CONTENTS 



PAGE 



No. 1. The Distribution and Activities of Bacteria in Soils of the 



Arid Eegion, by Charles B. Lipman 1 



No. 2. Studies on the Phenoldisulphonic Acid Method for Determin- 

 ing Nitrates in Soils, by C. B. Lipman and L. T. Sharp 21 



No. 3. The Effects of Calcium and Magnesium Carbonates on Some 

 Biological Transformation of Nitrogen in Soils, by W. P. 

 Kelley 39 



No. 4. The Aluminum Eeduction Method as Applied to the Deter- 

 mination of Nitrates in ' ' Alkali ' ' Soils, by Paul S. Burgess 51 



No. 5. Studies Upon Influences Affecting the Protein Content of 



Wheat, by G. W. Shaw 63 



No. 6. The Effect of Copper, Zinc, Iron, and Lead Salts on Ammoni- 

 fication and Nitrification in Soils, by C. B. Lipman and 

 P. S. Burgess 127 



No. 7. Studies on Ammonification in Soils by Pure Cultures, by 



C. B. Lipman and P. S. Burgess 141 



No. 8. Humuj and Humus-Nitrogen in California Soil Columns, by 



E. H. Loughridge 173 



No. 9. New Experiments on Alkali Soil Treatment (Preliminary 



Eeport), by Charles B. Lipman and Leslie T. Sharp 275 



No. 10. ii'undamental Interrelationships between Certain Soluble Salts 



and Soil Colloids, by L. T. Sharp 291 



No. 11. Influence of the Composition and Concentration of the Nutri- 

 ent Solution on Plants Grown in Sand Cultures, by Arthur 

 Hugo Ayres 341 



No. 12. Certain Effects under Irrigation of Copper Compounds upon 



Crops, by E. H. Forbes 395 



No. 13. Experiments on the Effects of Constituents of Solid Smelter 

 Wastes on Barley Growth in Pot Cultures, by C. B. Lipman 

 and W. F. Gericke 495 



Index 589 



Errata : 595 



