UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1377 
Washington, D. C. T March, 1926 
A STUDY OF THE VALUE OF CROP ROTATION IN 
RELATION TO SOIL PRODUCTIVITY 
Bj 
WILBERT W. WEIR, Associate SoU Technologist 
Bureau of Soils 
CONTENTS 
Page 
Introduction 1 
Primary Objects of Study 3 
Method of Study 3 
Effects of Crop Rotation and of the Use of Fertilizers on Crop Yields 10 
Rotation and Fertilizer Efficiencies as Affected by Soil Reaction 44 
Summary of Relative Values of Crop Rotation and of Conjoint Effects of Rotation and 
the Use of- Fertilizers 54 
Value of Crop Rotation and of the Use of Fertilizers in Maintaining and Increasing Soil 
Productivity 57 
General Discussion 60 
General Summary and Conclusions €5 
Literature Cited 68 
WASHINGTON 
GOVERNMENT PRINTING OFFICE 
1926 
