THE EFFECTS OF COPPER CARRIERS ON
CROP PRODUCTION .EN ORGAMC SOILS

Thesis for the chroo of M S
MICHtGAN STATE COLLEGE '
Willem A. van Ec’k _
1954

THE-15‘s

This is to certify that the

thesis entitled

The Effects of Copper Carriers on Crop
Production in Organic Soils

presented by

Willem A. VanEck

has been accepted towards fulfillment
of the requirements for

Master of Science degree in Soil Science

WLW

Major professor

Date August 2; 19511

0-169

m BEETS 01' COPPER CARRIERS

on 030? PRODUCTION IN ORGANIC sous,

By
W111en.A. van Eek
W

.L THESIS
Sdbldtted.to the School of Graduate Studiee of Michigan
State College of.Agr1cu1ture and Applied Science
in partial fulfillment of the requirenente
for the degree of

MSTER 01' SC 11801

Department of 5011 Science
1951+

Tnfiflfi

 

MHOWLIDGIHENT

The euthor wishes to ecknovledge the assistance rendered to hi-
by the staff and his colleagues of the Soil Science Department of
Iichigen State College. .

Special attention is directed to Dr. J. 1'. Davis under whose
guidance the work was done; to Dr. L. I. Turk, Dr. B. L. Cook, and Dr.
I. Lawton. for their part in expediting the work.

The author is thankful for the help of Dr. E. J. Benne end hie
staff of the Agricultural Experiment Station, Agricultnrtl Chemistry
Depart-mt. He expresses hie gratitude to Geigy Gelpany, Inc.. Dev
York, and to the “undbeuvhundig Bureau Veer Sporenclenent-Ieststoffen'
for nking enileble samples of copper cerriers.

his study was side possible by the financial support of the

Calumet and Heels, 1110.. Geld-st, Michigan.

3356530

TABLE OF CONTENTS

PAGE
IMRODUCTION......................... l
MEWOILITEATUBE.....................
Essential nature of capper for plants . . . . . . . . . . .

Physiologicel role of copper in plants . . . . . . . . . . .

\OMWU

Symptoms of copper deficiency . . . . . . . . . . . . . . ..
Copper in the soil . . . . . . . . . . . . . . . . . . . . . 11
Nature end effect of different copper carriers . . . . . . . 16

mm: MT I O O O O O 0 O O O O O O O O O O O O O O I O O O O 18

311011361131 PrOCOdur. e e e e e e e e e e e e e e e e e e e 18
Objoctivtl e e e e e e e e e e e e e e e e e e e e e e e e 18
Dxperimntalprecedure.................. 18

Analyticelprocedure................... 21
Experimentelreeulte.................... 2h
Spinach......................... 2h
Heedlettuce....................... 30
Sudan grass . . . . . . . . . . . . . . . . . . . . . . . 35
Soilsnalyeis...................... 35

Discus-101......................... 1&2

a

mmm II o e e e e e e e e e e e e e e e e e e e e e e e
hurl-011ml PrOCQdur. e e e e e e e e e e e e e e e e e e e “'5
0b JOCt 1", e e e e e e e e e e e e e e e e e e e e e e e e “‘5

Experimentalpreceduro.................. 1&5

PAGE

A‘uyt 1c“ Procedure 0 O O O O O O O O O O C O O O O O O D ”'6

3:

hperinentelresults....................
Discussion......................... 1&8
WIMTIII........................ 52
hperinentalpreeedure................... 52
Objectives.................V....... 52
hperimentelprocedure.................. 52
Analyticalprocedure................... 5”
Experimental results and discussion . . . . . . . . . . . . 5“
SUMMARY........................... 59
LIMLTUREGITED....................... 62

II.

III.

17.

VI.

VII.

LIST OF TABLES

PAGE

Original Location, Type, and Acidity of Organic Soils -

1953 . . . . . . . . . .‘. . . . . . . . . . . . . . . 19
The Effects of Application of Two Copper Carriers en

Yield and Copper Content of Spinach Grown in the

Greenhouse on Eight Organic Soils - 1953 . . . . . . . 25
The Effects of Application of Two Copper Carriers on the

Yield of Lettuce Grown in the Greenhouse on Right

Organic Soils - 1953 . . . e . . . . . . . . . . . . . 31
The Effects eftkpplicatien of Two Copper Carriers on

Yield.and Copper Content of Sudan Grass Grown in the

Greenhouse en Eight Organic Soils - 1953 . . . . . . . 36
The Copper Contents of Eight Organic Soils Before and

.Lfter the Cropping of Spinach, Head.Lettuce, and Sudan

Grass Under Greenhouse Conditions - 1953 . . . . . . . 1&1
The Effects of.Applic8tien of Four Copper Carriers on

Yield and Copper Content of Sudan Grass Grown in the

Greenhouse on Organic Soil, and the Effect of the

Cropping on the Copper Content of the Soil - 1953 . . h?
The Effect of Leaching of an Organic Soil Column en the

Movement of Two Copper Carriers from the Top Six

Inches into the Lower Horizons Under Greenhouse

Conditions and at Three pH Levels - l95h . . . . . . . 55

LIST OF PLATES

Pun ' PAGE

1. The Effect of Application of Two Copper Carriers on the
GrewthofSpinachonSoilz.............. 26

2. The Effect of.Application of Two Copper Carriers on the
Growth of Spinach on Soil 5 . . . . . . . . . . . . . . 27

3. The Effect ef.kpplicatien of Two Copper Carriers on the
Growth of Spinach on Soil 7.. . . . . . . . . . . . . . 28
h. Copper Deficiency Symptoms in Spinach on Soil 7 . . . . . 29

5. The Effect of Application of Two Copper Carriers on the
Growth of Head Lettuce on Soil 2 . . . . . . . . . . . 31

6. The Effect of Application of Two Copper Carriers en the
Growth of Head Lettuce on Soil 5 . . . . . . . . . . . 32

7. The Effect ef.Application of Two Copper Carriers en the
I Growth of Head Lettuce on Soil 7 . . . . . . . . . . . 33
8. Copper Deficiency Symptoms in Head Lettuce . . . . . . . 3h

9. The Effect of Application of Two Copper Carriers on the
Growth of Sudan Grass on Soil 2 . . . . . . . . . . . . 37

10. The Effect of Application of Two Copper Carriers en the
Growth of Sudan Grass on Soil 5 . . . . . . . . . . . . 38

11. The Effect ef.Applicatien of Two Copper Carriers on the
Growth of Sudan Grass on Soil 7 . . . . . . . . . . . . 39

12. Copper Deficiency Symptoms in Sudan Grass . . . . . . . . ho

PLATE ’ PAGE
13. The Effect of Application of Two Copper Carriers on the

GrewthofSudanGrassonSoil9............ G9
114. General View of Experiment III as Set Up in the Green-I

houle O O O O O O O O O O O O O O O O O O O I O I O 0 O 58

INTRODUCTION

.Although the presence of copper in plant tissues was demonstrated
as early as in 1816, the essentiality of the element in plant growth
was not proven until many years later.

re: a long time, it had been known that copper compounds increased
crop yields. However. it was not until 1926 that diminished plant
growth was found to be correlated with a deficiency of copper in the
soil. After the first discovery, symptoms of copper deficiency were
found throughout the world.

