Produced by Bryan Ness, Jana Srna and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/American Libraries.) UNIVERSITY OF ILLINOIS Agricultural Experiment Station. BULLETIN NO. 94. NITROGEN BACTERIA AND LEGUMES (WITH SPECIAL REFERENCE TO RED CLOVER, COWPEAS, SOY BEANS, ALFALFA, AND SWEET CLOVER, ON ILLINOIS SOILS). BY CYRIL G. HOPKINS. Work and Knowledge are a stronger team than Work and Work. [Illustration] URBANA, ILLINOIS, FEBRUARY, 1904. SUMMARY OF BULLETIN NO. 94. 1. Soil nitrogen cannot be used by plants until it is changed to the form of nitrate nitrogen by the nitrifying bacteria. Page 307 2. Atmospheric nitrogen cannot be used by any agricultural plants, excepting legumes, and even leguminous plants have no power to obtain nitrogen from the air unless they are provided with the proper nitrogen-gathering bacteria. Page 309 3. As a rule each important agricultural legume must have its own particular species of bacteria. Page 311 4. The frequent failure of red clover in normal seasons, especially on normal soils occupying the highest land, is undoubtedly due in part at least to the absence of the proper bacteria (sometimes the soil lacks lime or phosphorus). Page 313 5. On the very acid soils, where clover has never been grown successfully, applications of ground limestone should be made where legumes are to be grown. Page 315 6. Cowpeas need not be inoculated, because the cowpea bacteria are usually either present in the soil or are introduced with the seed in sufficient numbers to effect a good degree of infection if the soil is suitable and if cowpeas are seeded upon the same land for two successive years. Page 317 7. Cowpeas grown on infected soil on the University of Illinois soil experiment field contained four times as much nitrogen as the same kind of cowpeas grown on similar land which was not infected. Page 319 8. As a rule soy bean fields should be inoculated when first seeded to soy beans, otherwise they may be grown on the same land for three or four years before the soil becomes thoroughly infected. Page 320