The introduction of Rhizobium japonicum to soil by seed inoculation of non-host legumes and cereals

Abstract

The field introduction of soybean rhizobia into a black earth soil by inoculating winter crops of wheat, oats, peas, and lupins was partly successful. There was an erratic establishment of R. japonicum in the rhizosphere of field grown plants. In glasshouse tests, R. japonicum multiplied in jars planted to oats, barley, wheat, peas, lupins, and soybeans, but not in unplanted jars. The degree of stimulation of nodule bacteria varied between species and was greatest with the host legume, soybean. The comparative number of rhizobia in the rhizosphere and in the root-free soil (R : S ratio) also varied but was not necessarily highest with soybean nor with legumes as a whole. It is concluded that this inoculation technique might overcome problems associated with damage to seed inocula by fungicide treatments or high soil temperatures.