
%0 Journal Article
%A Herridge, DF 
%A Roughley, RJ 
%A Brockwell, J 
%T Low survival of <I>Rhizobium japonicum</I> inoculant leads to reduced nodulation, nitrogen fixation and yield of soybean in the current crop but not in the subsequent crop
%J Australian Journal of Agricultural Research
%D 1987/02/01
%V 38
%N 1
%P 75-82
%K 
%R https://doi.org/10.1071/AR9870075
%U https://www.publish.csiro.au/paper/AR9870075 
%X Reports of nodulation failures in first-year crops of soybean, resulting in nitrogen deficiency and low yield, have been common in Australia. In experiments simulating commercial practice, successive crops (1982-83, 1983-84) of soybean were sown into soil containing either a very small population of Rhizobium japonicum (rhizobia-low; 2 g-1 soil, 3-9 cm), or a large population (rhizobia-high; 270 000 g-1). The soil was a vertisol at Breeza, N.S.W. Each crop was inoculated with R. japonicum at a normal rate (n = 25 x 1010 organisms per 100 kg of seed) or at 100 x normal (100n) or was not inoculated (o). The 1982-83 crop was sown in hot (maximum air temperature 3g¦C), dry weather, and < 1% of the inoculant survived the first day. This did not affect nodulation in rhizobia-high plots and production of foliage and seed nitrogen was satisfactory, irrespective of rate of inoculation. In contrast, nodulation was inadequate in all rhizobia-low soil (although 100n > n > o) and the N content of foliage and seed was correspondingly reduced. In spite of poor nodulation in these rhizobia-low treatments, a substantial population of R. japonicum (18 000 g-1soil) developed between seasons. When the plots were re-sown in 1983-84, nodulation, growth and yield of the crops, irrespective of the initial rhizobial status of the soil, were equally good, and there was no response to further inoculation. Poor nodulation of first-year crops of soybean is a likely consequence of failure to establish adequate numbers of R. japonicum in the soil at sowing. 
