A complex relationship exists between the soybean plant and symbiotic Rhizobium. The multiplication of the Rhizobium is dependent on the nitrogen fertility of the soil. On the other hand, the soybean plant can apparently use either nitrogen from the soil or that fixed by bacteria. However, a temporary shortage of nitrogen causing chlorosis did not affect yields in this study. When nitrogen became available later in the season the soybean plant was able to attain the same yield potential.

This research was partially supported by a grant from the Oil Seed Crops Research Trust, Fresno, California, and co-operative agreement between the University of California and the U. S. Department of Agriculture.