No. 4.] CHEMICAL AND FAKM MANURES. 149 



1891, and showed that where soda replaced potash in var3nng 

 amounts the crops sufiered far less than when the potash 

 was replaced by lime. From this he concluded, quite con- 

 trary to the then prevalent opinion, that soda can act as a 

 direct plant food, and replace potash to some extent. Pasf- 

 noul * also obtained results pointing in the same direction, 

 and Wagner and Dorsch f a little later expressed their own 

 conclusions as follows: "The soda is able to exert a de- 

 cided influence upon the development of plants, and that cul- 

 tivated plants are able to produce almost half as much more 

 yield out of one and the same amount of potash when they 

 are manured with sodium chlorid" (common salt). Stahl 

 Schroder I now comes forward with data and arguments 

 which to his mind overthrow the conclusions and results 

 just mentioned, and he states plainly that he believes he 

 has proved "that soda cannot take the place of the pot- 

 ash which is necessary to the building up of the organic 

 substance." 



Experiments upon the soda question, embracing fiftj'-eight 

 plots in the field and more than as many pots, have now been 

 in progress at the Khode Island station for several years, 

 and, as a result of these, it may be definitely stated that, 

 when the supply of readily assimilable potash is limited, 

 soda is of some use, though whether as a direct or indirect 

 manure cannot be determined until the analysis of the crops 

 can be completed. The question whether plants can utilize 

 soda as direct plant food savors perhaps too much of pure 

 science to appeal to all practical farmers. Yet the question 

 whether or not soda may be substituted for potash to some 

 extent in the manwes a2')plied to the land will doubtless be 

 considered practical by all. If the potash in our manures 

 can be sufficiently reduced so as to make the soda which 

 may be substituted for it effective, without lowering the 

 yield or quality of the crop enough to more than offset the 

 lesser price of the soda, it becomes important that it should 

 be known. No benefit from soda appears, in the Rhode 

 Island experiments, when a generous amount of potash is 



* Annales Agronomique 17 (1891), pp. 538-544. 

 t Die Stickstoffdungung, Berlin, 1892, pp. 227-242. 

 + Jour, fiir Landwirthschaft 47 (1899), pp. 49-84. 



