CONTENTS. 



Page. 



Introduction 7 



Questions asked 7 



Answers obtained 8 



The sufficiency of the data submitted 12 



Continuous cropping compared with alternate cropping and summer tillage 14 



General statement 14 



Conclusions concerning summer tillage and continuous cropping 18 



Crop rotation compared with continuous cropping 20 



Outline of the three-year rotations 20 



Explanatory notes 23 



A common basis of comparison 24 



Comparison of the relative farm value of crops of wheat, oats, and barley pro- 

 duced by each of the nine rotations and by continuous cropping 41 



The tabular summary 41 



Disked corn stubble better than summer tillage for spring wheat and oats. . 45 

 Disking corn stubble gives better results than plowing for spring wheat 



which is to follow 49 



The relative merits of fall and spring plowing depend upon local conditions 



of soil and climate 50 



The relation of wheat and oats to summer tillage in a three-year rotation. . 51 

 Wheat, oats, corn a better sequence on spring plowing than oats, wheat, 



corn at most stations 52 



Rotations for the conservation of organic matter in the soil 55 



Five-year rotation (No. 1) 57 



Six-year rotation (No. 2) 61 



Four-year rotation (No. 3) 62 



Four-year rotation (No. 4) 63 



Four-year rotation (No. 5) 64 



The principles of crop rotation 65 



Factors involved 65 



Rules to be observed in planning rotations 67 



Conclusions from experiments 67 



Precipitation records 72 



Index 75 



187 5 



