This study was carried out in 1996/97, 1997/98 and 2000/01 crop seasons in Cruz Alta, state of Rio Grande do Sul, Brazil, aiming at evaluating the efficiency of commercial inoculant formulations, isolated and in combination with Mo and Co foliar fertilizer in an area that has been under no tillage for eight to twelve year and where Bradyrhizobium had already been established. In the 1996/97 crop year, the treatments were: non-inoculated control; 200 kg ha-1 of nitrogen fertilizer, split twice and without inoculation; inoculant Nitragin Cell-Tech/50 and 80 kg seeds, with and without fungicide and, with and without foliar fertilizer Basfoliar Co Mol; inoculant Emerge Pó; inoculant Emerge PM and, Basfoliar Co Mol. In the 1997/98 crop year, the treatments were: non-inoculated control; the inoculants Emerge Pó; Emerge PM; Nitragin Cell-Tech and Rizo-liq; Nitragin Cell-Tech + Basfoliar Co Mol and Basfoliar Co Mol. In the 2000/01 crop year, the treatments were: non-inoculated control; 200 kg ha-1 nitrogen fertilizer, split twice and without inoculation; inoculant standard; Emerge PM; Rizo-liq Plus; Rizo-liq Plus + foliar fertilizer Rizomicro; Rizomicro; Gelfix; Gelfix + foliar fertilizer CoMofix; Rhizofix; Rhizofix + CoMofix; CoMofix and inoculant Bionutri. The root dry matter, N grain content and grain yield did not differ among treatments in the three cropping seasons. Only in the 1997/98 crop season there were differences in plant height between treatments, with better results with Nitragin Cell Tech + Co Mol. The application of 200 kg ha-1 of nitrogen fertilizer decreased the nodule weight. The lack of response of soybean to inoculation can be attributed to the established population of Bradyrhizobium, which were in appropriate number and efficiency.
Glycine max; inoculation; nodulation; cultivation system; Mo; Co
