CYRIL GEORGE HOPKINS 



On normal soils phosphorus is frequently the limiting ele- 

 ment of crop production. Various forms of phosphorus are 

 available for supplying this deficiency, such as barnyard ma- 

 nure, steamed bone meal, basic slag, acid phosphate, and raw 

 rock phosphate. In the Illinois system of permanent soil fer- 

 tility, Doctor Hopkins provided for the abundant use of finely 

 ground rock phosphate, since a wealth of experimental data 

 from the fields maintained by the University has proved con- 

 clusively that, except under special conditions, this form may 

 be used with considerable profit and with much less expense 

 than the other forms, altho there may be special conditions 

 under which some of the other forms are desirable. 



There are two well defined types of farming occurring in 

 Illinois, the grain system and the live-stock system. Both of 

 these are perfectly legitimate, proper, and profitable systems 

 of farming. Both of these types, moreover, are absolutely 

 essential to the development of the highest stage of civiliza- 

 tion ; as long as man demands bread, butter, meat, and milk, 

 and until we are willing that our standards of living should 

 be lowered, both types must exist. Doctor Hopkins recog- 

 nized this fact, and in the Illinois system of permanent soil 

 fertility made provision for the maintenance of fertility on a 

 permanent and profitable basis on both the live-stock and the 

 grain farm. In either type of farming, limestone and phos- 

 phates must be used in order that the growth of legumes, so 

 essential both in soil improvement and in the feeding of live 

 stock, may be made possible. 



While Doctor Hopkins took particular pains to point out 

 and emphasize the possibility of maintaining the fertility of 

 the soil on the grain farm on a permanent and profitable basis, 

 he also made important contributions to our knowledge re- 

 garding methods of maintaining the fertility of the live-stock 

 farm. His teachings in this respect are of tremendous im- 

 portance since they provide for the extension of live-stock 

 farming to large areas where heretofore the proper feeds could 



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