SB 139

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IB 139

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NITED STATES DEPARTMENT OF AGRICULTURE

DEPARTMENT BULLETIN NO. 1379

Washington, D. C January, 1926

ELECTROCULTURE
By Lyman J. Briggs, 1 A. B. Campbell, R. H. Heald, and L. H. Flint, Office
of Biophysical Investigations, Bureau of Plant Industry

CONTENTS

Normal electrical state of the atmosphere 1 Summary of experiments at Arlington Ex-

Electrical field employed in electrocultural periment Farm 15
experiments 2 Review of other investigations in electrocul-
Electrocultural experiments with miscel- ture 17
laneous crops... 3 Experiments with soil currents 17
Electrocultural field experiments with grains. 4 Experiments with modified potential
Electrocultural experiments in the plant gradients. 21
house 13 Literature cited 32

The term "electroculture" as used in this bulletin refers to practices

designed to increase the growth and yield of crops through electrical
treatment, such as the maintenance of an electric charge on a net-
work over the plants or an electric current through the soil in
which the plants are growing.
During the past 75 years many experiments in electroculture have
been carried out with varying degrees of refinement. Some of these
experiments indicate that the yield of crops can be materially in-
creased by electrical treatment. Others, conducted along similar
lines, fail to show any marked response to the treatment. In this
latter class are included the experiments conducted by the Office of
Biophysical Investigations of the Bureau of Plant Industry, which
are reported in the following pages. This report is followed by a
brief account of other investigations in this field. Investigations
relating to the cultivation of plants under electric lights are not in-
cluded in the review of the literature of electroculture, the response
of the plants under such conditions being due primarily to the heat
and light into which the electrical energy has been transformed.
NORMAL ELECTRICAL STATE OF THE ATMOSPHERE
Since the effect of using a charged network over growing plants is
to change the electrical state of the atmosphere surrounding the plants
it seems desirable to discuss briefly the normal electrical conditions in
the atmosphere and the changes produced by the charged network.
An examination of the electrical conditions in the atmosphere over
an open field on a clear day shows that there is a force tending to
move a positively charged body downward; in other words, the
electrical field of force is identical with that which would exist if the
earth were charged negatively.
1
Physicist, Bureau of Standards, since 1920.
62149°— 26f 1

"irraob
2 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

On fine days, the potential gradient in the atmosphere is almost

invariably positive in sign (that is, a positive charge tends to move
downward) and the magnitude of the vertical gradient is of the order
,

of 100 volts per meter, though it is continually varying. When thun-

derstorms are in the neighborhood, the potential gradient may be
either positive or negative and changes sign frequently. The magni-
tude of the potential gradient also undergoes wide fluctuations,
during stormy weather frequently attaining values of 10,000 volts
per meter, 100 times the normal gradient.
A further examination of the lower atmosphere shows that charged
particles or ions are always present. Both positive and negative
ions are found, the positive ions generally being somewhat more*
numerous. They consist of groups of molecules loosely bound
together and canying a charge. Frequently these small ions attach
themselves to dust particles, thus becoming large ions, which move
much less rapidly than the small ions.
When the potential gradient is positive, the negative ions move
upward and the positive ions downward to the ground, thus con-
stituting an electric current flowing from air to earth. This current
is due almost entirely to the small or free ions, the mobility of the
large ions being so low that their influence on the conductivity of the
air can be disregarded. The magnitude of the current from the air
to a unit area on the earth's surface is extremely small, being only
-8
2X10"-12 amperes per square meter or 5X10 amperes per acre.
The strength of the current is proportional to the potential gradient,
to the number of ions per unit volume, and to their mobility. The
average number of free ions is of the order of 1,000 per cubic centi-
meter, the positive ions constituting somewhat more than one-half
the total number. Their mobility is such that they migrate with a
velocity of about 1 centimeter per second when subjected to a poten-
tial gradient of 100 volts per meter.
Although the air-earth current per unit area is extremely small,
it is sufficient when applied to the whole of the earth's surface to
reduce the negative charge of the earth to one-half its initial value in
about 10 minutes. The explanation of the maintenance of the
negative charge of the earth under such extraordinary conditions is
one of the outstanding problems in atmospheric electricity {12, J+l)?

ELECTRICAL FIELD EMPLOYED IN ELECTROCULTURAL EXPERI-

MENTS
In most of the field experiments conducted at the Arlington
Experiment Farm, the standard height of the network was 5 meters,
and the potential of the network was approximately 50,000 volts.
The average potential gradient under the network was therefore of
the order of 10,000 volts per meter, or about 100 times the normal
gradient in fine weather. This would produce an air-earth current
about 100 times the normal current as long as the ion content of the
air remained normal. However, a marked ionization occurred at the
network, so that the number of positive ions per unit volume under
the network was much higher than normal. This was shown by
means of measurements made when the network was charged and a
gentle breeze blowing. On the windward side of the network the
conditions were normal, but on the leeward side a decided increase
^ The serial numbers (italic) in pare 'thes^t$f^^"^ e <g^ej ited>"
! at the end of this bulletin.

. RtQEtVfcD

FEfi'26 1926
 ELECTROCULTTJRE

was observed in the ion content of the air which drifted from under
the network. This effect could be traced to a distance of several
hundred feet from the network.
The principal change in the environment of plants grown under a
charged network appears then to consist in a marked increase in the
strength of the air-earth current which flows through the plants to
the ground.
If the drifting charge from the experimental plat should pass over
the control plat, it would increase the air-earth current to the control
plat to some extent, owing to the increase in the number of ions per
unit volume. But even under such conditions the current flowing
into the control plat would necessarily be small in comparison with
that flowing into the experimental plat, since both the ion content
and the potential gradient are much higher under the network and
the current is proportional to the product of these factors.

ELECTROCULTURAL EXPERIMENTS WITH MISCELLANEOUS CROPS

—
Experiments in 1907. Electrocultural experiments were first under-
taken by the department 3 in 1907, using vegetables for the most
part as test crops. The test plat, which was 138 by 106 feet, was
divided into three sections 44 by 106 feet, the center section being used
as the experimental area and the two outside sections as controls.
The crops were planted in continuous rows across the three sections,
so that the center third of each row was under treatment.
A Wagner mica-plate electrostatic machine was used as a high
potential source. It was inclosed in a tight case, permitting the use
of drying agents to keep the machine in the best condition for opera-
tion. The positive pole was connected to an open wire network
strung on glass insulators, and the negative pole was grounded. The
network covered the experimental plat and was placed high enough
to permit the use of a horse cultivator. The applied potential varied
somewhat with weather conditions, but usually exceeded 50,000
volts. The network was charged throughout the night, from late
afternoon until early morning. The plants were subjected to the
electrical treatment 656 hours in all, extending from June 20 to
September 16. The yields are shown in Table 1.

