Since the 2015/2016 season, Embrapa Soja (Paraná) and the Paraná Rural Development Institute (IDR-Paraná) have monitored and validated the adoption of good biological nitrogen fixation (BNF) practices among farmers in the state. Their field tracking shows an average 8.33% productivity gain from seed co-inoculation. Co-inoculation is the combined application of two or more beneficial microorganisms, strengthening BNF while improving profitability and supporting economic and environmental sustainability.
Results from the past decade are compiled in the publication Co-inoculation of soybeans with Bradyrhizobium and Azospirillum in the 2024/2025 crop in Paraná, which presents outcomes from Paraná fields through Technological Reference Units (URTs). The authors are André Mateus Prando, Arnold Barbosa de Oliveira, Divania de Lima, Edison Ulisses Ramos Júnior, Edivan José Possamai, Eliana Aparecida Reis, Marco Antonio Nogueira, and Mariangela Hungria, according to a press release.
“In these 10 years, the URTs, which are conducted directly in commercial crops on rural properties, have allowed to evaluate and validate the effectiveness of the technology in practice. The results obtained year after year confirmed that the proper use of inoculation/co-oculation increased soybean productivity and exempted farmers from costs with nitrogen fertilization in the crop, ensuring increased profitability and environmental benefits for the whole society,” say researcher André Prando, from Embrapa Soja, and Edivan Possamai, technical coordinator of the IDR-Paraná Grains project.
IDR-Paraná’s statewide network of Technological Reference Units (URTs), developed with Embrapa’s support, enabled the inclusion of Bradyrhizobium inoculation in the technology validation protocol starting in the 2015/2016 season. Co-inoculation began to be validated in the 2017/2018 harvest, as research advanced and evidence showed that Azospirillum— a plant growth-promoting bacterium — works alongside Bradyrhizobium to increase soybean productivity, according to a press release.
According to Possamai, data for the 2024/2025 season were collected from 22 URTs established in commercial fields across 17 municipalities in different regions of Paraná.
“These URTs, due to their geographical diversity, are important references for inoculation and co-oculation technology. They offer an overview of what happened in the harvest, since the places have different types of soil, climate, cultivation systems, succession to various crops (second crop corn, wheat, oats, stee, etc.), sowing seasons (early, normal or late) and levels of technologies used by producers,” analyzes Possamai.
According to a survey by IDR-Paraná and Embrapa Soja, average grain yield reached 3,916 kg/ha in co-inoculated areas, compared with 3,615 kg/ha in areas without inoculation. In the 2024/2025 season, the average yield recorded in URTs using co-inoculation also exceeded both the Paraná state average (3,663 kg/ha) and the national average (3,561 kg/ha), according to the National Supply Company (Conab).
At the state level, 64% of Brazilian Paraná soybean growers surveyed reported using inoculants in the 2024/2025 crop. Co-inoculation with Bradyrhizobium and Azospirillum averaged 28% adoption in the same season, according to ANPII Bio, based on market research conducted by Kynetec in Paraná.
Benefits of the Technology
Research by Embrapa Soja scientists Mariangela Hungria and Marco Antonio Nogueira indicates that annual soybean inoculation with Bradyrhizobium — even in long-established production areas that have previously used inoculants — helps sustain high yield potential without the need for nitrogen fertilizer.
Building on that practice, Embrapa began recommending co-inoculation starting in the 2013/2014 season, combining Bradyrhizobium with a second bacterium, Azospirillum brasilense, using two strains (Ab-V5 and Ab-V6).
“Soybean plants coinoculated with Bradyrhizobium and Azospirillum have more abundant and early nodulation, increasing the gains provided by annual inoculation only with Bradyrhizobium,” says Hungary.
