30 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTUBB. 



FLORIDA AND GEORGIA. 



The Florida and Georgia State Experiment Stations have con- 

 ducted no field experiments with ground raw rock^ continuing be- 

 yond one year. 



Because of the limited data given and the short duration of these 

 experiments, their repetition is not justified. 



ILLINOIS. 



The Illinois Experiment Station recommends the use of ground 

 raw rock phosphate as a fertilizer more strongly than any other sta- 

 tion ; in fact it is the only station which now advises the use of this 

 material for general farming above any other phosphate carrier. 



Hopkins first advocated the use of raw rock phosphate in 1903,^ 

 basing his recommendations on the work of the Ohio and Maryland 

 stations. In most of the early published work of the Illinois station 

 steamed bone meal was the phosphate carrier used,^ though it is 

 stated that on certain plots raw rock phosphate was substituted for 

 the former. What plots these were, however, is not made clear. 



In the summer of 1905 * the results of some pot culture experiments 

 conducted in order to compare the relative fertilizer values of raw 

 rock phosphate and steamed bone meal were published. 



The soil used was the gray silt loam of the Lower Illinois glacia- 

 tion and wheat was the crop employed in the test. The pots were 

 10^ inches in diameter, but their height and cubic capacity are not 

 given. The author states that equal money values of the two phos- 

 phates were employed in this test, that is, three times as much raw 

 rock phosphate was added as bone meal. While the actual rate of 

 application per pot and per acre are not given, it is presumed that 

 the rate was the same as for the field experiments, viz, 200 pounds 

 steamed bone meal per acre per annum and 600 pounds of raw rock 

 phosphate. In certain pots the phosphate was turned under with a 

 good growth of clover, in others with manure, and in still others with 

 both clover and manure. The results of this comparative test are 

 given in Table VIII, the yields being expressed both in grams per 

 pot and bushels per acre. 



ipia. Agr. Expt. Sta., Bui. No. 3, pp. 3-6 '(1888); Bui. No. 10, pp. 21-27 (1890); 

 Bui. No. 13, pp. 9-15 (1S91) ; Bui. No. 82, p. .^97 (1905) ; Tre.ss Bulletin No. 77 (1908). 



Ga. Agr. Expt. Sta., Bui. No. 2, pp. 35-37 (1889) ; Bui. No. 25 (1894) ; Bui. No. 26 

 (1894) ; Bui. No. 27 (1894). 



2 111. Agr. Expt. Sta., Circular No. 68, April, 1903. 



8 111. Agr. Expt. Sta., Bui. No. 99, March, 1905; Circular No. 96, July, 1905; Circular 

 No. 97 (1905) ; Bui. No. 115 (1907). 



♦ Ill, Agr. Expt. Sta., Circular No. 9T (1905), 



