. The mixture of milk of lime and manganese chloride is termed
Weldon, or manganese, mud.

Oxidation by plant roots

That roots of plants have an extracellular oxidizing power “‘ may be
demonstrated by the use of suitable chromogens,”’ according to Schreiner
and Reed (1909). In regard to their work on root oxidation in culture
solutions containing alpha-naphthylamine, these investigators state (page
17 of reference cited) that ‘‘ when the oxidation is performed by the grow-
ing roots of a plant, the oxynaphthylamine is deposited upon the surface
of the roots in characteristic zones. ... . . The zone of primary meris-
tematic cells immediately back of the root cap is marked by a distinct
narrow band of color.’”’ The browning of the roots of wheat in solutions
of manganese salts resembles the staining caused by the oxidation of alpha-
naphthylamine.

The reports of investigators indicate that such browning is character-
istic of plants other than wheat, when grown in manganese solutions.
This browning has been reported as consisting of a deposit of manganese
dioxide. As far as can be ascertained by the writer, no proof has been
offered for this statement. That the dioxide is formed, however, is indi-
cated by the following: The black deposit is insoluble in water but
dissolves in hydrochloric acid. When this solution is evaporated and the
residue is fused with an alkali carbonate on platinum foil, the character-
istic green color of the alkali manganate is developed. Furthermore,
the blackened roots are capable of liberating chlorine from a solution of |
a chloride and sulfuric acid. If the plants thrive long enough in the man-
ganese solution, the whole root system becomes blackened.

In writing of the deposit of manganese dioxide, Miss Houtermans (1912)
states that the blackening is probably the result of enzymotic processes.
The browning is the result of the oxidation which occurs on the surface of
the root. The fixed alkali hydroxides precipitate from solutions of man-
ganese salts manganous hydroxide, white, which readily turns to brown
manganic hydroxide in the air or in contact with other oxidizing agents.
Since manganous hydroxide is formed in the solution of a manganese
salt by hydrolysis, it seems that it is deposited on the roots, as such, and

394 E. P. Dreatrick

is there oxidized to a higher oxide, as the insoluble brown deposit. Soon
after the heavy deposition of the oxide, disintegration of the root occurs.

Schreiner and Reed (1909) conclude that ‘‘the process of oxidation by
roots is largely, if not entirely, due to the activity of a peroxidase produced
by the roots.’ That the deposit is not caused merely by the instability
of the manganese solutions in the presence of organic matter is indicated
by the absence of any blackening on pieces of string or wood placed in
them. A definite relation has been established between stimulants of
this oxidizing power and stimulants of growth. Schreiner, Sullivan, and
Reid (1910:9) state that ‘ oxidation by plant roots is a factor which
has considerable agricultural interest, especially from the viewpoint that
such oxidation is able to change the organic matter in the medium in
which the plant is growing and that processes promoting oxidation play
a large part in the best methods of soil cultivation.”

The effect of manganese on the oxidizing power of the roots of wheat
seedlings was therefore investigated. Seedlings were set up as before in
nutrient solutions (931 parts per million of salts) and grown for two weeks.
Portions of these solutions were then treated with small quantities of the
aloin solution and allowed to stand for twenty-four hours, and a com-
parison was then made of their relative oxidation. The results appear in
table 14:

TABLE 14. Errecr or MANGANESE SULFATE ON OXIDATION BY Roots

Oxidation in solutions

Parts per million of manganese

With Without

plants plants
Oc. A JR ER AT, ERE a Soa ne 100 0
| ee Nr Ree ER PN eae Pee Wegt, Ae ee Gad Sey s BANG Sa 184 0
Ls Rn Aen nar nen og Lfrrnerdiaae fies) cde a ol i oS eg i bans Ais 191 0
LO PERT Re SEEN TI EG ae a non gee 181 0
Ls Ure Ee A PE eS ATS TI a AE TRON fA Yd Ck 244 0
LOO eee ete, ote os epe heel sts, Oe ER I oe eee ee 250 0
TOO 2 pe eee REE ERE eee 206 167

In every case the cultures in which plants had grown oxidized the aloin
more than did those in which no plants were grown. In fact, the aloin
was but faintly oxidized in the checks, and with the exception of the one
containing the greatest quantity of manganese the degree of oxidation

—_— ="

Tue Errect or MANGANESE COMPOUNDS ON SOILS AND PLANTS 395

was considered as zero. When phenolphthalin was used as an indicator
similar results were obtained, altho some trouble was experienced with
these solutions because of the carbon dioxide content.

