Nov. 8,1915 Relation of Sulphur Compounds to Plant Nutrition 
235 
isms and the rate of ammonification and destruction of organic matter, 
while the sulphates activate but slightly in these directions. The 
processes mentioned are admitted to be of great importance to the 
plant's nutrition and environment, involving, as they must, not only a 
more rapid formation of readily soluble compounds of nitrogen and a 
possible destruction of harmful organic materials, but a greater satura¬ 
tion of the soil moisture with carbon dioxid, resulting in increased 
solution of mineral materials necessary for rapid growth. 
While from the application of analytical chemistry and mathematics 
we should be led to give equal importance to phosphorus and sulphur 
in plant production, from their relation to important soil biochemical 
processes we must certainly ascribe to phosphorus the more important 
r 61 e. It has been demonstrated beyond question in certain phases of 
fermentology that cellular and enzymic activities are markedly increased 
by the presence of soluble phosphates. Harden and Young (4) have 
shown that the activation of the yeast cell or its zymase is greatly 
accelerated by the presence of these substances, and we how know 
that such activation by phosphates is not confined to the yeast plant 
but may also extend to the soil flora. 
Consequently, in the case of phosphorus we have at least two factors 
operating to make it important in the soils—supply and physiological 
action; while in the case of sulphur the more important r 61 e will be 
merely as a source of supply. This, however, may not always be its 
only function, as will be shown later, where in the case of red clover 
it appears to have rather specific effects on root development; but 
besides such specific effects it appears at present that sulphur as sulphate 
in the soil serves essentially as the source of needed sulphur. It, there¬ 
fore, in our judgment becomes important to accumulate information 
as to which agricultural plants will be affected by an increased concentra¬ 
tion of sulphates in the soil water. 
For some time sulphur in its elemental form has been used in the control 
of certain plant diseases. Incidental to this work there has accumulated 
much contradictory evidence relating to its effect on the crop yield. 
Opinion has been freely expressed as to how it acts in the soil, but with 
little definite agreement. In France especially, investigations have 
been active on the use of elemental sulphur with a large number of 
different plants. Work has been done with turnips, beans, celery, 
lettuce, potatoes, onions, spinach, and other crops. Various results 
have been obtained, but generally increased yields have been reported. 
Boullanger and Dugardin (1) place elemental sulphur among the cata¬ 
lytic fertilizers and have reported very favorable results from its use. 
They are of the opinion that its action is on the soil flora, in some way 
stimulating the breaking down of organic matter and ammonia produc¬ 
tion, although their observations show that it has quite a retarding 
action on nitrification. They further made the interesting observation 
