PERMANENT SOIL FERTILITY 



own farm, and others at remote places; and he showed the 

 farmer how these could be brought together and utilized for 

 the increase of crops. He instituted a system of chemical 

 analysis of soils which made it possible for every farmer in 

 the state to know the chemical analysis of the soils on his 

 farm, even tho his farm might contain as many as three or 

 four different kinds of soil; and having this knowledge, he 

 could then restore the lacking elements of fertility. 



Doctor Hopkins went further than this. He established 

 in Illinois a series of experiment fields for the purpose of in- 

 vestigating the problems of soil fertility. These fields were 

 not only a means of investigation but they served also as a 

 means of demonstration to the farmers of the state. They 

 were located on every large type of soil in Illinois on the 

 sandy soils, on the peaty soils, on black clay loam, and in fact 

 on every kind of soil found in any large area in this state. 



The experiments carried out in these fields have proven 

 different things. They have proven the possibility of perma- 

 nent agriculture. They have proven that land which is not 

 treated not rationally treated and which is cropped year 

 after year, gradually grows poorer and poorer the longer it is 

 farmed. On the other hand, these fields have proven that these 

 lands, when properly treated by the addition of the elements 

 of fertility which are not supplied in any other way except 

 by the effort of man, gradually grow more and more fertile 

 with each rotation the longer the system of soil feeding is 

 continued. I have visited these fields at the beginning of the 

 undertaking, and in some of them it seemed almost hopeless 

 that profitable crops could be raised ; and then with the next 

 rotation of crops I would see an improvement in those parts 

 of the fields properly treated; and with succeeding rotations 

 I would see them becoming still better until they were large- 

 yielding and profitable fields. 



Another thing these fields have shown is that a rational 

 soil treatment is a sort of insurance of crops; that is, they 



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