SECOND CROP CORN SUBJECTED TO PHOSPHORUS SOLUBILIZING AND BIOLOGICAL NITROGEN FIXING BACTERIA

Abstract

An alternative to reducing the use of nitrogen fertilizers is biological nitrogen fixation and among the technologies to increase the efficiency of phosphorus use, phosphate solubilizing microorganisms stand out. In this way, the objective was to evaluate the second harvest of corn subjected to phosphorus-solubilizing and biological nitrogen-fixing bacteria. The experiment was conducted under field conditions from March to June 2021 in the south-central region of the state of Tocantins, Brazil. The experimental design used was a randomized block design with seven treatments and four replications. The treatments included: T1 = no mineral fertilizer (NPK) + biological nitrogen fixation (BNF) + phosphate-solubilizing microorganisms (PSM); T2 = 240 kg ha-1 of NPK + BNF + PSM; T3 = 240 kg ha-1 of NPK; T4 = 140 kg ha-1 of NPK; T5 = 140 kg ha-1 of NPK + BNF; T6 = 140 kg ha-1 of NPK + PSM; and T7 = 140 kg ha-1 of NPK + BNF + PSM. The mineral fertilizer used was a 05-35-00 formulation (NPK), with inoculation of phosphate-solubilizing bacteria (PSM: Bacillus megaterium and Bacillus subtilis) and biological nitrogen-fixing bacteria (BNF: Azospirillum brasilense). The study evaluated plant height (PH), stem diameter (SD), leaf area index (LAI), and crop yield (CY). For plant height and stem diameter, the treatment with 240 kg ha-1 of NPK + BNF + PSM showed the highest values, reaching 0.75 m and 11.18 mm, respectively. The leaf area index increased by 18.45% with the same treatment, reaching 245.84 cm² compared to the second-highest value of 200.37 cm² in the treatment with 140 kg ha-1 of NPK + BNF + PSM. In conclusion, the treatment with 240 kg ha-1 of NPK, inoculated with Azospirillum brasilense, Bacillus megaterium, and Bacillus subtilis, resulted in the highest plant height, stem diameter, leaf area index, and productivity compared to the other treatments.