Missouri Corn Growers' Association. 



339 



or forty years, finally giving place to a definite and systematic 

 rotation system. In many of the newer sections of the west the 

 one-crop system of corn or wheat is still practiced. As we come 

 east we first find a region just west of the Mississippi river where 

 the two-crop system is largely practiced. As we proceed east- 

 ward we finally find in Ohio, New York, Pennsylvania and other 

 eastern states regions in which systematic crop rotation is very 

 definitely defined. In Missouri and surrounding states we are 

 just passing from the two-crop system to that of a definite rota- 

 tion, and a great many of our farmers are beginning to practice 

 definite rotations. This will become more pronounced as our 

 lands grow older and thinner under the present system of man- 

 agement. 



More or less manure and fertilizers are used with all three of 

 these systems, but such treatment usually accompanies the last 

 two. 



The effect of the cropping system on the yield of corn is 

 well illustrated by the work of the Illinois Experiment Station*, 

 where different plots of land have been under different cropping 

 systems for more than thirty years. 



EFFECT OF CROPPING SYSTEMS ON THE YIELD OF CORN. 

 ILLINOIS EXPERIMENT STATION. 

 (Average yield of three last years of corn.) 



Crop years. 



1905-'6-'7 

 1903-'5-'7 

 1901-'4-'7 



Cropping system. 



Corn every year 

 Corn and oats 

 Corn, oats, clover 



13-year experiments 



35 bushels per acre 

 62 bushels per acre 

 66 bushels per acre 



29-year experiments. 



27 bushels per acre 

 46 bushels per acre 

 58 bushels per acre 



The original productive capacity of the land on which these 

 experiments were conducted was more than 70 bushels per acre. 

 It will be seen that there has been some decrease in yield in all 

 cases, but the decrease has been less where rotation was practiced 

 than where one or two-crop systems were employed. This is due 

 largely to the fact that the organic matter of the soil has been 

 more nearly maintained under rotation and also to the fact that 

 certain insect pests and plant diseases have been better con- 

 trolled by rotation. 



Similar data have been obtained at the Missouri Experi- 

 ment Station, as will be seen from the following table: 



♦Illinois Agricultural Experiment Station, Bulletin 125, 1908. 