Table 1. — Yields following electrocultural treatment of miscellaneous crops under

test at Arlington Experiment Farm in 1907
4 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

The lack of uniformity in the yields of the control plats A and C in

the 1907 experiments (Table 1) is such that no great dependence can
be placed in these results. It is significant, however, that in only one
of the 10 trials recorded did the treated plat show any evidence of a
substantial increase in yield when compared with the mean of the
control plats.
—
Experiments in 1908. In the 1908 trials the wires were run di-
rectly over the treated rows and kept at a height of 6 to 18 inches
above the plants by means of adjustable brackets on which the
insulators were mounted. The control rows ran parallel to the
treated ones at a distance of 6 }/% feet and were separated from them
by intermediate guard rows.
In one part of the plat the wires over the plants were charged
positively to about 50,000 volts from 4 p. m. to 7 a. m. each day, 955
hours in all. In the other part of the plat the wires were charged
and discharged rapidly by connecting them to one terminal of the
secondary of an induction coil, the other terminal being grounded.
In this case the potential ro^e to about 20,000 volts and then dis-
charged suddenly through a small spark gap between the wires and
the ground.
The treatment first described is similar to that employed by Lem-
strom and believed by him to result in increased yields. In these
experiments, however, neither treatment gave any evidence of in-
creased growth. The detailed yields consequently are not of special
interest.

ELECTROCULTURAL FIELD EXPERIMENTS WITH GRAINS

In selecting a location for the electrocultural field experiments near
Washington, three conditions were sought: (1) A uniform soil, (2)
available electric power, and (3) accessibility from the laboratory in
Washington, since the equipment had to be visited daily during the
experimental season. Soil uniformity is particularly difficult to find
in the environs of Washington, and the Arlington Experiment Farm
forms no exception in this respect. It seemed to be the best avail-
able location, however, and portions of sections A, B, and E were
made available for the experiments, which were carried on from 1911
to 1918. Sections A and B proved very disappointing with regard
to their uniformity, and the most reliable results were obtained in
section E. These experiments will be first described.
The Lodge-Newman apparatus used in the experiments from 1912
to 1915, inclusive, was designed in England primarily for electro-
cultural work and consists essentially of a 110-volt induction coil,
operated by a mercury interrupter, and a rectifier. Five Lodge
valves 4 designed to rectify the high-tension alternating current were
placed in series with the network, thus allowing only the positive
impulses from the secondary of the coil to reach the network (33).
The negative pole was grounded. Two balls 25 millimeters in diam-
eter, one of which was grounded and the other connected to the net-
work, were used to determine the potential, assuming a breakdown
gradient of 3,000 volts per millimeter.
Systematic measurements of the current from the network were
not made, but the current could be determined approximately from
the potential of the network and the known power characteristics of

* For a description of the valves, see Lodge, O. (.84).

 ELECTROCULTURE 5

the machine used. The current from the network over the experi-
mental plat in section E was of the order of 0.1 to 1 milliampere per
acre, depending on the voltage and network used. This is of the
order of 10,000 to 100,000 times the intensity of the normal air-earth
current.
EXPERIMENTS IN SECTION E
It has been shown by j0rgensen and Priestley {26) that the ioniza-
tion from the highly charged network is by no means limited to the
area beneath the network, but may be carried by the wind to a con-
siderable distance, depending on the weather conditions. It was
consequently deemed advisable to separate the treated and control
plats so far as practicable. Accordingly, two plats of half an acre
each (132 by 165 feet) were selected in section E
which were sepa-
rated by a distance of 350 feet, one plat being directly north of the
other.

:
ygrfftiitt^ Hi in 11
 —
BULLETIN 1379, U. S. DEPARTMENT OP AGRICULTURE

Table 2. — Yields of winter wheat on -plats following electrocultural treatment (posi-

tive charge), section E, Arlington Experiment Farm, in 1914

Ratio of treated
Yields (pounds)
to control
Plat

Shock Grain Shock Grain

Treated. 2,332 644.8

1.02 0.97
Control _ 2,281 656.5

—
Experiments in 1915. Wheat was again sown in the autumn of
1914. The fall treatment was omitted, owing to bad weather. In
1915 the network was charged positively by the Lodge- Newman
apparatus twice a day from 4 to 7 a. m. and from 5 to 8.30 p. m., a
total of 345 hours. The distance between the cross wires of the net-
work this year was 6 feet. The plats were divided at harvest into
east and west halves. The yields are shown in Table 3.
In both plats two bad spo^s developed on the western halves, in
which the grain was much poorer than the average.
Table 3. Yields of winter wheat on plats following electrocultural treatment (posi-
tive charge), section E, Arlington Experiment Farm, in 1915

Ratio of treated
Yields (pounds)
to control
Plat
Shock Grain Shock Grain

Eastern half:
Treated 832 321.5
1.01 0.92
Control 822 350
Western half:
Treated 716 303
1.32 1.19
Control 540 254.5
Total:
Treated 1,548 624.5
1.14 1.03
Control- 1,362 604.5

—
Experiments in 1916. In the fall of 1915 winter wheat was again
sown, as it was desired to get a test with the network charged
negatively, about 45,000 volts, instead of positively as heretofore.
A powerful static machine was used to supply the current, and it
was run from 4 p. m. to 8 a. m. daily (totaling 800 hours) during
the spring, the fall treatment being omitted.
The plats were divided into eastern and western halves at the
time of harvest and again showed considerable variation. The
yields are given in Table 4.

Table 4. — Yields of winter wheat on plats following electrocultural (negative)

treatment, section E, Arlington Experiment Farm, in 1916

Plat
 .

ELECTROCULTURE

—
Experiments in 1917. Wheat was again sown in section E in
October, 1916, and allowed to mature the following summer without
treatment, as an additional check on the soil conditions. At time of
harvest in 1917 the plats were again cut into eastern and western
halves, the south plat being the one which had received the elec-
trical treatment in previous years. The yields are shown in Table 5.
Comparison with the rye yields of 1913 shows that the south
(treated) plat apparently gained slightly in its relative productivity
during the five years, but the change is well within the errors of field
trials.

Table 5. — Yields of winter wheat on plats without electrocultural treatments,

section E, Arlington Experiment Farm, in 1917

Ratio of south to
Yields (pounds)
north plats
Plat

Shock- Grain Shock Grain

Eastern half:
South plat. 1, 028. 580. 5
1.00 0.92
North plat- 1, 025. 031.0
Western half:
South plat_ 1, 502. 5 557.0
1.08 .98
North plat 1, 439. 5 567.5
Total:
South plat. 3, 190. 5 1,137.5
1.04 .95
North plat 3,004.5 1,198.5

Experiments in 191S. —In the

1917 winter wheat (Ourrell)
fall of
was sown on the and in the spring a i^-inch mesh
plats in section E,
galvanized-iron screen 132 feet long by 15 feet high was erected 20
feet south of the check plat. It was thought that the grounded
screen might protect the north plat from the drifting charge, but
later measurements show that it is of doubtful value.
The static machine was again used, with the positive pole con-
nected to the network. The number of cross wires was increased
to one every 3 feet. This increased the current and reduced the
potential of the network to about 30,000 volts.
Although the winter was exceptionally cold the stand in the spring
was excellent. Treatment was started April 15 and continued for
46 days from 4 p. m. to 8 a. m. each day, a total of 736 hours.
At harvest the eastern and western halves of each plat were kept
separate and weighed. The yields are shown in Table 6.

