Combining Fully Acidulated Phosphates with Phosphate-Solubilizing Microorganisms for Urochloa brizantha Fertilization

Aimed to evaluate the productive, morphological and nutritional characteristics, in addition to the accumulation of nutrients in the aerial part of Urochloa brizantha cv. Marandu subjected to phosphorus chemical sources and its interaction with phosphate-solubilizing inoculant. The experiment was developed in Colorado do Oeste, RO, Brazil, being adopted a randomized block design with three replications. The treatments consisted of different phosphate fertilizer doses associated or not with phosphate-solubilizing microorganisms (PSM): 0% P; 50% P; 100% P; 50% P + 250 mL ha-1 PSM; 50% P + 500 mL ha-1 PSM; 50% P + 750 mL ha-1 PSM; and 50% P + 1000 mL ha-1 PSM. Triple superphosphate was used as a chemical fertilizer, and fertilization with chemical fertilizer and PSM occurred on November 19th, 2021. The results for the morphological characteristics and yields of Marandu grass showed significant differences. The different arrangements and phosphate doses influenced the green matter yield and dry matter yield, both using the 50% P + 1000 mL ha-1 PSM presented higher yields (3,642.75 kg ha-1 and 1,049.10 kg ha-1, respectively). Higher crop growth rate results in green matter were also found when employing a combination of 50% P + 500 mL ha-1 PSM and 50% P + 1000 mL ha-1 PSM. Dry matter had a significant effect on the bromatological composition, with higher results observed when using 50% P alone (34.55%). Regarding the accumulation of nutrients in the aerial part, the highest P accumulation in Marandu grass was observed when utilizing 100% P, resulting in an accumulation of 15.4 kg P ha-1. Inoculation with PSM for fertilization of U. brizantha cv. Marandu grass does not have adverse effects on the increase in P availability to the plant, resulting in adequate yield and crop development associated with the productive potential of the area.