Nodulation, growth and yield of soybean [Glycine max (L.) merrill] as influenced by biofertilizer and inorganic fertilizers in assosa zone, Western Ethiopia

The productivity of soybean in Assosa Zone particularly in Assosa and Bambassi districts is very low due to poor soil fertility management practices which resulted in severe soil acidity and low N-fixing inoculant in the soil. Hence, this experiment was conducted to evaluate the influence of biofertilizer and inorganic fertilizers on nodulation, growth and yield of soybean [Glycine max (L.) Merrill].

During the period 2019–2020 factorial combinations of four levels of biofertilizer inoculants [without inoculant (B1), SB12 inoculant (B2), MAR1495 inoculant (B3) and SB12 plus MAR1495 inoculants (B4); and four inorganic fertilizer types NP (F1), NPS (F2), NPB (F3) and NPSB (F4) at their recommended rates for soybean] were laid out in a randomized complete block design (RCBD) with three replications in Assosa and Bambassi districts, Assosa Zone, Western Ethiopia. Number of effective nodules per plant, leaf area index and grain yield were collected following the standard procedures and were analyzed using SAS software version 9.1.3 and significant mean differences were separated using Duncan's multiple range test (DMRT) at 5% significance level.

Number of effective nodules per plant, leaf area index and grain yield were highly significantly (P<0.01) affected by the interactions of biofertilizer and inorganic fertilizers at both locations and years. Thus, the maximum grain yield (2621.67 kg) was obtained from (SB12+MAR1495) + NPSB at Assosa and the maximum grain yield (2460.20 kg) was obtained from SB12+NPS at Bambassi. Hence, (SB12+MAR1495) + NPSB and SB12+NPS are recommended for higher soybean grain yield for Assosa and Bambassi districts and similar agro-ecologies, respectively.