30 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
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 
104 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. 
1Fla. Agr. Expt. Sta., Bul. No. 3, pp. 3-6 (1888); Bul. No. 10, pp. 21-27 (1890) ; 
Bul. No. 13, pp. 9-15 (1891); Bul. No. 82, p. 397 (1905) ; Press Bulletin No. 77 (1908). 
Ga. Agr. Expt. Sta., Bul. No. 2, pp. 35-37 (1889) ; Bul. No. 25 (1894); Bul. No. 26 
(1894); Bul. No. 27 (1894). 
2Tll. Agr. Expt. Sta., Circular No. 68, April, 1903. 
$Jll. Agr. Expt. Sta., Bul. No. 99, March, 1905; Circular No. 96, July, 1905; Circular 
No. 97 (1905) ; Bul. No. 115 (1907). 
Jil, Agr. Expt. Sta., Circular No. 97 (1905). 
