1902.] PUBLIC DOCUMENT — Xo. 33. 25 



Since 1893 no phosphate has been ai)plied to any part of 

 the field. The object in view in withholding phosphates 

 has been to test the lasting ((ualities of the several mate- 

 rials. At the beginning of the present season, supposing 

 the crops harvested to have been of average composition, 

 and that there has been no loss of phosphoric acid by leach- 

 ing (which is improbable), there mast have remained of the 

 total phosphoric acid applied to the several plots the fol- 

 lowing amounts in each : — 



Pounds. 



Phosphatic slag, . . . . . . . .53.6 



Mona guauo, . . 29.7 



Florida phosphate, . . . . . . . . 132.4 



South Cai'oliua rock pho.sphate, ..... 102.0 



Dissolved bone-black, 9.5 



Throughout the entire period of the experiment (1890 to 

 date), materials supplying nitrogen and potash have been 

 applied in e(iual amounts to all plots. Since 1893 the 

 (juantities applied have been made very large, in order to 

 make it certain that the crops grown may find in the soil all 

 the nitrogen and potash they can possibly need. All the 

 plots in the field were limed at the rate of one ton to 

 the acre of quick-lime, slaked, spread after ploughing and 

 deepfy worked In with a harrow in the spring of 1898. 

 The crops which have been raised on the field previous to 

 this year, in the order of their succession, are potatoes, 

 wheat, scrradella, corn, barley, rye, soy beans, Swedish 

 turnips, corn, oats and cabbages. Representing the yield 

 on the plot giving the highest returns by 100, the relative 

 efficiency* of the dift'erent phosphates at the beginning of 

 this year stood as follows : — 



Per Cent. 



Phosphatic slag, 100.0 



Ground South Carolina rock, 92.3 



Dissolved bone-black, .90.7 



Mona guano, 88.3 



Florida phosphate, 71.5 



Taking into account the crops grown since 1895, when for 

 the first time a plot to wlilch no phosphate was a])pllcd was 

 included, the phosphates have the following relative rank :* — 



* Swedish turnips, grown in 1897, have not Jjeen included in computing these 

 percentages as that crop was alFected by disease not apparently connected with the 

 fertilizers used. 



