872 ANNUAL REPOIlT OF THE Off. Doc. 



No details of yields for each year have been reported, but tbc re- 

 sults so far have been stated by Prof. Brooks as follows: 



1. The blag phosphate evidently furnishes phosphoric acid in an 

 exceedingly available form, the yield being almost equal to dis- 

 solved bone black. 



2. Florida soft phosphate is apparently a very inferior material, 

 the phosphoric acid evidently becoming available only with great 

 slowness. 



3. Steamed bone meal appears to be inferior in availability to raw 

 bone meal. 



TESTING THE RELATIVE ABILITY OF DIFFERENT CROPS 

 TO USE VARIOUS FORMS AND SOURCES OF PHOSPHATES. 



This is a subject which has been given considerable attention by 

 the Maine and Cornell Experiment Stations. The study has been 

 conducted both in the field and in pot experiments. 



These experiments, which have been made in the pots or boxes 

 with sand and artificial soils, while instructive in showing the rela- 

 tive ability of different plants to use various phosphates, yet they 

 have been conducted under such abnormal conditions that the re- 

 sults obtained can not be applied in regular field practice. Par- 

 ticularly is this true in the use of the insoluble phosphates which 

 have been found to be most available upon soils which contained 

 considerable organic matter. 



The first: test conducted by the Maine Station was made in the 

 field on the farm of H. L. Leland, at East Saugerville, on a slaty 

 gravel soil. The detailed results of this test are given in the Annual 

 Report of that Station for 1891, page 142. Part of the growing 

 season was verv drv, which materiallv interfered with the vields ob- 

 tained and no doubt to some extent with the results in general. 



The following table shows the crops and phosphates used in the 

 test, with the results obtained: 