The bluing of gum guaiac was also used as an indication of the oxidizing
power of the roots. The reagent, which was poured on the surface of the
cultures, followed the path of the roots where it was oxidized. The
objection has been raised that due consideration was not given to the
oxidizing power of the manganese sulfate. It was found that a solution
of gum guaiac is oxidized immediately by a solution of manganese sulfate
containing approximately 10,000 parts per million of manganese. A
solution of 1000 parts per million, however, gave only a slight bluing
after three hours. Immediate bluing was obtained by the roots of plants
grown in the presence of 10 parts per million of manganese in the form
of the sulfate, while the bluing by the roots of the check plants was slow
and not so intense.

A

Effect of manganese sulfate on soil bacteria

Numerous investigators have reported that the activity of the lower
forms of plant life is increased by the presence of manganese salts. In
order to test this point, cultures were set up to determine the effect of
manganese sulfate on the ammonification of dried blood and the nitrifica-
tion of ammonium sulfate in soil. These cultures were prepared from a
fresh stock of Dunkirk silt loam, which had been passed thru a two-
millimeter sieve and which contained 12 per cent (dry basis) of water.
Portions of the soil each weighing 112 grams were placed in eight-ounce
salt-mouth bottles. When properly treated the cultures were placed on
the laboratory desk and covered with a moist pad, made of cheesecloth
and cotton, to prevent the evaporation of water. It was found that in
this way a large number of cultures could be kept at a constant moisture
content with the expenditure of a minimum amount of labor. The
cultures were run in quadruplicate and were incubated at room temper-
ature. Two days after the cultures were set up, the soil in each bottle
was stirred so as to insure uniformity in the distribution of the salts added.
At the end of the incubation period, the soil in each bottle was stirred
with 475 cubic centimeters of distilled water for three minutes and then
allowed to settle for twenty minutes, and the supernatant liquid was
filtered thru a Pasteur-Chamberlain filter. Aliquot portions of the filtrate
were then analyzed for ammonia and nitrates. The ammonia was deter-

396 EK. P. Dreatrick

mined by adding concentrated sodium hydroxide, distilling, and titrating
the distillate with tenth-normal hydrochloric acid. The nitrates were
determined by the phenol-disulfonic-acid method, using the Schreiner
colorimeter to read the intensity of color.

Ammonification.— To the soil used for ammonification tests was first
added 0.5 per cent of dried blood. The manganese sulfate was added
after the soil had been weighed out and placed in the culture bottles.
Sufficient water was used as the solvent of the manganese sulfate to bring
the soil in each culture to a moisture content of 25 per cent (dry basis).
The cultures were incubated for one week, at the end of which extracts
and determinations were made as described above. The results are given
in tables 15 and 16: .

TABLE 15. Errect or MANGANESE SULFATE ON AMMONIFICATION OF DriED BLoop IN
DuNEIRK Sitt Loam

(Cultures incubated for seven days)

Nitrogen
as ammonia, Relati
Parts per million of manganese added average of oe a
4 cultures nt oa
(milligrams)
| hel tee Seaman ne Re AS yor te a Nr SES ns Snel aig) a 34 100
LORS SAO EE SESE ee re ee 47 138
| POMEL ais eR IRE ge Sa ES. oir nig eine 4 Gels Cusny 53 156
SOA he wich eyes etre co Oe eee ee oR See ee 47 138
BOL ee. Ae: Geis sess Aes, ERE ae RS OE renee eee 54 159
7, aap On ee Nie ae (Oe ere en le Aten eh ek 58 170
TOO 6 eee ec eC en ne ee ie 67 197

TABLE 16. Errect or MANGANESE SULFATE AND 20,000 Parts per MILLion oF CALCIUM
CARBONATE ON AMMONIFICATION OF DrigD Bioop In DUNKIRK SiLt Loam

(Cultures incubated for seven days)

