HOW CROPS FEED. 



A TREATISE ON THE 



ATMOSPHERE AND THE SOU 



AS RELATED TO THE 



Nutrition of Agricultural Plant? 



WITH ILLUSTRATIONS. 



SAMUEL W! JOHNSON, M.A., 



PKOFESSOB OP ANALYTICAL AND AGRICULTURAL CHKMISTRY IN THK SHBPFIELD 

 80IKNTIFI0 SCHOOL OF YALB COLLEGE ; CHEMIST TO THE CONNEC- 

 TICUT STATE AGKICULTITRAL SOCIETY; MEMBER OF THE 

 NATIONAL ACADEMY OF SCIENCES. 



NEW YORK: 



OKANGE JUDD COMPANY, 



1910 