Table 6. — Yields of winter wheat on plats following electrocultural treatment (posi-

tive charge), section E, Arlington Experiment Farm, in 1918

Plat
 —
8 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

A general view of the experimental field as it appeared on 8, May

1918, is shown in Figure 1.
After the 1918 crop was harvested, measurements of the charge
carried by the wind were undertaken. A
flame collector was used,
which was connected to the gold leaf of an electroscope, the case
being grounded. A
full-scale deflection of 25 divisions represented
a potential of about 1,000 volts. In all the measurements the
collector was held at a height of 1 meter above the ground.
A light south wind was blowing the day the measurements were
made. With no charge on the network, a very slight deflection of
the gold leaf could be noticed. With the network charged, however,
the full-scale deflection occurred very rapidly at any point under and
within 20 feet outside the network on all sides, even to the south,
the direction from which the wind was coming. At 50 feet south,
only about 1 division deflection was obtained. North from the net-
work the deflection to full scale was slower and more irregular the
greater the distance from the network, and when only 2 feet south of
the screen along the south side of the north plat the maximum deflec-
tion obtainable was about 20 divisions. Just north of the grounded
screen the maximum deflection obtained was about 9 divisions. As
the collector was moved farther north from the screen and into the
control plat, the deflection again increased, until at the center of the
control plat it was off the scale again. The grounded screen along
the south side of the control plat thus afforded little protection from
the drifting charge. At a point 1,000 feet from the network, the
last point observed, a full-scale deflection was obtained. At all
points beyond 100 feet from the network over the south plat the
deflection was very irregular and unsteady.
The Weather Bureau records show that during the 46 days of
treatment in 1918 the wind was due south only 3 days. Owing to
the distance of 350 feet between the treated and control plats, the
wind would have to be nearly due south to carry any appreciable
charge over the control plat.

SUMMARY OF EXPERIMENTS IN SECTION E

The relative yields of the south (treated) and north plats in section
E are summarized in Table 7.

Table 7. Summary of yields of rye and winter wheat on the south (treated) and
north (untreated) plats, section E, Arlington Experiment Farm, in six stated
years

Year
 ELECTROCULTUEE 9

half of the control plat. Aside from this, there appears to be a gradual
increase in the total yield of the south plat relative to the north one,
irrespective of whether a positive charge, a negative charge, or no
charge at all was used. It is of interest to note that the grain ratios
with a positive charge on the network are all slightly higher than the
ratio in 1917, when no treatment was given; with the negative charge
the reverse is true. This seems consistent, for if increasing the posi-
tive gradient of the electrostatic field tends to stimulate growth, then
to reverse the sign of the field may perhaps tend to inhibit growth.
Opposed to this speculation is the fact that the negative field appar-
ently had no effect on the ratio of the total yields of the two plats.
In brief, while there is some evidence of a slight increase in grain
yield when wheat is grown under a network which is positively charged
to a high potential, the observed effect is so small that it is well within
the experimental errors of field trials.
EXPERIMENTS IN SECTION B
—
Experiments in 1911. The first electrocultural field experiments at
Arlington Experiment Farm were made in 1911 with grains in sec-
tion B, employing a plat which had been seeded in strips to wheat
the previous fall. In the spring of 1911 a network of small wire was
installed over the eastern half of the plat, covering half of each
variety. The network was 7 feet high with wires at intervals of 3
feet, connected to the positive pole of a static machine operating at
a potential of about 40 to 50 kilovolts. The machine was in opera-
tion six days a week from 3 p. m. to 7 a. m. except during rainy
weather from early spring to harvest.
Table 8 shows the relative yields of the treated and control halves.
Table 8.-
10 BULLETIN 1379', U. S. DEPARTMENT OF AGRICULTURE

Table 9. — Yields of winter wheat on plats folio wing clectrocultural treatment (posi-
tive charge), section B, Arlington Experiment Farm, in 1912
 ELECTBOCULTUEE 11
Table 11.- -Yields of corn on plats following electrocultural treatment (alternating
charge), section B, Arlington Experiment Farm, in 1914
12 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE
SUMMARY OF EXPERIMENTS IN SECTION B

The 1916 results show about 15 per cent difference in the yield of
the plats when no electrical treatment was used, the control plat
giving the higher yield. During the preceding three years the yields
of the two plats were approximately equal. If the 1916 results are
accepted as indicating the relative productivit} of the two plats
7-

under normal conditions, the conclusion follows that during the pre-
ceding three years the electro cultural treatment increased the yield
15 per cent or more and that an alternating charge on the network
was equally as effective as a high positive charge. During the time
the network was connected to the alternating-current power line the
charge was changing sign 50 times per second, the maximum gradient
was about 1,500 volts per meter, and there was no appreciable ioniza-
tion at the network. The conditions were so different from those
prevailing when the network was charged to a steady high positive
potential that it seems highly improbable that the effect on the grow-
ing crop would be the same unless the effect is nil under both condi-
tions, the 1916 results not being representative. The latter conclu-
sion seems the more probable, and this is supported by the experi-
ments in section A which follow.
EXPERIMENTS IN SECTION A
A plat in section A of the same dimensions as the one in B was also
used for electrocultural tests. The north half of this plat was
equipped with a 16-foot network similar to the B network except that
it had twice as many cross wires (5 yards apart) The two networks
.

were connected electrically, so that both received the same charge.

—
Experiments in 1914- Soybeans were planted in section A in June,
1914, and subjected to a 6,600-volt 25-cycle treatment (alternating
charge) continuously from July 15 to October 19, when the crop was
harvested. The total weight of the crop from each plat was deter-
mined just after cutting, again after drying in the field, and finally
after threshing. The weights recorded are shown in Table 14.
Table 14.— Yields of soybeans on plats following electrocultural treatments {alter-
nating charge), section A, Arlington Experiment Farm, in 1914
 —
ELECTROCULTTJRE 13

Table 15. Yields of rye on plats following electrocultural treatments (alternating

charge), section A, Arlington Experiment Farm, in 1915

Plat
 —
14 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

cage of 3^-inch mesh. The frame was connected to the positive

pole of the static machine, the other pole being grounded. The
frame was charged four hours a day, from 3 to 7 p. m., from February
21 to March 24. The plants were again allowed to grow without
treatment from March 25 to April 7. During each period weigh-
ings were made to determine the loss due to transpiration, and
water was added when necessary to maintain approximately the
initial moisture content of the soil.
Table 17 shows the rate of transpiration for each pot during the
three periods and the ratio of the treated to the control set. It
will be noted that during the period of treatment no sensible change
occurred in the transpiration ratio.

