Agronomic efficiency of inoculation with Bacillus consortium - B. subtilis CCTB04 + B. amyloliquefaciens CCTB09 + B. pumilus CCTB05 - in corn and soybean crops under different soil and climate conditions in Brazil
ABSTRACT Sustainable corn (Zea mays L.) and soybean (Glycine max L.) production in tropical soils is challenged by high phosphate fertilizer dependence and low phosphorus (P) use efficiency. This study assessed the agronomic efficiency of BTP 010-19 (B. subtilis + B. amyloliquefaciens + B. pumilus) in compensating for a 25% reduction in recommended phosphate fertilization under diverse field conditions. Multi-location field trials were conducted across four Brazilian edaphoclimatic regions using a randomized complete block design. Treatments included inoculation factors (non-inoculated control, BTP 010-19 via seed treatment and in-furrow, and a positive control with Pseudomonas fluorescens and Azospirillum brasilense) and P doses (75% and 100% of recommended). The results demonstrated that BTP 010-19 application, particularly in-furrow, significantly enhanced grain yield in both crops. In corn, BTP 010-19-FURROW achieved the highest mean yield (8,264.25 kg ha-¹), representing a 7.1% increase over the non-inoculated control. Crucially, at 75% of the recommended P rate, this inoculation strategy boosted corn yield by 9.2% and soybean yield by 13.9%. These impressive gains were associated with improved root architecture, evidenced by a 6.6% increase in corn root length and a 5.0% increase in soybean root length, alongside significant shoot (8.4%) and root (19.4%) biomass gains in corn. The stability of 1000-grain weight and foliar nutrient concentrations indicated that growth promotion was primarily driven by enhanced nutrient use efficiency rather than increased uptake. These findings validate the Bacillus consortium’s practical potential to effectively offset substantial phosphate reductions, fostering the sustainable intensification of corn and soybean production in tropical soils.