Nitrogen |
a as ammonia, Relative
Parts per million of manganese added average of t
4 cultures ee ie:
(milligrams)
Oss Sete a eae ect ees 3 ae, en rr 87 100
OO) EPI ae RS ahi MO aR Tae Shh ein ie ae es Bee ee 96 110

DOO EW eis Fat Gee Pe yee oa kinhs hh. >. aad CE pee ee en 109 125

_ Tue Errect or MANGANESE CoMPouNDS ON SoILs AND PLANTS 397

The addition of manganese sulfate to the soil resulted in a positive
stimulation in the ammonifying power. The addition of calcium car-
bonate resulted in a greater stimulation than that caused by the manga-
nese alone. The stimulation of the manganese is not so great in alkaline
soil as in soil deficient in calcium. This is as ae be expected, for the
solubility of the manganese is decreased.

Nitrification.— To the soil used for nitrification tests, 220 parts per
million of nitrogen in the form of ammonium sulfate was added. The
calculated quantities of solutions of manganese and ammonium sulfate
were mixed, and were added to the soil in the culture bottles together
with sufficient water to bring the soil to a moisture content of 25 per cent
(dry basis). The cultures were incubated for four weeks. At the end
of this time the extracts and determinations were made as described,
and the results, expressed as parts of nitrates per million parts of dry
soil, are given in tables 17 and 18. The experimental error of this deter-

TABLE 17. Errect or MANGANESE SULFATE ON NITRIFICATION OF AMMONIUM SULFATE
IN DUNKIRK Srtt LoAM

(Cultures incubated for thirty days)

Nitrates,
average of
Parts per million of manganese added 4 cultures Relative
(parts per amounts
million
of soil)

De i al 2 eget th a uae Seg? Pea OY es ev ee ee 234 100
TD)» spec get 24: no chet OCW CGR oo Oc OE er 2a ae nie 236 101
BAD), onic sls SB he ORE ESE ee IR. teense tara Ar, Seman Se 252 108
Se = eS dee es Beh! Oct See RS CooL Ce oe ee a ae 197 84
Ei Eat a SEV e MRE. URC A CT RT ie es 8 156 67
(De ecinse 6 paneer eu tn iiel beaten Ai a it Ae Ie ee ee Ae 136 58

TDD oo webs s etka U belo & EEA coo cenl ee teh oto Rane nen Se ae an gee 122 52

mination is large, and the data given in the tables indicate that manganese
sulfate in low concentrations did not affect the nitrifying power of the
soil. In soils containing larger amounts of manganese, however, the
nitrification was checked.

398 E. P. DeatrRIcK

TABLE 18. Errect or MANGANESE SULFATE AND 20,000 Parts PER MiLiion or Catcrum
CARBONATE ON NITRIFICATION OF AMMONIUM SULFATE IN DUNKIRK SILT Loam

(Cultures incubated for thirty days)

Nitrates,
average of
4 cultures Relative
(parts per amounts
million
of soil)

Parts per million of manganese added

Conclusions

The experimental data here reported seem to justify the following
conclusions:

1. Manganese salts added to water cultures affect the growth of wheat
seedlings. The comparison of relative weights shows that when presented
to the plant in high concentrations, both the sulfate and the chloride
exert a toxic effect. In lower concentrations, manganese causes a marked
stimulation.

2. The degree of toxicity is reduced by full nutrient solutions and the
reduction is directly proportional to the concentration of the nutrient
salts. Likewise, the food stored in the endosperms reduces the toxicity
of the plant poiscn.

3. The toxic influence results in the browning of the roots and the
bleaching of the leaves. The yellow leaves of the manganese plants
contain more manganese than do the green ones. :

4. Manganese salts added to soil form manganese dioxide in proportion
to the basicity of the soil, and thus develop a power to oxidize organic
matter as shown by the oxidation of aloin or phenolphthalin.

5. Manganese sulfate in water cultures stimulates the oxidizing power
of the roots of wheat seedlings.

6. Low concentrations of manganese sulfate were found to stimulate
the ammonification of dried blood in soil. The nitrification of ammonium
sulfate was inhibited.

ae ee ee ee

Tue Errect of MANGANESE COMPOUNDS ON SOILS AND PLANTS 399

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Memoir 17, The Translocation of Calcium in a Soil, the second preceding number in this series of
publications, was mailed on February 12, 1919.

iii