SOIL FERTILITY 



401 



( FARM MANURE 



Flo. 192. Wheat, 1011, I'rbana field. Cover crops and farm manure plowed under. Aver- 

 age yield, 34.2 bushels per acre. (Illinois Soil Reports.) 



NANUHC 

 HOCK PMOSPHATI 



Flo. 193. Wheat, 1J>11, l T rhann fiolil. Cover crops nnil fnrm manure plowed under. 

 Finrly ground rook phosphate applied. Average yield, 51.8 bushels per acre. (Illinois -^'U 

 Reports.) 



26 



