UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 699 



Contribution from the Bureau of Soils 

 MILTON WHITNEY, Chief 



Washington, D. C. 



October 16, 1918 



ANALYSIS OF EXPERIMENTAL WORK 



WITH GROUND RAW ROCK PHOSPHATE 



AS A FERTILIZER 



By 



W. H. WAGGAMAN and C. R. WAGNER, Scientists In 

 Investigation of Fertilizer Resources, assisted by R.' F. ^ 



GARDDfER, Scientist in Soil Laboratory Investigations 



CONTENTS 



Introduction coo. o. go 

 History .oco.c.oo. 

 Theoretical considerations > . . 

 Methods of Studying the Subject 

 • Laboratory work . = ' o = . 



Pot and Greenhouse Work . 



Field EzperimentB o o o o 



Results of Experiments o* c . c 

 / Experience of Farmers with Raw 



Phosphate as a FertUizer o . o 

 Summary .cc<ooo<o 

 Conclusions c.o.c.ao 



Rock 



Page 

 o 28 



112 



lis 



120 



WASHINGTON 



GOVERNMENT PRINTING OFUCB 



1918 



