PERMANENT SOIL FERTILITY 



not be produced. On all the experimental fields of the Uni- 

 versity just one-half of the work is devoted to the maintenance 

 of soil fertility in live-stock farming. The live-stock farmers 

 of Illinois should have a deep sense of gratitude to Doctor 

 Hopkins for his work in their behalf. 



If a system is to be permanent, the materials removed from 

 the soil must be returned at least in the proportion in which 

 they are removed by natural processes, including the amount 

 removed by the crop and the amount lost in the drainage 

 water. This would seem to be such a simple axiomatic truth 

 that it need not be dwelt on ; however, it is a point which must 

 be constantly emphasized. For years Doctor Hopkins has 

 protested against the use of the complete commercial fertilizer 

 to supply soil deficiencies. He pointed out that the use of 

 two or three hundred pounds of an ordinary commercial fer- 

 tilizer of a 2-10-2 grade, which adds only five or six pounds 

 of nitrogen, could act only as a soil stimulant ; for, if increased 

 crops are obtained by its use, they can be had only at the ex- 

 pense of the nitrogen already in the soil, since the requirement 

 for a 100-bushel crop of corn is 100 pounds of nitrogen. The 

 Illinois system of permanent soil fertility, therefore, condemns 

 in unmeasured terms the use of such soil stimulants, among 

 which must be classified ordinary commercial fertilizers and 

 gypsum. 



In the briefest way possible, the very essential points un- 

 derlying the Illinois system of permanent soil fertility as 

 worked out by Doctor Hopkins have thus been merely touched 

 upon. But it is the desire at this point to emphasize the fact 

 which Doctor Hopkins reiterated that the Illinois system of 

 permanent soil fertility rests upon a sane and safe scientific 

 basis, and, because it makes abundant use of cheap, natural, 

 raw products, such as legume nitrogen and finely ground lime- 

 stone and rock phosphate, it is both a permanent and profitable 

 system of soil fertility. This is the heritage to the Illinois 

 farmers left by him in whose memory we have met to-day. 



