| | ---- | | --- | | Total | 2490 | | 59 | -----------------+-----------+--------+--------+--------+--------- C1—Ten plants, | Tops | 3300 | 4.33 | 143 | with bacteria | Roots | 520 | 1.53 | 8 | present. | Tubercles | 290 | 5.76 | 17 | | | ---- | | --- | | Total | 4110 | | 168 | 124 | +--------+--------+--------+ C2—Ten plants, | Tops | 1730 | 2.32 | 40 | without bacteria | Roots | 400 | .88 | 4 | | | ---- | | --- | | Total | 2130 | | 44 | -----------------+-----------+--------+--------+--------+--------- THE SOY BEAN BACTERIA. Soy bean bacteria are evidently much less likely to be carried with the seed than are the cowpea bacteria. The soy bean plant grows more erectly than the cowpea (see Circular No. 69, “The Cowpea and Soy Bean in Illinois”), and the crop is quite commonly harvested with a self-binder which keeps it quite free from dirt. The soy bean seed is nearly round and smooth, and the seed coat is not commonly cracked. These facts may explain why the soy bean seed carry so few bacteria as compared with cowpeas. On one of the soil experiment fields on the university farm at Urbana, where soy beams have been grown for three years, no tubercles could be found on the plants either the first or second year, and only an occasional plant with tubercles could be found the third year. In 1902 a series of plots, some of which had been treated in different ways with applications of limestone, phosphorus, and potassium, were seeded with soy beans. No tubercles could be found at any time during the season on the soy beans growing on any of the different plots. In 1903 the same plots were again seeded to soy beans, and at the same time part of each plot was inoculated with infected soy bean soil drilled in with the seed at the rate of about 500 pounds of infected soil to the acre. When the plants were only a few weeks old tubercles were to be found upon many plants growing where the infected soil had been applied, and before the close of the season at least half of these plants in the inoculated part of the field had one or more tubercles upon their roots, and some plants could be found whose roots were abundantly provided with tubercles. (See Plate 4.)