Copper is now a normal constituent of the applied fertilisers on
reclaimed organic soils and certain podsolic soils in different parts of
the world.

The occurrence of copper deficiency on organic soils in Michigan
was first reported in 193“. These soils cover about one-eighth of the
land surface of the state. They have gradually become of high economi-
cal importance, where it was profitable to reclaim the land for the
production of crops of high acre value.

.At places where copper deficiency was apparent, copper sulphate
has been used as a satisfactory material for control of this deficiency.
Recently, a nunber of other copper carriers have been applied.with
similar'beneficial effects.

Several studies have been made to detect the behavior of copper in
the soil, which led only to suggestive conclusions.

The present study was undertaken to compare several copper carriers

in their effect on a number of crops grown on copper deficient organic

soils.
In another experiment, two copper carriers were compared in

respect to their behavior in the soil profile.

REVIEW OF LITERATURE

Extensive reviews of the literature on the role of copper in plant
and animal life have been presented in the previous studies on this
subject carried out in the Soil Science Department of Michigan State
College (11, 22, 29, 33, he) and also by others (21, 2h, 35, I41, us,
51).

Recent views on the physicoachemical nature and the physiological
role of copper in living organisms were discussed in the Copper

Metabolism Symposium of Johns Hopkins University (36).

Epsential Nature gf Cgppe; i; Plants

“sissner, as quoted by Scharrer (#8), analysed plant tissue for
copper in 1816 and found it present in small quantities. Following
his work. many others detected capper in the tissue of plants as well as
in other organisms and later also in the soil.

Scharrer (48) reviewed Quateroli who stated in 1918 that copper
was a normal and essential element in plant growth.

Prior to 1930, many experiments were carried out to investigate
the influence of copper on living organisms and to determine the ranges
of concentrations within which the element acts beneficially (6). Im—
proved analytical proceduree have provided means for studying the role
of heavy minerals in the nutrition of fungi and higher plants (7)
particularly after the concentrations of these minerals in chemical rea-

gents employed could be reduced to satisfactory low levels.

h

In 1926, Hudig et a1. (26) observed accidentally that copper sulphate
applied to the soil had a beneficial effect on the earlier described
'reclamation disease“ which occurred in cereal crops on newly reclaimed
peat lands in Holland. It was first believed (7, 149) that copper
inactivated certain toxic substances in the soil. further studies gave
more evidence that it was the lack of copper itself which was responsible
for the deficiency disease.

In 1931. Sommer (50) and Lipman and McKinney (32) concluded on the
basis of water culture studies. that copper is essential in the nutri-
tion of’plants. To demonstrate this, the authors used purified reagents
and water redistilled from pyrex because even traces of copper wore in
some instances sufficient for nornl growth.

Arnon and Stout (3) investigated the specific need of copper for
plants on the basis of the following criteria for eeeentiality of a
Idnor element:

(a) .L deficiency of the element makes it impossible for the plant

to complete the vegetative or reproductive stages of its
life cycle.

(b) Such a deficiency is specific to the element in question

and can.be prevented or corrected only by supplying this
element.

(c) The element is directly involved in the nutrition of the

plant. quite apart from.its possible effects in correcting
some'unfavomable microbiological or chemical condition of

the nutrient medium.

Eesentiality on this basis was evidenced in experiments with
tomatoes, where deficiency symptoms were corrected by the application of
two gamma of copper per acre of soil or after spraying with a 0.02 parts
per million solution of copper sulphate.

Piper (hh) confirmed the essential nature of capper in experiments
with oats growing in nutrient solutions. Traces of copper caused yields
which.were 200 to 1200 per cent higher than those produced in check
solutions. Optimum growth was obtained throughout a wide range of

copper concentrations in the nutrient solution.
Physiological Role of Copper in Plants

In 1911, Montemartini, as quoted by Scharrer (#8), stated that
copper in small quantities stimulated respiration and assimilation of
plants.

Densch and Bunnius (17) found in 1924 that copper increased the
amount of organic substance formed in the plant minly due to the in-
crease of carbohydrates. '

Thatcher (56) showed that copper was important in the oxidation.
reduction reactions within the plant.

Copper is concentrated in the chloroplasts of green leaves where
it might be involved in the primary light reaction of photosynthesis.
Although the chlorophyl molecule itself does not contain copper, the
element might play a role in the formation of chlorophyl. This function
may be indirect since not always chlorotic effects are observed under

copper deficient conditions. Nevertheless, considerable increases in

6
chlorophyl content have been shown after application of copper to plants
(#2). On the other hand, lack of copper may result in a decrease in
chlorophyl formation. Treatments with copper may have a protective
effect against chlorophyl destruction, resulting in a retardation of the
physiological aging of plants, a darker green coloring of the leaves, and
a protection against harmful effects of frost.

Copper is an active part of a number of copper-protein enzymes
which oxidise mono— or polyphenols as well as ascorbic acid according to
their specific function (2). Mbst of these oxidases have been detected
in plants. Mulder (ho) found low oxidase activity in potatoes grown on
soils low in copper.

The experiments of Brown and Hendricks (13) showed that the ascorbic
acid oxidase activity in corn and wheat plants is markedly reduced by
limited copper supply. Wheat produced a lower yield, probably because
the enzyme is a terminal oxidase in this plant. The activity of the
enzyme is a good index of the available copper supply when deficiency
symptoms are not visual (12).

Mareton (35) concluded that a universal explanation for the role of
copper had not been revealed, pointing at the obscurity of the function
of copper containing oxidases in the respiratory mechanism of plants.

Rademacher (h8) noted that a lack of copper affected the growth of
plant reproductive organs much more than it did the vegetative growth.
There were differences in response by different crops. Oat varieties
which showed different response to copper applications did not differ in

copper content in deficient and non-deficient plants. Some varieties

which did not respond to copper stored the element in the grain. The
uptake of copper was highest at the early stages of growth, the amount
and duration of the uptake depending on the copper content of the soil
and the plant species or variety. He prevented copper deficiency symptoms
with copper sprays and could correct then even after these symptoms had
appeared.

Harmer (22), working with Michigan organic soils, found that there
were large variations in response of crops to copper, dependent on a
number of factors: the kind of crop, the reaction of the plowed soil
layer and of the drained underlying layers, the drainage conditions in
the soil and the seasonal climate. In general, most crops were benefited
by copper applications if the natural pH of the soil is 6.0 or less but
more responsive crops responded at even higher acidities. Because of
differences of pH and seasonal climate, crops with different root systems
responded differently to copper.

Piper (an) stated that copper is necessary for growth in the early
seedling stage, and apparently remains essential so long as active growth
continues. as revived growth in dying deficient oat plants by the appli-
cation of a trace of copper. Deficiency symptoms could only‘bo induced
to normal plants by transfer into a deficient medium if the plants were not
older than three weeks. He concluded.that the absolute alnunt of copper
present is far more important than the concentration, provided toxic
amounts are not present. Copper content in the dry matter of oat plants
was greatest in the young stages, and decreased rapidly as growth

proceeded.

