EFFECT OF DIFFERENT CONCENTRATIONS OF MAN¬ 
GANESE SUTPHATE ON THE GROWTH OF PLANTS 
IN ACID AND NEUTRAL SOILS AND THE NECES¬ 
SITY OF MANGANESE AS A PLANT NUTRIENT^ 
By J. S. McHargue 
Department of Chemistry, Kentucky Agricultural Experiment Station 
INTRODUCTION 
In a study of the literature on the nutrition of plants, one is impressed 
with the lack of definite knowledge concerning the necessity of a number 
of elements frequently found in appreciable amounts in the ash of dif¬ 
ferent species. 
For many years it has been taught and accepted by agronomists and 
plant physiologists that only lo of the elements are essential for the 
normal growth and maturation of plants. These essential elements 
are carbon, hydrogen, oxygen, nitrogen, calcium, magnesium, potassium, 
phosphorus, sulphur and iron. In addition to these, it is also well 
known that as many as 20 or 30 others are frequently found in small 
amounts in plants which have grown under natural conditions. 
Within recent years many data have been obtained which indicate 
that a few of these so-called nonessential elements may have important 
functions in the plant’s economy. During the past 25 years, perhaps, 
' more attention has been given to the acquisition of knowledge con¬ 
cerning the occurrence, distribution, and probable functions of manga¬ 
nese in soils and plants than to any other one of the elements referred to. 
The number of contributions to the literature on the relation of manga¬ 
nese to various phases of agriculture number no less than 100. As a 
matter of convenience these contributions may be divided into two 
general classes, depending upon the object to be attained. Investigators 
of one class, apparently, have been interested in determining whether 
or not manganese has any commercial value from the standpoint of a 
necessary fertilizer, while those of the other class have sought to determine 
whether or not manganese is an essential element in the vegetable 
economy and, if so, to assertain its functions. 
HISTORICAL 
Manganese was discovered by Scheele (9) ^ in 1774. He found that 
the soil contained small amounts of this element and that it was assimi¬ 
lated by plants that grew in the soil; however, he made no effort to 
determine whether manganese was necessary for plant growth. 
In 1864 Sachs { 8 ) conducted experiments, the purpose of which was 
to determine whether or not manganese was necessary in plant economy. 
He proved that manganese could not replace iron in plant growth, but 
1 Accepted for publication Nov. 6, 1922. 
This investigation, begun at the Kentucky Agricultural Experiment Station in 1916, was continued, 
with the consent of the Director, at Cornell University where part of the results were offered in partial 
fulhllment of the requirements for the degree of doctor of philosophy. Since September, 1922, the work 
has been carried on at the Kentucky Station. The paper presents in part the results of the investigation 
at Cornell, the earlier results, and the recent findings at the Kentucky Station. 
2 Reference is made by number (italic) to "Literature cited," p. 793 - 794 - 
Journal of Agricultural Research, 
Washington, D. C. 
aen 
Vol. XXIV, No. 9 
June 2, 1923 
Key No. Ky.-ia 
( 781 ) 
