CONTENTS xiii 



PAGES 



CHAPTER XIII 



Denitri-fication 



Why this Loss? 132 



Loss of Nitrates from Manure and Soil 133 



Factors Influencing Denitrification 135 



Function of Denitrifiers 136 



CHAPTER XIV 



Non-Symbiotic ]Sfitroge?i Fixation 



Development of Our Knowledge 139 



Where do Nitrogen Fixers Occur? 142 



Conditions for Growth 143 



What do They Feed Upon? 144 



From Whence Their Energy? 144 



Crop 146 



How is the Nitrogen Fixed? 147 



Properties of Azotobacter 148 



Soil Inoculation 148 



Soil Gains in Nitrogen 15X 



CHAPTER XV 



Symbiotic Nitrogen Fixation 



Belief of the Seventeenth Century 156 



Later Work , 156 



The Nodules 159 



Conditions Favoring Growth , 160 



Moisture 161 



Influence of Fertilizers 162 



Legumes Associated with Non-legumes 162 



Soil Gains in Nitrogen 163 



Shall We Inoculate? 165 



How Inoculate? 167 



"Method Involving the Use of One Commercial Culture" 168 



"Alternative Method" 169 



Hope of the Future 169 



CHAPTER XVI 



Legumes and Soil Fertility 



Essential Elements 171 



Plant Food Added by Legumes 172 