In commenting on the value of copper analysis of plant material,
Stoeanorg (53) called attention to the fact that the S—shape curves
for the relation of nutrient uptake and amount of dry matter formed
occurred at all stages of deficiency and maturity. Consequently, chemi-
cal analysis of plant materials my often give copper values for deficient
plants Just as high as for non-deficient plants. Chemical plant analysis
alone should be used with caution and reservation as a diagnostic -
criterion of the deficiency of soils and crops in any plant nutrient.

In most cases, it was essentially more important to determine the
plant available capper. Steenbjerg (52) attempted to determine this
value by extracting soils with ammonium nitrate or hydrochloric acid of
varying concentrations.

Loopor (31) reviewed the results of copper analyses and concluded
they were disappointing because of variability and overlapping of figures
from nor‘l and deficient soils. In these analyses, the nature of the
extracting salt was probably a far more critical factor in obtaining the
final values. Variability in results might have been due to the exchange-
able form of those less mobile ions or because the non-exchangeable
mineral sources were adequate for copper needs. The presence of a
microbial flora in the soil complicates the estismtion of the supply of
any element by extraction methods in the laboratory.

Steeanerg (52) doubted that copper deficiency in the soil could be

determined by extraction methods, but at least a relative figure could

9

be obtained for that part of the soil copper that is most likely avail-

able to plants.
§ymptoms of Copper Deficiency

Copper deficiency may slightly reduce growth or may be serious
enough to kill the plants.

lilder (39) working with cereal crops in copper water cultures
observed that at a period two weeks after germination the leaves turned
around the length axis and wilted from the tip downwards while their
color changed to brownish yellow or white. None of the plants formed
heads. The youngest leaves of peas became dry and wilted with a bright
yellow color. Potato leaves turned darker and tubers were poorly
developed.

Reclamation disease was first observed in grain crops (26), in
which it caused chlorotic symptoms at the leaf tips. Legumes, boots and
cereals failed to set seed. Similar symptoms were reported fron.Scandi-
navia (55), South Australia (M), and Florida (1).

larly workers experienced difficulties in inducing copper deficiency
eymptoms‘bocauso of the lack of satisfactory techniques for obtaining
copper free nutrient media (8).

Piper (#4), growing oats in water cultures, listed the most charac-
teristic symptoms of deficiency in order of increasing severity as follows:
(a) defective seed formation, (b) failure to produce ears, (c) consider-
able secondary tiller formation, (d) limpness and drooping of the leaves

‘by loss of turgor, (a) death of the emerging loaf tip before unrolling,

10
(f) death of tiller before elongation occurred.

Deficient plants remained immature and green at the time treated
plants were mature and dried out. First symptoms generally appeared
as retarded growth about two weeks after germination.

Another recognized copper deficiency disease is 'exanthema” or die-
back in subtropical fruit trees (1). Watershoots bear abnormally large
leaves and grow in S—shape. Young shoots bore gumncontaining swellings,
which bursted open in ruptures from which gum exuded, leading to die-
back of the shoots. Similar symptoms were observed in California,
Ilerida, South Africa and Western Australia.

Microscopic study of young capper deficient tomato plants by Reed
(#6) showed that palissade cells of affected leaves contain many large
hyperchromatic plastids. These ultimately degenerated and form.aggro-
gates at the cell ends. Separation of adjacent palissade cells below
the stomata formed cavities which leads to disappearance of the cells
owing to lysis of their contents: necrotic areas of the leaves thus
appeared.

Other deficiency symptoms in plants have been described (37. 59)
and reviewed by Gilbert (21) and Lal and Subba Rao (30).

Oversupply of copper showed to have harmful effects on plant growth.
Slight toxicity in beets led to severely stunted growth while young
leaves were chlorotic and iron deficient followed by intervenal necrosis.

Severe toxicity led to death of the plant.

Coppgr in the Soil

The essential relationship between the presence of copper in
soil and plants was not well defined before the accidental discovery
of the cause of Ireclamation disea‘se'I in 1926 (26).

After suitable techniques were developed, it was shown that under
deficiency conditions only a small part of the soil copper was utilized
by the plant since much of the element was fixed in the upper soil
horizons of certain profiles.

Smith (h9) explained this fixation by suggesting that an organic
and poisonous compound, llgliedin", was inactivated by cupric ions.

Bademacher reviewed extensively'by Scharrer (#8), analyzing podsol
profiles, found that the small amounts of copper not percolated down-
wards were adsorbed in the humic topsoil layers: in fact, the intensity
of deficiency symptoms shown by plants was a function of the humus
content of the topsoil. The extraction of humus from these sandy soils
corrected copper deficiency symptoms in plants.

Mulder (39) showed that certain types of peaty substances in the
soil fixed relatively large amounts of copper into forms unavailable to
copper selective organisms and hydrogen sulphide producing bacteria
fixed copper into an unavailable fora.

Dawson and Hair (36) concluded from their chemical experiments
that some combination of protein and lignin involving the phenolic 05—
group of lignin was responsible for the formation of copper complexes

in the soil.

12

Steeanerg and Boken (54) found that availability of copper
depended on pH value, hums content, amount of sand and clay, nature of
previous crop and on the effect of other nutrient elements. He deter-
mined available copper by extraction of the soil with dilute hydro...
chloric acid. Availability was lowest at pH 5.5 to 6.5 and within this
range of values the crop response to applied copper sulphate was
greatest.

lost workers reported a lower availability of copper at decreased
acidity (#3, 1414). In organic soils, however, response to copper
applications by most of the responsive crops occurred at a pH lower
than 6.0 (22). According to Truog (57) , availability of copper was
highest between pH values of 5.0 and 7.0.

Lucas (33) observed a stronger binding of copper in the soil at
pH values of 3.0 and 7.2 than at 6.0. Copper sulphate was precipitated
in the soil-water suspension at pH of 4.7. Results from a treatment
of a hydrogen soil with copper acetate suggested that copper is
immobilized as the Cu“-ion and as the monovalent complex (Cu039000)".
Divergence in experimental results on the influence of acidity on avail-
ability could be explained by believing that a plant's need for copper
is a function of the general nutrient balance within the plant. The
effect of the law of the minimum was recognised in the reclamation of
heatherlands in Europe. Copper applications corrected “reclamation
disease'I if the total nutrient balance was atisfactory.

‘ Lundblad et al. (314) stated that copper deficiency was caused

mainly by an absolute deficiency in the soil itself rather than by the

13
humus content. However, if there was a correlation between the humus
content of the topsoil and copper availability, a deficiency of
copper might well result in a high humus content rather than be caused
by it. That might result from a decrease in the rate of decomposition
of organic substances if the microbial activity is affected unfavor-
ably by copper deficiency.

Steenbjerg and.Boken (5“) also called attention to the low
original copper content of newly cultivated peat soils which dropped
even to lower levels after large dressings of the major nutrients.

In evaluating deficiencies, it may'be more important to consider the
relative amount of copper present in the soil.

Truce (5?). like others (27), distinguished three different forms
in which an element could occur in the soil on the‘basis of its avail-
ability to plants. Brun, as cited by Gilbert (21), called these forms
water soluble, adsorbed and fixed. The latter could not be removed
without destruction of the soil. A soil could be high in total copper
yet low in available copper. Season of year, preparation of samples,
analytical procedures affected the values obtained.

Jamison (28) called attention to the possible importance of a
continuous small supply of copper from the slowly soluble or slowly
replaceable form in the soil.

