«70 



ANNUAL REPORT OF THE 



Off. Doc. 



In addition to the phosphates each plot received an application of 

 about 300 pounds of nitrate of soda, 400 pounds potash magnesia 

 sulphate per acre. These quantities were continued until 18D3 and 

 since that lime have been made very much larger though uniform for 

 all the plots. 



The applications of phosphates were continued annually until 189o 

 and since that time none have been used. The object of withholding 

 jjliosphate Avas to test their lasting effects. Subtracting the amount 

 of phosi»horic acid removed by the crops harvested from that applied, 

 there should have remained in the soil at the end of 1901, about the 

 following quantities of phosphoric acid per acre: 



TABLE 23. 



Showing- Quantity of Phosphoric Acid Remaining in the Soil at the End of 



Ten Years Cropping. 





Kfnd of Phosphate. 



■a 

 c 



3 

 o 



a, 



Slag phosphate 



Mona Island guano 



Florida phosphate, 



South Carolina phosphate 

 Dissolved bone black, ... 



876 

 208 

 927 

 714 

 66 



The crops which have been raised on the plots in the order of their 

 succession are potatoes, wheat, serradella, corn, barley, rye, soja 

 beans, Swedish turnips,* corn, oats and cabbage. 



Representing the 3'ield of the plat giving the highest return by 

 100, the relative efficiency of the phosphates at the beginning of 1902 

 stood as follows: 



Per cent. 



Slag phosphates, 100 . 



Ground South Carolina rock, 92.3 



Dissolved bone black, 90.7 



Mona Island guano, 88.3 



Florida phosphate, 71.5 



In 1898 these plots were all limed at the rate of one ton per acre of 

 quick lime. The slag phosphates which contains considerable Vnw 



•Swedish turnips were a failure on account of dlEease and the results of this crop were not 

 used In computing the relative yields. 



