INDEX 



Page. 



Aeration, soil of experimental plats 23 



Agropyron occidentale, occurrence in sod of experimental plats 9 



Alkali salts. See Salts, alkali. 



Ammonia in dry soil treated in various ways 11, 22-23 



nitrites, and nitrates in soil, extraction, results of various methods 11 



Ammonification, relation to variation of nitrates 22^23 



Bacteria, behavior in soil 28 



nitrifying, growing season 23-24 



Bazarewski, L. von, nitrification in soil, remarks 13, 24 



Bellefourche, S. Dak., inauguration of experiments in dry-land agriculture 8 



Bouteloua oligostachya, occurrence in sod of experimental plats 9 



Buffalo grass, occurrence in sod of experimental plats 9 



Bulbilis dactyloides, occurrence in sod of experimental plats 9 



Carex filifolia, occurrence in sod of experimental plats 9 



stenophylla, occurrence in sod of experimental plats 9 



Color, foreign organic, in soil, cause of error in determination of nitrates 10 



Corn, nitrates present in plat, comparison with spring-wheat and fallow plats 16-17 



roots, withdrawal of nitrates 17-18 



Crops, nitrogen content, increase with increased nitrifying activity in soil 18 



Denitrifieation, relation to variation of nitrates, etc 22- 23 



Dry-land experiments. See Experiments, dry-land. 



Experiments, dry-land, field history of plats 9 



methods of making chemical determinations 9-11 



nitrates in fallow plat 12-14 



results of chemical determinations 12-27 



Fallow plat, comparative variation of moisture, precipitation, and nitrates. . . . 19-20 



nitrates present, comparison with spring-wheat and corn plats... 16-17 



removal, comparison with wheat plat 15 



variation *. 12-14 



summer, objections 26-27 



relation of nitrification 26-27 



Fixation, nitrogen, statement of F. Schneider 24 



Food, organic, for nitrifying organisms, effect on nitrogen content of soil 24 



Gipma grass, occurrence in sod of experimental plats. . .' 9 



Grass, buffalo, occurrence in sod of experimental plats 9 



grama, occurrence in sod of experimental plats 9 



Grasses, varieties in sod of experimental plats 9 



"Gumbo" land. See Land, "gumbo." 



Hunt, T. F., statement on depth of nitrification in soil 13 



Introduction to bulletin 7-8 



Land, "gumbo," experiments in handling for crops 8-28 



McLeod, A. F., Whitson, A. R., and Stoddart, W. C, statement concerning 



nitrogen content of soil 25-26 



173 



29 