Table 17. Transpiration rate of geranium plants in pots under electrocultural

treatment in the plant house at Washington, D. C, in 1913
 ELECTROCULTURE 15
WATER REQUIREMENT
An
investigation of the effect of a high potential gradient on the
water requirement of cowpeas was undertaken in a plant house
during the winter of 1918. Eighteen large galvanized-iron cans,
each holding about 125 kilograms, were filled with well-mixed soil
and fitted w^th special covers to prevent evaporation. The cow-
peas were planted through holes in the covers, the openings being
sealed with w&x. The pots were weighed at the beginning and at
the end of the experiment, and a record was kept of the water added
to each pot, from which the total quantity of water transpired by
the plants in each pot could be determined. In brief, the procedure
was that followed by Briggs and Shantz (10, 11) in their water-
requirement measurements.
These pots were divided into three sets of sLx each. Set No. 1
was placed on an insulated stand, with each pot connected to the
positive pole of a static machine; set No. 2 was grounded and placed
under a positively charged iron-wire screen suspended about 2 feet
above the plants; and set No. 3 was used as a control and was protected
from the influence of the charged sets by a well-grounded ware screen.
The potential supplied by the static machine was above 50,000 volts.
As soon as the treatment started trouble was experienced with
the set beneath the charged network, soot and dust (large ions) being
deposited on the leaves and stems of the plants, and in fact all over
the house. A coating would collect on the leaves over night during
the course of a 16-hour treatment. The plants were washed several
times, but they did not thrive, owing in part at least to the great
reduction in photosynthesis resulting from the coating on the leaves.
This set was finally discarded.
The other two sets, however, grew well throughout the experi-
ment, although they were not so vigorous as plants grown out of
doors in the summer. The positions of the pots in a given set were
interchanged weekly, so as to provide average light conditions for
each pot.
The plants were cut May 2, after 54 days of treatment for 16 hours
each day (from 4 p. m. to 8 a. m.), and they were dried at 100° C.
and weighed. The water requirement of the plants in each pot
wT as computed by dividing the total wT eight of water transpired
by the dry weight of the crop. The mean water requirement for
each set of six pots with its probable error was as follows: For the
treated set. 449 ±4; for the control set, 429 ±5. A slightly higher
w ater requirement is thus showm for the treated set, the observed
r

increase being 4 ±1.2 per cent. If some of the water molecules

escaping through the stomata of the leaves carried a positive charge,
they w ould move away from the leaf more rapidly than under normal
r

conditions, owing to the strong electric field. This would be equiva-

lent to a virtual increase in the vapor pressure gradient near the
leaf and would tend to increase the evaporation rate. Although the
above suggestion is highly speculative, it would be of interest to
repeat the experiment, applying the electric charge during the
daylight hours when the transpiration rate is highest.

SUMMARY OF EXPERIMENTS AT ARLINGTON EXPERIMENT FARM

Electrocultural experiments extending over a period of eight years
have been conducted at the Arlington Experiment Farm, Rosslyn,
Va., for the purpose of determining whether a highly charged network
 —
16 BULLETIN 1379, U. S. DEPARTMENT OP AGRICULTURE

will increase the yield of crops growing under it. The electrical
treatment was usually given during the early-morning and late-
afternoon hours. The general experimental procedure was similar
to that employed in experiments in England in which the electrical
treatment is reported to have given increased yields.
These experiments do not show any well-defined increase in yield
due to electrical treatment. There is an indication of a slight
increase in the yield of wheat when grown under a positively charged
network, but the observed increase is well within the experimental
error of field trials.
The results of these field experiments are summarized in Table 19.
The relative productivity of the plats when not subjected to the
electrical field was determined in order to provide additional informa-
tion in interpreting the results, a precaution which has not been
generally observed by other investigators. discussion of the A
yields from each section will be found in the text embodying the
description of the experiments.

Table 19. Summary of the results of the electrocultural experiments in sections A,

B, and E, Arlington Experiment Farm, in stated years
[The treated and control plats in sections A and B were each three-fourths of an acre in area; those in section
—
E half an acre each, separated by an interval of 350 feet. Abbreriations and symbols. Column 2: C = Cow-
peas (crop cut for hay); R = Winter rye; S = Soyheans; \V = Winter wheat. Column 3: Numbers refer
to preceding tables. Column 4: A=25-cycle alternating current; N = No treatment; — = Negative
direct current; += Positive direct current. Column 12: * = Yield of plats treated in previous years]
 ELECTROCTJLTURE 17
Plant-house experiments were also made on the effect of an electric
charge on the transpiration rate and the water requirement of plants.
The effect observed was well within the errors of experiment.
The use of electrocultural methods in their present state of develop-
ment as a practical means of increasing the yield of crops in this country
is not recommended.

REVIEW OF OTHER INVESTIGATIONS IN ELECTROCULTURE

Electrocultural experiments may be divided into two main classes:
(1) Those in which the soil is the medium of conduction and (2)
those in which the air is the medium of conduction. Experiments of
the first class cover the use of soil currents resulting (1) from an
externally applied electromotive force, (2) from the galvanic action
of the soil moisture on zinc and copper plates buried in the ground,
and (3) from the use of metallic uprights designed to collect and
carry atmospheric electricity to the soil. Experiments of the second
class are those in which the normal air-earth current is increased by
means of a highly charged network over the plants or decreased by
inclosing the plants in a grounded cage made of metal screen.

EXPERIMENTS WITH SOIL CURRENTS

Among the first experiments with soil currents on a large scale

were those by Ross, prior to 1844, (44) in New York. He buried a
copper plate 5 feet by 14 inches perpendicularly in the earth with
the 5-foot edge horizontal, and at a distance of 200 feet a zinc plate
of the same dimensions was similarly buried. The two plates were
connected above the ground, forming a galvanic cell. Potatoes were
drilled in rows between the plates and also in a similar plat without
plates. At the end of the experiment some of the potatoes from both
plats were measured, those from the treated plat averaging 2^2
inches in diameter, while those from the control averaged only half
an inch.* The total weights at harvest are hot given, and conclusive
assurance that the two areas were of equal fertility at the outset is
lacking. The supposed beneficial effect is rendered doubtful through
the subsequent discontinuance of so simple a treatment.
About this time Solly (46) conducted in England 70 small tests
similar in principle to those of Ross, the plates being 4 by 5 inches
and spaced only 6 inches apart. Grains, vegetables, and flowers
were planted between the electrodes. On comparing the appearance
of the treated and untreated plants a beneficial effect was recorded
in 19 cases, a harmful effect in 16 cases, and no effect in 35 cases.
Solly concluded that electricity has practically no effect on plant
growth.
Fitchner (16) has recorded large increases from treatment with
galvanic currents. From his figures alone the experiments would
indicate increases of 16 to 127 per cent due to treatment. The
statement was made, however, that the treated plats were provided
with drains but that the control plats were not. Such conditions do
not constitute good experimental practice and leave the results open
to question. This same objection holds for accompanying experi-
ments on the decomposing action of the galvanic current on soil.
c
62149
18 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

