This book is based on applied research whose main objectives were: 1- To study the effect of co-inoculation of Rhizobium and PGPRs on growth and yield of soybean and 2- To investigate the effect of co-inoculation of Rhizobium and PGPRs on nodulation and N2-fixation of soybean by employing xylem ureide technique. In the research experiment we conclude that different parameters such as plant density, nodule number, yield, N content, and N2-fixed were investigated to confirm whether the PGPRs improved N2- fixation capacity of soybean along with chemical fertilizer as compare to application of chemical fertilizer alone and control.