New York Agricultural Experiment Station. 239 



treatment of ground phosphatic rock. This treatment is given at 

 a large expense for the purpose of rendering the phosphoric acid 

 more available to growing plants. The cost of this ingredient to 

 the farmer would be much less if this treatment were unnecessary 

 and if the natural phosphates after mechanical preparation could 

 be successfully and profitably used. 



One of the problems in plant nutrition, economically important 

 and to some extent scientifically interesting, is the availability to 

 plants of the mineral phosphates after certain methods of prepara- 

 tion. Numerous observations have been made along this line with 

 results that are quite definite, and we now find a recognition in 

 practice, especially in European countries, of the usefulness of 

 certain so-called insoluble phosphates in the production of particu- 

 lar crops. Of the experiments conducted in this country touching 

 this problem, those carried on at the Maine Experiment Station 

 during several years under forcing-house conditions, are perhaps 

 the most extensive and have yielded the most definite and striking 

 results. The phosphatic materials used in these experiments were 

 acid phosphate (dissolved Florida rock), very finely ground un- 

 dissolved Florida rock (floats), and Redonda phosphate, that is, 

 a hydrated phosphate of iron and aluminum, which before using 

 was dehydrated by the application of heat, this process rendering 

 it much more soluble in ammonium citrate and inferentially 

 more available to plants. The results of several years' work are 

 summarized by Merrill in the report of the Maine Agricultural 

 Experiment Station for 1898, page 74. 



experiments at this station. 

 After an understanding with the Director of the Maine Experi- 

 ment Station, experiments similar in method and purpose to those 

 referred to above were begun under the direction of the writer in 

 1896 and were continued at intervals until 1900. As the results 

 reached were mainly confirmatory of those secured at the Maine 

 Station, their publication was for a time not considered to be a 

 matter of especial importance as the conclusions reached would 

 not add in auy especial manner to existing knowledge. In view. 