In 1881, F. Elfving (15) undertook an interesting series of experi-

ments with different seedlings growing in culture solutions through
which he passed battery currents of different strengths. After
germination the seedlings were mounted on corks which were floated
in the solution between electrodes 6 by 4 centimeters in size. He
found that in nearly every case the root would turn and grow in a
direction against that of the electric current. Plates of carbon,
zinc, and platinum were used, and all gave the same effect. Elfving
attributes this phenomenon of orientation to the slowing up of the
growth on the side of the root toward the positive pole. This same
phenomenon was noticed by Plowman (40, 41) hi 1902-03.
Holdefleiss (23) in 1884 selected several rows of sugar beets in a
field which showed a good stand and uniform conditions. In this
field copper plates 50 centimeters square were sunk perpendicularly
in the ground 50 centimeters deep, so that the plates included two
rows of beets. At the other end of the rows, 56 meters distant,
other plates were sunk, and between the two a 14-cell Meidinger
battery was connected. This same arrangement .was used on a potato
field. Further experiments were conducted with copper and zinc
plates 33 meters apart connected by a solid copper wire. The report
of the experiments stated, in substance:
all treated plats throughout the
(1) That an electric current was present on
season, its presence being determined by a sensitive electrometer; (2) that the
rows of beets and potatoes between plates which were connected to the battery
showed no difference in growth at any stage of their development; (3) that the
beets and potatoes in rows between the zinc-copper combinations assumed a
somewhat fresher and stronger appearance about 10 days after the beginning of
the experiment, and the harvest showed an increased yield ranging from 15 to
24 per cent.

It should be remembered, however, that in experiments with soil

currents the path of the current is not wholly by the most direct
route from one electrode to the other, but that the lines of flow
spread out through the soil in a way similar to the spreading of the
lines of force between the poles of a bar magnet.
Experiments conducted by Wollny (48) included five plats 4 by 1
meter each in size separated by a path 1.2 meters wide and by boards
sunk 25 centimeters in the ground. On plats 1 to 3 a zinc plate
was sunk at both of the narrow sides, and these were connected as
follows: Plat 1, induction coil operated by three Meidinger elements;
plat 2, a battery of six Meidinger elements; plat 3, a battery of
three Meidinger elements. On plat 4 a zinc plate was sunk on one
end and a copper plate at the other, the two being connected above
ground by a copper wire. Plat 5 constituted a check or control plat.
Each plat was divided into four equal parts 1 square meter each
in area and seeded. Numbers of plants up on different dates showed
practically no effect for any of the different treatments. The yields
recorded at harvest time, based on an equal number of plants per
square meter, are shown in Table 20.
 ELECTROCULTURE 19

Table 20. — Yields of rye, rape, bean, and potato plants after electrocultural treat-
ments in 1SS3, according to Wollny
20 BULLETIN 1379, U. S. DEPAETMENT OF AGRICULTURE

kinds of seeds, it was found that in every case the seeds grew much
quicker in the boxes containing the plate. Hemp seed was fully an
inch above the surface before controls showed any plants. The
observation was made also that plants in the zones nearest the plates
were the first to come up. Watering with dilute acetic acid was
found to cause quicker growth for treated plants—possibly because
of increased current resulting from the acid-metal reaction. Upon
repeating these experiments, Leicester decided that the only action
of the current was to stimulate the plant until the initial store of
food was used up. No data were recorded in either of his reports.
Berthelot (3) conducted some tests with soil currents to determine
whether electricity aided in the fixation of nitrogen by plants. Suit-
able control plats were provided. He reported that the treated
plants grew much more rapidly, being nearly twice the weight of
the control plants at the end of four to six weeks. Although not
complete or definite, the experiments were abandoned for various
reasons.
Kinney (27) made an extensive series of experiments to determine
the influence of electrical currents on germination. Seeds were sub-
jected to different current strengths for different periods of time and
then put in suitable germination apparatus and the subsequent
growth noted. An intermittent treatment of 30 seconds per hour
was given in some cases, arranged by clock contacts. Two different
arrangements were used for the treatments. In one a dass cylinder
containing the seeds was equipped at each end with electrodes.
These were pressed against the seeds through which the current Mas
thus directly passed. In the other, the seeds were placed in wet
sand held between perforated metal disks, which were used for the
electrodes. The entire layer was held in a glass funnel in which the
growth of the radicle could be measured without removal. Eight
sets of 25 seeds eacli were used in each test, one set being the control
and the other seven receiving different strengths of current. Experi-
ments with barley showed that the growth of treated seeds increased
as the current strength increased up to a certain optimum value,
above which the growth decreased with increase in current strength.
With white mustard, rape, and red clover the optimum treatment
for both roots and stems was identical.
Plowman (40, 41) has recorded the results of experiments con-
ducted at the Harvard Botanical Gardens on the influence of soil-
conducted currents on plant life. Platinum or carbon electrodes
were used, with potentials ranging from 5 to 500 volts. The regu-
lation of temperature was a serious difficulty —
a fact mentioned for
the first time in connection with such experiments and one that may
have been ignored in earlier reports. Plowman found that seeds
near the anode were always killed by a current of 0.003 ampere or
more if continued for 20 hours. Seeds at the cathode were little
affected by currents less than 0.08 ampere.
Gerlach and Erlwein (19, 20), at Bromberg, investigated the
effect of weak soil currents on germination and growth. The field
was made up of seven plats of 200 square meters each. Current
was taken from a car line and led to the three treated plats, which
were provided with iron plates 20 meters long by 30 centimeters
wide and 2 millimeters thick sunk into the soil at both ends. Each
of the seven plats was seeded half with barley and half with potatoes.
 ELECTROCULTURE 21

The treatment continued 24 hours a day for 86 days for barley and
139 days for potatoes, beginning in April. Both barley and potatoes
showed excellent growth, but no differences between the treated and
control plats were discernible at any time. Other experiments
were conducted with plants grown in boxes provided with copper
and zinc plates connected overhead by wires. Trials with rye,
wheat, anci lupine gave no difference between treated and untreated
crops.
Homberger (24) reported that the passage of high-frequency
currents through the soil was beneficial to plant growth. His
experiments were conducted on a small scale, using flowerpots with
only a few plants, the treatment consisting of three applications
daily until the temperature of the soil reached 35° C, when the
current was cut off. The leaves and stems of the treated plants
showed more chlorophyll than the controls. A photograph shows
one pot each of treated and control plants, the treated plants being
about five times as high as the others. In order to determine
whether the heating was the main cause of increased growth another
pot was subjected to test currents for five minutes daily. These
plants were about four times the height of the controls when photo-
graphed. From these comparisons Homberger concluded that the
oscillating field and not the temperature was the main cause of the
stimulation, and he believed his results to be due to chemical changes
taking place under the influence of the oscillating electromagnetic
field, analogous to the catalytic action of light.
In 1907 (17) and 1909 (18) Gassner reported upon experiments
with charged soil which indicated a general unfavorable action upon
plant growth.
Kovessi (28) obtained unfavorable results in researches involving
some 1,100 experiments.
Considerable publicity has been given to an apparatus called a
"geomagnetifier," a sort of lightning rod designed to gather in
atmospheric electrical energy and supply it to the crops. Among
those who have reported favorable results through the use of such
apparatus are Maccagno (35), Basty (2), and Paulin (39).
At the present time methods of electroculture employing soil-
conducted cm-rents have few proponents.
EXPERIMENTS WITH MODIFIED POTENTIAL GRADIENTS
Grandeau (21), in 1878, reported studies on the effect of the
electrical condition of the atmosphere upon the growth of vegetation
He grew plants in a Faraday cage consisting of four iron rods 1.
centimeter in diameter by 1.5 meters high, holding fine iron wires
forming 15 by 10 centimeter meshes. The cage was grounded in
order to destroy the normal electrical field. Experiments were
made with tobacco, corn, and wheat. The plants under the cage
were reported weak and slender. Six stalks of wheat grown in
free air weighed 6.57 grams, as compared with 4.95 grams for six
stalks grown under the cage.
Grandeau was led by these experiments to the belief that high
trees act as a grounded network, in that they shield the vegetation
beneath their foliage from the action of the normal electrical field,
thereby causing a decreased rate of growth. With a sensitive
Thompson electrometer, he compared the strength of the field in the
22 BULLETIN 1379, U. S. DEPARTMENT OP AGRICULTURE

