12 UNIVERSITY OF ILLINOIS 



elements of fertility. He therefore incorporated into the Illinois Sys- 

 tem of Permanent Agriculture the use of such natural forces and re- 

 sources as are available, free and equally to all farmers alike, and 

 which cost nothing ; instead of resorting to the costly processes of fer- 

 tilizer manufacture in order to accomplish this purpose. This principle 

 is one of the distinctive features of the Illinois system of permanent 

 agriculture. For example, in pursuance of this theory, he used bac- 

 teria to get the soil nitrogen, discarding the commercially prepared, 

 highly expensive forms of nitrogen. He used soil acids of decompo- 

 sition to render soluble the insoluble phosphates in place of those com- 

 mercially and more expensively prepared. The mineral elements 

 needed for the soil he secured as nearly as possible in their most natural 

 forms; as, for example, raw rock phosphate, prepared only by being 

 finely ground ; and lime, used in the form of coarsely ground limestone. 



FERTILITY Is MAINTAINED AND INCREASED 



He recognized the fact that every crop grown takes something 

 out of the soil, and no matter how great the resources of fertility may 

 be, unless that which is taken out is returned, the soil will eventually 

 be exhausted. On the other hand, he saw that with a system of soil 

 treatment which would provide for the return to the soil of those 

 elements which are removed, the fertility of soil so treated could be 

 maintained indefinitely; and in case more was returned to the soil 

 than was taken from it, such soil would steadily increase in 

 productiveness. 



Still further, he realized that lands naturally barren, or lands 

 long since exhausted by farming and abandoned by man, could be made 

 once more productive by the same process. A very distinctive feature 

 of the Illinois system of permanent soil fertility is that it builds up 

 the soil to a permanently higher state of fertility. We may take, by 

 way of example, the practise of applying to the brown silt loam type 

 of soil, which contains twelve hundred pounds of phosphorus per acre 

 in the stratum turned by the plow, one ton per acre of fourteen per 

 cent raw rock phosphate during each five-year rotation. After de- 

 ducting the loss of phosphorus occasioned by taking off two sixty- 

 bushel crops of corn, a sixty-bushel crop of oats, a thirty-bushel crop 

 of wheat, and a crop of two tons of clover, there would be accumulated 

 in the soil at the end of four rotations, or twenty years, a quantity of 

 unused phosphorus sufficient to build up the phosphorus content of the 

 soil to well above the standard for fertile soils, which is two thousand 

 pounds per acre. This is in contradistinction to other systems of fer- 