Leeper (31) reviewed the question of availability. wide varia.
bility in the values for so-called available copper might be explained
by these statements: (a) “The exchangeable form of these less mobile

ions is not as readily available as often assumed,“ or (b) IThe non-

exehangeable sources, if large enough, may be adequate for the plant

14
needs.“ He pointed out that deficiency symptoms occur also on not
only plants grown on soils low in organic matter. There were many
agents in the soil (e.g. microorganisms) which compete with the plant
for the soil copper. These processes made the correlation of actual
deficiencies with chemical analysis and the estimate of available
copper‘uncertain.

There are interrelationships between the effect of copper and
other elements. According to Willis and Piland (58) copper acted as
an oxidation catalyst in the soil and regulated the uptake of iron.
An oversupply of iron to plants grown on organic soils was prevented
by copper application. In 1921+, Densch and Hunnius (1?), established
that the uptake of iron by plants was decreased by copper application.

Zinc toxicity to plants on organic soils was reduced by the pre-
sence of copper (33). This agrees with Thatcher's opinion (56) that
copper and zinc were a pair of mutually coordinating catalysts for
oxidation-reduction reactions.

According to Brown (11), the absorption of copper by plants
affected the uptake of iron, nitrogen, potassium, phosphorus, calcium,
magnesium, and silica.

llsewhere in the literature, report has been made of the antago-
nistic effects of copper and other elements: molybdenum (36), mangan-

ese (9). boron (9). potassium, and aluminum.

15

The residual effect of copper in the soil is obviously connected
with its behavior in this medium.

.L major part of the applied copper is rendered unavailable in
the soil so that the applications recommended are much higher than a
plant normally requires. Recommendations vary widely and are dependent
on texture, humus content and natural supply of the soil, and on the
specific requirements of the plant.

Hudig (26) found forty pounds of anhydrous copper sulphate per
acre to be sufficient for the correction of reclamation disease for a
P°riod of nine years, but the crystalline form should be used to obtain
this lasting effect. In order to be effective, the fertilizer should
be applied before planting time in the presence of adequate soil moisture.

In Germany, an application of forty to one-hundred sixty pounds per
acre of copper sulphate was sufficient for the plant's needs for a
number of years on podsolic soils. In Hichigan, recommendations for
copper deficient organic soils are twentyafive to fifty pounds per acre.

Cunningham, reporting in 1936, found that on New Zealand peat
land an adequate supply of copper was obtained by topdressing annually
five pounds of copper sulphate per acre, which should bring the capper
content of pasture soils close to 10 parts per million.

A residual effect of copper applied to water cultures was first
observed‘by Densch and Bunnius (17). In general, copper has a much
higher residual effect in the heavier mineral soils than in organic

soils. Leaching losses may be considerable in sandy soils.

16

Rademacher, quoted by Scharrer (b8), analyzing podsol profiles,
found that most of the applied capper was held in the topsoil (A1
horizon). This agrees with findings of Lucas (33), that in organic
soils copper was mainly held in the upper four to eight inches of the
profile. A similar tendency may exist in a clay with a fair amount
of organic matter. This may explain why there is a difference in
degree of deficiency in plants with different root lengths.

Thus. in soils in which leaching losses are small, the supply of
copper may still be decreased by fixation in the top soil or in the

uppermost layer high in organic matter.
Fatgre and Effects of Different Qgpper Carriers

Copper sulphate was used in the early experiments to study the
effect of copper on microorganisms and later on for plants. In 1882,
Phillips, as quoted by Scharrer (#8), used copper oxide and found that
it had similar stimulating effects on plant growth.

Reclamation disease in Northwestern Europe has been cured with
copper sulphate exclusively. The fact that such large quantities of
copper sulphate were used in this way stimulated the search for sub-
stituting copper carriers.

In 1936, a lime-copper compound (0.3-0.6 per cent copper) was
used effectively. Later, waste products of German steel mills were
utilised whereby 600-900 kilograms of slag were substituted for 100
kilograms of copper sulphate.

Steeanerg and.Boken (5h) tested a number of capper bearing

minerals and copper chemicals under greenhouse and field conditions.

17

They found that several of the slightly soluble compounds were suitable
as copper fertilizers if ground to sufficient fineness. Copper oxide
(containing 80 per cent copper) gave excellent results in the green-
house (where it was applied in a pure state) and in the field (applied
as ashes of sulphur pyrites and copper pyrites).

In Australia, roaster residues from pyrite burners and oxidized
copper are compared favorably with copper sulphate but the presence
of other minor elements in the former compounds may account to a great
extent for their beneficial effect, particularly where used in soils
deficient in other elements.

Steenbjerg (52) suggested three factors of importance in evaluat-
ing copper carriers: (a) the degree of fineness, (b) the Icopper
surface" (actually, the amount of copper within the fineness class), and

(c) the price per kilogram of copper.

EXPERIMENT I
Experimental Procedure

Objectives. The purpose of this experiment was to compare the
effectiveness of applied copper oxide and copper sulphate in increas—
ing the dry weight and copper content of a number of crops. Eight
copper deficient organic soils were selected for the cultivation of
spinach, head lettuce, and Sudan grass .. crops which had.been shown

to be responsive to copper on certain organic soils.

lgpggimental pggcedure. Organic soils, as listed in Table I,
were obtained from eight different locations in Michigan. The soils
were screened through a quarter inch mesh screen and mixed uniformly.
Equal amounts by volume were placed in two-gallon glazed jars.

.All Jars received a general treatment of 3000 pounds of 5-10-30
fertilizer per acre, formulated from ammonium nitrate (NEQN03), mone—
potassium phosphate (KfléPOu), and potassium chloride ([01). Miner
element carriers were applied as follows: 200 pounds of manganese
sulphate (MnSOh.HQO) per acre, 50 pounds of borax (Eath07.10320) per
acre, and 25 pounds of zinc sulphate (Zn30h.HZO) per acre. .All
fertilisers were finely ground in a mortar and thoroughly mdxed with
the soil in each jar.

Three treatments were replicated six tines; (1) no copper, (2)
12.5 pounds per acre of Calumet Brown Copper Oxide (50 per cent copper),
and (3) 25 pounds per acre of C.P. Copper Sulphate (CuSOh.5H20, 25

per cent copper).

TABLE I

ORIGINAL LOCATION, TYPE, AND.ACIDITY OF ORGANIC SOILS - 1953

 

 

 

€22, Location County Soil type pH"I
1 Airport. Clinton Rifle 1+.o the
2 Buschlen Sanilac Rifle h.2 b.8
3 Lynn Calhoun Rifle 5.0 6.0
h Brighton washtenaw Rifle 3.8 h.3
5 Dollarville I Schoolcraft Rifle “.3 6.0
6 Dollarville II Schoolcraft Rifle 4.7 5.8
7 Andersen Lapeer Rifle 3.8 &.5
8 Schoenfeld Lapeer Rifle h.3 5.9
9 Much Iarm 011gtgg Houghton 6.0 ...

1
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*pH of original soil and of incubated soil after
liming with six tons per acre ofcalcium carbonate.

