Frações de fósforo no solo e produção forrageira do capim marandu (Urochloa brizantha) implantado com microrganismos solubilizadores de fósforo

Abstract

The objective of this study was to evaluate the effect of different forms and doses of application of phosphate solubilizing microorganisms on the forage production of marandu grass and on the P fractions present in the soil. The experimental design used was the entirely randomized design with eight treatments and five repetitions. The treatments used were: absence of phosphate solubilizing microorganisms (control), seed inoculation, inoculation + soil spraying 15 days after emergence (250 mL ha-1), inoculation + soil spraying 15 days after emergence (500 mL ha-1), ground spraying 24 hours pre-seeding (250 mL ha-1), ground spraying 24 hours pre-seeding (500 mL ha-1), ground spraying 24 hours post-seeding (250 mL ha-1), and ground spraying 24 hours post-seeding (500 mL ha-1). The Mehlich 1 P contents of the soils ranged from 1.18 ± 0.20 to 3.16 ± 0.32 mg dm-3, with differences (p>0.05) among treatments, where the inoculation + soil spraying treatment 15 days after emergence with 250 mL ha-1 showed the highest value. The P REM contents of the soils ranged from 1.87 ± 0.07 to 5.32 ± 0.21 mg dm-3, with differences (p>0.05) among treatments, where the treatment with soil spraying 24 hours post-seeding with 500 mL ha-1 presented the highest value of P REM, but did not differ statistically from the treatment with soil spraying 24 hours pre-seeding with 500mL ha-1. The chemical attributes of the soil were significantly affected by the presence and mode of application of the inoculant with phosphate solubilizing microorganisms; however, the variability in the observed responses does not allow determining the effects of phosphate solubilizing microorganisms on the forage production of marandu grass.