86 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
one of the four tracts. The average results obtained in nine years 
for each crop on the tiled and untiled land are given in Table XIJ, 
which is compiled from four tables given in Soil Report No. 8 of the 
Illinois station. 
TABLE XII.—Average yields of corn, soy beans, wheat, and clover obtained on, 
four series of plots at Fairfield, Ill., in an experiment conducted for nind 
years (1905-1913, imclusive). 
Average yield per acre. 
Treatment. Soy 
Corn, eetas Wheat, | Clover, Oats, | Cowpeas, - 
8 years. | ¢ y rere 7 years. | 6 years. | lyear. | 4 years. 
Bushels. | Bushels. | Bushels. | Bushels. | Bushels. | Bushels. 
Residues, lime, phosphate rock...........- 36. 58 8. 23 13.79 0. 67 35. 8 6.08 
Cropresidues #75). ati ai ol Os PEs. 48 28. 90 6. 28 4.17 45 27.9 5.10 
Tons 
Marm-manure.-*- so ee Sets sk ie eso ectes 35. 54 6. 02 5. 21 0. 57 32.5 5. 68 
Manure, lime, phosphate rock............-. 46. 91 9.09 | 18.03 1.61 38.7 7.53 
| Bushels 
Organic manures, lime, phosphate rock... 41. 86 8. 67 15. 90 0. 82 Slee 6. 80 
Organic manures 2 4a ese eee aces 32. 21 6. 16 4.69 - 48 30. 2. 5. 40. 
Increase due to lime and phosphate 
TOC eee ere fees OX65a1 0 225 Tg AY . 34 7.0 1.75 
The authors state that the first four years of this experiment should 
be regarded as preliminary, partly because of the impossibility of 
obtaining full benefit from such treatments during the first rotation 
period,-and also because the system of returning manure and crop 
residues in proportion to the yields produced was not begun until the 
first rotation was completed. But even taking the average yields of 
the various crops during both the first and second rotations, it will 
be seen that the plots treated with large amounts of raw-rock phos- 
phate in connection with lime and organic manures produced consid- 
erably larger crops than those receiving no phosphate. The effect 
of the phosphate, however, was apparently more marked during the 
second rotation period, as can be seen by referring to the more de- 
tailed figures given in Soil Report No. 8 of the Ilnois station. 
Two experiments with raw-rock phosphate conducted over a period 
of five years were reported by Hopkins* in 1915. : 
One field at Ewing, Franklin County, consists of a gray silt loam 
on compact clay (prairie soil), the other at Raleigh, Saline County, 
is situated on a yellow-gray silt loam of the common upland timber 
type. The previous history of the fields is not given, however, nor are 
any data presented showing the uniformity of the fields or the size 
of the plots into which they were divided. Each field contained 4 
series of 10 plots each, and since a four-year rotation of wheat, a 
legume, oats, and corn was followed, each crop was grown every year. 
Both live-stock and grain systems of farming were practiced on each 
farm. 
1711. Agr. Expt. Sta., Circular No 181 (1915). 
q 
uw 
Tele o> a 
a 
Sag 
ie at Gis 
~ 
“ 
