UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 355 



Contribution from the States Relations Service 

 A. C. TRUE, Director 



Washington, D. C. 



PROFESSIONAL PAPER 



AprU 13, 1916 



EXTENSION COURSE IN SOILS 



FOR SELF-INSTRUCTED CLASSES IN MOVABLE 

 SCHOOLS OF AGRICULTURE 



By 



A. R. WHITSON, Professor of Soils, University of Wisconsin, 



and H. B. HENDRICK, Assistant in Agricultural 



Education, States Relations Service 





CONTENTS 





Page 



Page 



Lesson I. 



Origin, Formation, and Com- 



Lesson VII. The Phosphorus and Potas- 





position of Soils 2 



sium of Soils 47 



II. 



The Soil and Plant Growth . 10 



VIII. Manures and Fertilizers . . 54 



m. 



Physical Properties of the Soil 17 



IX. Soil Acidity and Liming . . 62 



IV. 



The Water Supply of the Soil . 24 



X. Management of Special Soils 68 



V. 



Soil Temperature and Drainage 31 



XI. Soil Adaptation to Crops . . 80 



VI. 



The Nitrogen Supply of the 



i XII. Crop Rotations and Soil 





Soil 41 



Fertility 84 



WASHINGTON 



GOVERNMENT PRINTING OFFICE 



1916 



