142 MASS. EXPERIMENT STATION BULLETIN 162. 



The comparative results with corn surely show in a most striking way 

 the paramount importance of potash for that crop on this soil, while 

 it is brought out with equal clearness that the effect following the applica- 

 tion of phosphoric acid is comparatively insignificant. It is pertinent 

 here to call attention to the fact that the field in which these experiments 

 have been tried is of the same character, both as to geological origin and 

 past treatment, as the soils for which analyses showing extraordinary 

 quantities of potash both in surface and subsoils have been made. 

 An analysis of this soil has shown it to contain .38 per cent, acid soluble 

 potash in the surface soil, which undoubtedly means at least 40,000 pounds 

 total potash in the first 3 feet in depth to the acre. 



It "wdll be of interest here to inquire whether similar results should be 

 anticipated with the corn crop in other parts of the State. The station 

 has conducted thirty-one soil test experiments with corn in different 

 parts of the State, every county, except Dukes and Nantucket (islands), 

 and most of the leading soil types being covered. With hardly an excep- 

 tion the results have been of the same general character with those on 

 our own grounds, and in full agreement with those as to general teaching. 

 A few averages only ^vill be here presented. ^ 



Average per Acre in Thirty-one Corn Crops {Soil Tests). 



These results, wliile not demonstrating so great a degree of superiority 

 for the potash as compared with the phosphoric acid as our home experi- 

 ments, still indicate that it, rather than phosphoric acid, is the element 

 chiefly required. ^ 



The Hay Crop. — A good basis of comparison of the effects, respectively, 

 of phosphoric acid and potash upon this crop is afforded by the results 

 upon the fields devoted to comparative trials of different phosphates 

 (phosphate field) and of different potash salts (field G). The hay crop 



1 For details see Bulletins Nos. 9 and 18, Hatch Experiment Station, and annual reports. 



- In our soil test experiments dissolved bone black or acid phosphate at the rate of 320 pounds 

 per acre has always been used as the source of phosphoric acid, and muriate of potash at the rate 

 of 160 pounds per acre as the source of potash. It is recognized that in using these amounts we 

 are applying potash at a heavier rate per acre than phosphoric acid, — about 80 pounds to about 

 54 pounds. It is pointed out, however, that while the ratio of application of phosphoric acid to 

 potash is as 1 : 1.5, the ratio of these elements in the crop is 1 : 6.7, so that phosphoric acid is ap- 

 plied in much the larger proportion as compared with the crop requirement. 



