50 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
TaBLE XXV.—Results of seven years’ work on Burnside experiment field 
(1909-1915). 
Yield per acre. - 
Applica- 
Fertilizer. tion per Soy- 
acre.! | Corn, Oats, | Clover, | Corn, bean | Wheat, | Corn, 
1909. 1910. 1911. 1912. hay, 1914. 1915. 
1913. 
Towne s.| Bushels.| Bushels.| Pounds.| Bushels.| Pownds.| Bushels.| Bushels. 
Rock phosphate...-.-....... 2, 000 
SO eer gta ri } 3.8 9.3| 2,436] 32.9] 1,688 11.9 34.8 
IN GIT s ee we ane ee ee | Se yee en 9.0 9.0 668 9.5 628 200) 4.9 
Acid phosphate.............. 800 | = ; 
Paci eee ee 400 14.3 11.9 2,168 45.7 2,272 19.2 46.6 
Acid phosphate eages sees a 800_| aya 13.6 2,328 43.5 2112 18.1 50.9 
INO Bhima oe re eee ey erence | 20. 4 14.0. 1,292 30.3 1,176 G3 ba oie gd ES 
Potashis) jose eccspoceeet- a 400 | 11.9 10.5 764 17.6 560 Ley 5.3 
1 The fertilizers were applied at rate per acre stated in summer of 1908, again at the same rate in 1912, 
and at one-fourth the above rate in 1915. 
2 The station states that this plot should not be considered a check plot. 
While the plot treated with raw rock phosphate and potash gave 
yields below and no better than the check plots in 1909 and 1910, 
respectively, from then on it forged ahead rapidly, indicating that 
the crops were benefited by the phosphate treatments after the latter 
became more thoroughly distributed in the soil through cultivation. 
The yields of the acid phosphate plots, however, greatly exceeded (in 
all but one instance) those of the raw-rock plot, even though the less 
soluble material added over four times as much phosphoric acid to the 
soil. While no data are given showing their relative natural fertil- 
ity, it is said that the raw-rock plot was handicapped by being 
naturally less fertile than the other plots in the experiment field. 
The results of six other experiments comparing acid phosphate 
with raw rock phosphate, conducted for periods of from three to 
four years in various parts of the State, are given by Roberts in this 
same bulletin. Their limited duration, however, coupled with the 
fact that the weather conditions were very bad during two of the 
years, render detailed considerations of the results unwarranted in 
this paper. 
The data presented by the Kentucky station are insufficient to be 
conclusive, although the results of the field experiment cited did 
indicate that raw rock, while inferior to acid phosphate, increased 
crop yields after the lapse of a year or more. 
LOUISIANA. 
Of the 18 experiments with ground rock phosphate or “ floats” 
carried on by the Louisiana Experiment Station, 101 were conducted 
through periods of from one to four years. These are not repeated 
in detail. 
i1La. Agr. Expt. Sta., Buls. Nos. 3, 4, 6 (1886); 7, 8, 11 (1887); 14 (1888); 20 
(1889) ; 28 (1890) (old series). Buls. Nos. 8 (1891); 14, 16 (1892); 26, 29 (1894) 
(new series). 
