Partial substitution of mineral nitrogen fertilizers (MNF) through inoculation of soybean seeds with Bradyrhizobium japonicum as a biofertilizer in presence of low dose of mineral nitrogen fertilizer (MNF) (48 kg N ha-1) and complete substitution by using biofertilizer inoculation individually or combined with two different rates of farmyard manure (24 and 48 m3 ha-1) as a N organic source were compared with the recommended dose of MNF (167 kg N ha-1), on soybean growth and yield components have been studied, under field experiment conditions, for two successive summer growing seasons of 2009 and 2010. Obtained results revealed that inoculation of soybean seeds with Bradyrhizobium japonicum, in general, increased nodule numbers, nodules dry weight and nitrogenase enzyme activity as well as microbial population, compared to application of recommended dose of MNF. These increases led to associated increases in N, P and K contents of straw and seed and therefore enhanced yield and yield components of soybean plant. Biofertilizer inoculation + low N dose of MNF, gave the highest values of both nitrogen use efficiency (NUE) i.e. 28.07% and nitrogen uptake efficiency (NPE) i.e. 22.54%. On the other hand, combined treatments of biofertilizer inoculation+48 m3 FYM ha-1, which represents one of the choice of complete MNF substitution, recorded significant values and best results in both seasons for all the above mentioned parameters associated with soil and plant among the concerned treatments, exception being obtained with NUE and NPE parameters. |