open with that under vegetation. The results indicated that under
trees and shrubs the potential gradient was greatly reduced. The
experiments of Grandeau were confirmed by Mascart (36).
As opposed to the conclusion of Grandeau, the modern greenhouse
of steel construction constitutes in itself an approximation to a
Faraday cage about the plants growing within it, and yet the develop-
ment of the plants is surely not seriously impaired in consequence.
Likewise, Briggs and Shantz (10, 11), in their investigation of the
water requirements of plants, carried hundreds of pots of plants to
full maturity under a grounded metal framework, covered above and
on the sides with metal screen of ^-inch mesh, which must have
annulled the normal electrostatic field; yet the plants grown within
the inclosure were almost without exception superior in development
and luxuriance of foilage to those grown in similar pots outside.
Lemstrom (32) conducted in Finland a long series of experiments
to determine, if possible, the influence of static electricity on plant
growth. The presence of strong electric charges in the atmosphere
of northern regions, as indicated by the northern lights, linked with
the astonishing development of vegetation in such regions, led him
to regard atmospheric electricity as an important factor in plant
growth. Garden vegetables, fruits, and small grains were subjected
to several different treatments in these investigations both in green-
houses and in open fields. Lemstrom summarized the results of his
experiments as follows:
(1) The real increase due to electrical treatment has not yet been exactly
determined for the different plants, but we are approaching its smallest value by
fixing it at 45 per cent.
(2) The better and more scientifically a field is cultivated and manured, the
greater is the increase percentage. On poor soil it is so small as to be scarcely
perceptible.
(3) Some vegetables can not endure the electric treatment if they are not
watered, but then they will give very high percentage increases. Among these
are peas, carrots, and cabbage.
(4) Electric treatment when accompanied by hot sunshine is damaging to
most vegetables, probably to all; wherefore if favorable results are to be arrived
at the treatment must be interrupted in the middle of hot and sunny days.

Experiments similar to those conducted in Finland were conducted

in England, Germany, and Sweden with like results. A
detailed
description of all of these experiments may be found in " Electricity
in Agriculture and Horticulture," by Lemstrom (32).
Priestley (42, 43) reported on the experiments of Newman (37)
at Golden Valley Nurseries at Bitton. A
small Wimshurst machine
was used, one terminal of which was grounded and the other connected
to wires suspended over outside plats and also to wires in seven glass-
houses. The wires were hung 16 inches above the tops of the plants
and were provided with discharge points hung at short intervals.
The machine was operated 9.3 hours a day for 108 days between
March 27 and July 26, the first half of the period in daytime and the
latter half at night. Control plats were provided in all cases similar
to the treated plats except without wires. The results recorded
are given in Table 22.
 ELECTROCULTURE 23
Table 22.— Results of electrochemical treatment of garden crops at Bitton, as
reported by Newman

Crop
24 BULLETIN 1379, IT. S. DEPARTMENT OF AGRICULTURE

Table 24. Results of electrocultural treatment of potato varieties at Dumfries,

Scotland, by Dudgeon in 1911 and 1912

Variety
 — _

ELECTROCULTURE 25

These results indicate a 49 per cent increase in grain and an 88 per

cent increase in straw for the electrical treatment.
The Liverpool City and Electrical Engineers reported on experi-
ments conducted near Liverpool, England, in 1917. Two plats in
newly plowed pasture land separated by about 375 feet were used,
an analysis indicating that the surface and subsoil were of the same
character. Various plant crops were grown, and in general the elec-
trified area gave substantial increases in yield over the control area.
A copy of this report is on file in the Office of Biophysical Investi-
gations, Bureau of Plant Industry.
Honcamp (25) has summarized the results of several previous in-
vestigations and pointed out serious objections to the methods used.

Table 26. Results of electrochemical treatments of oat crops at Mocheln, Germany,

according to Gerlach and Erlwein

Relative yields Composition (per cent)

Electrical and soil treatment Grain Straw

Grain Straw
Dry mat- Nitrogen Dr y mat " Nitrogen
ter e

No electricity:
Fertilizer, irrigation 26.60 34.40 91.4 1.94 77.4 0.32
Do 28.80 32.20 92.4 1.70 76.2 .27
Fertilizer, no irrigation. 20.60 24.40 87.9 2.13 73.5 .46
Do 20.90 22.10 89.9 2.04 74.3 .38
No fertilizer, no irrigation __ 19.60 19.40 90.4 1.85 78.8 .32
Do 19.60 17.40 90.1 1.67 79.8 .32
Direct current:
Positive, fertilizer, irrigation 27.80 36.20 90.4 1.94 71.6 .27
Negative, fertilizer, irrigation 27.80 37.20 91.7 1.74 72.9 .24
Positive, fertilizer, no irrigation 21. 60 24.40 90.5 2.16 74.5 .36
Negative, fertilizer, no irrigation 20.50 22.50 91.2 2.07 73.7 .30
Positive, no fertilizer, no irrigation. 21.00 23.00 84.4 1.88 76.6 .28
Negative, no fertilizer, no irrigation 17.80 18.20 90.4 1.72 78.4 .28
Alternating current:
Fertilizer, irrigation 26.20 31.80 91.7 1.81 78.4 .28
Do 26.00 32.00 90.6 1.78 77.9 .23
Fertilizer, no irrigation 19.50 21.50 91.3 2.16 73.2 .33
Do 19.90 21.10 89.8 2.11 75.9 .30
No fertilizer, no irrigation 18.00 18.00 91.1 1.84 82.2 .28
Do._ 18.00 18.00 91.4 1.83 85.0 .26

Summary of Relative Yields of Grain and Straw

High-tension current

No elec-
Soil treatment tricity Direct
Alter-
nating
Positive Negative

Grain:
No fertilizer, no irrigation 19.60 21.00 17.80 18.00
Fertilizer, no irrigation... 20.75 21.60 20.50 19.70
Fertilizer, irrigation 27.70 27.80 27.80 26.10
Straw:
No fertilizer, no irrigation 18.40 23.00 18.20 18.00
Fertilizer, no irrigation.. 23.25 24.40 22.50 21.30
Fertilizer, irrigation 33.30 36.20 37.20 31.90