20

Three of the six replications received the equivalent of six tons
per acre of C.P. calcium carbonate and the other three received five
and one-half tons of calcium carbonate plus one-half ton of magnesium
carbonate. The addition of lime raised the pH of the soils approxi-
mately one kaunit.

For each soil type, moisture equivalent and maximum water-holding
capacity were determined. After applying the fertilisers, the soils
were incubated for several weeks at approximate moisture equivalent.

The seed was treated with.Arasan at time of planting in order to
prevent injury to plants by damping-off.

Nobel spinach was planted January 13 and harvested March 7;
Imperial #56 lettuce was planted march 29 and harvested May 23; and
Sudan grass was grown from June 27 until August 2.

Spinach was thinned to six plants per pot, lettuce to five plants,
and Sudan grass to eight plants. Harvesting was performed at the time
plants started to form heads.

(Additionally, 1500 pounds of 5.10-30 fertilizer were applied
after harvesting the spinach, while an equivalent of 2000 pounds of
this mixture was applied after harvesting the lettuce, both times in
solution form. t

The Jars were placed on movable benchesuand regularly rotated to
avoid the effect of environmental factors as much.as possible. Light-
ing by fluorescent lights extended daylight from 5:30 P.M. until 10:30
P.M.

Both fresh weight and oven-dry weight (700 C.) of the harvested

plants were Obtained.

21

Analytical procedure. The method of analysis of plant material
for copper was originally described.by Callan and Henderson (15), was
tested with satisfactory results by Coulsen (16), while the present
standard procedure was proposed by Butler and Allan (11;).

Plant material was ground in a Wiley mill through a 60 mesh
screen. Known weights of oven-dry samples were placed in porcelain
crucibles and ashed overnight in a muffle furnace at 150° c. The ashed
material was digested in 3 cc. of concentrated hydrochloric acid and
boiled for one minute. The solution was transferred to a 250 cc.
volumetric flask. The residue was washed with boiling water until free
of chlorides. Aliquots of 50 cc. or less were placed in 125 cc.
separatory funnels and shaken with 5 cc. of a fifteen per cent citric
acid solution. Ammonium hydroxide (1:1 solution) was added until
litmus paper turned.bluo. Ten milliliter of a ten per cent sodium
diethyl dithiocarbamate solution were added and shaken. The copper-
carbamate complex was then extracted'by shaking with four milliliter
carbon tetrachloride for three minutes. The extraction was repeated
three times with an equal amount of CClu for two minutes each time.

The CClu layer was drawn off each time into a 25 cc. Erlenmeyer flask.
The extracted 001“ was filtered through a small quantity of anhydrous
sodium sulphate in a Number to Whatman filter, into a 25 cc. volumetric
flask, and brought up to volume with carbon tetrachloride. The concen-
tration of copper was determined in a Cenco-Sheard-Sanford photelometer
using a Corning lantern blue glass filter (Number 55h, with maximum

transmittance of #500.X) and one centimeter absorption cells. The

22
readings were compared against a blank solution and based on the
standard curve for this instrument.

The soils were analyzed for copper spectrographically. The
spectrographic method employed uses a National Spectrographic Labora—
tory Source Unit which produces an alternating electrical current of
13 amperes and 7000 volts. This current deve10ps a spark'between two
electrodes on which the sample under investigation can.be placed.
After passing through a narrow slit, the light is dispersed in a
Littrow prism, incorporated in a Hilger Large Littrow Spectrograph,
and recorded on a photographic emulsion. The radiant energy produces
a blackening on the deve10ped negative the density of which is to a
certain extent proportional to the intensity of the light falling on
it. The relation of density and the logarithm of the light intensity
is a straight line for a considerable intensity range. For the parti-
cular photographic emulsions and conditions of exposure, this relation
has been prepared graphically in advance. .A working curve is prepared
with a series of samples of known cepper concentrations covering the
range of copper values which may be expected in the analyses. This
curve relates the logarithmic ratio of Cu and Li with the capper coup
centration.

Samples for analysis were prepared as follows:

The soil material was dried overnight at 100° 0. Samples of
two grams were placed in porcelain crucibles and ashed overnight at 6000
C. To the ashed material one milliliter of a lithium solution (contain-

ing five grams of lithium chloride per 100 grams) was added, which was

23
brought up to ten milliliter volume with 1:1 hydrochloric acid. The
lithium served as an internal standard to eliminate the uncertainties
of the relation between light intensity and line density. This ele—
ment was useful because its concentration remained unchanged in what-
ever sample was investigated and the densities of its lines could thus
be used as a relative standard of intensity against the lines of any
other element. The ash and liquid were stirred up in the crucible.
From the mixture, aliquots of 25 microliters were placed on the smooth.
out top of spectrographic carbon electrodes. Electrodes employed were
3/16 inch in diameter and were made by the National Carbon Company.

Six aliquots were taken from each crucible. The electrodes were dried
under an infra—red lamp and were placed three millimeters apart on the
proper place in the apparatus. Electrical current applied.between the
electrodes volatalized the attached material in a spark, an image of
which was ultimately formed on the photographic emulsion. The

exposure time was sixty seconds. Each glass plate with emulsion was
used for obtaining the spectrograms of nine samples in triplicate. The
glass plates were developed according to standard procedure. On the
negative thus processed, the emission lines of any elemeht showed up as
black lines of varying densities. The emission line used for copper
was at 32h? X and the one for lithium was at 3232 2. Each represented
one of the persistent lines (raies ultimes) of copper and lithium, the
densities of which fell within the straight line portion of the cali-
bration curve. The relative density of the copper line was then

computed from the readings of the densities of the respective lines of

2h
lithium and copper, as per cent transmission in the densitometer,
following the relation d = log :2, = log l_. From this the logarithp
mic ratio log :93. could be derived and is the working curve the corres-

I
ponding value rt; the per cent copper could be read.

Experimental Results

Spinach. As shown in Table II, the application of copper with
one exception increased the yield of spinach on all soils.

In all but three cases these yield increases were significant at
the five per cent level. The exceptions were with the use of copper
sulphate on soils 7 and 8, and with copper oxide on soil h. On all
soils except numbers 1, h, and 8 higher yields of spinach were ob—
tained when copper oxide was applied compared with the copper sulphate
treatments. These differences, except for soil 6, were not significant
at the five per cent level.

At the one per cent level of significance, the application of
copper resulted in higher yields of spinach on soils 1, 2, 3, and 6.
On soil 3, only the application of copper oxide resulted in a higher
yield.

Spinach plants showed the first symptoms of copper deficiency
in the fourth week after germination. Serious deficiency was charac—
torized.by the following symptoms: retardation of growth was evident
in the fourth week after germination; stems remained thin and tender
and root development was poor; leaves remained small - they wrinkled
and wilted and finally died, while the leaf color turned from'blue-

green to yellowish; plants did not bear flowers. (See Plate b.)

25

 

 

 

 

 

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30

Head lettuce. As shown in Table III, the application of copper
increased the yield of lettuce on all soils except number 8, and
where the sulphate was applied to soil 7. In most cases differences
were large enough to be significant at the five per cent level. This
was not true for sulphate on soil 1 and for the oxide on soil 7.

