An investigation of problems associated with the inoculation of soybeans (Glycine max (L.) Merrill) with Rhizobium japonicum (Kirchner) Buchanan

If soybeans are to have a place in New Zealand farming, system, they must be grown economically, in terms of yield produced and costs of production. Inoculation with rhizobia will no doubt help to achieve this aim if the potential beneficial effects on nodulation can be exploited to the fullest extent, thereby lessening dependence on the use of artificial nitrogen fertilizers. In this investigation into the problems associated with inoculation of soybeans with Rhizobium japonicum, various strains of R. japonicum were characterised to recognise their cultural, morphological, physiological and bio-chemical properties. Their abilities to form nodules on soybeans and fix nitrogen were subsequently studied. The best strains were selected for field trials with varieties of soybeans to find out the best combination. Detection of R. japonicum indigenous in some New Zealand soils was attempted to verify the need to inoculate soybean seeds planted in the field in order to achieve nodulation. So far in New Zealand, no attempts have been made to explain the failure of inoculation of soybeans with R. japonicum in the field. It was therefore felt appropriate to venture into this aspect of study. It is hoped that the present study will stimulate further attempts in the future to explain the failure of inoculation of soybeans with a more systematic and fundamental approach in New Zealand.