THE SCIENTIFIC BASIS OF THE ILLINOIS 



SYSTEM OF PERMANENT SOIL 



FERTILITY 



By ROBERT STEWART 

 Chief in Soil Fertility, University of Illinois 1 



O IXTY years ago Liebig, the father of agricultural chem- 

 istry, made the following statement: "Agriculture is, of 

 all industrial pursuits, the richest in facts, and the poorest in 

 their comprehension. Facts are like grains of sand which are 

 moved by the wind, but principles are these same grains ce- 

 mented into rocks." The great contribution made to Ameri- 

 can agriculture by the late Doctor Hopkins was the gathering 

 together, classifying, interpreting, and unifying, by his own 

 investigations, the known facts of agriculture into a definite 

 whole as practiced and taught by him in a system of perma- 

 nent soil fertility. 



Many of the facts upon which the Illinois system is based 

 have been known for many years and even centuries, and have 

 been developed by other men in other institutions and in other 

 times. It remained, however, for Doctor Hopkins to bring 

 together and to unify these isolated facts into a definite work- 

 able system, the keynote of which is permanency, and by his 

 own investigations to demonstrate clearly that the system 

 could be understood and used by the average farmer on his 

 own farm, with profitable results. In his interpretation of the 

 facts upon which this system is based all men have not agreed, 

 and some even still do not agree with him. But the system 

 rests on the sure foundation of facts supported by an abun- 

 dance of experimental data now available from the fields and 

 laboratories of the University of Illinois operated under his 

 direction. 



Dean of the College of Agriculture, University of Nevada. 

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