14 MAINE -TATE COLLEGE 



nitrogen question and which may yield results of equal practical 

 importance. 



All who have given especial attention to the subject of plant 

 nutrition will, undoubtedly, agree that the foraging powers of 

 plants for the elements contained in the ash, vary greatly. This 

 fact is recognized by the majority of observing farmers, as is shown 

 bv the following common - Wheat requires a rich soil." 



"Corn is a grass feeder." '-Oats are an exhaustive crop " 



Notwithstanding that these views _ the variation in 



foraging powers of different crops have been held by many for 

 years, no one is prepared to say just how it is exerted. We are 

 hardlv readv to express an opinion whether the greater vigor of 

 certain plants as compared to other - .rown on the sam<r 



is due to their superior foraging powers for all of the elements con- 

 tained in their ash, or for one or more particular elemr 



It seems quite as likely, however, that some plants are able to 

 use certain soil compounds of potash or phosphoric ac ;h are 



not available to other plants, as it did that the legumes were able 

 to obtain nitrogen from sources that were not available to the 



Believing that a study of the foraging powers of differ: 

 cultural plants would reveal facts of scientific interest, and at the 

 same time of practical value to agriculture, the writer commenced 

 a series of experiments, in the fall of 1892, des : the 



readiness with which different plants obtain their phosphoric acid 

 from insoluble phosphc. 



le reason why phosphoric acid was selec hich to make 



in preference to any other sul that 



in practical manuring with crude phosphates, and also in their use 



in experimental work, different crops had apparen: 



differences in their abilities to gather phosphoric acid from such a 



EXPERIMENTAL METHODS. 



In order to have the work as much as possible under control the 

 experiments were conducted in boxes in the college forcing h: 

 These boxes were of wood, fifteen inches square and twelve inches 

 deep. For soil a fine sand was used, taken from a sand bank about 

 three feet below the surface. This sand was drawn to the forcing 

 house, screened and thoroughly mixed by repeatedly shoveling it 

 over, after which a sample was taken and the content of potash 



