400 AGRICULTURE OF MAINE. 



pounds of carrots, 183 pounds of potatoes, and 63 pounds of 

 onions; 45 pounds potash, with soda, gave 390 pounds of pota- 

 toes, 249 pounds of carrots, and 138 pounds of onions. 



Each weight represents the total yield from small triplicate 

 areas. Equal amounts of nitrogen and phosphoric acid were 

 applied in each case. As the crops grew side by side, although 

 not on equal areas, indications are afforded of the relative 

 deficiency of potash and value of soda for the three crops. 



From three to four-tenths of the actual increase caused by 

 both the soda and the additional amount of potash is seen to 

 have been caused by the soda. The deficiency of potash was so 

 great, with only 15 pounds of potash, that the addition of soda 

 did not result in normal yields. Had the deficiency been less 

 and a larger amount of soda been added, it is probable that 

 practically normal yields would have been obtained. Two weight 

 parts of soda are chemically equivalent to three parts of potash 

 and the two materials were added in this proportion in the 

 experiment. 



Owing to the fact that the manurial treatments had been con- 

 tinued for a number of years, the potash had not only become 

 very deficient in certain plats, but the soda must have exerted, 

 previously, much of its eft'ect. 



The experiment has indicated during its course that an appli- 

 cation of soda to most of our granite soils would insure the pro- 

 duction of normal crops, if potash should be unobtainable in 



1915- 



One weight part of soda is equivalent to about three parts 



of nitrate of soda and about two parts of either crude soda ash 

 (sodium carbonate) or common salt. Aside from being a source 

 of soda, the soda ash would reduce the acidity of acid soils ; for 

 this purpose it is equivalent to an equal w^eight of ground lime- 

 stone. 



Director Hartwell states that there is soda enough in the 

 moderate application per acre of 200 pounds of nitrate of soda 

 and 270 pounds of soda ash to be equivalent to 300 pounds of 

 potash; so that, if only a third of it really took the place of 

 potash, it would be temporarily equal to adding 100 pounds of 

 the latter. 



In his book ''Fertilizers and Manures," Doctor Hall of the 

 Rothamsted (England) Experiment Station says: 