On soils 1, 2, 3, and 7 treated with copper oxide, lettuce out-
yielded the treatments with copper sulphate. The reverse was true on
soil 6. These differences were significant at the five per cent level.

with all soils excpet 7 and 8, and for the sulphate treatment on
soil 1, copper caused highly significant (1 per cent level) yield
increases of head lettuce. On three of the soils, numbers 1, 2, and
3, the plants fertilized with the oxide produced greater yields than
did those which received the sulphate. The reverse was true in the
case of soil number 6.

Marked deficiency symptoms appeared after formation of the third
pair of leaves approximately four weeks after emergence. The symptoms
of serious deficiency were as follows: the plants remained small
with small stiff leaves, this short stems, and poor root development;
the leaves turned yellow starting at the margin, and finally wilted
and became necrotic. The most serious deficiency showed up in plants
grown in soils 5 and 6, with less serious deficiency symptoms occurr-

ing in plants 2, 3, and h. (See Plate 8.)

31

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35

§Ed§p_g£ggg, Data in Table IV show that the application of
copper increased the yield of Sudan grass on all soils. These dry
weight yield increases were significant at the five per cent level on
soils 2, 3, 4, and 6, and on soil 1 where treated with copper oxide.
Plants treated with copper oxide out-yielded those which received the
sulphate on soils 1, 3, and 6, but these differences were not signifi-
cant.

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yields on soils 2, 3, h, and 6. On all other soils yields were not
increased by either form of copper.

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first symptoms of deficiency in the fourth week after germination.
Typical symptoms of severe deficiency were as follows: plants did
not form more than two or three internodes; stems remained thin and
weak and the root system was poorly developed; leaves were short and
narrow, tender and overhanging —— their veins often pronounced as
darker lines on a lighter green.background; leaf color turned yellow-
ish at tip and margin and this tissue finally wrinkled and rolled up

(See Plate 12), becoming dry and necrotic; heads did not form.

Soil analysig. Data obtained from analyses of soil samphes for
copper are listed in Table V.

The copper contents of the original soils varied from 10 to 17
parts per million. The lowest concentrations were found in soils 1,
2, and 5; the highest in soils 7 and 8. A comparison of the copper

contents of original soils and blanks shows that soil copper was not

36

 

 

 

 

 

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utilized‘by the plant to an appreciable extent.

Copper sulphate applications increased the copper content of the
soils to about twofold that of the original soils whereas copper
oxide increased the copper concentrations to three or four times the
original values. Since in both cases the equivalents of 6.25 pounds
per acre of metallic copper were applied, this difference could not be
explained. In general, there was no difference in yield resulting from
the nature of the carrier nor was there a marked difference in the
copper content of plants where the two materials were used, so that
the difference in soil capper content was not due to difference in
plant uptake.

There was no relation between soil acidity and original copper
content of the soil, nor could there be observed a relation'between pH
of the soil and the response of the crops to copper application.

there the original capper content of the soil was 15 parts per
million or more, crops showed very little response to copper applica—
tions, whereas crops grown on soils with lower initial copper contents

responded markedly to copper treatments.
Discuggion

With a few exceptions in favor of copper oxide, there was no
difference between the efficiency of copper sulphate and copper oxide
to correct copper deficiency in plants grown on copper deficient
organic soils. Application of‘both copper carriers equally increased

the yields of dry matter plant material of spinach, head lettuce, and

”3
Sudan grass. Both carriers increased the copper content of spinach
and Sudan grass, but there was a tendency in both crops that applica-
tion of sulphate resulted in higher copper contents in the plants.

Johnson (29) and Fraser (20) described similar effects of copper
oxide and copper sulphate. Fraser pointed out that although the
beneficial effects of oxide and sulphate were similar, there were
several secondary properties which made copper oxide into a more desir-
able copper fertilizer. In connection with the suggestions of Steenb-
Jerg (52) such factors as the fineness of the fertilizer and the price
per pound of metallic copper, the evaluation of the two carriers comes
out in favor of copper oxide.

There was not much difference between the response to copper
application of the three crops on each soil, but there was a marked
difference if different soils were compared. From the limited number
of soils used, it was condluded that response to copper was shown only
by crops grown on soils with a copper content lower than 15 parts per
million.

There was no apparent relation between the copper contents of the
untreated soils and that of the plant material grown on the respective
soils. .According to the plant analyses data, the copper applications
increased the copper content of spinach plants an average of one-
hundrod per cent. Sudan grass plants, on the other hand, did not in-
crease in copper as a result of treatment. It is clear, that even when
copper deficient plants contain copper in as high a concentration as

healthy'plants, the absolute amounts of copper in the latter are always

considerably higher.

The copper contents of the copper sulphate treated soils could
be explained by the addition of the copper sulphate over the initial
copper content. The final analysis for copper oxide treated soils
gave unexpected high.values in all cases, which could hardly'be ex-
'plained on the basis of a difference in copper uptake by the plants.
do appears from.a comparison of copper contents of the original soils
and of the‘blanks after cropping (particularly where the blank yielded
as high as the treatments), negligible amounts of copper are taken up
from the soil.

Although ashing of plant mterial at uso’ c. - as suggested by
Johnson (29) -— resulted in values not far different from results by
other workers in similar material, most satisfactory figures were ob—
tained'by ashing at.5oo' Q. It was believed that at least such a tem-
perature is necessary to account for all the copper present. In each
case where any carbon is left after ashing, one has to re-ash the
sample after adding a few milliliters of water or nitric acid and

breaking the particles.

EXPERIMENT II

,gxperimental Procedure

 

Objectives. This experiment was set up after a number of other
copper carriers became available. It seemed justified to compare the
effects obtained by the application of copper oxide and copper sul—
phate with those of the new carriers. From this comparison it might
be concluded whether it is the copper content of the copper carrier
which is the decisive factor for crop response or whether the form

of the carrier is important.

Egpegggpntal procedure. The organic soil for this experiment
had a pH of 6.0 and was obtained from the Michigan State College Muck
Experimental Farm (soil number 9 in Table I).

The soil was.screened and mixed uniformly after which equal
weights were placed in two—gallon glazed jars.

All jars received a uniform treatment of 5—10—30 at the rate of
3000 pounds per acre. TThe fertilizer formula was the same as reported
for Experiment 1.

Four different copper carriers were compared:

(a) anhydrous copper sulphate GP reagent (25 per cent metallic
copper)

(b) Calumet'brown copper oxide (50 per cent metallic copper)
(c) Sequestrene ELZCu (13 per cent metallic copper)
(d) Ground Copper Slag SEIvD (1.5-1.8 per cent metallic copper)

Each copper carrier was applied at a rate equivalent to 6.25 pounds

#6
metallic copper per acre and compared with a blank treatment to which
no copper was applied. In addition, Sequestrene and SEND were also
set up in two treatments and applied at a rate equivalent to»12.5
pounds metallic copper per acre. Each treatment was replicated four
times.

Sudan grass was planted June 1n and harvested August 2. The
plants were thinned to ten per pot. The other procedures were as

described for the first experiment.

Analytical procedure. The soils were analyzed spectrographically
and the plant material was analyzed for capper according to the sodium

diethyldithiocarbamate method as outlined under Experiment I.
Experimental Results

Yield data and the capper contents of plants and soils are pre-
sented in Table VI.

