Evaluation of Sugarcane Yield Response to a Phosphate-Solubilizing Microbial Inoculant: Using an Aerial Imagery-Based Model

The use of microbial inoculants has become an effective alternative for increasing crop yields, reducing production costs, and improving environmental sustainability. Farmers are very interested in microbial inoculants involved in the solubilization of non-labile phosphorus due to the increasing demand for phosphate fertilizers and the scarcity of natural sources of this nutrient. Thus, the Brazilian Agricultural Research Corporation (Embrapa), in partnership with the Simbiose Company (Rio Grande do Sul, Brazil), has developed a commercial phosphate-solubilizing inoculant combining the Bacillus subtilis CNPMS2084 and Bacillus megaterium CNPMS119 strains. The present work evaluated the effect of different doses of this Bacillus strain inoculant in combination with phosphate fertilization on sugarcane crops in three experimental fields for two successive production seasons (plant cane and first ratoon). Vegetation indices (VIs) were calculated with the help of aerial images collected regularly during the phenological phases of vegetative growth and ripening and used in association with weather and yield data to develop a predictive model for the effect of the bioinoculant on the sugarcane crop. The results showed that the doses of 500 and 750 mL/ha of Bacillus strain inoculant applied in the planting furrow and during ratoon management were the most effective to increase tons of cane per hectare (TCH) and tons of sucrose per hectare (TSH) compared to treatments without inoculant application. These results agree with the forecast generated by the statistical model developed to predict the impact of the bioinoculant on the increase in sugarcane biomass. Afterward, the fitness of the model to estimate the effect of the Bacillus strain inoculant on the sugarcane yield was demonstrated when field data from commercial areas of sugarcane treated with the bioinoculant were compared to data from control fields without application, confirming the positive effect of the commercial Bacillus strain inoculant for sugarcane crops as well as the model's effectiveness in handling and predicting yield from data obtained from commercial areas.

Automated summary

This study evaluated the effect of a commercial phosphate-solubilizing inoculant on sugarcane crops and developed a predictive model for its impact on yield. The results showed that the appropriate dosage of the inoculant significantly increased sugarcane yield, and the predictive model demonstrated good fitness in estimating the effect of the inoculant on yield.