in this country. The demonstration of the evils of 

 single cropping is mathematical in its completeness. 

 At the experiment station of the Agricultural College 

 of the University of Minnesota they have maintained 

 44 experimental plots of ground, adjoining one another, 

 and as nearly identical in soil, cultivation and care as 

 scientific handling can make them. On these have been 

 tried and compared different methods of crop rotation 

 and fertili/ation. together with systems of single crop- 

 The results of ten years' experiment arc now 

 available. On a tract of good ground sown continu- 

 ousiy for 10 years to wheat, the average yield per acre 

 for the first five years was 20.22 bushels and for the 

 next five 16.92 bushels. Where corn was grown con- 

 tinuously on one plot, while on the plot beside it corn 

 was planted but once in five years in a system of rota- 

 tion, the average yield of the latter for the two years it 

 was under corn was 48.2 bushels per acre. The plot 

 where corn only was grown gave 20.8 bushels per acre 



lu first five and i i.i bushels for the second five of 

 tlu -e fenrs, an average of 16 bushels. The difference 



\ erage of these two plots was 32.2 bushel . or twice 

 the total yield of the ground exhausted by the single- 

 crop system. The corn grown at the end of the 10 years 

 was hardly hip liujh. the ears small and the grains 

 li-ht. But the cost of cultivation remained the same. 

 And the same is true of every other grain or growth 

 when raised continuously on land unfertilized. We 

 frequently hear it said that the reduction in yield is 

 due to the wearing out of the soil, as if it was a 