On the Continent during this period many electrocultural experiments

were carried out, using networks charged to high potentials. Reports by
Hostermann (22), Gerlach and Erlwein (19, 20) Clausen (13) Breslauer , ,

(9) and others indicate that no benefit may be expected from the use
,

of the network. The German experiments made use of an extensive

26 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

and variable complex of conditions, designed to include the study of

positive and negative potential in relation to fertilizers and irrigation
and the relation of these factors to the composition of grain and straw.
The results shown by Gerlach and Erlwein reporting experiments
with oat crops at Mocheln are selected as representative. (Table 26.)
It may be well worth while to consider Table 26 in some detail,
since it seems to represent a thoroughly impartial study of the
methods which have given success elsewhere.-
The instances in which duplicate trials were run and the agree-
ments to be noted for these cases show rather conclusively that lack
of uniformity in soil conditions was not a disturbing factor in these
experiments. The six plats giving notably higher yields are those
with fertilizer and irrigation. These are in good agreement and show
no appreciable advantage for the three types of electrical treatment
represented, the averages for relative yields only being as shown in
the summar}^ of Table 26.
The plats in these experiments were about one-fourth acre each,
the control plats being separated from the electrified plats by about
325 feet. The potential of the direct-current network was about
30,000 volts, whereas that of the alternating current was about
20,000 volts. The statement of Lemstrom that the better the con-
dition of the field the more favorable the influence of the high-tension
discharge is not substantiated by these trials. In brief, the German
experiments give little evidence of any definite crop increase at-
tributable to the electrical treatment.
In 1913 Dorsey conducted greenhouse experiments in Ohio with
radishes and lettuce, using a high-frequency current. In a letter to
Doctor Briggs dated August 8, 913, he reported the relative weights
1 1

of 10 plants selected at random from each area. These are shown in

Table 27.

Table 27. Results of electrocultural treatments of greenhouse radishes and lettuce

in 1913, according to Dorsey
 —
ELECTROCULTURE 27

and three hours in the afternoon. A

generally favorable influence for
the discharge treatment was reported. Unfortunately total weights
were not included. The results for the second year were generally
unfavorable for the discharge treatment, and Dorsey concluded that
Eerhaps slight differences in the slope of the two plats may have
een responsible for the favorable results of the first year. 5
At the present time perhaps the best evidence of plant response to
electrical discharge is that obtained by Blackmail (4, 5, 6, 7, 8)
of the electroculture committee of the British Ministry of Agricul-
ture and Fisheries. His experiments extend over a period of years
and comprise field trials, pot cultures, and laboratory tests, all of
which he interprets as affording converging evidence for a favorable
growth response to the application of electricity. On account of the
practical possibilities associated with a treatment assuring increased
growth it seems desirable to examine in some detail the data which
ave given rise to this assurance.
The field trials carried on in England by Blackman and his as-
sociates have given the results which are summarized in Table 28.

Table 28. Results of electrocultural treatments of grain crops in England, as

reported in field experiments by Blackman

Crop and year

28 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

These tabulated values are in many ways not subject to biometrical

analysis; they represent the results of experiments carried out with
varied complexes of soil, season, acreage, crop, and electrical treat-
ment. Nevertheless, in the absence of any definite knowledge con-
cerning the conditions under which an electrical treatment may be
presumed to be most effective there is perhaps no better index than
a comparison.
Of 33 trials shown in Table 28, 21 indicate an increase for treated
areas, whereas 12 indicate a decrease. The treated areas return a
yield represented by the range 76 to 184 when the untreated areas
return a yield represented by 100 and give an average increase of
14 per cent. This increase is based upon yields reported for experi-
ments regardless of crop or seasonal normality, and Blackman esti-
mates the more reliable experiments as indicative of an average
increase in yield of about 22 per cent. In either case, such an in-
crease would seem sufficient to be of promise from an agricultural
standpoint. If an attempt is made to determine from these tabu-
lated values the conditions under which the increases were obtained,
serious difficulties are immediately encountered.
Unfortunately the normal productivity of the electrified and
control areas is in most cases unknown, and a serious lack of soil
uniformity is evident from the yields of different portions of control
areas. For example, in the 1919 and 1920 plats with oats at Lin-
cluden, which occupied the same areas for the two years, the control
yields were as shown in Table 29, in which the relative yields of the
corresponding treated areas for the same years, the controls being
taken as 100, are also shown for comparison:

Table 29.
 —
ELECTBOCULTUEE 29

Table 30. Analysis of the average results of electrical treatments of oat plats at
Lincluden, England, in the years 1917 to 1920, inclusive
30 BULLETIN 1370, U. S. DEPARTMENT OF AGRICULTURE

In contrast to the field experiments, however, the pot-culture trials

afford results from several similarly treated pots and plants, so that
an estimate of individual experiments may be made by comparing
the differences between treated and untreated plants with the prob-
able errors involved in the measurements.
When the pot-culture records are examined in this way, it becomes
evident that the treated and untreated plants present substantial
differences. With uniform soil and seasonal factors for electrified
and control plants the association of these differences with the
treatment becomes intimate. The fact that these differences favor
the control plants about as often as the treated plants emphasizes
the complexities involved and makes one less certain that these
differences are definitely attributable to the electric discharge.
The laboratory experiments of Blackmail and his associates have
been on the effect of a direct current of very low intensity on
the rate of growth of the coleoptile of barley. Differences in the
growth rate of treated and control plants were noted over short
periods. The small differences attributable to the direction of the
current and the pronounced after effects obtained make the inter-
pretation of the data difficult and uncertain.
In general, then, one finds in Blackman's experiments many
significant differences between the electrified and control plants.
In some instances the relation of the discharge to these differences
may well be questioned. In others the relation appears to be an
intimate one. and the significance of such differences is the immediate
concern of further research in electroculture.

Table 32. Summary of elcctrocultural trials

1
 ELECTROCTJLTTJRE 31

The researches of Maimbray, Nollet, Bose, Menon, and Jalabert would

indicate that electricity accelerated the development of plants, both in their
germination and in their subsequent development. Nuneberg, many years
afterward, repeated the same experiments with the same results. Linne and
Kostling observed the same effects. Achard confirmed these results. Berthelon,
in a treatise on the electricity of plants, has summarized the information on the
subject and substantiated it by further research of his own. Gardini, from work
carried on at Lyon, affirmed the influence of electricity on vegetation. Carmoy,
d'Ornoy, and Rosieres have defended this opinion in the Journal de Physique.
These doctors base their conclusions on the identity of natural and artificial
electricity, on the continual electrified condition of the atmosphere, and on the
meteorological phenomena which indicate in a more or less sensitive manner
the presence of electricity; the different elevated parts of plants, which are in
themselves excellent conductors of electricity, offer in their leaves, as De Saussure
has observed, the proper points to receive the electric fluid. All these . . .

experiences led to the opinion stated when Ingenhousz published experiments

which proved that electricity would not produce the effects upon plants which
had been attributed to it; that electrified seeds 6 would not germinate quicker
than others. These experiments, reported in the Journal de Physique for
December, 1785, were confirmed in the same journal for December, 1786, were
given further support in May, 1788, and were finally summarized in "Experi-
ences sur les vegetaux." Various other workers later confirmed these re-
searches. It seems to me at present [1S00] that the opinion of those who believe
that electricity does not favor vegetation is more logical than the contrary
opinion.

