CONTENTS 



Introduction " 7 



Description of the soil in which the experiments were conducted 8 



Field history of the plats 9 



Methods of making determinations 9 



Discussion of results of determinations 12 



Nitrates in the fallow plat 12 



Nitrates in the spring-wheat plat 14 



Comparison of nitrates in fallow, spring- wheat, and corn plats 16 



Withdrawal of nitrates by corn roots 17 



Relation of nitrification to field factors 18 



The disappearance of nitrates 21 



Denitrification 22 



Seasonal variations in nitrification 23 



Change of water-soluble nitrates to albuminoid nitrogen 25 



Relation of nitrification to summer fallow 26 



Summary -* 27 



Index 29 



173 



5 



