150 MASS. EXPERIMENT STATION BULLETIN 162. 



Phosphates compared and Rates per Acre. 



Plot. 



Materials supplying Phosphoric Acid. 



Pounds 

 per Acre. 



None, ...... 



Arkansas rock phosphate, ' 

 South Carolina rock phosphate, 

 Florida soft phosphate, 

 Basic slag meal, . . . . 



Tennessee phosphate,* 



None 



Dissolved bone black, 



Raw bone meal, 



Dissolved bone meal, 



Steamed bone meal, . 



Acid phosphate, 3 



None 



376 

 376 

 364 

 538 

 296 



522 

 404 

 432 

 380 

 500 



1 Apatite used in 1897-1905; Arkansas since 1908. 



2 Navassa phosphate used in 1897-1900; Tennessee since 1901. 



3 Owing to a clerical error in copying, which occurred in 1901, this phosphate was used only at 

 the rate of 380 pounds per acre from 1901 to 1913, inclusive. 



Crops Grown. 

 As already stated, the field had been continuously in grass for a long 

 period of time previous to the beginning of this experiment. While in 

 grass it had, during the latter part of this period at least, received moderate 

 annual top-dressings of chemicals. The year previous to the beginning of 

 the experiment it was plowed and planted to corn without fertilizer, with 

 a view to noting the relative productive capacity of the different plots. 

 The date of planting was June 27; the date of harvesting, September 26, 

 the corn being in milk. The yields were as follows : — 



Yields of Corn without Fertilizer, 1896. 



