280 SYSTEMS OF PERMANENT AGRICULTURE 



The record for yields for 1898 and 1899 appears not to have been 

 published, but the report states that in 1898 the yield of corn was 

 good upon all of these phosphate plots, and that there was but 

 little difference between the yields of oats on the different plots 

 in 1899. In the Report for 1900 the following summaries are made 

 by Professor Brooks: 



"Taking into account all of the crops which have been grown upon this 

 field, except the Swedish turnips (rutabaga), which were affected by disease 

 not apparently due to the fertilizer which had been used on a portion of the 

 plots, and the yields of which, therefore, as expressed in figures, would be mis- 

 leading, and representing the aggregate yield which stands highest, by 100, the 

 efficiency of the different phosphates is as follows : 



Phosphatic slag . . . 100.0 



Ground South Carolina rock . 92.3 



Dissolved bone black . . 90.7 



Mona guano . . . .88.3 



"There was at first no no-phosphate plot used in the experiment, but we have 

 had a no-phosphate plot since 1895. Taking into account the yields of the 

 several plots since 1895, and excepting the Swedish turnips, which were grown 

 in 1897, for reasons above stated, the phosphates have the following relative 

 rank: 



South Carolina rock phosphate 100.0 

 Phosphatic slag . . .99.0 

 Dissolved bone black . . 97.7 

 Mona guano .... 95.4 

 No phosphate . . .55.4 



"The following conclusions appear to be justified by the results which we 

 have obtained: 



"It is possible to produce profitable crops of most kinds by liberal use of 

 natural phosphates, and in a long series of years there might be a considerable 

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

 higher priced dissolved phosphates." 



"Between ground South Carolina rock, Mona guano, and the phosphatic 

 slag there is no considerable difference in the economic result." 



It will be seen that the South Carolina rock phosphate produced 

 larger yields than the dissolved bone black with all of the fourteen 

 different crop products reported, excepting potatoes the first year, 

 wheat straw the second year, and barley straw the fifth year. It 

 should be kept in mind, too, that no adequate provision was made 

 . for supplying decaying organic matter to this soil during the eleven 



