1 
RELATION OF SULPHUR COMPOUNDS TO PLANT 
NUTRITION 
By E. B. Hart, Chemist , and W. E. Tottingham, Assistant Chemist, Department of 
Agricultural Chemistry, University of Wisconsin 
INTRODUCTION 
The four elements, nitrogen, phosphorus, potassium, and calcium, still 
play the most important rdle in soil treatment. For a number of years, 
however, other materials which stimulate growth in vegetation have been 
studied by chemists and agronomists. t 
The so-called catalytic fertilizers, such as the salts of manganese, have 
often been shown to increase plant growth. In addition, studies have 
been made of radium, lithium, sodium, arsenic, barium, copper, and some 
other elements. While these may stimulate plant growth, their appli¬ 
cation is not at present regarded as of economic importance. These ele¬ 
ments are either not at all necessary for the plant’s cycle of growth or, 
so far as we know, are abundantly supplied in all ordinary soils. 
In the case of sulphur the relation appears to be somewhat different. 
It was pointed out in 1911 by Hart and Peterson (5) 1 that the total sul¬ 
phur content of the soils examined was low, being approximately equal 
to the phosphorus content. This work has been confirmed by Shedd (12) 
for Kentucky soils and by Robinson (11) for the important soil types of 
the United States. It was further shown by Hart and Peterson (5) that 
the sulphur content of our common farm crops was considerable, cereal 
grains containing about half as much sulphur as phosphorus and legume 
hays sometimes more sulphur than phosphorus, while the Cruciferae, 
such as cabbage, turnips, etc., may contain two to three times as much 
sulphur as phosphorus. 
It has been urged by Hopkins (6) that the high sulphur content of 
plants does not represent their needs, but merely shows the superabun¬ 
dance of sulphates in the soil water, with an extraordinary consumption 
by the plant. This may apply to the stem and roots of plants, but not 
to the seed. The seeds maintain a fairly constant composition and, as 
shown by Peterson (9), either contain but traces of sulphates, or more 
probably none at all. The criticism, then, that a high sulphur content 
of a plant merely represents a large soil supply can not possibly hold for 
seeds. It is true that the sulphate sulphur and probably other forms of 
sulphur in the stems and roots of plants will vary with the soil supply. 
In these plant parts sulphates may be present where the soil supply is 
plentiful. The same statement, however, is equally true of phosphates. 
1 Reference is made by number to “ literature cited,” p. 249. 
Journal of Agricultural Research, Vol. V, No. 6 
Dept, of Agriculture, Washington, D. C. Nov. 8,1915 
a a Wis.—1 
9839°—15 - 2 
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