126 



MISSOURI AGRICULTURAL RETORT. 



TABLE NO. I. 

 Latest corn yields from the University of Illioois Soil Experiment Fields at Urbaaa. 



yield with the same rotation started i6 years later, was seventy-five 

 bushels {yy bushels for three-year average). The figures at the top 

 of the table show how comparatively easy it is to lower the producing 

 power of a soil. These plots are on good land, well surface drained^ 

 and tile drained. They are all in a twenty-acre field of naturally uniform 

 land; they were planted at the same time with the same good seed corn^ 

 received the same cultivation, and were subject to the same seasonal 

 conditions, the only difference being in the rotation practiced and, on 

 some of them, in the treatment applied. 



You will notice the varying yields resulting, first, from following the 

 three rotations — continuous corn, corn and oats, and corn, oats and 

 clover — second, from continuing these same rotations sixteen years 

 longer on one set of plots than on the other. Let me call your attention 

 in particular to the effect of this very desirable rotation, corn, oats and 

 clover, upon this soil. It is quite commonly thought that such a rota- 

 tion will indefinitely maintain the producing power of a soil. The facts 

 do not show this, however, for, where followed for eleven years, this 

 rotation has given a yield of seventy-seven bushels as an average for 

 the last three, but where this same rotation has been followed for six- 

 teen years longer, the yield has been reduced to fifty-nine bushels. To 

 be sure, strictly grain farming has been followed upon these plots, no 

 stock has been fed and no manure has been returned. But it is upon the 

 subject of grain farming that I have been asked to speak. Let me say, 

 that we have yet to find a soil in Illinois whose producing power can be 

 indefinitely maintained by crop rotation alone. A rotation in which we 

 have such a crop as clover producing larger corn yields is simply a mearrs 



