48 EXPERIMENT STATION. [Jan. 



acid and potash in available form must now be considerably 

 better than at the beginning of the experiment; and there 

 can be little doubt that a lesser application of these fertilizer 

 elements in the immediate future will prove suificient to give 

 satisfactory crops. 



VL — Comparison of Phosphates on the Basis of Equal 

 Application of Phosphoric Acid. 

 The past season is the tenth of this experiment, the object 

 of which is to determine, as measured by crop production, 

 the relative availability of different materials which may be 

 used as sources of phosphoric acid. All these materials have 

 from the first been applied in such quantities as to furnish 

 phosphoric acid at the rate of 96 pounds per acre in the case 

 of each of the materials under comparison. The field com- 

 j^rises thirteen plots, each containing one-eighth of an acre. 

 Three of the plots have received no phosphoric acid since 

 the experiment began. One of these is located at either end 

 of the field, the third in the middle. The phosphates under 

 comparison are the following: apatite (fine ground). South 

 Carolina rock phosphate (fine ground), Florida soft phos- 

 phate, basic slag meal, Tennessee rock phosphate (fine 

 ground), dissolved bone black, raw bone meal, dissolved bone 

 meal, steamed bone meal and acid phosphate. Materials sup- 

 plying nitrogen and potash liberally are applied to each of 

 the plots annually, and in such quantities as to furnish nitro- 

 gen at the rate of 52 pounds and potash at the rate of 152 

 pounds per acre. In the case of a few crops requiring espe- 

 cially high manuring (onions and cabbages), a supplementary 

 application of quick-acting nitrogen fertilizers has been made 

 to all plots alike. Owing to the impossibility of procuring 

 the material, no apatite was applied to plot 2 during the past 

 season. The crops which have been gro^vn in the field during 

 the progress of the experiment are as follows : corn, cab- 

 bages, corn, in 1900 two crops, — oats and Hungarian grass 

 (both for hay), onions, onions, cabbages, and mixed grass 

 and clover. The field was seeded in the spring of 1905 with- 

 out a nurse crop. It was cut twice during the season, but 

 the i)rodiict, largely mixed with weeds, was not weighed. 



