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CONTENTS. 



Introduction 



Yield op Nitrogen in different Crops 

 Yield of nitrogen in wheat and barley 

 Yield of nitrogen in root-crops 

 Yield of nitrogen in leguminous crops 

 Yield of nitrogen by a rotation of crops 

 Yield of nitrogen in the mixed herbage of grass land 

 Yield of nitrogen in MeUlotus leucantha 



Summary op yield of Nitrogen in Crops.. 



Sources op the Nitrogen in Crops . . 



Combiiied nitrogen in rain, etc. 



Other supposed sources of combined nitrogen 



Do plants assimilate free nitrogen ? . . 

 Recapitulation 



page 

 5 



7 

 9 

 9 

 11 

 13 

 14 

 16 

 17 



17 

 18 

 21 

 22 

 29 



The Nitrogen op the Soil as a source op the Nitrogen of Crops £0 



Nitrogen in the soils of the experimental wheat plots . . . . . . 32 



Nitrogen in the soils of the experimental barley plots . . . . , . 39 



Nitrogen in the soils of the experimental root-crop plots . . . . . . 40 



Is THE Soil a source op the Nitrogen op the Lbguminos^ ? . . 41 



Nitrogen in the soils of the experimental clover plots . . . . . 42 



The soils of the MeUlotus leucantha and white clover plots . . . . 45 



Nitrogen as nitric acid in the Melilotus and white clover soils . . . . 40 



Nitrogen as nitric acid in other soilu and subsoils . . . . . . . . 48 



Nitrogen in some of the soils of the experimental mixed herbago ])lo(8 . . 51 



Source of the nitrogen of clover grown on rich garden soil . . 55 



Q-ENERAL Conclusions .. ., .. .. .. - . 57 



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