492 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
TABLE XVII.—Average annual yields of crops grown in a four-year rotation on 
two series of plots on South Farm, Urbana, Ill., 1903-1915, inclusive—Contd. 
3 years. | 2 years. | 3 years. ee 2 years. 
, : Bushels. 
Residues, lime, phosphate rock!..__.............--- 62. 4 53.6 4759) aes 163.7 
Residues, lime, phosphate rock 1.._...........-.---- 61.5 52.8 4655 4 aes Bone 12.3 
A RASSSNKO NB KEXSS Us 3 AUS Sap Be aime ERNE CC) = co Se Gara ry 53.8 42.7 QS G4\ ceeee eee 10.7 
Tons. 
Mente let ya te cee 2. ois nee sets chee actos 58. 4 47.6 295155 | ie See 0. 84 
Manure, lime, phosphate rock! ........0........--- 63.0 48.5 49.4 )| 2c sccpes Tb ale 
Manure, lime, phosphate rock!....................-- 63. 2 50. 2 os PSS fee Shs od 1.34 
1 Plots on which lime was applied were not introduced into the experiment until 1910. 
The results of this experiment point very strongly to the conclu- 
sion that raw rock used in liberal amounts in connection with organic 
manures is effective in increasing crop yields. But hke many other 
experiments no data are reported which allow one to determine the 
relative efficiency of raw rock and acid phosphate. 
In April 1916 Hopkins? reported the results of three long-time ex- 
periments at Cutler, Odin, and Mascoutah, in southern Illinois. 
These are the only experiments reported by Hopkins of Illinois work 
comparing the fertilizer value of steamed bone, acid phosphate, 
ground raw rock phosphate, and basic slag. Crop residues were re- 
turned to the land and potash and hme applied. At Odin and Mas- 
coutah only half of each plot was limed. Fertilizers were applied 
once during each rotation in sufficient quantity to supply annually 
200 pounds bone, 333 pounds acid phosphate, 666 pounds raw rock, 
and 260 pounds slag (equal money values at that time). The results 
of the experiments are given below in Tables XVIII and XIX. 
TABLE XVIII.—Average yields of corn, oats, wheat, and hay in two long-time 
experiments. 
Odin field (1904-1915). Mascoutah field (1904-1913).2 
Treatment. 
Corn, Oats, Hay, Corn, Oats, Wheat, 
3 crops. | 3crops. | 6crops. | 4crops. | 2crops. | 2 crops. 
Bushels. | Bushels. Tons. | Bushels. | Busheis. | Bushels. 
Residues, lime, bone, potash...........--- 33.9 47.8 1.30 45.4 38.6 26.3 
Residues, bone, potash. ......-..---------- 31.4 50.9 . 94 48.6 42.6 25.9 
Residues limes potash ce ac-n--ee-eee 26.7 43.9 1.07 38.9 37.2 23.6 
RVesiduesMp ObaSWer =e -mye see se se eae 27.6 43.9 . 64 39.7 27.3 22.6 
Residues, lime, acid phosphate, potash... . 30. 2 43.5 1.19 44.0 37.0 25.4 
Residues, acid phosphate, potash.....-...- 29.9 52.8 SUE 40.2 42.2 Dok 
Residues, lime, rock phosphate, potash.... 32.3 48.4 1. 28 47.2 38.9 26.7 
Residues, rock phosphate, potash...----.- 27.0 52.2 5 (2 45.6 37.4 26. 2 
Residues, lime, potash...¢.....----------- 27.3 48.1 12 38. 4 40.5 25m 
IReSIGUeS, OLAS DNs eset ace nee ees 21.7 41.1 -61 38. 6 31.0 20.7 
Residues, lime, basic slag, potash.......... 32a 55.8 Pad 45.6 43.0 26.5 
Residues, basic slag, potaSh...-.........-- 27.3 50.3 . 78 47.8 33.8 25.8 
171]. Agr. Expt. Sta. Circular No. 186, April, 1916. 
2 Crops of legumes turned under in 1908 and 1911. 