Treatments with copper resulted in highly significant yield in-
creases (at the one per cent level) compared with the blanks. There
were no significant differences in yield which resulted from the appli-
cations of copper oxide, cOpper sulphate and sequestrene. The ground
copper slag proved to be inferior to the other materials.

Where the rate of application of sequestrene was doubled, the
yield of Sudan grass was decreased but the decrease was not significant.
A doubled application of slag, however, was favorable to the production

of Sudan grass but the extra amount did not significantly increase the

1»?
TABLE VI

m MCTS OF APPLICATION OF 1003 COPPER CARRIERS ON YIELD
AND COPPER CONTENT OF SUDAN GRASS GROWN IN THE GREENHOUSE
ON OMANIC SOIL", AND THE EFFECT OF THE CROPPING
ON THE COPPER CONTENT OF THE SOIL - 1953

 

 

 

 

 

 

 

 

 

 

 

 

 

 

to
Treatment (pounds Grams" Per cent copper

__ er acre per 3” intlant in so 1
Before

r 1 ---- -—-- 0.0010
After cropping
we: 0 M 0-0010 9-0010
WJLMY 0.0011 4.9030
Copper
sulphate 35.0 73.22 0.0010 0.53210
Wrens 50.0 81540 0 . 0011 0.0030
5 us no 100-0 §1J+2 0.0002 $9935
Ground copper
glee—SEW 375.0 vans 0.001; mm
Ground capper

1 SIM) 0.0022

 

 

 

 

*I..S.D. 5 per cent - 6.30
1 per cent - 8.6h
Oven—dry weights: averages of four replications.

"mick Experimental Farm Inch, Bought on Mick,
pH 6.0.

yield.beyond that obtained where the rate of copper was 6.25 pounds
per acre. This double application of copper slag was sufficient to
result in yields which were about equal to those obtained where the
lower rate of the oxide and sulphate were used,‘but they were still
lower than those obtained as a result of the single application of
sequestrene.

Any copper carrier;when applied to the soil, prevented the
appearance of copper deficiency symptoms on Sudan grass plants. The
deficiency symptoms developed on plants from the soils to which no
copper was added were similar to those described in Experiment I
(See Plate 13).

On the basis of the analyses of the plant material, there was
little or no increase in the copper content of Sudan grass due to the

application of copper to the soil at the rate of 6.25 pounds per acre.

Discugsion

The results of this experiment were simdlar to those of lxperio
meat I with respect to capper oxide and copper sulphate in that there
was no difference in the yield from both treatments.

The sequestrone copper complex is a chelated complex of ethylene-
diamdne tetra-acetic acid with the cupric ion containing 13 percent
copper metallic. It was recently made available by the Goigy Company,
Incorporated, Insecticide Division, as a technically pure, water
soluble, crystalline powder. Preliminary experiments elsewhere showed

severe injury to leaves of beans and apples after foliar applications,

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50
and doubtful results from soil applications to celery and potatoes.
Applications of one and fifteen pounds per acre in the setting water
with tobacco resulted in death of the plants.

Under the conditions of this experiment it was shown that this
organic complex, when applied at the same rate of actual copper, pro-
duced about the same results as were obtained from applications of
copper oxide and copper sulphate.

The ground copper slag was obtained under the name IDutch minor
element fertiliser SIMD'. The chemical composition of this compound
is given as follows (in per cent by-volumo):

Copper 1.5 to 1.8: cobalt 0.1 to 0.2: nine 2 to 3: silicic
acid 30 to 35: aluminum oxide 6 to 12: iron 15 to 20; manganese 0.2 to
0.3: magnesium oxide 1.5 to 3.0; calcium oxide 5 to 10; traces of
borax, molybdenum and other minor elements.

.At the same rate of actual copper, copper slag applications gave
lower yields than any of the other three carriers. Application of a
double amount of this compound still resulted in lower yields than
were obtained from other carriers.

.The experiment showed that not the absolute amount of actual
copper was decisive for the yield obtained, but rather the nature of
the carrier. Irom.the results of the experiment little could be
concluded on the nature of the carrier which was most effective in
correcting copper deficiency. since little is known about the behavior
of copper in soils. It could be that the finely divided nature of

copper slag is causing it to be more easily fixed in the soil; or the

51
content of other elements might be high enough to have toxic effects
on the crop.

Recent greenhouse experiments (38) with eats on copper deficient
sandy soil showed that treatments with copper slag resulted in higher
yields of dry matter compared with copper sulphate treatments. It
might'be questioned in how far this effect was due to the supply of
other minerals. Iron a practical standpoint, a low—grade copper
carrier seems not to be desirable for general use if its application
does not show effects much different fremtthese from high-grade

carriers.

IIPERIMENT III
Experimental Procedure

Objgctives. This experiment was set up to find out what happens
to copper oxide and copper sulphate when it is added to organic soils.
The data obtained are of a qualitative nature in that the procedure
was designed to show the. residual effect of the two carriers in the
top six inches of an organic soil profile. Attention was also given
to differences in the reactions of copper applied to organic soil

under different levels of soil acidity.

Experimental procedur . Organic soil (Rifle peat, Sanilac
County, pH M2) was screened and mixed uniformly. One part of the
soil was limed with C.P. calcium carbonate at a rate of five tons per
acre, while another part was uniformly mixed with lime at ten tons per
acre, and a third portion was left untreated. All the soil was then
incubated in two-gallon glazed Jars for a period of one month.

Eighteen cylindrical clay tiles (12 inches long and u inches in
diameter) were obtained for the leaching studies. These were washed
and coated on the inside with shellac. One side of the tile was sealed
off with a piece of nylon screen on top of which was fastened a plastic
cover.

The tiles were set up in three treatments of six tiles as follows:
(1) unlined soil, pH Ml; (2) soil limed with five tons per acre,

pH 5.2: (3) soil lined with ten tons per acre, pH 6.0. The bottom six

53

inches of each tile was filled.with soil, rather tightly packed and
watered to obtain a rather compact soil mass. After a few days, the
top halves of the tiles were filled with soil of the same treatment
as was present in the bottom half. Each treatment was then split in
two parts. For three of the tiles, the newly added topsoil was care-
fully mixed with the equivalent of 500 pounds per acre of copper sul-
phate while the other three received 250 pounds per acre of copper
oxide. The tiles were filled with the prepared soil up to about a
half inch below the top. The plastic cover on the bottom.was taken
off, leaving only the nylon screen.

Pieces of multiplex board with four—inch holes in the center were
used as covers for one-gallon Jars. One of the tiles containing the
organic soil was sealed over the hole in each board._ This made it
possible to leach the soil and catch the leachato.

The moist soil was.kept saturated with water for a few days, and
then was leached with one liter of distilled water which was repeated
every five days for a period of five weeks. In total, seven liters of
water were added to the top of the soil in each tile. The percolating
water was caught in the Jars. The top of the tiles were kept covered
with paper.

For the collection of soil samples from the profile, the tiles
were cut lengthwise into two halves. Each cylinder of soil was cut
into two-inch sections starting from the bottom. Just below the top
six inches where the copper was applied, two one-inch sections were

collected. The central portion of each section was collected for

54
copper analysis. This procedure eliminated the possibility of using
soil in contact with the tile.

The leachate in the Jars were transferred to large beakers and

evaporated down on a hot plate.

