1902.] PUBLIC DOCUMENT — No. 35. 27 



The plots which stand highest this year are the same as 

 those standing highest in the general averages which have 

 been shown above, viz., the ones receiving phosphatic slag 

 and ground South Carolina rock phosphate. The low stand- 

 ing of the plot which received Florida phosphate is, as in 

 former years, very striking ; it stands this year below the 

 no-phosphate plot. It should be remembered, however, 

 that the latter has not been included in this experiment as 

 long as the Florida phosphate plot ; and it may well be that 

 the original store of phosphoric acid in the soil of the no- 

 phosphate plot is to a much less degree exhausted than is 

 the case on the other plots. It must be concluded that the 

 phosphoric acid supplied by the Florida phosphate is in a 

 form of combination rendering it exceedingly unavailable. 



In the writer's opinion, the oat crop is a much less certain 

 indicator as to the condition of the soil as regards available 

 phosphoric acid than are the crops belonging to the cabbage 

 and turnip family. This is indicated by the fact that the 

 differences in yields with oats this year are much less than 

 were the differences with turnips and cabbages. As the 

 turnips, as already stated, were badly affected by disease, 

 figures for this crop are not presented. The relative yields 

 with cabbages last year were as folloAvs : — 



Per Cent. 



South Carolina rock phosphate, 100.0 



Dissolved bone-black, 73.0 



Phosphatic slag, 60.0 



Mona guano, . . . . . . . . .55.3 



Florida rock phosphate, 14.7 



No phosphate, 6.9 



It should be noticed that the relative position of the sev- 

 eral phosphates is nearly the same as this year, but the dif- 

 ferences are far greater. 



In conclusion, attention is called to the fact that the crops 

 on this field in recent years have not been satisfactory in 

 amount, even on the best plot. The fact that no phos- 

 phoric acid in any form has been applied during the last 

 nine years sufficiently accounts for the relatively small 

 yields. Our results, however, indicate a relatively high 

 degree of availability for the phosphoric acid contained in 

 the South Carolina rock and in phosphatic slag. There can 



