Nov. 8, 191S 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 

 role. 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 now 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 role 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 efifects 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 (i) 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 



