EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 4] 
TABLE XVI.—Three and five year average yields per acre of corn, oats, clover, 
wheat, soy beans, and alfalfa, obtained on North Farm, Urbana, Ill., 1908- 
1915, inclusive. . 
Average yields per acre. 
1908-1910 1911-1915 
, Treatment. 
Corn, | Oats, | Clover,| Wheat,| Corn, | Oats, | ,°°¥. | Clover,| Alfalfa, 
3 years. |3 years. |3 years. |5 years. |5 years.|5 years. 4 1 year. |5 years. 
None.. gcascsosanponausogsoDE 49.4 40.8 2.30 22.2 53.9 46.3 1.60 2.50 2.21 
Cropresiduese 3.022 a. Sg 43.4 ]1(1.93)} 23.5 56. 4 47.8 |1 (21.3) | 1 (0.74) 1.85 
EAC RAE ee aac nino civic oe 69.3 46.2 2.53 24.8 63.6 54.6 1.68 2. 20 1. 68 
Residues, lime Pees GoW eke - 8.1 45.7 | 1 (2.02) 25.0 59, 2 49.7 |) (20.7) | 1 (1.08) 1.72 
Manure, lanes. =. 3,052 02 74.9 47.5 2.94 28.1 63. 4 57.3 1.72 2.81 2. 25 
Residues, lime, phosphate 
rock, 600 pounds........... 83.8 54.5 | 1 (2.64) 39.1 66.0 64.3 |! (22.6) | 1 (2.48) 3. 28 
Manure, lime, phosphate 
rock, 600 pounds........... 86.6 55.4 4.17 38.3 67.6 64.9 1.92 4.04 3. 25 
Residues, lime, phosphate 
rock, potash's:-:.--2..22-- - 86.7 53.5. | 1 (1.99) 38. 2 63.7 64.5 |} (24.2) | 1 (1.41) 3. 22 
Manure, lime, phosphate 
rock, potash. ..2. 22% 242..)... 90.9 53.6 3.90 37.4 64.6 69.3 2.09 3.91 3.31 
Manure, lime, phosphate ° 
LOCK ee ee ee pee sok 81.3 54.3 3.79 42.9 61.0 7255 2.19 4.24 3.45 
1 Bushels of seed. 
The plots receiving phosphate treatments in every instance gave 
substantially greater average yields than those on which no phos- 
phate was applied. These increases, however, can not be entirely 
attributed to raw rock phosphate, since the previous applications of 
steamed bone meal no doubt influenced considerably the crop yields. 
The results of one or more additional rotations should be obtained 
before it is wise to draw conclusions from this experiment. 
On the South Farm, at Urbana, a four-year rotation is practiced 
on two series of plots. Raw rock phosphate has been applied at the 
rate of 500 pounds per acre per annum and ground lmestone at the 
rate of 8 tons per acre once in 1910 and 1911. Beginning in 1912 
the subsequent applications of limestone were at the rate of 2 tons 
per acre every four years. 
The average results of 12 years’ work on two series of plots on the 
South Farm are given below in Table XVII. 
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. 
Average yield per acre. 
Treatment. 
Corn, Oats, Wheat, | Clover, | Soy beans, 
7 years. | 7 years. | 7 years. | 3 years. | 2 years. 
Bushels. | Bushels. | Bushels. | Bushels. Bushels. 
Residues: phosphatemocke. 6 3 s.8.s.esecsee <cicesese = = 60. 2 40.6 40.4 0.71 LY 
esidues phosphate LOCK... 9. -<-..- 40. ----+-- 222 -- 59.1 39.5 38.7 115 1155 14.9 
EVOSIC OS ete Sees eo se - a ua ee ae 50.6 35. 9 28.5 1.30 13.0 
Tons. Tons 
URES TUT spare a eg te NC in na cata ovale ctayess ys 54.6 36.6 28.7 2.12 1.0 
Manne, phosahate rock... 2a.2--222--- cee - = 2 ee ne 59. 1 38.8 41.2 3.94 1533 
Mantne- phosphate nock....4e2 . seh esee Sener eee 60.9 38.8 42.0 3.99 1.4 
ee 