Analytical procedure. The soil samples collected for copper
analysis were treated spectrographically as described under Experiment
I.

The leachates averaging four liters in quantity were made to
small volume by evaporation in large Pyrex beakers and were then trans-
ferred to seven centimeter wide porcelain crucibles. The latter were
evaporated to dryness in the even, ignited overnight in the furnace

at 500. 0., and further treated like the soil samples.

Qgperimental Result; and Discuspio;

The data obtained from the spectrographical copper analyses on
the soil samples and the leachates are given in Table VII.

The procedure followed in the experiment was entirely original.
Since the early studies with copper, it was known that copper is re-
tained and fixed in the soil layer rich in organic matter.

from the figures in Table VII, it can be concluded that copper did
not move downwards in any appreciable amounts. The figures for the
layer six to seven inches below the soil surface, just below the top-
soil with added copper, are a little higher than the original soil

copper content which is likely due to contamination of the sample with

TKBLE VII

55

THE EFFECT OF LEACHING OF.AN ORGANIC SOIL COLUMN".I WITH EATER ON THE
MOVEMENT OF TWO COPPER CARRIERS FROM THE TOP SIX INCHES INTO

THE LOWER HORIZONS UNDER cutaneous: CONDITIONS AND.LT
THREE pH LEVELS - 195u~s

 

Inches below

Copper oxide,

applied to top soil

Copper sulphate
250 pounds per acre 500 pounds per acre

applied to top soil

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

soil surface (0 ”) 10- ')
'1 2 3 i’ ll 1 2 3 if
Ne lime, pH h.1

4-6 260 280 250 263 280 255 285 273
6-7 15 #9 21 26 31 15 19 22
7—8 12 15 ll 13 l7 15 13 15

Residue of evap—

orated leachate #3 153 on 53 b5 70 80 g§1_

5 tons per acre of lime, pH 5.2

“-6 270 265 270 266 320 #20 330 360
6-7 22‘ 18 19 20 20 22 29 2#
7.8 18 15 15 16 18 15 13 15

Residue of evap-

‘orated leachate S7 56 69 61 _, 66 80. 74 #23

10 tons per acre of lime, pH 6.0

“-6 370 310 390 357 380 450 350 393
6—7 20 16 M8 28 16 h&» 16 25
7—8 13 13 15 1b 17 15 17 16

Residue of evap—

orated leachate an 59 ::1___§§ “hr 73 8h 6

 

 

 

 

 

 

 

 

*Copper content original soil, 11 parts per million.

'*Cepper values expressed as parts per million,‘based
on oven—dry material.

56
topsoil when the samples were taken. It is clear that these figures
are close enough to the original copper content to Justify the exper-
imental method employed.

The copper content of the top soils agreed with the computed
summnts of copper added to this layer (.0400 to .0500 per cent Cu)
closest in profiles with the highest pH and were almost half this
value in the most acid soil. This difference might be due to the
faster rate of decomposition of the organic soil material where lime
was applied so that the analyses of the latter should be based on a
different volume weight.

There was no difference in the mobility of copper at the differ-
ent pH levels. Earlier workers found that copper mobility in soils
depended on the soil acidity. Since in this experiment a difference
in mobility at different pH levels might be expected, it was intended
to raise the initial soil pH to 5.5 and 7.0 by the addition of five
and ten tons of lime per acre, respectively.

Although the data of the copper analyses of the leachatos were
not analyzed statistically, there seemed to be no indication that pH
level had any influence on these values. ‘ At all three pH levels, the
copper contents of the leachates were higher when collected from
copper sulphate treated soil columns. However, the variation between
the values from.replications seemed not to guarantee that this relation
1' significant. Based on an approximate quantity of leachate of four
liters, the copper contents of the leachates were so small that they

did not indicate that any copper moved down from the top part of the

57

column.

The spectrographical copper analysis of the residues of the evap—
orated leachates gave some difficulties. ,It was hard to pipet off a
representative sample from the acid-digested residue since the latter
transformed into a gelatinous mass. On the plate the 3232 I lithium
line was hardly visible so that it was doubted that the values for

the copper lines were reliable.

58

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SUMMARY

In this study, Calumet copper oxide and anhydrous copper sul-
phate were compared in their effect on yield and copper content of
spinach, head lettuce, and Sudan grass grown in the greenhouse on
eight organic soils.

The soils selected originated from different locations in
Michigan and were copper deficient for responsive crops under field
conditions. Proper quantities of 5-10-30 fertilizer, manganese
sulphate, zinc sulphate and borax were applied, Lime was applied in
two treatments with and without magnesium carbonate. The soils were
placed in two-gallon Jars.

There were three treatments for each soil: (1) no copper;

(2) 6.25 pounds of copper per acre as copper oxide; (3) 6.25 pounds
of copper per acre as copper sulphate.

The results were the following:

1. Copper oxide was as effective as copper sulphate in
correcting copper deficiency in all three crops, resulting in similar
increases in yield and copper content of plant material. In a few
cases the application of copper oxide resulted in significantly
higher yields (five per cent level) than when copper sulphate was
applied.

2. Comparison of initial capper contents of the soils and
those in the blanks failed to show an appreciable uptake of copper

from the soil by the plants.

60

3. Copper applications increased the copper content of
plant material from 0 to 200 per cent. The increase was higher in
spinach than in Sudan grass. For spinach, copper sulphate increased
the copper content of plant material more than copper oxide. For
Sudan grass there was little difference in the effect of both
carriers.

u. Within the range of soil acidities on hand (pH h. 5 to
6.0), a relation between soil pH and.plant response to copper appli-
cations could nof be observed.

5. Plants showed no response to copper application when
the copper content of the original soil is 15 parts per million or
higher., Below a soil copper content of 15 parts per million all
crops responded to copper amendments.

6. Application of magnesium to the soil did not result in
significantly higher crop yields than when only calcium carbonate was
used for lime application.

7. Most satisfactory results from copper analyses were ob—
tained if plant material was ashed at 500° C. for twelve hours and
re—ignited for two hours after wetting and breaking the particles.

In another experiment, four copper carriers were compared in
their effect on yield and coppercontent of Sudan grass grown in the
greenhouse on organic soil. The carriers were: Calumet copper oxide,
anhydrous copper sulphate, Sequestrene HAZCu cupric—complex (disodium
cupric ethylenediamine tetraacetate trihydrate) and Ground Copper Slag

SEND (a low-grade copper-foundry waste product). The following results

61
were obtained:

1. Copper oxide, copper sulphate and Sequestrene did not
differ in their effect on the yield and copper content of Sudan grass.
Application of any copper carrier resulted in a yield increase of about
two hundred per cent over the blank and no copper deficiency symptoms
were observed.

2. Ground copper slag application resulted in lower plant
yields than any other carrier if applied on the same copper basis.

Columns of organic soil, ranging in pH from.h.l to 6.0, and to
the top part of which copper had been added as copper sulphate and
copper oxide, were leached with water. This experiment led to the
following observation:

1. Regardless of the kind of copper carrier or the level
of pH of the soil, there was no movement of copper from the topsoil

downwards.

(1 )

(2 )

(3 )

(h )

(5)

(6 )

(7 )

(8 )

(9 )

(10)

(11)

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77 31