EXPEEIMEISTTAL WORK WITH RAW ROCK PHOSPHATE. 



35 



Table ^1.— Average of results of nine years' work on three series of plots at 

 Galesburg, III. — Six-year rotation employed, consisting of corn, corn, oats, 

 wheat, clover, and timothy. 



Average yield per acre. 



Com, 

 9 years. 



Oats, 

 5 years. 



Wheat, 

 5 years. 



Clover, 



4 years. 



Timothy, 

 4 years. 



Lime 



Residues , lime 



Manure, lime 



Cover crop, manure, lime 



Lime 



Lime, phosphate rock 



Residues, lime, phosphate rock 



Manure, Ume, phosphate rock 



Cover crop, manure, hme, phosphate rock 



Lime 



Lime, phosphate rock, potash 



Residues, Ume, phosphate rock, potash 



Manure, lime, phosphate rock, potash 



Cover crop, manure, hme, phosphate rock, potash 



Lime 



Residues 



Residues, phosphate rock 



Residues, phosphate rock, potash 



Residues, lime, nitrogen, phosphate rock, potash. 

 None 



Bushels. 

 65.66 

 70.16 

 77.21 

 76.68 

 71.64 

 78.57 

 79.68 

 81.38 

 82.93 

 73.01 

 80.89 

 81.68 

 81.37 

 83.94 

 74. 23 

 72.32 

 76.21 

 78.38 

 81.59 

 70.82 



Bushels. 

 48.24 

 47.08 

 48.34 

 50.20 

 49.50 

 54.64 

 50.76 

 56.80 

 53.56 

 47.28 

 53.48 

 52.72 

 56.36 

 55.50 

 49.60 

 49.42 

 51.62 

 48.44 

 56.18 

 51.98 



Bushels. 

 27.98 

 31.16 

 29.54 

 31.06 

 30. 66 

 34.66 

 35.22 

 33.30 

 35.32 

 28.92 

 34.46 

 34.74 

 32.46 

 33.96 

 27.90 

 28.82 

 33.78 

 36.46 

 35.95 

 29.04 



Tom. 

 1.75 

 1.63 

 2.19 

 1.90 

 2.03 

 2.40 

 1.90 

 2.41 

 2.31 

 1.81 

 2.53 

 11.40 

 2.77 

 2.73 

 1.82 

 1.82 

 1.85 

 11.51 

 11.21 

 L55 



Tons. 

 1.81 



2 1.43 

 1.90 

 1.96 

 1.96 

 2.18 



n.50 

 2.11 

 2.27 

 2.05 

 2.58 



2 1.87 

 2.20 

 2.26 

 2.10 



2 1.67 



2 1.80 



3 2.33 

 22.83 



2.08 



1 One crop only. 2 Average of three crops. 



While the results given in Table XI are favorable to the use of 

 raw rock phosphate they are not tabulated in a manner which brings 

 out the true effect of this material. Manure was applied only after 

 the experiment had been under way for four years, and the residue 

 (or grain farming) system also was not fully in operation for some 

 years. The average yields of the plots on which " manure " and 

 " residues " were apparently applied therefore include the results 

 of years in which* no organic matter was used. 



For more detailed figures on this experiment the reader is referred 

 to Soil Eeport No. 7. 



Later this year (1913) the same authors^ published the results 

 obtained with raw rock phosphate in two complete rotations (nine 

 years) on the Fairfield experiment field, Wayne County, 111. Tlie 

 soil of this experiment field is the conunpn upland type of southern 

 Illinois, consisting of a gray silt loam on dense clay. The history of 

 the field is not given. 



The experiment field was divided into four tracts of 10 acres each, 

 " one half of the field, or 20 acres, is tile drained while the other half 

 has only the ordinary surface drainage. On both the tiled and un- 

 tiled land grain farming is practiced on one half and live-stock farm- 

 ing on the other half. A part of each of these divisions is treated 

 with 2 tons of limestone and 1 ton of ground phosphate rock per acre 

 every four years." No other commercial fertilizers were used. A 

 four-year rotation was practiced on this field, consisting of corn, 

 soy beans, wheat, and clover, each crop being grown every year on 



iIU. Agr. Expt. Sta., Soil Kept. No. 8 (1913). 



