THE OCCURRENCE OF COPPER, MANGANESE, ZINC, 
NICKEL, AND COBALT IN SOILS, PLANTS, AND ANIMALS, 
AND THEIR POSSIBLE FUNCTION AS VITAL FACTORS 1 
By J. S. McHargue 
Research Chemist, Kentucky Agricultural Experiment Station. 
INTRODUCTION 
A problem of fundamental impor¬ 
tance in agricultural research to-day is 
to ascertain which of the elements 
present in small quantities in soils, 
plants, and animals are necessary in 
the vital processes and what are their 
functions. The purpose of this paper 
is to show that some of the so-called 
nonessential elements are of common 
occurrence in Kentucky soils and in 
certain tissues of plants and animals 
produced on such soils and that their 
concentration is greatest in certain 
vital organs of plants and animals, a 
coincidence which suggests the possi¬ 
bility that such elements may have im¬ 
portant functions in the life processes. 
HISTORICAL DATA 
For a long time it has been taught 
and accepted that available compounds 
of only 10 elements are all that are 
necessary for the normal growth and 
maturation of agricultural crops. It is 
a well-known fact, however, that a 
much larger number of elements than 
10 occur in small amounts in fertile 
soils and in the ashes of normal plants 
that have grown in the soil. Palladin 
(IS, p. 82) 3 names 31 elements that 
have been found in the ashes of plants 
grown under natural conditions in the 
soil. The 10 elements which have 
heretofore been considered sufficient for 
the growth of plants are carbon, hydro¬ 
gen, oxygen, nitrogen, phosphorus, po¬ 
tassium, calcium, magnesium, sulphur, 
and iron. 
Within the past 50 years many inves¬ 
tigations have been recorded in chemi¬ 
cal literature which show that the 
elements arsenic, antimony, cadmium, 
copper, manganese, zinc, nickel, cobalt, 
barium, strontium, bromine, and iodine 
are widely distributed in soils and 
plants. In recent experiments obser¬ 
vations have been made which indicate 
that a few of the so-called nonessential 
elements may have more important 
functions in soils, plants, and animals 
than is generally recognized. 
Greaves (8, p. 119) states that arsenic 
is a constituent of virgin soils and that 
certain compounds of this element 
stimulate the processes of ammonifica- 
tion, nitrification, and nitrogen fixation 
in the soil. 
In 1866 Neubauer (12) published a 
method for the estimation of copper in 
the tissues of plants and animals. Later 
investigations show that this element 
is widely distributed in natural waters, 
soils, plants, and animals. Certain 
species of mollusks are known to be 
relatively rich in copper. 
Willard (16) reports that in 34 differ¬ 
ent samples of oysters collected at 
different points along the East Coast 
of the United States a minimum of 50 
parts per million and a maximum of 
1,700 parts per million of copper was 
found in the moisture-free matter. 
Bertrand (2) has published results 
which show quite appreciable amounts 
of arsenic, boron, iodine, copper, man¬ 
ganese, zinc, and fluorine to be of 
common occurrence in the tissues of 
plants and animals. He also offers the 
suggestion that copper, manganese, 
and vanadium may replace the function 
of iron in certain mollusks, Crustacea, 
and tunicates. 
Benzon (1) has recently published 
data from which he concludes that 
zinc functions as the so-called water- 
soluble vitamin B. 
Javillier (5, 6, 7) has shown that zinc 
is a constituent of normal plants and 
that conifers are relatively rich in this 
element. He concludes that plants 
which contain chlorophyll are benefited 
by the action of small amounts of zinc 
which perhaps act as a catalytic agent 
in the metabolic processes. 
Van Itallie and Van Eck (4) state 
that copper and zinc appear to be 
regular constituents of the liver. These 
metals were found in the newly born. 
i Received for publication May 24, 1924; issued April. Read before the Division of Agricultural and 
Food Chemistry of the American Chemical Society at its meeting in Milwaukee, Wis., Sept. 10-15, 
1923. 
»Reference is made by number (italic) to “Literature cited,” p. 196. 
Journal of Agricultural Research, 
Washington, D. C. 
13950—25t-7 
Vol. XXX, No. 2 
Jan. 15, 1925 
Key No. Ko. 17 
(193) 
