30 BULLETINS OF THE BUREAU OF PLANT INDUSTRY. 



* No. 71. Soil Inoculation for Legumes; with Reports upon the Suc- 



cessful Use of Artificial Cultures by Practical Farmers. 

 By George T. Moore, Physiologist in Charge of Labora- 

 tory of Plant Physiology. 1905. 72 pp., 10 pis. Price, 

 15 cents. 



Contents : Introdnction — The fixation of free nitrogen — Beneficial effect of 

 leguminous crops— Direct effect of nodules tijdou legumes — Effect of nodule- 

 bearing legtunes upon succeeding crops — Artificial inoculation of the soil — 

 Soil transfer — Nitragin — Nature of the organism — Cross-inoculation and spe- 

 cific characters — Methods of cultivation — Effect of varying conditions : Light, 

 heat, and air; acids and alkalis; nitrates; moisture — ^Yhere is nitrogen 

 fixed? — Nodules not always beneficial — Symbiosis or parasitism? — Infection 

 and fixation of nitrog'en without nodules — Inoculation by pure culture — 

 Methods of using liquid cidture — Time of inocidation — When inoculation is 

 unnecessary — When inoculation is necessary — When to expect failure with 

 inoculation — Eesults — Reports: Alfalfa; red clover; cowpeas ; garden peas; 

 beans ; soy beans ; hairy vetch ; crimson clover ; sweet peas ; field peas ; 

 velvet .beans ; berseem ; peanuts ; miscellaneous — Summary. 



* No. 72. Miscellaneous Papers. I. Cultivation of AVlieat in Per- 



manent Alfalfa Fields. By David Fairchild, Agricul- 

 tural Explorer. II. The Salt Water Limits of Wild 

 Rice. By Carl S. Scofield, Botanist, Grain Grade In- 

 vestigations. * III. Extermination of Johnson Grass. 

 By AV. J. Spillman, Agrostologist. * IV. Inoculation of 

 Soil with Nitrogen-Fixing Bacteria. By A. F. Woods, 

 Acting Chief of Bureau. 1905. 30 pp., 3 pis., 4 figs. 

 Price, 5 cents. 



Contents : Cultivation of wheat in permanent alfalfa fields. The salt- 

 water limits of wild rice : Introduction — The method of testing salinity — The 

 regions investigated — Conclusions. Extermination of Johnson grass : Intro- 

 duction — Character of the soil — Methods of treatment — Implements used — The 

 production of hay. Inoculation of soil with nitrogen-fixing bacteria : Intro- 

 duction — The commercial jn-oduction of cultures — When inoculation is neces- 

 sary — When inoculation may prove advantageous — When inoculation is un- 

 necessary — When failure is to be expected — Cost of cultures — Increasing 

 cultures — Preparing and using the culture solution — Keeping cultiires for 

 future use- — Danger of inoculation by soil transfer — Pure-culture inoculation. 



* No. 73. The Development of Single-Germ Beet Seed. By C. O. 



Townsend, Pathologist, and E. C. Rittue, Assistant. 1905. 



26 pp., 8 pis., 6 figs. Price, 10 cents. 



Contents : Introduction — Single and multiple germ beet seed — The beet 

 flower — The first seed selection — Germination and vitality — Greenhoiise exper- 

 iments — Seed beets in 1903 — Beet seed in 1903 — Change of location of experi-' 

 ments — Progress of the work in 1904 : Planting and growth of the seed beets; 

 arrangement of single flowers; methods of pollination; gathering the seed; 

 percentage of single-germ seeds — Conclusion — Description of x^lafes. 



No. 74. The Prickly Pear and Other Cacti as Food for Stock. By 



David Griffiths, Assistant Agrostologist in Charge of 



Range Investigations. 1905. -18 pp., 5 pis., 1 fig. Price, 



5 cents. 



Contents : Introduction^ — History — Geographical distribution of economic 

 cacti in the United States — Methods of feeding : Singeing the spines ; singe- 

 ing with a torch ; steaming ; chopping by machinei-y ; other chopping devices ; 



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