28 HATCH EXPERIMENT STATION. [Jan. 



be no doubt that profitable crops of most kinds can be pro- 

 duced by liberal use of these natural phosphates ; and in a 

 long series of years there would be a considerable money 

 saving in depending, at least in part, upon these rather than 

 upon the higher-priced dissolved phosphates. It may, how- 

 ever, be doubted whether, under the conditions prevailing 

 in ordinary farm or garden practice, it. is ever wise to de- 

 pend exclusively upon the natural phosphates. The best 

 practice would probably be found to consist in using one 

 of these in part, and in connection with it a moderate quan- 

 tity of one of the dissolved phosphates. 



V. — The Compakison of Phosphates on the Basis of 

 Equal Application of Phosphoric Acid. 



The phosphates under comparison on this basis include 

 apatite, South Carolina rock phosphate, Florida soft phos- 

 phate, phosphatic slag, Tennessee phosphate, dissolved bone- 

 black, raw bone, dissolved bone, steamed bone and acid 

 phosphate. The experiments have been in progress five 

 years, each phosphate being applied yearly to the same 

 plot. There are three no-phosphate plots, which serve as a 

 basis for comparison. The plots are one-eighth of an acre 

 each in area. 



The phosphates yearly applied are used in quantities suf- 

 ficient to furnish actual phosphoric acid at the rate of 96 

 pounds to the acre. All plots are .manured alike with ma- 

 terials furnishing nitrogen and potash in available forms 

 and in equal amounts to each. The materials used furnish 

 nitrogen at the rate of 52 pounds and potash at the rate of 

 152 pounds per acre. The preceding crops have been : 

 corn, cabbages, corn, and in 1900 oats for hay, and Hun- 

 garian grass, also cut for hay. The yields of all these 

 crops have been large, even on the three plots in the field 

 which received no phosphate. The results have been ren- 

 dered somewhat obscure by the natural variation in the pro- 

 ductiveness of the plots in different parts of the field. 

 Plot 1, which receives no phosphoric acid, is naturally 

 much more fertile than any other plot in the field, and in 

 estimating the significance of the results this plot should be 



