PHOSPHATES IN MASSACHUSETTS AGRICULTURE. 141 



Average Increases per Acre in Potato Crop (Bushels). 



The Corn Crop. — ■ The corn crop has been used in soil test work in 

 this station far more extensively than potatoes, and the results bear 

 verj' decisive!}^ upon the question of the relative necessity of application 

 of phosphoric acid and potash in our agriculture. In the experiments 

 upon the south soil test acre, which have been continued from 1889 to 

 the present time, ten corn crops have been grown. ^ The average results 

 are shown in so far as they bear upon the question under discussion in 

 the tables w^iich follow: — 



Average Increase per Acre in Nine ^ Corn Crops (South Soil Test). 



When used alone, .... 

 When added to nitrate, . 

 When added to the other,' . 

 When used in complete fertilizer, . 



Produced by the Use of 



PHOSPHORIC ACID. 



Grain 



(Bushels). 



1.7 

 2.7 

 6.3 

 14.2 



Stover 

 (Pounds). 



—39.0 

 212.0 

 534.4 

 911.7 



Grain 



(Bushels). 



26.3 

 20.8 

 30.9 

 32.5 



Stover 

 (Pounds). 



2,043.3 



1,748.8 

 2,616.7 

 2,447.2 



The crop in this field in 1913 was corn following crimson clover sown 

 in 1912 and plowed under in the spring of 1913. The crop where phos- 

 phoric acid alone had, then, been yearly applied for twenty-five years 

 (lime in 1899, 1 ton per acre; 1904, 1 ton per acre; and 1907, § ton per 

 acre excepted) was at the following rates per acre: grain, 11 bushels 

 (10 of which were soft), and stover, 2,180 pounds. Where potash had 

 been used alone for the same number of years and under the same con- 

 ditions the yield v/as grain, 52.6 bushels (7.7 of which were soft), and 

 stover, 4,360 pounds. 



1 For full reports see bulletins and reports of the Massachusetts Agricultural Experiment Station 

 (known as the "Hatch" Experiment Station, 1888 to 1906). 



2 The crop for 1910 is not included in figuring averages, since through accident the appropriate 

 fertilizer was not applied in that year to one plot. 



' That is, phosphoric acid added to potash or potash added to phosphoric acid. 



