HIGHLIGHTS:

Common bean can be grown efficiently in an organic system with diazotrophic bacteria as nitro-gen (N) source.

Application of poultry manure is not only expensive, but the nutrient content is also inadequate.

Seed inoculation, co-inoculation and additional inoculation provided higher yields and profitabil-ity in common bean crop.

ABSTRACT

The symbiosis of common beans with nitrogen-fixing bacteria provides an efficient approach to sustainable and economical food production. Therefore, this study aimed to evaluate the application of cost-effective nitrogen management strategies in organic common bean cultivation, including the application of poultry manure and organic liquid fertilizer, seed and co-inoculation with diazotrophic bacteria (Azospirillum brasilense and/or Rhizobium tropici), and supplementary Rhizobium tropici inoculation. The study spanned three years in a well-established organic cultivation field (2018) and an initial organic cultivation area (2019 and 2020) in Brazil. It was arranged in a randomized blocks design in a 2 × 5 (2018) and 2 × 6 (2019 and 2020) factorial scheme, with four replicates. The most profitable strategy involves seed inoculation with Azospirillum brasilense and additional inoculation with Rhizobium tropici at stage V_4-5 (fifth trifoliate leaf fully expanded), while the most costly strategy was the application of poultry manure at the V₃ stage (first trifoliate leaf fully expanded). Thus, the use of diazotrophic bacteria for seed inoculation and co-inoculation (Azospirillum brasilense and/or Rhizobium tropici) ensured financial returns and system profitability in common bean cultivation.

Key words:
Phaseolus vulgaris L.; Azospirillum brasilense; Rhizobium tropici; economic performance