/ 



EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 41 



Table XVI. — Three and five year average yields per acre of corn, oats, clover, 

 wheat, soy beans, and alfalfa, obtained on North Farm, Urbana, III., 1908- 

 1915, inclusive. 



Treatment. 



Average yields per acre. 



1908-1910 



Com, 

 3 years. 



Oats, 

 3 years. 



Clover. 

 3 yearsi 



1911-1915 



Wheat, 

 5 years. 



Cora, 

 5 years. 



Oats, 

 5 years. 



Soy 

 beans, 

 4 years. 



Clover, 

 1 year. 



Alfalfa, 

 5 years. 



None 



Crop residues 



Manure 



Residues, lime ; 



^Manure, lime 



Residues, lime, phosphate 



rock, 600 pounds 



Manure, lime, phosphate 



rock, 600 pounds 



Residues, lime, phosphate 



rock, potash 



Manure, lime, phosphate 



rock, potash 



Manure, lime, phosphate 



rock 



Bush. 

 49.4 

 51.5 

 69.3 

 58.1 

 74.9 



83.8 



86.6 



86.7 



90.9 



81.3 



Bush. 

 40.8 

 43.4 

 46.2 

 45.7 

 47.5 



54.5 



55.4 



53.5 



53.6 



54.3 



Tom. 



2.30 

 1(1-93) 



2.53 

 1 (2. 02) 



2.94 



1 (2. 64) 

 4.17 



1(1.99) 

 3.90 

 3.79 



Bush. 

 22.2 

 23.5 

 24.8 

 25.0 

 28.1 



39.1 



38.3 



38.2 



37.4 



42.9 



Bush. 

 53.9 

 56.4 

 63.6 

 59.2 

 63.4 



66.0 



67.6 



63.7 



64.6 



61.0 



Bush. 

 46.3 

 47.8 

 54.6 

 49.7 

 57.3 



64.3 



64.9 



64.5 



69.3 



72.5 



Tons. 



1.60 

 (21.3) 



1.68 

 (20. 7) 



1.72 



(22. 6) 

 1.92 



(24.2) 

 2.09 

 2.19 



Tons. 



2.50 

 1 (0. 74) 



2.20 

 1(1.03) 



2.81 



1(2.48) 

 4.04 



1(1.41) 

 3.91 

 4.-24 



Tons. 

 2.2i 

 1.85 

 1.68 

 1.72 

 2.25 



3.28 



3.25 



3.22 



3.31 



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. Eaw rock phosphate has been applied at the 

 rate of 600 pounds per acre per annum and ground limestone 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 groivn in a four-year rotation on 

 two series of plots on South Farm, Urbana, III., 1903-1915, inclusive. 





Average yield per acre. 



Treatment. 



Corn, 

 7 years. 



Oats, 

 7 years. 



Wheat, 

 7 years. 



Clover, 

 3 years. 



Soy beans, 

 2 years. 





Bushels. 

 60.2 

 59.1 

 50.6 



54.6 

 59.1 

 60.9 



Bushels. 

 40.6 

 39.5 

 35.9 



36.6 

 38.8 

 38.8 



Bushels. 

 40.4 

 38.7 

 28.5 



28.7 

 41.2 

 42.0 



Bushels. 

 0.71 

 1.15 

 1.30 

 Tom. 

 2.72 

 3.94 

 3.99 



Bushels. 

 15.2 





14.9 



Residues 



13.0 



Manure 



Tons. 

 1.0 





1.3 



Manure^ phosphate rock 



1.4 