At the present time (1924), there is still a diversity of opinion

concerning the influence of electricity in plant development. The
electroculture committee of the British Ministry of Agriculture and
Fisheries recommends (1923) the continuation of experiments with
high potential discharge, 7 Newman (3S) in England considers
electroculture by the same method as offering practical assurance
of increased returns. Baines (1) points out a wonderland of electro-
biological relationships. On the other hand the experiments of
Gerlach and Erlwein (19, 20) in Germany and the experiments
reported in the first part of this bulletin show no increased growth
definitely attributable to electrical treatment.

• Leighty and Taylor (

31
) report experiments with electrified seed which indicate no advantage gained
by treatment.
7 Typewritten report on file in the Office of Biophysical Investigations, Bureau ot Plant Industry.
 LITERATURE CITED
(1) Baines, A. E.
1921. Germination in its electrical aspects. 185 pp., lllus. London
and New York.
(2) Basty F.
1908. Essais d'electroculture tentes a Angers en 1908. (Extrait.) In
Bui. Soc. Etudes Sci. Angers, aim. 37 (1907), pp. 87-92.

(3) Berthelot, M.
1889. Recherches nouvelles sur la fixation de 1 Azote par la terre
vegetale. Influence de l'electricite. In Compt. Rend. Acad.
Sci. [Paris], tome 109, pp. 281-287.

(4) Blackman, V. H.
1918-1924. [Electrical treatment of fields.]
„.,..,
Gt. Brit. Mm. Agr. and
Fisheries Interim Rpts. 1-6 (1917-23). [Mimeographed.]

(5) 1924. Field experiments in electro-culture. In Jour. Agr. Sci., vol. 14

(1923), pp. 240-267.

(6) and J0rgensen, I.

1917. The overhead electric discharge and crop production. In Jour.
Bd. Agr. [London], vol. 24, pp. 45-49, illus.
(7) and Legg, A. T.
1924. Pot-culture experiments with an electric discharge. In Jour.
Agr. Sci., vol. 14, pp. 268-286, illus.
(8) and Gregory, F. C.
1923. The effect of a direct electric current of very low intensity on the
rate of growth of the coleoptile of barley. In Proc. Roy. Soc,
London, ser. B, vol. 95, pp. 214-228, illus.
(9) Breslatjer, M. . .

1912. Amount of energv needed for electro-culture. In Electrician,

vol. 69, pp. 889^890.

(10) Briggs, L. J., and Shantz, H. L.

1913. The water requirement of plants. I. U. S. Dept. Agr., Bur.
Plant Indus. Bui. 284, 49 pp., illus.

(11) 1914. Relative water requirements of plants. In Jour. Agr. Research,

vol. 3, pp. 1-63, illus.

(12) Chree, C.
1910. Atmospheric electricity. In Enc. Brit., vol. 6, pp. 860-870,
illus.

(13) Clausen.
1911. Die Erfolge der Elektrokultur in Hedewigenkoog. In Landw.
Wchnbl. Schles.-Holst., Jahrg. 61, pp. 83-86.
(14) Dudgeon, E. C.
[1912]. Growing crops and plants by electricity. 36 pp., illus.
London.
(15) Elpving, F.
1882. Ueber eine Wirkung des galvanischen Stromes auf wachsende
Wurzeln. In Bot. Ztg., Jahrg. 40 (1881), pp. 257-264, 273-278.
(16) Fitchner, E.
1861. Agronomische Zeitung, 1861, p. 550. [Not seen. Reference
from Bruttini, A., L' influenza dell' elettricita sulla vegeta-
zione, p. 148, Milano, 1912.]

(17) Gassner, G.
1907. Zur Frage der Elektrokultur. In Ber. Deut. Bot. Gesell., Bd.
25, pp. 26-38, illus.

(18) 1909. Pflanzenphysiologische Fragen der Elektrokultur. In Mitt.

Deut. Landw. Gesell., Jahrg. 24, pp. 5-7.
32
 ELECTROCUL.TURE 33

(19) Gerlach, M., and Erlwein, G.

1910. Versuche ueber Elektrokultur. In Elektrochem. Ztschr., Jahrg.
17, pp. 31-36, 66-68, illus.

(20) 1910. Versuche iiber die Einwirkung der Elektrizitat auf das Pflanzen-
wachstum. In Mitt. K. Wilhelms Inst. Landw. Bromberg,
Bd. 2, pp. 424-453, illus.
(21) Grandeau, L.
1878. De l'influence de l'electricite atmospherique sur la nutrition des
plantes. (Extrait.) In Compt. Rend. Acad. Sci. [Paris],
tome 87, pp. 60-62, 265-267, 939-940.
(22) HOSTERMAN.N.
1910. Geschichte und Bedeutung der Elektrokultur unter Beruck-
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34 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE

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 ORGANIZATION OF THE
UNITED STATES DEPARTMENT OF AGRICULTURE
December 2-2, 1925

Secretary of Agriculture W. M. Jardine.

Assistant Secretary R. W. Dunlap.
Director of Scientific Work
Director of Regulatory Work Walter G. Campbell.
Director of Extension Work C.W. Warburton.
Director of Information Nelson Antrim Crawford.
Director of Personnel and Business Adminis-
tration W. W. Stockberger.
Solicitor R. W. Williams.
Weather Bureau Charles F. Marvin, Chief.
Bureau of Agricultural Economics Thomas P. Cooper, Chief.
Bureau of Animal Industry John R. Mohler, Chief.
Bureau of Plant Industry William A. Taylor, Chief.
Forest Service W. B. Greeley, Chief.
Bureau of Chemistry C. A. Browne, Chief.
Bureau of Soils Milton Whitney, Chief.
Bureau of Entomology L. O. Howard, Chief.
Bureau of BiologicalSurvey E. W. Nelson, Chief.
Bureau of Public Roads Thomas H. MacDonald, Chief.
Bureau of Home Economics Louise Stanley, Chief.
Bureau of Dairying C. W. Larson, Chief.
Fixed Nitrogen Research Laboratory F. G. Cottrell, Director.
Office of Experiment Stations E. W. Allen, Chief.
Office of Cooperative Extension Work C. B. Smith, Chief.
Library Claribel R. Barnett, Librarian.
Federal Horticultural Board C. L. Marlatt, Chairman.
Insecticide and Fungicide Board J. K. Haywood, Chairman.
Packers and Stockyards Administration John T. Caine, in Charge.
Grain Futures Administration J. W. T. Duvel, in Charge.

This bulletin is a contribution from

Bureau of Plant Industry William A. Taylor, Chief.

Office of Biophysical Investigations G. N. Collins, Senior Botanist in

Charge.
35

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III