CONTENTS 



Page. 



Introduction 7 



Methods employed in bacteriological investigations of iho soil at Fallon, Nev.. 8 



Requirements to be met • 8 



Counts of bacteria 9 



Ammonification 9 



Nitrification 10 



Denitrification 11 



Nitrogen fixat ion 11 



Nitrifying power of soils at different depths 12 



Nitrification of samples in solution 19 



Chlorids and sulphates 21 



Denitrification 22 



Relative numbers of bacteria in different soils 24 



Detailed study of soil typical of extensive areas 25 



Conclusions 32 



Index 35 



ILLUSTRATIONS. 



Page. 

 Fm. 1. Location of sampling plats in the experimental fields of the Truckee- 



Carson Experiment Farm, south of Fallon, Nev 8 



2. Diagram showing the nitrification of ammonium sulphate in samples of 



soil from different depths from plats 100 and 110, Truckee-Carson 

 Experiment Farm 12 



3. Diagram showing the nitrification of ammonium sulphate in samples of 



soil from different dejjths from plat 120, Truckee-Carson Experiment 

 Farm 13 



4. Diagram showing the nitrification of ammonium sulphate in samples of 



soil from different depths from plat 130, Truckee-Carson Experiment 

 Farm 13 



5. Diagram showing the nitrification of ammonium sulphate in samples of 



soil from different depths, from plats 160 and 170, Truckee-Carson 

 Experiment Farm 14 



6. Diagram showing the nitrification of ammonium sulphate in samples of 



soil from different depths from plat 180 (poor soil) and plat 190 (good 



soil ), Truckee-Carson Experiment Farm 15 



7. Diagram showing the nitrification of ammonium sulphate in samples of 



soil from different depths from plat 200, Truckee-Carson Experiment 

 Farm 16 



8. Diagram showing the nitrification of ammonium sulphate in samples of 



soil from different depths from plat 210, Truckee-Carson Experiment 



Farm 16 



211 5 



